Recombinant African swine fever virus Protein H108R (War-127)

What is the H108R protein and what is known about its function in ASFV?

The H108R protein is encoded by the H108R gene of African swine fever virus (ASFV), the etiological agent of African swine fever (ASF). H108R is a previously uncharacterized protein that has been shown to localize at the inner envelope of the virus particle . The protein varies between 108-111 amino acids in length across different ASFV isolates and contains a predicted transmembrane region between amino acids 6 and 23 in its N-terminal region .

While the exact function of H108R remains not fully characterized, research has demonstrated that it plays a significant role in viral virulence. Deletion of the H108R gene from the highly virulent ASFV-Georgia2007 (ASFV-G) genome strain results in reduced virulence in domestic swine, indicating its importance in ASFV pathogenesis . The protein appears to have no homology with other known proteins, as comparisons with 19,175 protein families using the Pfam program yielded no significant matches .

The H108R gene is considered a late gene in the viral replication cycle, with its expression overlapping the kinetics of the B646L gene (encoding the p72 protein) based on transcriptional analysis in primary swine macrophages .

How is the H108R gene conserved across different ASFV isolates?

The H108R gene demonstrates notable genetic diversity across different ASFV isolates and genotypes. Analysis of nine ASFV isolates representing different genotypes revealed variations in protein length and amino acid composition . The length of the H108R protein varies between 108 and 111 amino acids, with the largest versions containing three amino acid insertions found in isolates Malawi Lil-20/1, Ken06.Bus, and Kenya 1950 .

Interestingly, the H108R gene shows 100% identity among multiple isolates associated with the epidemic Eurasian lineage, indicating high conservation throughout this pandemic lineage. A unique feature in this lineage is the substitution S54F observed in the Georgia 2007/1 isolate, a representative of the pandemic lineage .

How does deletion of the H108R gene affect ASFV replication in vitro?

In primary swine macrophage cultures, which are the natural target cells during ASFV infection in swine, deletion of the H108R gene affects viral replication kinetics. The recombinant virus ASFV-G-ΔH108R (with H108R gene deleted) shows delayed replication compared to the parental ASFV-G strain .

These findings indicate that while the H108R gene is not essential for virus replication, its absence delays the ability of ASFV-G to replicate in primary swine macrophage cell cultures. This suggests that H108R plays a role in optimizing viral replication efficiency rather than being absolutely required for productive infection .

What are the detailed molecular mechanisms by which H108R contributes to ASFV virulence?

While the H108R protein has been established as a virulence factor, the precise molecular mechanisms by which it contributes to ASFV pathogenesis remain under investigation. Current evidence shows that H108R contains a transmembrane region between amino acids 6 and 23, suggesting it may function as a membrane-associated protein . This is consistent with the finding that H108R localizes to the inner envelope of the virus particle .

The essential role of H108R in ASFV virulence appears consistent with the functions of other small transmembrane proteins found in related viruses. For example, the I5L protein in poxviruses, which shares some structural features with H108R, has been associated with enhancement of viral replication and virulence . This suggests possible conservation of function across different large DNA viruses.

The delayed replication observed in ASFV-G-ΔH108R indicates that H108R may play a role in optimizing viral replication cycle efficiency. Given its late expression profile, H108R might function in virion assembly, maturation, or release processes. Alternatively, it could be involved in host immune evasion mechanisms that contribute to virulence but are not strictly required for replication in cell culture .

The five codons identified as under purifying selection (encoding amino acids 22, 23, 28, 41, and 45) span a highly conserved region of the protein, suggesting critical functional importance. Further structural and functional studies focusing on these conserved regions may reveal specific protein-protein interactions or enzymatic activities that underlie H108R's contribution to virulence .

How was the H108R gene deletion mutant constructed and validated?

The ASFV-G-ΔH108R recombinant virus was developed using homologous recombination techniques with the highly virulent ASFV strain Georgia 2007 (ASFV-G) as the parental virus. The deletion process involved substituting the H108R gene with a cassette containing a fluorescent reporter gene, mCherry, under the control of the ASFV p72 promoter .

