A koala retrovirus, or KoRV, has been rolling through koala populations in Australia from the north to south. It’s passed among the animals like other types of viruses — what’s called horizontal transmission — but it has also started to wriggle its way into the germline. Koalas are now being born with the virus already integrated into their genomes — vertical transmission.
The virus has left koalas susceptible to infections and types of cancer. But it’s also extended scientists an opportunity to research the transition as a virus goes from exogenous (external) to endogenous (built into the genome), a process that hasn’t played out in humans in hundreds of thousands of years. It’s like a marsupial-enabled time machine.
In a new paper, [geneticist William] Theurkauf and colleagues report what appears to be an initial immune-like response that cells deploy to recognize viruses as foreign.
It’s not always effective, given that viruses do make it into the genome. But the system that the researchers described works by distinguishing something foreign as different from the self, and tries to block it.
“We think we’ve stumbled on this innate recognition response,” Theurkauf said.
Read full, original post: What a koala virus tells us about the human genome — and how it defends itself against viral invasions