African Swine Fever Virus

Overview and Taxonomy of African Swine Fever Virus

African swine fever virus (ASFV) is a unique and complex pathogen that has drawn global attention due to its devastating impact on domestic pigs and wild suids. As the sole member of the family Asfarviridae and the only known DNA arbovirus, ASFV occupies a singular place within the virus taxonomy. Its classification, structural organization, and diverse genotypic profiles have been the subject of exhaustive research, which is essential for understanding its pathobiology and potential avenues for control.

Taxonomic Classification and Genetic Diversity

ASFV belongs to the genus Asfivirus within Asfarviridae. Unlike many other swine pathogens, ASFV is a large, double-stranded DNA virus with an icosahedral morphology and a complex multilayered structure. The virus is unique among pathogenic DNA viruses in that it is transmitted by soft tick vectors of the Ornithodoros genus, a fact recognized by organizations such as the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization (FAO) [3]. Genetic analysis, especially of the gene encoding the major capsid protein p72 (B646L), has allowed researchers to classify ASFV into 24 distinct genotypes. In addition, serogroup classification through antibody-mediated hemadsorption inhibition helps assign strains to up to eight serogroups, thereby underpinning the virus’s antigenic diversity [5]. The genetic variability observed in ASFV is driven by mutation, gene deletion, and recombination events, which in turn influence virulence and transmission dynamics. This genetic plasticity has posed significant challenges for vaccine development and control strategies [2, 5].

Morphological and Structural Features

At the structural level, ASFV is a marvel of viral architecture. Cryo–electron microscopy studies have provided high-resolution images, revealing that the mature ASFV particle is composed of at least five distinct layers. The outermost capsid, primarily formed by the major capsid protein p72, is organized into pentasymmetrons and trisymmetrons that confer the virus its characteristic icosahedral symmetry [4]. Beneath the p72 shell, several minor capsid proteins form an intricate network, which plays a role in stabilizing the core and ensuring the structural integrity of the virion. These structural details are not only taxonomically significant but also critical in understanding how ASFV interacts with host cells and evades immune responses. Numerous proteins, both structural and nonstructural, are encoded within its large genome, ranging from approximately 150 to 200 open reading frames, with many of these proteins remaining poorly characterized [1, 2]. The complexity of the ASFV proteome is a key factor in its varied replication strategies and immune evasion mechanisms.

Lifecycle, Host Range, and Transmission

From an epidemiological standpoint, ASFV’s identification as the only DNA arbovirus highlights its unusual lifecycle. The virus is maintained in nature through a sylvatic cycle involving wild suids, such as warthogs, and soft ticks, which serve as reservoirs without developing significant clinical disease. In contrast, when introduced into domestic pig populations, ASFV often causes acute hemorrhagic fever with mortality rates approaching 100% [3]. This dichotomy underlines the importance of comprehending the virus’s taxonomic and ecological niche. The virus’s ability to infect both insect vectors and mammalian hosts further complicates efforts to control its spread, as highlighted by its recent incursion into geographically diverse regions including Europe and Asia. Institutions such as the Centers for Disease Control and Prevention (CDC) and WOAH have underscored the economic and food security implications of ASFV outbreaks, reiterating the need for robust surveillance and rapid diagnostic methods.

Evolutionary Implications and Phylogenetic Relationships

The evolutionary trajectory of ASFV is marked by significant genetic drift and occasional recombination events that lead to distinct viral lineages. Comparative genomic analyses have demonstrated that while the overall mutation rate might be relatively low for a virus with such a large DNA genome, even minor genetic changes can result in notable phenotypic consequences. For instance, specific gene deletions or modifications, such as those found in multigene families (MGFs) located at the termini of the genome, have been directly associated with alterations in virulence and transmissibility [2]. Phylogenetic reconstructions, based on both full‐genome sequences and specific marker genes such as p72, reveal a “star-like” structure in some populations, indicating periods of rapid expansion following the introduction of highly virulent strains into naive pig populations [5]. This evolutionary insight is critically important when considering the design of live attenuated vaccines, as targeted deletions of virulence-associated genes must strike a balance between attenuation and immunogenicity.

Implications for Disease Control and Vaccine Strategies

The exceptional taxonomic status and complex biology of ASFV necessitate a deep understanding of its genome and protein functions. The interplay of multiple viral factors with host immune mechanisms, mediated by an array of both structural and regulatory proteins, is central to the virus’s ability to suppress host innate and adaptive immune responses [1, 2]. This detailed taxonomic and molecular characterization has influenced the development of diagnostic platforms, many of which are now designed to detect specific ASFV genes that serve as phylogenetic markers for tracking viral evolution and origin during outbreaks. Furthermore, such taxonomic insights assist major international bodies, including the WOAH and the World Health Organization (WHO), in updating disease status and control guidelines that are essential for safeguarding global swine industries.

In summary, African swine fever virus stands apart from other pathogens not only because of its unique taxonomic classification as the lone member of Asfarviridae but also due to its elaborate genome, structural complexity, and multifaceted interactions with both its arthropod vector and mammalian hosts [3-5]. The confluence of these factors makes ASFV a particularly challenging pathogen whose study remains at the forefront of veterinary virology and global animal health research.

