Long-term protective immunity to goatpox in goats after a single immunization with a live attenuated goatpox vaccine

In this study, the duration of immunity following a single-dose vaccination using an attenuated live goatpox vaccine (GTPV/Uttarkashi/1978 strain) was evaluated in goatpox-seronegative goats for 52 months. Long-term immunity was evaluated by clinical protection upon virulent virus challenge and serum neutralization assay applied to serum samples. The rise in the level of GTPV-specific antibodies was found to reach a maximum at 21 days post-vaccination, and these antibodies were maintained for 1 to 2 years after immunization, with a steady decline. Upon virulent virus challenge at 12, 24, 42, and 52 months post-vaccination, protection in all the vaccinated animals was evident (100%), whereas, the control animals developed severe clinical disease. This is the first time that the long-term immunity of a live goatpox vaccine has been investigated up to 52 months after vaccination in goats by virulent virus challenge and demonstration of serum neutralization titres. This vaccine has immense potential for controlling and eradicating goatpox from an enzootic region.