In Vitro Characterization of a Koala Retrovirus

ABSTRACT Recently, a new endogenous koala gammaretrovirus, designated KoRV, was isolated from koalas. The KoRV genome shares 78% nucleotide identity with another gammaretrovirus, gibbon ape leukemia virus (GALV). KoRV is endogenous in koalas, while GALV is exogenous, suggesting that KoRV predates GALV and that gibbons and koalas acquired the virus at different times from a common source. We have determined that subtle adaptive differences between the KoRV and GALV envelope genes account for differences in their receptor utilization properties. KoRV represents a unique example of a gammaretrovirus whose envelope has evolved to allow for its expanded host range and zoonotic potential.

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Infectious KoRV-related retroviruses circulating in Australian bats

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1915400117 ◽

2020 ◽

Vol 117 (17) ◽

pp. 9529-9536 ◽

Cited By ~ 9

Author(s):

Joshua A. Hayward ◽

Mary Tachedjian ◽

Claudia Kohl ◽

Adam Johnson ◽

Megan Dearnley ◽

...

Keyword(s):

Leukemia Virus ◽

Reverse Transcriptase Activity ◽

Close Relative ◽

Emerging Viruses ◽

Basal Group ◽

Serologic Evidence ◽

Mouse Cells ◽

Gibbon Ape Leukemia Virus

Bats are reservoirs of emerging viruses that are highly pathogenic to other mammals, including humans. Despite the diversity and abundance of bat viruses, to date they have not been shown to harbor exogenous retroviruses. Here we report the discovery and characterization of a group of koala retrovirus-related (KoRV-related) gammaretroviruses in Australian and Asian bats. These include the Hervey pteropid gammaretrovirus (HPG), identified in the scat of the Australian black flying fox (Pteropus alecto), which is the first reproduction-competent retrovirus found in bats. HPG is a close relative of KoRV and the gibbon ape leukemia virus (GALV), with virion morphology and Mn2+-dependent virion-associated reverse transcriptase activity typical of a gammaretrovirus. In vitro, HPG is capable of infecting bat and human cells, but not mouse cells, and displays a similar pattern of cell tropism as KoRV-A and GALV. Population studies reveal the presence of HPG and KoRV-related sequences in several locations across northeast Australia, as well as serologic evidence for HPG in multiple pteropid bat species, while phylogenetic analysis places these bat viruses as the basal group within the KoRV-related retroviruses. Taken together, these results reveal bats to be important reservoirs of exogenous KoRV-related gammaretroviruses.

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Transspecies Transmission of the Endogenous Koala Retrovirus

Journal of Virology ◽

10.1128/jvi.02597-05 ◽

2006 ◽

Vol 80 (11) ◽

pp. 5651-5654 ◽

Cited By ~ 82

Author(s):

Uwe Fiebig ◽

Manuel Garcia Hartmann ◽

Norbert Bannert ◽

Reinhard Kurth ◽

Joachim Denner

Keyword(s):

Neutralizing Antibodies ◽

Opportunistic Infections ◽

Leukemia Virus ◽

Virus Detection ◽

Immune Deficiencies ◽

Gibbon Ape Leukemia Virus ◽

Koala Retrovirus ◽

Protein P15e

ABSTRACT The koala retrovirus (KoRV) is a gammaretrovirus closely related to the gibbon ape leukemia virus and induces leukemias and immune deficiencies associated with opportunistic infections, such as chlamydiosis. Here we characterize a KoRV newly isolated from an animal in a German zoo and show infection of human and rat cell lines in vitro and of rats in vivo, using immunological and PCR methods for virus detection. The KoRV transmembrane envelope protein (p15E) was cloned and expressed, and p15E-specific neutralizing antibodies able to prevent virus infection in vitro were developed. Finally, evidence for immunosuppressive properties of the KoRV was obtained.

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