Molecular Pathogenesis of African Swine Fever Virus

African swine fever virus (ASFV) is a large, double‐stranded DNA virus and the sole member of the Asfarviridae family. The molecular pathogenesis of ASFV is extraordinarily complex, stemming from its unique genome structure, the array of viral proteins it encodes, and its multifaceted mechanisms for evading and subverting host immune responses. This pathogen, which poses significant economic and animal health threats globally as recognized by FAO, WHO, and WOAH, primarily infects cells of the monocyte–macrophage lineage and orchestrates an intricate series of events that culminate in severe hemorrhagic fever in domestic pigs [3, 12].

Viral Entry, Tropism, and Early Replication

ASFV primarily targets porcine macrophages where it exploits specific cell entry mechanisms and intracellular pathways to establish productive infection. The virus capsid, characterized by its icosahedral structure detailed through cryogenic electron microscopy [4], is not only an architectural marvel but harbors epitopes essential for host cell recognition and subsequent internalization. Once bound to the cell surface, ASFV enters its target cells via complex endocytic processes that may involve receptor-mediated endocytosis and macropinocytosis. Its ability to efficiently hijack these cellular uptake pathways contributes to the pronounced tropism exhibited for the innate immune cells, a key factor underpinning its pathogenic profile.

Subversion of Innate Immune Responses

Central to ASFV pathogenesis is the virus’s capacity to manipulate and mitigate host antiviral defenses. Several viral proteins specifically target critical components of cellular interferon (IFN) pathways. For instance, members of the multigene families (MGF), such as MGF505-7R and MGF360-9L, serve as potent interferon antagonists. MGF505-7R, in particular, has been demonstrated to negatively regulate the cyclic GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING) signaling cascade, a fundamental pathway for the induction of type I interferons following DNA virus detection [10, 11]. Through direct interactions and degradation of signaling intermediaries such as STING, ASFV impairs downstream activation of TANK-binding kinase 1 (TBK1) and interferon regulatory factors (IRFs), thereby substantially reducing IFN-β production.

Additionally, proteins like A137R also contribute to immune evasion by modulating autophagic pathways. By hijacking the autophagy-mediated lysosomal degradation machinery, A137R targets key kinases such as TBK1, blocking the nuclear translocation of IRF3 and further dampening the host antiviral response [7]. These strategic viral interventions underscore the virus’s ability to replicate robustly in an environment where innate immunity is critically blunted.

Modulation of Inflammatory Responses and Cytokine Storm

ASFV infection is characterized by profound dysregulation of inflammatory cytokine networks. The virus not only suppresses early antiviral responses but can also trigger a secondary phase of hyperinflammatory cytokine production. Studies have documented rapid increases in proinflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor-alpha (TNF-α) during acute ASF outbreaks [15]. In some instances, the infection leads to a cytokine storm that exacerbates tissue damage, contributes to the vascular leakage observed in hemorrhagic presentations, and ultimately precipitates rapid clinical deterioration.

The underlying mechanisms for this dysregulation include viral interference with the NF-κB pathway. The I10L protein of ASFV, for instance, has been shown to inhibit NF-κB activation by binding to the IκB kinase (IKK) complex, thereby preventing the phosphorylation and subsequent degradation of IκBα [14, 19]. This inhibition curtails the normal transcription of numerous proinflammatory cytokines, yet paradoxically, other viral factors may later override this block, leading to an imbalanced inflammatory milieu. Such a two-phase mechanism, initial immune suppression followed by uncontrolled cytokine production, underscores the multifaceted pathogenic strategy of ASFV.

Viral Structural Proteins and Intracellular Assembly

Beyond immune modulation, ASFV’s molecular pathogenesis is intimately tied to its sophisticated assembly process. The virus encodes over 150 proteins, many of which are involved in the formation and integrity of its multilayered virion structure. The major capsid protein p72, along with several minor capsid and inner membrane proteins, contributes to structural stability while also potentially modulating host immune recognition [4, 13]. Any perturbation in the expression or function of these structural proteins can significantly impact virus infectivity and virulence, as evidenced by studies demonstrating that deletion of specific virion components such as pH240R leads to aberrant virion morphogenesis, reduced infectious particle production, and altered induction of inflammatory cytokines in primary macrophages [18].

The functional interplay between structural and non-structural proteins is critical for viral replication. For example, certain structural proteins not only serve as protective shells for the viral genome but also interact with host cellular factors to facilitate viral genome release into the cytoplasm. These processes are tightly coupled to the overall success of viral replication and dissemination within the host.

Genetic Determinants of Virulence and In Vivo Pathogenesis

Genomic diversity and the specific constellation of virulence factors encoded by ASFV are central to its pathogenic potential. The virus continually evolves, acquiring mutations and gene deletions that can modulate its virulence and transmission dynamics. Deletion studies have been instrumental in dissecting the roles of individual genes; for instance, the removal of genes like MGF360-9L or members of the MGF505 family from the virulent ASFV background results in attenuated strains with diminished capability to suppress IFN responses, thus suggesting a direct role of these genes in virulence [6, 8, 9]. Moreover, deletion of pH240R has also been correlated with decreased virus production and heightened expression of inflammatory mediators, further cementing the importance of these gene products in driving the clinical manifestations observed during infection [16, 18].

