Isolation and Characterization of a Novel Gammaherpesvirus from a Microbat Cell Line

Shabman, Reed S.; Shrivastava, Susmita; Tsibane, Tshidi; Attie, Oliver; Jayaprakash, Anitha; Mire, Chad E.; Dilley, Kari E.; Puri, Vinita; Stockwell, Timothy B.; Geisbert, Thomas W.; Sachidanandam, Ravi; Basler, Christopher F.

nucleotide sequences identified by deep sequencing or PCR-based approaches on bat-derived tissue samples (16) (17) (18) 31) . These sequences correspond to only small portions of gammaherpesviruses, and isolation of infectious gammaherpesviruses has not been reported in the literature. Given that the virus was isolated from a cell line that was established many years earlier, one cannot be certain that the virus was present when the cells were first isolated. Therefore, it is difficult to be certain, based on the available data, that the virus is of bat origin. It could, for example, have been introduced during maintenance of the cells and have a nonbat source in nature. Nonetheless, several lines of evidence point to this being an actual bat gammaherpesvirus. First, the virus was isolated from cells of bat origin. Further, the cell line is of apparent tumor origin, consistent with the ability of gammaherpesviruses to transform infected cells (reviewed in references 32 and 33). Second, phylogenic analysis of gB indicates that the closest related sequence is from a sequence obtained from Myotis bat tissues. Additionally, phylogenetic analysis of selected ORFs with homology to mammalian host genes indicates a close relationship with microbat host gene products. Specifically, the most closely related gB sequence in GenBank to BGHV8 gB is a gB sequence obtained from Myotis ricketti bats, although the virus from which the sequence is derived has not been cultured. Finally, among 10 ORFs that do not share homology with EHV-2, seven were similar to proteins in other herpesviruses and therefore were assigned a name standard to other gammaherpesvirus accessory genes. These include v-FLIP, v-OX2, DHFR, v-Bcl-2, CCP, and MIR2 ORFs at the far 5= end of the genome. We observed that several of these encode accessory proteins with homology to host factors and that the closest host homologue is a predicted bat protein. the Myotis OX2, with a more divergent C terminus. KSHV OX2, a secreted glycoprotein, activates myeloid lineage cells, resulting in proinflammatory cytokine production (34, 35) . Although proof that this virus is found in nature in bats requires isolation of the virus from wild-caught animals, the findings outlined above provide support for a bat origin for the novel virus.