MicrobiologyBytes

Since West Nile virus (WNV) surprised everyone by breaking out in the USA in 1999, it has become known that one of the characteristic features of WNV in the Western Hemisphere is the occurrence of pathogenic lineage I strains, which are different from typically avirulent lineage II strains found in the traditional home range of the virus. This high pathogenesis, and consequently the number of deaths associated with WNV in the USA, has always been something of a mystery. A recent paper in the Journal of Virology explains the ability of the type I strains to cause this pathogenesis.

By comparing a type I isolate from Texas and an avirulent type II isolate from Madagascar, workers at the University of Texas Southwestern Medical Center in Dallas showed that the difference in behaviour is due to interferon resistance in the type I strains. Normally, West Nile virus infection of cells induces components of the JAK-STAT signalling pathway required for interferon activity. The pathogenic strain of the virus was able to prevent phosphorylation of the STAT1 and STAT2 components of the JAK-STAT pathway, so blocking the antiviral effect of interferons. This new finding gives rise to the hope that future anti-West Nile virus therapies could be devised which work by modulating the interferon response in infected patients, rather than by attacking the virus directly (Keller BC, et al. Resistance to alpha/beta interferon is a determinant of West Nile virus replication fitness and virulence. J Virol. 2006 80: 9424-34).

This entry was posted on Monday, November 6th, 2006 at 12:58 pm and is filed under Health, Medicine, Microbiology, Parasitology, Science, Virology. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.