A Vaccine Based on the A/ASIA/G-VII Lineage of Foot-and-Mouth Disease Virus Offers Low Levels of Protection against Circulating Viruses from the A/ASIA/Iran-05 lineage.

Nagendrakumar Balasubramanian Singanallur,Bob Statham,Aldo Dekker,Phaedra Lydia Eblé,Anna Barbara Ludi,Wilna Vosloo,Abdelghani Bin-Tarif,Donald P King

doi:10.3390/v14010097

Abstract

The recent emergence and circulation of the A/ASIA/G-VII (A/G-VII) lineage of foot-and-mouth disease virus (FMDV) in the Middle East has resulted in the development of homologous vaccines to ensure susceptible animals are sufficiently protected against clinical disease. However, a second serotype A lineage called A/ASIA/Iran-05 (A/IRN/05) continues to circulate in the region and it is therefore imperative to ensure vaccine strains used will protect against both lineages. In addition, for FMDV vaccine banks that usually hold a limited number of strains, it is necessary to include strains with a broad antigenic coverage. To assess the cross protective ability of an A/G-VII emergency vaccine (formulated at 43 (95% CI 8–230) PD50/dose as determined during homologous challenge), we performed a heterologous potency test according to the European Pharmacopoeia design using a field isolate from the A/IRN/05 lineage as the challenge virus. The estimated heterologous potency in this study was 2.0 (95% CI 0.4–6.0) PD50/dose, which is below the minimum potency recommended by the World Organisation for Animal Health (OIE). Furthermore, the cross-reactive antibody titres against the heterologous challenge virus were poor (≤log10 0.9), even in those cattle that had received the full dose of vaccine. The geometric mean r1-value was 0.2 (95% CI 0.03–0.8), similar to the potency ratio of 0.04 (95% CI 0.004–0.3). Vaccination decreased viraemia and virus excretion compared to the unvaccinated controls. Our results indicate that this A/G-VII vaccine does not provide sufficient protection against viruses belonging to the A/IRN/05 lineage and therefore the A/G-VII vaccine strain cannot replace the A/IRN/05 vaccine strain but could be considered an additional strain for use in vaccines and antigen banks.

Highlights

The A/IRN22/2015 virus was isolated from bovine tongue epithelium from a cow infected with foot-andmouth disease virus (FMDV) in 2015 and was identified as a representative field isolate of the A/G-VII lineage
For the five field isolates tested, these results indicate that there is poor antigenic match between the A/G-VII vaccine and the field isolates (r1 -value < 0.3) and that the vaccine is unlikely to provide good protection
Bovine Vaccinated Sera (BVS) for the vaccine strains compared were provided by Boehringer Ingelheim. * The isolates did not show any detectable neutralising antibody titres against A/G-VII bovine vaccinate sera and represented as

Summary

Introduction

Foot-and-mouth disease (FMD) is a contagious disease of cloven-hoofed animals that can cause high morbidity in affected animals, but mortality is usually low. The mortality rates depend on the age of the animal, with young animals more likely to succumb to the disease. FMD is an economically important disease of livestock and may spread over large distances [1].

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Results

Conclusion