Retrovirus historical discoveries may help modern-day outbreaks

As modern-day Australian koala bears face extinction from an AIDS-like retrovirus, scientists discover that retrovirus families and varieties have been operating among mammalian populations for 100 million years.

Retroviruses are among the most cunning and frustrating creatures in the known universe. They operate in a manner by which they replicate the specific DNA of the host they have just penetrated, incorporating themselves into the very genome of the host - effectively creating the ultimate experience in stealth invasion and reproduction, as any given immune system will not defend against its own DNA infrastructure. HIV is the most infamous of retroviruses, having killed millions of people all over the world and having threatened the health and well-being of entire continents. But looking beyond the more anthropocentric perspectives on retroviruses, the story of their history and their impact is surprisingly dramatic. In fact, the modern-day Australian koala bear is facing extinction due to the replication of a successful retrovirus. While this may serve as a reminder to human beings on the need to eradicate HIV, it may also help explain other mammalian extinctions that have occurred over time. Scientists have recently discovered that retroviruses have been a challenge to mammalian populations since the very appearance of mammal species on the planet 100 million years ago. The discovery of the remains of an ancient HIV-like variety embedded in the genome of a two-toed sloth demonstrates the long-standing relationship between this stealthy family of viruses and our mammalian ancestors. Scientists were surprised at the finding, previously believing that retroviruses had been around for 15 million years. The breadth of the history of the retrovirus varieties also helps to understand their evolutionary sophistication. 100 million years is a good amount of time for any species to perfect a function or a series of successful reproductive behaviors. The findings help researchers understand more about how mammals fare against complicated viral organisms and may also shed light on how dangerous cross-species pandemics - such as H1N1 - are caused.