Antibody response and resistance of Cyprinus carpio immunized with cyprinid herpes virus 3 (CyHV-3).

CyHV-3 (Cyprinid herpesvirus-3) is a large DNA virus that causes a fatal disease in koi and common carp. Infection with wild type or attenuated virus induces an immune response that renders the fish resistant to further virus challenges. The kinetics and affinity of the antibody response in immune fish depend on the temperature of the water. Virus-inoculated fish produce anti-CyHV-3 antibodies, which gradually decrease during 280 days post infection to a level slightly above that of naïve fish. The protection against the virus is proportional to the titer of anti-virus antibodies in recently inoculated fish. Nevertheless, these immunized fish, even with no-longer detectable antibodies, are resistant to virus infection, probably due to the subsequent rapid response of high affinity anti-virus antibodies. The fact that anti-virus antibodies neutralize in vitro the pathogenic effects of the virus emphasizes the central role probably played by the antibodies in anti-CyHV-3 protection in vivo.