The suitability of the 'emergency' foot-and-mouth disease antigens held bythe International Vaccine Bank within a global context

The International Vaccine Bank (IVB) based at the Institute of Animal Healt h (IAH) in Pirbright, United Kingdom (UK), routinely monitors the suitabili ty of the currently held strains of foot-and-mouth disease (FMD) vaccine vi rus, in anticipation that vaccine may be required to control FMD outbreaks that pose a threat to member countries. Using primarily the two-dimensional micro-neutralisation test (VNT), bovine polyclonal sera raised against eac h of the seven current 'emergency' antigens were utilised to measure the re lationship of IVB stocks to selected held isolates. The 'O' serotypes, Mani sa and Lausanne, exhibited adequate levels of cross-protection against most of the type 'O' field isolates examined. A(22) Iraq 24/64 showed the broad est spectrum of reactivity against the type 'A' field isolates examined and was supplemented by A(15) Thailand 1/60. Some type 'Asia 1' field isolates , particularly those from South East Asia, showed antigenic difference to t he Asia1 India 8/79 vaccine strain by VNT, but in-vivo testing in the guine a pig model indicated this to be insignificant. The only 'C' serotype repre sentative, C-1 Oberbayern, may be one of the least antigenically diverse of the current portfolio of bank antigens. Comparison of the serological and sequence data shows that despite significant genetic variation between the field isolates examined the antigens held by the IVB should still prove eff icacious in the field. (C) 2001 Elsevier Science Ltd. All rights reserved.