terça-feira, 14 de agosto de 2012
What Makes Bat Viruses So Deadly?
When it comes to harboring viruses deadly to humans, bats are grand champions. The flying mammals are the reservoir for everything fromrabies to Ebola. Now, scientists have found a new virus hosted by bats, one that doesn't seem to be able to cause disease in other animals. The discovery may provide clues to what enables some viruses to cause severe disease.
The new Cedar virus is named after the town of Cedar Grove in Queensland, Australia, where it was found in 2009. Australian scientists discovered it in urine from bat colonies while screening for the Hendra virus. Hendra and its close viral cousin Nipah are henipaviruses that kill between 40% and 100% of the animals and humans they infect, making them among the most deadly viruses known. In the laboratory, the team found that Cedar virus could infect ferrets and guinea pigs—the animals produced infection-fighting antibodies to the virus. However, they did not become clinically ill. What's more, there are no recorded cases in humans.
A genetic analysis revealed that the Cedar virus is also a henipavirus—but with a key difference. Unlike other henipaviruses, the Cedar virus does not produce what is called V protein. The V protein gives the Hendra and Nipah viruses the ability to evade the human immune system, making them deadly. By comparing the lethal and benign henipaviruses, "We may gain insights into what makes Hendra so dangerous," says molecular virologist Glenn Marsh of the Australian Animal Health Laboratory in Geelong. Marsh and his colleagues report their findings in a paper appearing online today in PLoS Pathogens.
The team's focus on the V protein is "intriguing, and deserves to be followed up," says Benhur Lee, a microbiologist at the University of California, Los Angeles, David Geffen School of Medicine.
Marsh says his team plans to conduct follow up experiments. "Using genetic engineering it may be possible to modify the virus so it does produce the V protein or alternatively put the gene from Hendra virus into Cedar virus and see if that makes the virus pathogenic." Lee warns, however, that even if the V gene does help make henipaviruses so dangerous, it's probably not the only gene responsible.