Evaluation of Potency and Duration of Immunity Elicited by a Multivalent FMD Vaccine for Use in South Africa

Immunogenicity of a foot-and-mouth disease (FMD) vaccine against serotypes O, A, SAT-2, and Asia-1 in the Middle East and many parts of Africa, Southeast Asia and Europe

Control of foot-and-mouth disease (FMD) is hampered by inadequate biosecurity measures, border transcending serotype strains and unavailability of broad coverage vaccines. In this investigation, six FMD antibody-free calves, aged 1.5-2 years, received a tetravalent, inactivated, aluminum hydroxide gel vaccine (Aphthovac-4) containing 6 PD50/dose of certain strains for protection against a wide range of strains in the Middle East, Africa, Southeast Asia, and parts of Europe. The vaccine contained 2 strains of serotype A/Asia (A/Asia (A/Iran-05 and A/Ind/40/2000 G-VII), 2 of serotype O (O/Middle East-South Asia topotype and O/Manisa/TUR/69), and one strain each of serotype SAT-2 (topotype VII) and Asia-1 (Sindh-8). Primary and booster doses were administered 3 weeks apart and sera were collected one week after the booster vaccination, preserved frozen then shipped to The Pirbright Institute, UK, for antibody evaluation by virus neutralization test (VNT) against 22 lineages circulating in the targeted regions. Serum titers against test strains of serotype A were high (range = 355- < 1413 or 2.6- < 3.15 log10), and those demonstrating relatively lower values included A/Irn/25/18 (G-VII), A/Irn-05 Far-11, A/Iran05 SIS-13 and SEA-97. Serotype O test strains presented higher titers (≤ 1/1413 or ≤ 3.0 log10), but O/Cathay, O/Panasia-2 ant-10 and one O/Ind-2001e lineage exhibited somewhat lower values (range (355-1024 or 2.6-3.01 log10). Antibodies against SAT-2 test strains (XIV Topotype) ranged between 128 and 178 (1.9-2.2 log10) in 5 animals (5/6, 83%), despite the reported high r1 values. Likewise, Asia-1 strain elicited a similar titer range against IRN/1/2020 in the same 5 animals. The 6th animal generally showed one dilution less. The results portray a dynamic antigenic change between the vaccinal and test strains, underscoring the value of strain matching, use of high payload and incorporation of double antigen lineages within each serotype to broaden coverage in enzootic and epizootic situations.

Spatial-temporal distribution and risk factors of foot and mouth disease outbreaks in Java Island, Indonesia from 2022 to 2023

BACKGROUND

Indonesia faced new outbreaks of foot and mouth disease in 2022 after being officially free from the disease for several decades. The outbreaks were first reported in East Java in April 2022 and subsequently spread to many regions in Indonesia. This study investigated the epidemiology and risk factors of foot and mouth disease outbreaks in Java, Indonesia, from 2022 to 2023. Descriptive, spatial, spatiotemporal, and risk factor analyses were conducted to investigate the patterns and risk factors associated with the outbreaks in Java.

RESULTS

Results showed that the outbreaks were distributed across the island. East Java was the most affected region. The outbreaks peaked in June 2022, followed by a downward trend until 2023. Positive spatial autocorrelations were found in both years, indicating that the outbreaks clustered in several areas. The spatiotemporal analysis found a total of 16 clusters in both years, with 11 clusters in 2022 and 5 clusters in 2023. The temporal distribution of clusters indicated a peak period from May to July, with 12 out of 16 clusters occurring during this time. Risk factor analysis found that environmental and agricultural-related factors, including annual precipitation, the presence of livestock markets, the presence of slaughterhouses, the presence of animal health centres, cattle population, and goat population, are significant risk factors for the occurrence of outbreaks in Java. Probability risk mapping found higher risk areas primarily distributed in the eastern and central parts of Java.

CONCLUSIONS

The outbreaks predominantly clustered in eastern and central parts of Java. The outbreaks peaked in June 2022, followed by a downward trend until the end of 2023. Environmental and agricultural-related factors significantly increased the risk of outbreak occurrence.

Foot and Mouth Disease Vaccine Matching and Post-Vaccination Assessment in Abu Dhabi, United Arab Emirates

