Interleukin-8 selectively enhances cytopathic effect (CPE) induced by positive-strand RNA viruses in the human WISH cell line.

Interleukin-8 (IL-8), a proinflammatory chemokine, is induced by viruses and appears in circulation during viral infections. We found that IL-8 enhanced cytopathic effect induced by the positive strand RNA virus, encephalomyocarditis virus (EMCV), in the human WISH cell line. The enhancement was dependent on IL-8 dose and virus dose and was reversible by specific monoclonal antibodies to IL-8. The chemokine was also able to increase EMC viral RNA synthesis and infectious virus yield. This IL-8 enhancing action was not observed in the case of the negative strand RNA virus, vesicular stomatitis virus (VSV), in WISH cells. We examined the activity of constitutive 2',5'-oligoadenylate synthetase (OAS), a pathway that was implicated in protection from EMCV but not VSV. The IL-8 action in EMCV-infected cells, unlike VSV-infected cells, was associated with decreased OAS activity in a manner that was independent of OAS gene expression. Understanding mechanisms of cytokine enhancement of viral activity may lead to novel ways to control viral infections.