The interplay of multiple viral genes determines the balance between virus replication, immune evasion, and the induction of host inflammatory responses. Such complex genomic architecture is a critical hurdle for vaccine development, as varying deletion patterns can dramatically alter pathogenic outcomes while influencing the persistence of the virus in blood and tissues [17, 20].

Impact on the Host and Epidemiological Implications

As ASFV manipulates host intracellular signaling and immune responses, the resulting pathogenesis not only leads to rapid and severe clinical symptoms in domestic pigs but also complicates diagnosis and disease control efforts, as recognized by global health authorities such as WOAH and FAO. The virus’s multifaceted molecular strategies, ranging from inhibition of interferon production to deregulation of inflammatory cytokines, ultimately result in the high morbidity and mortality observed in outbreaks worldwide [3, 12]. The economic impact of these outbreaks is profound, emphasizing the need for continued research into the molecular pathogenesis of ASFV to inform the rational design of vaccines and therapeutics that can safely and effectively control this devastating pathogen.

Collectively, the detailed understanding of ASFV’s molecular pathogenesis provides critical insights into the virus’s ability to suppress host antiviral defenses, disrupt cellular signaling pathways, and manipulate inflammatory responses, which together underpin the lethality and persistence of the virus in infected swine [3, 12, 15].

Epidemiology and Global Impact of African Swine Fever Virus

African swine fever virus (ASFV) has emerged as one of the most economically devastating pathogens affecting the global swine industry. Originating in sub‐Saharan Africa, ASFV is maintained in a complex sylvatic cycle involving wild suids and soft ticks of the Ornithodoros genus. In its natural reservoir, the virus tends to cause asymptomatic or mild infections; however, when it spills over into domestic pig populations, the outcome is often a highly lethal hemorrhagic fever with mortality rates approaching 100% [3, 21]. The intricate interplay between the virus and its various hosts has contributed to its persistent endemicity in Africa and subsequent spread to Europe, Asia, and most recently, the Americas, a progression that underscores its tremendous global impact.

Geographical Spread and Recent Outbreaks

After being confined principally to Africa for much of its documented history, ASFV began to spread beyond the continent with sporadic incursions into Southern Europe and the Caribbean during the latter half of the twentieth century. In particular, the re‐emergence in Eastern Europe and the subsequent outbreak in the Caucasus region in 2007 have been pivotal events. This outbreak, caused predominantly by genotype II viruses, served as a catalyst for the virus’s rapid dissemination across large swathes of Europe and Asia [5, 23]. The incursion in 2018 into China, a nation with over half the world’s pig population, represented a significant turning point, rapidly fueling a cascade of epidemics across Southeast Asia and threatening global pork supply chains [21, 28]. International agencies such as the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization (FAO) have repeatedly highlighted the virus as an emerging transboundary pathogen with extensive socio‐economic repercussions. The economic impact spans not only direct losses due to high mortality in pig populations but also indirect costs associated with trade disruptions, stringent culling policies, and the high costs associated with biosecurity and surveillance measures [3, 29].

Transmission Dynamics and Biological Mechanisms

ASFV’s epidemiological success is underpinned by several biological mechanisms that facilitate its spread and persistence. In domestic and wild pigs, the virus is transmitted through direct contact with infected animals, contaminated fomites, and ingestion of contaminated pork products. Its transmission is further complicated by its ability to persist in the environment and in various tissues, features that allow the virus to be maintained even under challenging conditions [21, 28]. Moreover, the role of insect vectors, particularly Ornithodoros soft ticks, should not be underestimated in some regions. These vectors contribute to viral maintenance in enzootic areas and can serve as reservoirs even when pig populations are temporarily reduced [3].

The virus’s genetic complexity, exemplified by a large double-stranded DNA genome encoding more than 150 proteins, also plays a critical role in its epidemiology. This genomic plasticity contributes to the existence of multiple genotypes and serogroups that complicate vaccine development and diagnostic standardization [5]. Molecular markers and genotyping strategies, as detailed in systematic reviews, have become essential tools in tracing the origins of outbreaks and in elucidating the evolutionary pathways of the virus [5, 22]. Evolutionary analyses of strains from Eastern Asia, for instance, reveal a “star-like” phylogenetic structure centered on the prototype genotype II strain [24]. Such knowledge is crucial for understanding how the virus adapts to new regions and hosts, informs risk assessments, and guides the development of biosecurity measures.

Global Economic and Societal Implications

The introduction and spread of ASFV into regions with intensive pig production have far-reaching economic implications. Outbreaks trigger immediate economic losses from the death of millions of pigs, but they also lead to longer-term disruptions in trade, food security, and local livelihoods. Countries experiencing outbreaks are forced to implement drastic control measures including culling of affected and at-risk animals, which in turn have an adverse economic impact on smallholder farmers as well as large-scale producers [29]. In addition to direct losses, indirect impacts include the cost of surveillance programs, biosecurity upgrades, and compensation schemes, all of which strain national resources.

In the context of global food security, ASFV presents a unique challenge. The virus does not infect humans; however, due to pig products being a major source of protein in many parts of the world, any significant decline in swine populations can drive up food prices and reduce the availability of affordable protein. This has prompted urgent calls from international organizations like the Centers for Disease Control and Prevention (CDC) and FAO for enhanced surveillance, rapid diagnostic testing, and coordinated international response efforts to contain outbreaks before they become epidemics [3, 21].

