Blacksburg, Va. -- Mosquitoes are like Typhoid Mary. They can spread viruses which cause West Nile fever, dengue fever, or yellow fever without themselves getting sick. Scientists long thought that the mosquito didn't care whether it had a virus hitchhiker, but have now discovered, "There is a war going on," said Zach Adelman, assistant professor of entomology at Virginia Tech.
The war is at the cellular level, between the host and invading RNA the strands of code that produce different kinds of viral proteins.
The mediators that balance the interactions between mosquito and virus are virus-derived short-interfering RNAs (viRNAs), which are generated by the mosquito's immune response to infection. "If the mosquito is not able to cut up the virus genome into viRNAs, an otherwise invisible infection becomes fatal-- for both the mosquito and the virus. In other words, to complete the circle and be transmitted back to a vertebrate host, the virus must submit, to some extent, to the mosquito's antiviral response," said Kevin M. Myles, assistant professor of entomology at Virginia Tech.
Myles, Adelman, and their Ph.D. students, who are with the Vector-borne Disease Research Group at Virginia Tech, report their findings about the war between the mosquito immune system and viruses in the Proceedings of the National Academy of Sciences (PNAS), scheduled to appear in the Online Early Edition the week of December 1-5, 2008. The article is, "Alphavirus derived small RNAs modulate pathogenesis in disease vector mosquitoes," by Myles; Michael R. Wiley of Ambler, Pa.; Elaine M. Morazzani of Vienna, Va.; and Adelman.
"We asked, "How is it that the mosquito can control the pathogenicity of these viruses so well, while humans with our more complex immune systems, often develop disease when infected?" said Myles.
The researchers used the arthropod-borne virus Sindbis -- a model virus for a wide variety of mosquito-transmit
|Contact: Susan Trulove|