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 |
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Authors: | Nagendrakumar Balasubramanian Singanallur Phaedra Lydia Ebl Anna Barbara Ludi Bob Statham Abdelghani Bin-Tarif Donald P King Aldo Dekker Wilna Vosloo |
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Institution: | 1.Australian Centre for Disease Preparedness, CSIRO-Health & Biosecurity, 5 Portarlington Road, Geelong, VIC 3220, Australia;2.Laboratory Vesicular Diseases, Department of Virology and Molecular Biology, Wageningen Bioveterinary Research, Houtribweg 39, 8221 RA Lelystad, The Netherlands; (P.L.E.); (A.D.);3.The Pirbright Institute, Ash Road, Pirbright, Woking GU24 ONF, UK; (A.B.L.); (B.S.); (A.B.-T.); (D.P.K.) |
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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. |
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Keywords: | foot-and-mouth disease virus vaccine efficacy serotype A/ASIA/G-VII lineage vaccine A/ASIA/Iran-05 lineage variant heterologous challenge cattle |
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