Surveillance, Control, and Diagnostic Strategies

Effective management of ASFV outbreaks hinges on early detection and rapid response. Advances in molecular diagnostics, ranging from recombinase-based isothermal amplification assays to CRISPR/Cas-based detection systems, have shown promise for rapid, on-site detection of the virus in resource-limited settings [25-27]. These technologies enable veterinary authorities and public health organizations to quickly identify infected herds and implement control measures, reducing the risk of transboundary spread. Additionally, the implementation of stringent biosecurity measures, as recommended by international health authorities, remains a cornerstone in preventing the introduction and establishment of the virus in previously unaffected regions [3, 29].

The development of robust surveillance systems is critical not only for outbreak response but also for ongoing epidemiological studies that inform our understanding of virus persistence and transmission dynamics. Surveillance systems that integrate data from both traditional methods and advanced molecular tools foster a more complete picture of ASFV epidemiology, enabling targeted interventions and more precise risk assessments, factors that are vital for mitigating the global impact of African swine fever.

Impact on Global Trade and Policy

The spread of ASFV has also led to significant changes in global trade policies related to pork and pig products. Import and export restrictions imposed by affected countries have disrupted international markets, forcing policymakers to re-evaluate and update disease control strategies. These measures, while necessary for controlling the spread of ASFV, have economic repercussions that are felt worldwide and underscore the interconnectedness of global food supply chains. Public health and agricultural authorities, including the CDC, WHO, and FAO, continue to work in tandem with national governments to harmonize response strategies and mitigate the economic fallout associated with ASFV outbreaks [3, 29].

In sum, the epidemiology and global impact of African swine fever virus present multifaceted challenges that encompass biological complexity, rapid geographic expansion, and far-reaching economic consequences. Detailed understanding of transmission dynamics and continuous surveillance are paramount to curbing the devastating toll of this virus on the global swine industry.

Diagnostics and Laboratory Detection Methods for African Swine Fever Virus

African swine fever virus (ASFV) remains one of the most economically devastating pathogens affecting global swine production, with regulatory agencies such as WOAH, FAO, and CDC emphasizing the importance of rapid and accurate laboratory detection for effective outbreak control. Due to the virus’s large double‐stranded DNA genome and its unique viral structure, a multitude of diagnostic methods have been established to provide timely identification and differentiation of ASFV from other swine pathogens.

Molecular Detection Methods

The gold standard in ASFV diagnosis is the detection of viral genomic sequences through nucleic acid amplification techniques. Real-time polymerase chain reaction (qPCR) assays have long been utilized due to their unparalleled sensitivity, rapid turnaround, and ability to differentiate genotypes based on conserved targets such as the B646L gene (encoding p72) [30]. In addition to conventional qPCR, groundbreaking advancements in isothermal amplification methods have led to the development of recombinase polymerase amplification (RPA) and recombinase-aided amplification (RAA) assays. These methods operate under constant temperature conditions of approximately 37–39°C, enabling rapid detection in less than one hour without the need for sophisticated thermal cycling equipment, making them particularly useful in resource-limited settings and outbreak scenarios where field-deployable diagnostics are essential [26, 30]. The inherent sensitivity of RPA/RAA, with detection limits reaching down to only a few copies per reaction, ensures that early-stage infections can be identified before significant viral propagation occurs within swine populations.

Recent innovation has coupled isothermal amplification with CRISPR-based technologies. For instance, approaches employing CRISPR/Cas12a have been integrated with both fluorescence readouts and lateral flow strip detection platforms. The CRISPR/Cas12a system is programmed with a specific CRISPR RNA (crRNA) to recognize ASFV gene targets, such as those encoding p17 or p72. Upon target recognition, Cas12a exhibits collateral cleavage activity against a reporter molecule, resulting in a visually detectable signal with high sensitivity and specificity. These methods achieve detection limits as low as 20 copies per reaction and can be completed within an hour, representing a significant leap in point-of-care ASFV diagnostics that aligns with guidelines provided by authoritative agencies [25, 27].

Additionally, CRISPR/Cas13a-based assays extend these capabilities by enabling RNA-targeted detection using lateral flow devices, further simplifying the process for on-site application and ensuring rapid decision-making during outbreaks [27, 32]. These novel CRISPR-based platforms not only offer robust sensitivity but are also highly specific, with no cross-reactivity against other common swine pathogens, which is critical given the similar clinical presentations sometimes observed in swine diseases.

Serological and Antigen Detection Techniques

While nucleic acid-based assays are indispensable for early diagnosis of ASFV infection, serological tests also play a crucial role, particularly in surveillance and epidemiological investigations. Indirect enzyme-linked immunosorbent assays (ELISAs) have been developed for the detection of ASFV-specific antibodies, producing robust antibody responses against viral proteins expressed during infection. Antigens such as pp62 and p72 have been targeted for their high antigenicity and capacity to elicit strong antibody responses in infected animals [33]. These ELISAs are capable of detecting specific antibodies with high sensitivity and repeatability, which is instrumental when differentiating infected from non-infected animals during large-scale surveillance operations recommended by WOAH.

