- in Britain, late summer and autumn. When a host becomes infected with BTV, either death ensues or an antibody response is mounted which renders the animal resistant to re-infection. This presents a challenge to persistence of bluetongue virus since animals quickly become "unavailable" for infection, particularly in areas where livestock populations are small. The virus must therefore contintually spread to new locations to find naive hosts | - in Britain, late summer and autumn. When a host becomes infected with BTV, either death ensues or an antibody response is mounted which renders the animal resistant to re-infection. This presents a challenge to persistence of bluetongue virus since animals quickly become "unavailable" for infection, particularly in areas where livestock populations are small. The virus must therefore contintually spread to new locations to find naive hosts |