Comparative DNA sequence analyses between ASFV-G-ΔH108R and ASFV-G revealed:

• An 86 nucleotide deletion (from positions 155,233 to 155,318) from the H108R gene

• An insertion of 1,226 nucleotides corresponding to the p72mCherryΔH108R cassette replacing the deleted H108R gene

• No undesired modifications in the rest of the ASFV-G-ΔH108R genome

Functional validation of the recombinant virus was performed through in vitro growth curves in primary swine macrophages and in vivo virulence studies in domestic pigs, confirming that the targeted deletion resulted in the expected phenotype of attenuated virulence .

What is the protective efficacy of ASFV-G-ΔH108R against challenge with virulent ASFV?

Animals that survive ASFV infection typically develop protective immunity against challenge with virulent homologous virus. To evaluate the protective efficacy of ASFV-G-ΔH108R, researchers conducted challenge studies with the virulent parental ASFV-G strain .

In these studies, four pigs that survived initial infection with ASFV-G-ΔH108R were challenged intramuscularly with 10^2 HAD50 of the parental virulent virus after 28 days. A control group of four naïve animals was also challenged under the same conditions .

The results demonstrated complete protection in the ASFV-G-ΔH108R-immunized animals:

These findings indicate that despite the attenuation of virulence, ASFV-G-ΔH108R infection induces a protective immune response capable of preventing clinical disease upon challenge with the highly virulent parental virus . This protective efficacy, even at the low dose of 10^2 HAD50, demonstrates the potential of ASFV-G-ΔH108R as a component of vaccine candidates against ASFV .

What techniques can be used to study H108R protein localization and interactions?

Several methodological approaches can be employed to study the localization and interactions of the H108R protein:

Subcellular Localization Studies:

• Immunofluorescence microscopy using H108R-specific antibodies in ASFV-infected cells at different time points post-infection

• Electron microscopy with immunogold labeling to precisely localize H108R within viral particles

• Cell fractionation followed by Western blot analysis to determine association with specific cellular compartments

• Generation of fluorescently tagged H108R constructs for live-cell imaging studies

Protein-Protein Interaction Studies:

• Co-immunoprecipitation assays to identify viral or host proteins that interact with H108R

• Yeast two-hybrid screening against viral and host protein libraries

• Proximity-dependent biotin labeling (BioID) to identify proteins in close proximity to H108R during infection

• Cross-linking mass spectrometry to capture transient interactions

These methodologies would build upon existing knowledge that H108R localizes to the inner envelope of the virus particle . Given that H108R contains a predicted transmembrane domain (amino acids 6-23), particular attention should be paid to membrane extraction conditions in biochemical approaches .

For functional studies, comparing wild-type virus with the ASFV-G-ΔH108R mutant at different stages of the viral life cycle could reveal specific processes affected by H108R deletion. Since H108R is expressed late during infection, focusing on late events such as virion assembly, maturation, and egress would be particularly informative .

How can evolutionary analysis of the H108R gene inform vaccine development?

Evolutionary analysis of the H108R gene provides valuable insights that can inform vaccine development strategies against ASFV. Key methodological approaches and their applications include:

Sequence Conservation Analysis:
The high conservation of H108R within the epidemic Eurasian lineage (100% identity) suggests it could be an effective target for vaccines aimed at controlling the current pandemic . Methodologically, this involves collecting and aligning H108R sequences from geographically and temporally diverse isolates to identify invariant regions.

Selection Pressure Analysis:
The identification of five codons under purifying selection (encoding amino acids 22, 23, 28, 41, and 45) indicates functionally critical regions that likely cannot tolerate mutations without compromising viral fitness . These conserved epitopes represent potential targets for vaccine-induced immunity that the virus may not easily escape through mutation.

Structural Prediction:
Computational methods to predict protein structure based on amino acid sequence can identify potential antibody binding sites or functional domains. For H108R, the transmembrane region between amino acids 6-23 and the five sites under purifying selection would be priority targets for structural analysis .

Cross-protection Studies:
Since H108R varies between ASFV genotypes, experimental studies evaluating cross-protection between heterologous strains following immunization with ASFV-G-ΔH108R would be valuable. This would involve challenging immunized animals with virulent strains representing different genetic groups of H108R .

These methodologies can guide the rational design of vaccines by determining whether a single H108R-based component could provide broad protection or if multiple variants might be needed to cover the genetic diversity of circulating ASFV strains.

What experimental designs are optimal for evaluating H108R deletion mutants as potential vaccine candidates?