Lateral flow immunochromatographic assays have also been developed to provide rapid, field-deployable diagnostics. A notable example is the use of self-assembled p72 trimers labeled with colloidal gold nanoparticles to form a visual detection strip assay. This method, which allows for a naked-eye readout within minutes, has demonstrated high specificity and sensitivity when tested against clinical samples, representing an attractive option for rapid on-site screening and decision-making [31]. Such lateral flow devices have the dual advantage of being cost-effective and user-friendly, which is essential for operations in regions where resource constraints may limit access to advanced laboratory infrastructure.

Furthermore, the development of these assays has been informed by detailed proteomic analyses of ASFV, ensuring that the most immunogenic and structurally conserved viral components are selected for diagnostic purposes. The inclusion of viral proteins that are critical for the virus assembly and replication cycle has ensured that both acute infections and historical exposures can be reliably detected, further aiding in outbreak preparedness and control measures.

Integration of Diagnostic Platforms in Field Settings

Given the complex epidemiology of African swine fever, diagnostic strategies must be versatile and adaptable to various field conditions. Integrated platforms that combine rapid nucleic acid amplification with CRISPR-mediated detection are particularly promising. These systems are designed for minimal equipment requirements and can be operated by personnel with limited training, aligning with recommendations provided by international organizations such as the WHO and CDC for rapid response to emerging animal diseases. Moreover, the ability to deploy such assays in decentralized laboratories or even directly in the field ensures that local outbreaks can be detected early, thereby limiting virus spread and reducing the need for economically devastating culling measures.

Multiplex approaches that combine both molecular and serological detection capabilities are also being explored. By simultaneously testing for viral DNA and specific antibodies, these multiplex assays provide a comprehensive view of an outbreak’s status, covering both current infections and epidemiological evidence of past exposure. This dual strategy enhances diagnostic accuracy and informs both immediate containment measures and long-term surveillance programs [25, 26, 30].

Laboratory Validation and Field Application

Before being adopted for widespread use, diagnostic assays for ASFV undergo rigorous validation according to standards set by WOAH and other international agencies. Comparative studies have shown that novel methodologies, such as CRISPR-based lateral flow assays and isothermal amplification methods, exhibit excellent agreement with standard qPCR results, with kappa values approaching or even exceeding 0.96 [26]. Such high levels of diagnostic concordance underscore the reliability of these assays for routine surveillance and outbreak investigations.

The deployment of these advanced diagnostic tools not only supports rapid case identification but also assists in mapping the epidemiological spread of ASFV. This is particularly important given the virus’s high contagion and mortality rates, where early detection and intervention are paramount to halting transmission within swine populations and mitigating the global economic impact of the disease.

By leveraging a combination of established molecular techniques and innovative CRISPR-based approaches, laboratories worldwide are now better equipped to detect and manage African swine fever outbreaks. Adherence to rigorous diagnostic standards, combined with the integration of portable, rapid testing platforms, forms the cornerstone of modern ASFV diagnostics, ensuring that health authorities can respond swiftly and effectively to this persistent threat [25-27, 30].

Genomic Insights in ASFV

African swine fever virus (ASFV) is a large double‐stranded DNA virus, unique for its size and complexity, with genomes spanning approximately 170–194 kilobase pairs and encoding between 150 and 200 proteins [21, 44]. Its genome is characterized by highly variable regions at both terminal ends, where multigene families (MGFs) play critical roles in virulence, immune evasion, and adaptation [2]. Comparative genomic studies have revealed that gene deletions or variations, particularly within MGF360, MGF505, and other multigene families, are often associated with alterations in viral virulence and host range [2, 38]. Through comprehensive genomic sequencing, researchers have been able to trace the origins of ASFV outbreaks and monitor evolving genetic differences over time. Genomics-based epidemiological studies, guided by complete viral genome sequencing and molecular markers [22], have established phylogenetic relationships among strains circulating in regions such as Eastern Europe and Asia, which is critical information for organizations like the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization (FAO).

Genomic studies have also been paramount in the rational design of live attenuated vaccine candidates. For instance, targeted deletion of virulence-associated genes, such as I177L, MGF505-7R, or H240R, has resulted in strains with attenuated pathogenicity that nevertheless confer robust immunity in pigs [18, 38, 41]. Researchers have exploited these genomic insights to create recombinants that not only reduce virus persistence in blood but also provide differential diagnosis between infected and vaccinated animals (DIVA) [17]. Furthermore, detailed analyses have illuminated the mechanisms by which ASFV modulates host signaling pathways, including the cGAS-STING and JAK-STAT cascades, to escape innate immune responses [42], thereby offering additional genomic targets for vaccine improvement.

Proteomic Insights in ASFV

Proteomic analyses have provided a window into the intricate structure and function of the ASFV particle. Early proteomic studies identified that the ASFV virion is composed of numerous viral proteins, including both structural and nonstructural components, with up to 68 viral proteins detected by mass spectrometry [13]. The viral proteome not only includes the well-known major capsid protein p72 but also a suite of minor capsid proteins that act in concert to stabilize the viral particle. Advanced techniques such as cryo–electron microscopy have enabled the reconstruction of the ASFV capsid at near-atomic resolutions [4, 43], revealing a sophisticated multilayered architecture built from thousands of protein copies. These structural investigations have uncovered the network of interactions between the major capsid protein, supportive minor proteins, and accessory factors that contribute to virus assembly and stability.

