Detection of various DNA and RNA viruses in bats in Yamaguchi Prefecture, Japan.

Bats are important natural hosts of various zoonotic viruses, including Ebola virus, Lyssa virus, and severe acute respiratory syndrome coronavirus (SARS-CoV). Although investigation of bats is valuable for predicting emerging infectious diseases from these animals, few surveys of bat-derived viruses have been conducted in Japan. In the present study, samples were collected from a total of 132 bats of 4 different species from 4 different locations within Yamaguchi Prefecture; these sample were employed for comprehensive detection of bat-derived viruses by polymerase chain reaction (PCR) and reverse transcription (RT)-PCR using primers universal for each of 4 different viral classes. As a result of PCR and RT-PCR, various herpesviruses, astroviruses, coronaviruses, and adenoviruses were identified from a total of 80 bats. The detected herpesviruses belong to the Betaherpesvirinae or Gammaherpesvirinae subfamily, the detected adenoviruses to the genus Mastadenovirus, the detected astroviruses to the genus Mamastrovirus; and the detected coronaviruses belong to the genus Alphacoronavirus. The detected sequences of 12 strains of 4 families showed 100 % amino acid identity with viruses previously detected either in China or South Korea. These findings expand our understanding of viruses carried by bats, and provide insights into the nature of bat-derived viruses in Japan.

Convergent evolution of antiviral machinery derived from endogenous retrovirus truncated envelope genes in multiple species.

Host genetic resistance to viral infection controls the pathogenicity and epidemic dynamics of infectious diseases. Refrex-1 is a restriction factor against feline leukemia virus subgroup D (FeLV-D) and an endogenous retrovirus (ERV) in domestic cats (ERV-DC). Refrex-1 is encoded by a subset of ERV-DC loci with truncated envelope genes and secreted from cells as a soluble protein. Here, we identified the copper transporter CTR1 as the entry receptor for FeLV-D and genotype I ERV-DCs. We also identified CTR1 as a receptor for primate ERVs from crab-eating macaques and rhesus macaques, which were found in a search of intact envelope genes capable of forming infectious viruses. Refrex-1 counteracted infection by FeLV-D and ERV-DCs via competition for the entry receptor CTR1; the antiviral effects extended to primate ERVs with CTR1-dependent entry. Furthermore, truncated ERV envelope genes found in chimpanzee, bonobo, gorilla, crab-eating macaque, and rhesus macaque genomes could also block infection by feline and primate retroviruses. Genetic analyses showed that these ERV envelope genes were acquired in a species- or genus-specific manner during host evolution. These results indicated that soluble envelope proteins could suppress retroviral infection across species boundaries, suggesting that they function to control retroviral spread. Our findings revealed that several mammalian species acquired antiviral machinery from various ancient retroviruses, leading to convergent evolution for host defense.