Rigorous evaluation of H108R deletion mutants as potential vaccine candidates requires carefully designed experiments addressing safety, immunogenicity, and efficacy. Optimal experimental designs should include:

Safety Assessment:

• Dose escalation studies (10^1 to 10^6 HAD50) to determine the minimum dose causing adverse effects

• Extended observation periods (≥28 days) to monitor for delayed adverse events or disease recrudescence

• Contact transmission studies to assess potential for spread to unvaccinated animals

• Environmental sampling to evaluate virus shedding patterns

• Sequential sacrifice studies with comprehensive tissue sampling to track virus distribution

Immunogenicity Studies:

• Longitudinal sampling to monitor antibody development (ELISA, virus neutralization assays)

• T-cell response assessment using ELISpot or intracellular cytokine staining

• Cytokine profiling to characterize immune response quality

• Comparison with other attenuated ASFV candidates to benchmark immune responses

Challenge Studies:

• Homologous challenge with parental virulent strain at various time points post-vaccination (early, mid, and late)

• Heterologous challenge with genetically diverse ASFV strains to assess cross-protection

• Dose-response challenge studies to determine level of protection against different infectious doses

• Natural exposure studies in endemic settings where feasible

Manufacturing Considerations:

• Genetic stability assessment through serial passages in vitro and in vivo

• Development of robust quantification methods for standardizing vaccine doses

• Shelf-life and storage condition studies to determine stability parameters

The published research with ASFV-G-ΔH108R provides a foundation for these studies, having demonstrated that at a dose of 10^2 HAD50, four out of five vaccinated animals survived with one showing a protracted but fatal form of disease . All surviving animals developed strong virus-specific antibody responses and were protected against challenge with the virulent parental strain . These promising results warrant the more comprehensive vaccine evaluation protocols outlined above.

How should researchers interpret the heterogeneous disease kinetics observed in ASFV-G-ΔH108R inoculated animals?

The heterogeneous disease kinetics observed in animals inoculated with ASFV-G-ΔH108R presents an important data interpretation challenge. In the published study, five pigs were intramuscularly inoculated with 10^2 HAD50 of ASFV-G-ΔH108R. One animal developed a protracted but fatal ASF clinical disease and was euthanized by day 9 post-infection, while the other four animals survived the entire 28-day observational period with minimal clinical signs .

When interpreting such heterogeneous responses, researchers should consider:

Viral Factors:
While the stock of ASFV-G-ΔH108R underwent 16 limiting dilution purification steps and was confirmed by NGS to contain the expected modifications , potential minor genetic heterogeneity within the viral population could influence disease outcomes. Researchers should consider deep sequencing of viruses recovered from animals with different outcomes to identify any adaptive mutations.

Dose-Dependent Effects:
The inoculation dose of 10^2 HAD50 may represent a threshold dose where individual variations in host response become more apparent. Higher doses might overwhelm host defenses more consistently, while lower doses might result in more uniform survival. A comprehensive dose-response study would help clarify this relationship.

Statistical Considerations:
With small group sizes (n=5), individual variations can significantly impact interpretation. Researchers should consider power analyses for future studies and potentially larger group sizes to better characterize the distribution of responses.

The protracted viremia observed in surviving animals (peaking around day 11 post-infection and steadily decreasing until day 28) suggests ongoing viral replication and immune control rather than complete viral clearance . This pattern may indicate a balance between viral replication and host immune response that results in control without clearance, similar to what is observed with some persistent viral infections.

Quantitative evaluation of immune responses induced by ASFV-G-ΔH108R infection requires comprehensive assessment of both humoral and cellular immunity using appropriate methodological approaches:

Humoral Immunity Assessment:

• ELISA-Based Antibody Quantification:

  • Develop ELISAs targeting multiple ASFV antigens (p72, p30, p54)

  • Determine antibody kinetics through time-course sampling (weekly for at least 28 days)

  • Measure different antibody isotypes (IgG, IgM) to characterize response maturation

  • Calculate endpoint titers and area under the curve for quantitative comparisons

• Functional Antibody Assays:

  • Virus neutralization tests to quantify neutralizing antibody titers

  • Antibody-dependent cellular cytotoxicity (ADCC) assays to assess Fc-mediated functions

  • Complement fixation tests to evaluate complement-activating antibodies

  • Avidity assays to determine antibody maturation and quality

Cellular Immunity Assessment:

• T-Cell Response Quantification:

  • Interferon-γ ELISpot assays using overlapping peptide pools covering major ASFV antigens

