Chuviruses (order Jingchuvirales) are widespread and highly diversified negative-strand RNA viruses, originally discovered in invertebrate populations through metagenomic sequencing. In recent years, new chuviruses were identified as exogenous and endogenous viral elements (EVEs) in vertebrates such as marsupials, reptiles and marine animals calling into question their original host specificity.
In this study, we isolated Tasmanian devil chu-like virus from Tasmanian devil facial tumor disease (DFTD), a transmissible cancer that originates in the Schwann cells from the nervous system. We screened a total of 154 samples for the presence of viral RNA, including primary tumor tissues and tumor cell lines. A very high level of RNA copies was recorded in one tumor cell line, whose microscopic analysis revealed an atypical cell morphology. Infection of marsupial and mosquito cell lines was performed to identify the tropism of the chu-like virus. Sequencing and phylogenetic analyses revealed that the Tasmanian devil chu-like virus has a unique origin and is distinct from known invertebrate-associated viruses as well as all chuviruses found in vertebrates.
This study is the first to describe an infectious chuvirus isolate of mammalian origin, and revises our understanding of the host specificity of the Chuviridae, long considered to exclusively infect invertebrates. This work opens the way to a better understanding of the cellular and molecular mechanisms of chuviruses in vitro, it’s involvement in the peripheral nervous system, and decipher their evolutionary history among vertebrates and invertebrates.