Abstract
An infectious endogenous retrovirus termed the RD114 virus is present in the genome of domestic cats, and as such has the potential to contaminate feline live attenuated vaccines manufactured using feline cells for cultivation. Recently, Miyazawa et al. reported that infectious RD114 viruses were present in certain live attenuated vaccines [Journal of Virology]. In this study, we attempted to confirm the presence of the virus in feline live multivalent vaccines (four products, 30 batches) approved in Japan by the LacZ marker rescue assay. Thirty percent of the vaccines tested were found to be positive for the infectious RD114 virus. This report confirms the presence of infectious RD114 virus in feline vaccines under the present experimental design. The pathogenicity of the RD114 virus and the adverse effects on cats of inoculation with feline live attenuated vaccines are unknown at present. Nevertheless, the same vaccines have been sold in European countries and in the United States. As the regulatory authority of Japan, we have decided not to take urgent action, such as banning the sale of vaccines containing the RD114 virus, and will continue to collect information about the virus and monitor any issues that may arise.