In addition, proteomic studies have elucidated the composition of the virion in terms of both viral and recruited host proteins. For example, research has identified host proteins, including those related to the cytoskeleton and membrane organization, that are incorporated into the viral particle during budding [13], suggesting that ASFV hijacks host cellular components to facilitate its assembly and dissemination. Moreover, functional proteomics has contributed to our understanding of key proteins that modulate host immune responses. ASFV proteins such as pMGF360-9L, pA137R, and others have been characterized for their roles in interfering with type I interferon production, either by degrading crucial transcription factors or by inhibiting signaling complex formation [6, 7, 36]. The identification of these proteins by proteomic and biochemical techniques has opened new avenues for antiviral drug development, as specific inhibitors targeting these proteins could potentially restore host immunity and reduce viral replication.

Notably, the integration of structural and functional proteomics has advanced our knowledge regarding the use of viral proteins as potential vaccine antigens. Detailed analyses of antigenic epitopes, especially on highly immunogenic proteins like p72, have guided the design of subunit and vector-based vaccines [34, 37]. This proteomic insight is invaluable for improving serodiagnostic assays as well, where recombinant forms of p72 and other structural proteins have been employed successfully in lateral flow tests and ELISAs to detect ASFV antibodies rapidly in the field [31, 45]. Such dual applicability underscores the central role that proteomic research plays in the development of both prophylactic and diagnostic strategies against ASFV.

Transcriptomic Insights in ASFV

A comprehensive understanding of ASFV–host interactions has also been achieved through transcriptomic profiling of infected cells. Genome-wide mapping of ASFV transcripts has delineated the complex temporal regulation of viral gene expression. Using technologies such as cap analysis gene expression sequencing (CAGE-seq), researchers have mapped transcription start sites (TSSs) across the ASFV genome, distinguishing between early and late promoters that govern the sequential transcription of viral genes [39, 40]. These studies reveal that ASFV uses alternative TSSs and promoter architectures to finely tune the expression of genes involved in replication, virulence, and immune evasion [40]. Transcriptomic data obtained from primary porcine alveolar macrophages, an essential target cell type for ASFV infection, has provided profound insights into both the viral program and the consequent reprogramming of the host cell [39].

Transcriptomic analyses have revealed that ASFV infection induces a dynamic host response characterized by the dysregulation of immune-related genes. For instance, during the early stages of infection, the virus suppresses proinflammatory cytokine gene expression, presumably through the action of viral proteins that interfere with key signaling pathways [35, 40]. In contrast, during the later stages of infection, changes in the host transcriptome are observed, including the upregulation of genes implicated in the NF-κB pathway and inflammasome activation, processes that have been linked to the cytokine storm observed in acute ASF cases [15]. Such transcriptomic alterations are indicative of the virus’s strategy to delay robust innate immune activation, thereby allowing efficient viral replication before the host can mount a full immune response.

Moreover, transcriptomics has served as a vital tool to evaluate the impact of targeted genomic modifications on viral gene expression. In vaccine development studies, transcriptome profiling of live attenuated vaccine strains with deleted virulence genes has verified that these deletions lead to compensatory changes in viral mRNA expression patterns [35, 41]. This molecular characterization confirms that such modifications attenuate the virus without compromising the expression of antigenic determinants critical for inducing protective immunity. In this context, national and international bodies such as the US Centers for Disease Control and Prevention (CDC) and WHO emphasize the importance of integrating transcriptomic data into vaccine design, thereby underscoring its role in counteracting economically significant pathogens like ASFV.

The integration of genomic, proteomic, and transcriptomic datasets not only provides a holistic view of the ASFV life cycle and its intricate interplay with the host immune system, but also informs the rational design of diagnostics and vaccines. By leveraging high-throughput technologies and comprehensive molecular analyses, investigators are progressively unraveling the mechanisms underlying ASFV replication, virulence, and immune evasion, a critical endeavor to curtail the devastating impact of this virus on the global swine industry.

Advances in Gene-Deleted Live-Attenuated Vaccine Strategies against African Swine Fever Virus

The pursuit of safe and efficacious vaccines against African swine fever virus (ASFV) has increasingly focused on live‐attenuated vaccine (LAV) strategies generated through targeted gene deletion. Given ASFV’s large, complex genome and its mastery in subverting host immune responses, rational deletion of virulence and immunomodulatory genes has emerged as a promising approach to develop LAV candidates that both attenuate pathogenicity and stimulate robust protective immunity in domestic pigs. Regulatory agencies such as the World Organisation for Animal Health (WOAH) and international bodies including the CDC and FAO underscore the urgent need for such vaccination strategies to protect a swine industry that is vital to global food security.

One of the most notable advances is the deletion of the I177L gene from virulent genotype II strains of ASFV. In a groundbreaking study, removal of I177L from the Georgia 2007 isolate resulted in complete attenuation even at high inoculation doses while affording sterile immunity upon challenge with a virulent parental strain [38]. Similarly, subsequent experiments evaluating multi-gene deletion strategies, such as the deletion of five genes including I177L along with additional targets [47], have further demonstrated that gene-deleted viruses can maintain immunogenicity while exhibiting a remarkable safety profile. The mechanism underlying this attenuation hinges on the removal of gene products that normally inhibit host innate immune responses; with their deletion, the host’s interferon and pro-inflammatory responses are less suppressed, thereby enabling early adaptive immunity to clear viral infection.