Despite the annual vaccination of livestock against foot and mouth disease (FMD) in the United Arab Emirates (UAE), outbreaks of the disease continue to be reported. The effective control of field outbreaks by vaccination requires that the vaccines used are antigenically matched to circulating field FMD viruses. In this study, a vaccine matching analysis was performed using the two-dimensional virus neutralization test (VNT) for three field isolates belonging to the O/ME-SA/PanAsia-2/ANT-10 and O/ME-SA/SA-2018 lineages collected from different FMD outbreaks that occurred within the Abu Dhabi Emirate in 2021 affecting Arabian oryx (Oryx leucoryx), goat, and sheep. In addition, post-vaccination antibodies in sheep and goats were measured using solid-phase competitive ELISA (SPCE) for FMDV serotypes A and O at five months after a single vaccine dose and a further 28 days later after a second dose of the FMD vaccine. An analysis of vaccine matching revealed that five out of the six vaccine strains tested were antigenically matched to the UAE field isolates, with r1-values ranging between 0.32 and 0.75. These results suggest that the vaccine strains (O-3039 and O1 Manisa) included in the FMD vaccine used in the Abu Dhabi Emirate are likely to provide protection against outbreaks caused by the circulating O/ME-SA/PanAsia-2/ANT-10 and O/ME-SA/SA-2018 lineages. All critical residues at site 1 and site 3 of VP1 were conserved in all isolates, although an analysis of the VP1-encoding sequences revealed 14-16 amino acid substitutions compared to the sequence of the O1 Manisa vaccine strain. This study also reports on the results of post-vaccination monitoring where the immunization coverage rates against FMDV serotypes A and O were 47% and 69% five months after the first dose of the FMD vaccine, and they were increased to 81 and 88%, respectively, 28 days after the second dose of the vaccine. These results reinforce the importance of using a second booster dose to maximize the impact of vaccination. In conclusion, the vaccine strains currently used in Abu Dhabi are antigenically matched to circulating field isolates from two serotype O clades (O/ME-SA/PanAsia-2/ANT-10 sublineage and O/ME-SA/SA-2018 lineage). The bi-annual vaccination schedule for FMD in the Abu Dhabi Emirate has the potential to establish a sufficient herd immunity, especially when complemented by additional biosecurity measures for comprehensive FMD control. These findings are pivotal for the successful implementation of the region's vaccination-based FMD control policy, showing that high vaccination coverage and the wide-spread use of booster doses in susceptible herds is required to achieve a high level of FMDV-specific antibodies in vaccinated animals.

Foot and mouth disease vaccine efficacy in Africa: a systematic review and meta-analysis

Background

Several factors, such as diverse serotypes, vaccination methods, weak biosecurity, and animal movements, contribute to recurrent Foot-and-Mouth Disease Virus (FMDV) outbreaks in Africa, establishing endemicity. These outbreaks cost over $2 billion annually, prompting a high-priority focus on FMDV vaccination. Despite extensive efforts, vaccine efficacy varies. This study aims to evaluate routine foot and mouth disease (FMD) vaccines in Africa via systematic review and meta-analysis.

Methods

A systematic review and meta-analysis were carried out following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Meta-analysis was conducted to assess the efficacy of FMDV vaccination using the meta for package of R.

Results

Vaccinated animals have roughly a 69.3% lower chance of FMDV infection compared to unvaccinated animals, as indicated by the pooled results from the random-effects model, which showed a risk ratio (RR) of 0.3073. There was a statistically significant heterogeneity (p < 0.05) across all of the included articles.

Conclusion

Overall findings suggest that if properly planned and implemented, FMDV vaccination programs and strategies in Africa could help control the spread of the disease throughout the continent and beyond.

A review of foot-and-mouth disease in Ethiopia: epidemiological aspects, economic implications, and control strategies

Foot-and-mouth disease (FMD) is a contagious viral disease that affects the livelihoods and productivity of livestock farmers in endemic regions. It can infect various domestic and wild animals with cloven hooves and is caused by a virus belonging to the genus Aphthovirus and family Picornaviridae, which has seven different serotypes: A, O, C, SAT1, SAT2, SAT3, and Asia-1. This paper aims to provide a comprehensive overview of the molecular epidemiology, economic impact, diagnosis, and control measures of FMD in Ethiopia in comparison with the global situation. The genetic and antigenic diversity of FMD viruses requires a thorough understanding for developing and applying effective control strategies in endemic areas. FMD has direct and indirect economic consequences on animal production. In Ethiopia, FMD outbreaks have led to millions of USD losses due to the restriction or rejection of livestock products in the international market. Therefore, in endemic areas, disease control depends on vaccinations to prevent animals from developing clinical disease. However, in Ethiopia, due to the presence of diverse antigenic serotypes of FMD viruses, regular and extensive molecular investigation of new field isolates is necessary to perform vaccine-matching studies to evaluate the protective potential of the vaccine strain in the country.

Preparation of purified vaccine from local isolate of foot and mouth disease virus and its immune response in bovine calves

Foot and Mouth Disease (FMD) is globally pandemic which badly affect the economics of livestock based countries like Pakistan. There are different types of Foot and Mouth Disease Virus (FMDV) among these types O is most prevalent in Pakistan. Recently Pakistan is producing approximately fifteen million doses of non-purified FMD vaccine against the demand of 160 million doses annually. More over the Pakistan is still striving for the development and optimization of concentration as well as purification of FMDV. The present project was designed to develop the technology for the purification of FMDV indigenously. The locally isolated and adapted FMDV type O virus was propagated on adherent culture of BHK-21cells to get final volume of virus one liter. This virus suspension was concentrated by peggylation as well as ultra-filtration method. The purification and quantification of concentrated virus was done by size exclusion chromatography. The results showed that peggylation is better method of concentration up to 603.75 µg/ml with 82.80 % recovery rate than ultra-filtration with 43.90 % followed by chromatography for purification. The PD₅₀ was calculated in bovines at 24, 12, 6, 3 and 1.5 µg of FMDV Ag/dose and it revealed that antigen load of 1.98 µg is the dose, where the 50 % of inoculated animals showed the protective antibody level based upon percent inhibition through antibody detecting ELISA. According to the British pharmacopeia, the vaccine should contain 3PD₅₀ which found equivalent to our findings about 6 µg/dose. The group of animal injected with 6/dose (3.23PD50) showed protective titer up to 20th week post priming.