  • Intracellular cytokine staining to identify polyfunctional T cells (producing multiple cytokines)

  • Proliferation assays to measure antigen-specific T-cell expansion capacity

  • Tetramer staining for direct enumeration of antigen-specific CD8+ T cells

• Innate Immune Response Evaluation:

  • Cytokine/chemokine profiling in serum using multiplex assays

  • Flow cytometric analysis of innate lymphoid cells, natural killer cells, and myeloid cell populations

  • Transcriptomic analysis of peripheral blood mononuclear cells to identify activated pathways

Correlation With Protection:

• Pre-Challenge Immune Correlates:

  • Multivariate analysis to identify immune parameters that correlate with subsequent protection

  • Machine learning approaches to develop predictive models of protection based on immune signatures

  • Comparison with immune profiles from recovered animals following natural infection

• Post-Challenge Anamnestic Responses:

  • Quantify recall responses following challenge

  • Compare magnitude and kinetics with primary response to identify memory components

  • Assess changes in antibody avidity and T-cell functionality as indicators of immune maturation

The published research demonstrated that animals surviving ASFV-G-ΔH108R infection developed a strong virus-specific antibody response , but more detailed immunological profiling as outlined above would provide deeper insights into the mechanisms of protection and guide further vaccine development efforts.

What genetic modifications could be combined with H108R deletion to optimize ASFV vaccine candidates?

Combination with Other Virulence Gene Deletions:

• Multigene family 360/505 (MGF360/505) members: Deletion of these genes has shown attenuation in several ASFV strains and could synergize with H108R deletion

• 9GL (B119L) gene: Its deletion reduces viral replication in macrophages and attenuates virulence

• CD2v (EP402R) gene: This gene is involved in hemadsorption and contributes to virulence

• DP96R gene: A virulence factor that modulates host inflammatory responses

Addition of Immunomodulatory Genes:

• Introduction of porcine cytokine genes (e.g., IL-12, GM-CSF) to enhance immune responses

• Incorporation of T-cell epitope tags to boost cellular immunity

• Addition of molecular adjuvants such as flagellin or heat-shock proteins

Targeted Modifications to Enhance Safety:

• Introduction of temperature-sensitive mutations to restrict replication in vivo

• Development of replication-deficient viruses through deletion of essential genes with complementation in production systems

• Incorporation of genetic safety switches (e.g., thymidine kinase mutations) that render the virus susceptible to antiviral drugs

Modifications for Practical Implementation:

• Introduction of genetic markers for differentiation of infected from vaccinated animals (DIVA)

• Modifications to enhance genetic stability during manufacturing

• Adaptations to improve thermal stability for field deployment in resource-limited settings

The researchers note that "ASFV-G-ΔH108R confers protection even at low doses (10^2 HAD50), demonstrating its potential to be used as an additional gene deletion to increase the safety profile of the preexisting vaccine candidate" . This suggests that H108R deletion could be most valuable as part of a multi-gene deletion strategy rather than as a standalone approach.

How might structural biology approaches enhance our understanding of H108R function?

Structural biology approaches could significantly advance our understanding of H108R function and guide rational vaccine design. Despite the importance of H108R in ASFV virulence, its three-dimensional structure and molecular mechanism remain unknown . Several complementary structural biology methodologies could address this knowledge gap:

X-ray Crystallography:

• Expression and purification of recombinant H108R protein or soluble domains

• Crystallization trials under various conditions to obtain protein crystals

• Diffraction data collection and structure determination

• Identification of potential functional sites and interaction interfaces

Cryo-Electron Microscopy (Cryo-EM):

• High-resolution structural determination of H108R within the context of the ASFV virion

• Visualization of H108R's position and interactions within the viral inner envelope

• Comparison of virion structures between wild-type and ΔH108R viruses to identify structural changes

• Subtomogram averaging to resolve local conformational states

Nuclear Magnetic Resonance (NMR) Spectroscopy:

• Solution structure determination of H108R or its domains

• Dynamics studies to identify flexible regions

• Chemical shift perturbation experiments to map protein-protein interaction sites

• Investigation of H108R interactions with potential binding partners

Computational Structural Biology:

• Homology modeling based on distant structural homologs

• Molecular dynamics simulations to predict functional motions

• Protein-protein docking to identify potential interaction partners

• Machine learning approaches to predict function from structure

These structural approaches could specifically address several key questions:

• How does the transmembrane region (amino acids 6-23) integrate into the viral envelope?