Another promising strategy involves the deletion of a cluster of genes that contribute to immune evasion and viral persistence. For example, the deletion of MGF110-5L-6L genes from the genome of a pandemic ASFV strain has been shown to reduce viral virulence and serves as a marker for Differentiating Infected from Vaccinated Animals (DIVA) [17]. The ability to incorporate a DIVA marker is of critical importance in regions where control efforts require reliable surveillance and differentiation of vaccinated animals from those naturally infected, a requirement emphasized by regulatory agencies such as WOAH and supported by guidelines from FAO. In this context, gene deletions that simultaneously attenuate virulence and facilitate serological diagnostics represent a dual benefit in controlling outbreaks.

Other gene deletion candidates include the removal of the A137R gene, where deletion has been observed to attenuate the virus and induce protection upon lethal challenge in pigs [41]. Similarly, deletion of the H108R gene from a highly virulent strain resulted in a marked reduction in virulence along with the induction of protective adaptive immunity, illustrating that targeting individual virulence factors can recalibrate the virus to a replication-competent yet nonlethal phenotype [48]. The selection of gene targets is fundamentally based on mechanistic insights into how ASFV modulates host antiviral pathways. Many deleted genes encode proteins that interfere with interferon signaling, NF-κB activation, or other components of the host’s innate immune response. By removing these factors, the attenuated virus is no longer capable of efficient immune subversion, enabling the host to detect and clear the virus more readily.

A critical advantage of gene-deleted ASFV vaccine candidates is their ability to induce both humoral and cellular immune responses matching those elicited by natural infection, without causing disease. For instance, studies have shown that immunization with gene-deleted strains can result in robust virus-specific antibody responses and strong T-cell mediated immunity, a balance that is essential for long-term protection [38, 46]. Moreover, the reduction in viral persistence in blood, as observed with deletion of genes such as EP402R either alone or in combination with others [20], further minimizes the risk of transmission from vaccinated animals while providing a means for rapid post-vaccination surveillance.

Beyond safety and immunogenicity, several research efforts have addressed the genetic stability and manufacturing considerations of gene-deleted vaccine candidates. The deletion of multiple genes must not only diminish virulence but also preserve sufficient replicative competence to ensure antigen expression. This delicate balance has been achieved in candidates such as the seven-gene-deleted ASFV, which continues to replicate in swine macrophage cultures at high titers while being fully attenuated in vivo [46]. The scalability of these vaccines is also a critical issue, as the capacity to propagate virus in established cell lines rather than primary macrophages can enhance production efficiency, a factor under ongoing investigation using cell line adaptation strategies [49, 50].

In recent years, a series of studies have built upon these advances by exploring combinations of deletions that target multiple aspects of ASFV pathogenesis. For example, combinatorial gene deletions that target interferon inhibitors (such as those encoded in the multigene families) along with genes related to red blood cell binding and persistence not only increase attenuation but have also been linked to reduced virus shedding in blood [20]. These multi-targeted approaches leverage detailed molecular insights into ASFV’s interactions with macrophages and other host immune cells, creating a virus that is sufficiently immunogenic, genetically stable, and less able to persist or revert to virulence.

Collectively, the progress seen in gene-deleted live-attenuated vaccines illustrates an evolving understanding of ASFV biology. By dissecting the roles of individual virulence factors, including proteins that interfere with interferon signaling, NF-κB activation, and other innate pathways, the scientific community is in a better position to design rationally attenuated strains. These advances not only provide hope for controlling the devastating effects of ASF on the global swine industry but also align with international guidelines and recommendations from global health authorities such as CDC, WHO, and WOAH. The integration of cutting-edge gene deletion strategies with rigorous safety and efficacy assessments continues to shape the future landscape of ASF vaccine development, promising a new era in veterinary vaccine research against this economically critical pathogen.

Future Perspectives: Control Measures, Challenges, and Emerging Therapeutic Approaches

The global threat posed by African swine fever virus (ASFV) continues to demand innovative and robust control measures, advanced diagnostic methods, and novel therapeutic strategies. Ongoing research, underpinned by insights into viral pathogenesis and immune evasion mechanisms, has pointed to several promising avenues for intervention while also highlighting major challenges that must be surmounted to protect animal husbandry on a global scale. Given the devastating economic impact of ASF and its listing as a notifiable disease by international organizations such as the World Organisation for Animal Health (WOAH) and the Food and Agriculture Organization (FAO), the integration of state‐of‐the‐art research with established biosecurity measures remains paramount [1, 3].

Advances in Vaccine Development and Genetic Attenuation

One of the primary frontiers in ASFV control is the development of effective and safe vaccines. Traditionally, control measures have relied on massive culling and stringent biosecurity protocols; however, the lack of a commercially available vaccine has proven to be a major challenge. Recent progress in live attenuated vaccine candidates, particularly through the rational deletion of key virulence genes, provides an encouraging pathway. Research has demonstrated that targeted gene deletions, such as those in the I177L gene, MGF360, and MGF505 gene families, can produce highly attenuated strains that not only ensure safety but also elicit robust immunity in infected swine [38, 51]. For instance, deletion of genes such as MGF505-7R, which is involved in antagonizing type I interferon production by targeting host signaling molecules, has been shown to reduce viral virulence and may serve as a critical target for attenuation strategies [6, 42].

