Distribution of infectious endogenous retroviruses in mixed-breed and purebred cats.

Endogenous retroviruses of domestic cats (ERV-DCs) are members of the genus Gammaretrovirus that infect domestic cats (Felis silvestris catus). Uniquely, domestic cats harbor replication-competent proviruses such as ERV-DC10 (ERV-DC18) and ERV-DC14 (xenotropic and nonecotropic viruses, respectively). The purpose of this study was to assess invasion by two distinct infectious ERV-DCs, ERV-DC10 and ERV-DC14, in domestic cats. Of a total sample of 1646 cats, 568 animals (34.5%) were positive for ERV-DC10 (heterozygous: 377; homozygous: 191), 68 animals (4.1%) were positive for ERV-DC14 (heterozygous: 67; homozygous: 1), and 10 animals (0.6%) were positive for both ERV-DC10 and ERV-DC14. ERV-DC10 and ERV-DC14 were detected in domestic cats in Japan as well as in Tanzania, Sri Lanka, Vietnam, South Korea and Spain. Breeding cats, including Singapura, Norwegian Forest and Ragdoll cats, showed high frequencies of ERV-DC10 (60-100%). By contrast, ERV-DC14 was detected at low frequency in breeding cats. Our results suggest that ERV-DC10 is widely distributed while ERV-DC14 is maintained in a minor population of cats. Thus, ERV-DC10 and ERV-DC14 have invaded cat populations independently.