• What is the structural basis for the five amino acid positions (22, 23, 28, 41, and 45) under purifying selection?

• How might the S54F substitution unique to the Georgia 2007/1 isolate affect protein structure and function?

• Are there structural elements that could be targeted for the development of antivirals?

Structural insights would complement the genetic and phenotypic data currently available for H108R and could potentially reveal unexpected functional relationships with proteins from other viral families, providing new conceptual frameworks for understanding ASFV biology and controlling infection.

What novel delivery systems could be developed for H108R-based vaccine candidates?

The development of effective delivery systems for H108R-based vaccine candidates represents a critical research frontier. While the current approach utilizes direct intramuscular inoculation with live attenuated ASFV-G-ΔH108R , alternative delivery strategies could enhance vaccine efficacy, stability, safety, and practical deployment:

Advanced Viral Vector Systems:

• Development of replication-deficient ASFV vectors expressing only protective antigens

• Utilization of heterologous viral vectors (adenovirus, alphavirus, poxvirus) expressing H108R alongside other ASFV antigens

• Prime-boost regimens combining different vector platforms to enhance immune responses

• Chimeric viruses incorporating protective epitopes from diverse ASFV strains

Non-Viral Delivery Platforms:

• Lipid nanoparticle-encapsulated mRNA vaccines encoding H108R and other ASFV antigens

• Virus-like particles (VLPs) displaying H108R in its native conformation

• Synthetic peptide vaccines targeting conserved epitopes identified through evolutionary analysis

• DNA vaccines with optimized promoters and molecular adjuvants

Mucosal Delivery Systems:

• Oral baits for wild boar vaccination using biocompatible encapsulation technologies

• Intranasal formulations with mucoadhesive properties to enhance mucosal immunity

• Aerosol delivery systems for herd-level vaccination in production settings

• Plant-based edible vaccines expressing ASFV antigens for oral delivery

Formulation Innovations:

• Thermostable formulations to eliminate cold chain requirements

• Sustained-release technologies for single-dose immunization

• Microencapsulation techniques to protect antigens from degradation

• Adjuvant combinations tailored to enhance both humoral and cellular immunity

When developing these delivery systems for H108R-based vaccines, researchers should consider several factors specific to ASFV and the H108R protein:

• The transmembrane nature of H108R may necessitate specific formulation approaches to maintain native conformation

• The late expression profile of H108R suggests it may need to be combined with early antigens for comprehensive immunity

• The demonstrated protective efficacy of ASFV-G-ΔH108R indicates that presentation of H108R in the context of other ASFV antigens may be optimal

These novel delivery approaches could address current challenges in ASFV vaccine deployment while leveraging the protective potential of H108R-based immunization strategies.

What are the key takeaways from current H108R research for the broader field of ASFV vaccinology?

The research on the H108R gene of African swine fever virus provides several significant insights with broad implications for ASFV vaccine development. The identification of H108R as a previously uncharacterized virulence factor represents an important advance in our understanding of ASFV pathogenesis . Several key takeaways emerge from this research:

First, the deletion of H108R from the highly virulent ASFV-Georgia2007 strain results in significant attenuation while maintaining immunogenicity and protective capacity. This demonstrates that targeted deletion of specific virulence genes can achieve an appropriate balance between safety and efficacy – a critical consideration for live attenuated vaccine development .

Second, the high conservation of H108R within the pandemic Eurasian lineage, combined with evidence of purifying selection on specific amino acid residues, suggests that H108R-based vaccines may be effective against currently circulating strains . This evolutionary stability makes H108R an attractive target for vaccine strategies against the ongoing ASFV pandemic.

Third, the demonstration that animals surviving ASFV-G-ΔH108R infection develop strong antibody responses and are protected against challenge with virulent ASFV-G establishes proof-of-concept for this approach . The fact that protection was achieved even at low doses (10^2 HAD50) suggests good immunological potency of the attenuated virus.

Fourth, the residual virulence observed in one animal indicates that H108R deletion alone may not provide optimal safety for all individuals . This highlights the importance of combinatorial approaches that integrate multiple gene deletions to enhance safety profiles while maintaining protective efficacy.

Finally, the localization of H108R to the viral inner envelope and its late expression profile provide clues about potential mechanisms of action that may inform the development of other attenuated vaccine candidates and antiviral strategies .

