Systematic review and meta-analysis of the effectiveness of polypeptide, virus-like particles, and viral vector vaccines for foot-and-mouth disease (2020–2025)

Figures

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  Fig. 1. PRISMA flow diagram of search results.

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  Fig. 2. Illustration of the animal model most used in foot and mouth disease studies for vaccine evaluation. Pigs were the most frequently used model (13 studies, 54.2%), reflecting their high susceptibility to FMDV and relevance as natural hosts for vaccine efficacy assessment. Guinea pigs and mice were each used in 6 studies (25.0% each), serving primarily for preliminary immunogenicity screening and dose optimization studies. Cattle were utilized in 5 studies (20.8%), despite being a primary target species for FMDV vaccination in field conditions. The relatively limited use of cattle represents a significant research gap, as immune responses may differ between species, potentially affecting the translatability of vaccine efficacy results to target livestock populations. Some studies employed multiple animal models, contributing to multiple categories in this analysis.

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  Fig. 3. Bar chart that shows the most commonly targeted epitopes. VP1 epitopes were the predominant target, appearing in 15 studies (62.5%), reflecting their immunodominant properties and role in viral attachment. Non-structural protein 3D epitopes were utilized in 2 studies (8.3%), while structural proteins 3 A, VP3, and VP4 were each targeted in 1 study (4.2% each). The dominance of VP1 epitopes aligns with established knowledge of their critical role in neutralizing antibody induction, though the limited exploration of other epitopes suggests potential opportunities for broader antigenic coverage in future multi-epitope vaccine designs. Data represent unique epitope targets; studies utilizing multiple epitopes contributed to multiple categories.

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  Fig. 4. A subgroup Forest plot analysis displaying individual study risk ratios (RR) with 95% confidence intervals (CI) for protection outcomes (protected vs. non-protected animals) across vaccine types (peptide-based, VLP, viral vector, and dendritic cell-based). Each square represents a study estimate, sized by weight; horizontal lines show CIs. Subgroup means are diamonds. RR > 1 indicates higher protection in vaccinated vs. control groups. Heterogeneity is quantified by I² (percentage of variation due to heterogeneity) and tau-squared (τ²).

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  Fig. 5. Forest plot displaying the overall pooled risk ratios (RR) with 95% confidence intervals (CI) for each vaccine platform, using a random-effects model to account for between-study variability. Each square represents a study estimate, sized by weight; horizontal lines show CIs. Pooled estimates are diamonds. RR > 1 favors the vaccine group over controls for protection outcomes. Heterogeneity is assessed via I² and tau-squared (τ²). The plot summarizes protective efficacy across platforms regardless of between-study variation.

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  Fig. 6. Fluctuation chart that illustrates the average total citations per year.

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  Fig. 7. Heatmap illustration of the global distribution of the FMDV research (a), the intensity of research collaborations and publication volume by country (b), and the country collaboration network using VOSviewer (c).

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  Fig. 8. Keyword co-occurrence intensity plot illustrating research hotspots from 2020–2025 using VOSviewer.