Furthermore, combinational gene-deletion approaches, where multiple interferon-antagonizing genes are simultaneously removed, present an opportunity to fine-tune the balance between safety and immunogenicity. Such approaches have yielded vaccine candidates that are sufficiently attenuated to avoid clinical disease, yet maintain the capacity to induce strong antiviral responses when administered at low doses [9, 51, 53]. These strategies are enhancing the possibility of deploying vaccines that meet the rigorous standards set by agencies such as the Centers for Disease Control and Prevention (CDC) in collaboration with international organizations concerned with zoonotic diseases and food security.

Immune Evasion and Targeted Antiviral Strategies

A recurring theme in ASFV research is the virus’s ability to manipulate host immune responses by modulating key signaling pathways. For example, viral proteins such as pA137R and pMGF505-7R have been implicated in the inhibition of NF-κB activation and type I interferon responses [6, 36]. Inhibiting these viral factors through targeted antiviral compounds or by designing vaccines that preempt their action may help restore effective immune responses. Small molecule inhibitors designed to block the function of viral proteases, ubiquitin-conjugating enzymes, or host-interacting motifs represent a promising class of therapeutics. Advances in our understanding of the molecular interactions between ASFV proteins and host cell factors, including those involved in the interferon signaling cascade (e.g., TBK1, IRF3, STAT proteins) [7, 11, 54], offer measurable targets for drug design.

Targeted disruption of virus-host interactions by emerging gene-editing techniques, such as CRISPR/Cas systems, is being actively explored both as a diagnostic tool and as a potential therapeutic modality. CRISPR/Cas12a-based detection methods have already been developed for rapid, sensitive, and on-site ASFV diagnosis [25, 27]. In parallel, the potential for CRISPR-based approaches to disrupt viral genomic sequences in infected cells could be a groundbreaking avenue, though challenges related to delivery and specific off-target effects remain to be addressed.

Emerging Diagnostic Modalities and Surveillance

Accurate and rapid detection of ASFV is critical to limiting outbreaks, and the future of surveillance relies on innovations that bridge the gap between laboratory accuracy and field applicability. Recent innovations, including recombinase-based isothermal amplification techniques such as RPA and RAA, combined with CRISPR/Cas12a lateral flow assays, have shown to be highly sensitive, capable of detecting as few as 20 gene copies per reaction within an hour [26, 27]. These methods offer a promising alternative to traditional qPCR-based diagnostics, especially in resource-limited settings where rapid decision-making is essential. Furthermore, they empower veterinary authorities globally, aligned with CDC and WHO protocols, to implement early detection measures, thereby reducing transmission and economic losses associated with ASF outbreaks.

Additionally, the development of portable, fluorescence-based point-of-care systems enables high-throughput screening of large numbers of samples. This approach, combined with next-generation sequencing (NGS) efforts to map the ASFV transcriptome and elucidate gene expression profiles during infection, provides comprehensive insights into viral evolution and epidemiology [39, 40]. Such integration of molecular epidemiology with rapid diagnostics is critical to inform both local and international control strategies as outlined by the FAO.

Challenges in Viral Persistence and Genetic Diversity

Despite advances in therapeutic and diagnostic technologies, several challenges persist. One major hurdle is the high genetic variability of ASFV, particularly in regions coding for multigene families that contribute to immune evasion and virulence [2, 22]. This genetic plasticity complicates both vaccine development and antiviral drug design because modifications in viral gene sequences may lead to vaccine escape or diminished drug efficacy. The ability of ASFV to persist in host cells and within the environment, partly owing to its intricate viral structure and stable genome, also complicates eradication efforts [3, 8]. Addressing these issues requires continuing genomic surveillance coupled with advanced bioinformatics to monitor viral evolution in near real-time, ensuring that control measures remain effective against emerging variants.

Role of Alternative Cell Culture Systems and Novel Therapeutics

In the context of vaccine production and virus study, novel cell lines that support high levels of ASFV replication while minimally altering the virus’s genotype are immensely promising. Recent breakthroughs in establishing immortalized porcine macrophage cell lines allow for the sustainable culture of ASFV with high viral titers [49, 50]. Such systems not only facilitate the rapid generation of vaccine candidates but also provide platforms for high-throughput screening of antiviral compounds.

Emerging therapeutic approaches also include immunomodulatory strategies. For example, therapeutic agents that can restore or boost the host’s innate antiviral responses, such as cytokine modulators to counteract the “cytokine storm” induced by virulent ASFV strains, are being considered as adjuncts to vaccination [15, 52]. These interventions might help mitigate the severe inflammatory responses and tissue damage observed in infected pigs, thereby reducing mortality rates and economic impact.

Integration of Control Measures into Global Health Frameworks

Drawing on support from international organizations like the WHO, CDC, and FAO, future control measures for ASFV will likely integrate advanced vaccines, rapid diagnostics, and targeted antivirals into cohesive management strategies. Emphasizing biosecurity, early detection, and rapid response protocols, coupled with continuous genomic monitoring, will enhance global preparedness against ASFV outbreaks. The intersection of innovative scientific research and practical control measures represents a dynamic and evolving area that holds great promise for safeguarding the swine industry and ensuring food security worldwide [1, 3, 29].

By continuing to leverage and expand upon these multifaceted approaches, the veterinary research community is steadily moving toward a future where the devastating impacts of African swine fever can be effectively controlled and ultimately minimized.

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