Transmission of Koala Retrovirus from Parent Koalas to a Joey in a Japanese Zoo
Md Abul Hashem, Fumie Maetani, Mohammad Enamul Hoque Kayesh, Taiki Eiei, Kyoya Mochizuki, Ayaka Ito, Hiroko Sakurai, Takayuki Asai, Kyoko Tsukiyama–Kohara
Abstract
KoRV is unique among retroviruses in that one strain (KoRV-A) is undergoing endogenization, whereas the other main subtype (KoRV-B) and another subtype (KoRV-C) are reportedly exogenous strains. Its transmission and pathogenesis are of interest in the study of retroviruses and are crucial for any conservation strategy geared toward koala health. This study provides new evidence on the modes of KoRV transmission from parent koalas to their joey. We found vertical transmission of KoRV-A, confirming its endogenization, but with closer conservation between the joey and its sire than its dam (previous reports on joeys are rare but have postulated dam-to-joey vertical transmission). This is also the first report of a KoRV-B-negative joey from KoRV-B-positive parents, contrasting with the few previous reports of 100% transmission of KoRV-B from dams to joeys. Thus, the results in this study give some novel insights for the transmission mode of KoRV.