These insights collectively advance our understanding of ASFV biology and provide a foundation for rational design of vaccines against this devastating disease of swine.

How might the findings on H108R influence regulatory approaches to ASFV vaccine approval?

The findings on H108R and the development of ASFV-G-ΔH108R have several implications for regulatory approaches to ASFV vaccine approval. Regulatory bodies will need to consider specific aspects of this research when developing frameworks for evaluating ASFV vaccines:

Safety Considerations:
The observation that one of five animals inoculated with ASFV-G-ΔH108R developed a protracted but fatal form of disease raises important safety concerns that regulators will need to address. This residual virulence suggests that regulatory frameworks might require:

• Larger safety studies with sufficient statistical power to detect low-frequency adverse events

• Extended observation periods beyond the standard timeframes

• Sequential sacrifice studies to evaluate virus distribution in tissues

• Environmental risk assessments for potential spread to non-target animals

Efficacy Standards:
The complete protection observed in surviving animals when challenged with virulent ASFV-G provides a benchmark for efficacy that regulators might incorporate into approval requirements:

• Demonstration of protection against homologous challenge as a minimum criterion

• Potential requirements for heterologous challenge studies to demonstrate breadth of protection

• Standards for measuring both clinical protection and reduction in virus shedding

• Guidance on acceptable correlates of protection for expedited approval pathways

Genetic Stability Requirements:
The development of ASFV-G-ΔH108R through deletion of the H108R gene and replacement with a reporter cassette highlights the importance of genetic stability assessments:

• Requirements for comprehensive next-generation sequencing validation

• Standards for monitoring genetic stability during manufacturing

• Guidelines for acceptable passage limits during production

• Requirements for post-approval genomic surveillance

Field Implementation Considerations:
The research findings suggest that regulatory frameworks might need to address:

• DIVA (Differentiating Infected from Vaccinated Animals) capabilities to support control programs

• Guidelines for implementing vaccination in different epidemiological contexts

• Post-approval surveillance requirements to monitor for emergence of escape variants

• Protocols for handling vaccinated animals in international trade contexts

These regulatory considerations will be critical in translating the promising research findings on H108R deletion mutants into approved vaccines that can be deployed effectively against the ongoing ASFV pandemic.

What interdisciplinary collaborations would most accelerate progress in H108R-based vaccine development?

Accelerating progress in H108R-based vaccine development requires strategic interdisciplinary collaborations that bring together diverse expertise to address complex challenges. Several key collaborative networks would be particularly valuable:

Structural Biology and Immunology Integration:
Combining structural biology approaches to elucidate H108R's three-dimensional configuration with immunological expertise to identify protective epitopes could accelerate rational vaccine design. This collaboration would:

• Map epitopes recognized by protective antibodies

• Design optimized antigens based on structural constraints

• Identify conserved structural elements across ASFV strains

• Develop structure-based vaccines with enhanced stability and immunogenicity

Virology and Computational Biology Synergy:
Integration of experimental virology with advanced computational methods would enhance understanding of H108R function and evolution:

• Predict effects of mutations on protein function and viral fitness

• Model evolutionary trajectories to anticipate potential escape variants

• Design gene deletion combinations with optimal attenuation profiles

• Simulate host-pathogen interactions to predict vaccine efficacy

Veterinary Medicine and Production Animal Science Partnership:
Collaboration between veterinary researchers and animal production scientists would ensure vaccines address practical field challenges:

• Develop vaccination protocols compatible with commercial production systems

• Design delivery methods suitable for both domestic and wild swine populations

• Integrate vaccines with existing biosecurity practices

• Evaluate economic impacts of vaccination strategies

Biotechnology and Regulatory Science Alignment:
Partnerships between biotechnology developers and regulatory science experts would streamline the path to approval:

• Design studies that address regulatory requirements from early development stages

• Develop innovative safety testing approaches specific to ASFV vaccines

• Create standardized assays for potency and efficacy evaluation

• Establish post-approval surveillance methods

Global One Health Collaborations:
International, cross-sectoral collaborations embracing the One Health concept would maximize impact:

• Coordinate vaccine field trials across different epidemiological contexts

• Harmonize control strategies between wildlife and domestic animal sectors

• Develop implementation strategies appropriate for diverse production systems

• Create equitable access frameworks for global deployment