Suppressing Cytokines Won't Protect Against Avian Flu

Study suggests therapeutic strategies should target viral replication, not cytokine response

WEDNESDAY, July 18 (HealthDay News) -- Chemical suppression of the 'cytokine storm' that occurs after infection with the Avian influenza virus does not prevent death, according to the results of a study in mice published online July 17 in the Proceedings of the National Academy of Sciences Early Edition.

Robert G. Webster, Ph.D., from St. Jude Children's Research Hospital in Memphis, Tenn., and colleagues studied whether inhibition of the cytokine response could protect against death due to the A/Vietnam/1203/04 (H5N1) virus, which was isolated from a recent human fatality.

The investigators show that mice deficient in the cytokines TNF-α, IL-6, or CC chemokine ligand 2 still succumbed to infection with the virus as do wild-type mice that have been pretreated with glucocorticoids. Inhibiting cytokines prevented weight loss during infection to some extent, but had no effect on mortality.

"These data suggest that early inhibition of viral replication is more promising than inhibition of the cytokine response in promoting host survival of H5N1 influenza virus infection," the authors write. "It is important to note that, for certain antiviral drugs, there is a narrow time frame during which their administration will be effective. Thus, continued research on targeting host responses to H5N1 is justifiable."

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