GROWTH IMPAIRMENT RESULTING FROM EXPRESSION OF INFLUENZA-VIRUS M2 PROTEIN IN SACCHAROMYCES-CEREVISIAE - IDENTIFICATION OF A NOVEL INHIBITOR OF INFLUENZA-VIRUS

The gene encoding M(2), the ion channel-forming protein of influenza virus ii was expressed under the control of an inducible promoter in Saccharomyces cerevisiae. By using single and multicopy plasmids containing GAL promoter-M(2) fusions, a correlation was observed between plasmid copy number and growth in medium inducing M(2) expression. Cells expressing M(2) from multicopy plasmids have reduced growth rates, suggesting that high levels of M(2) are toxic to growth. The addition of amantadine, a compound known to block the ion channel activity of certain M(2) alleles, restores the growth rates to wild-type levels in cells expressing an amantadine-susceptible allele of M(2) but not an amantadine-resistant allele of M(2), suggesting that M(2) expression in S. cerevisiae results in the formation of functional M(2) ion channels. Measurements of extracellular acidification by microphysiometry suggest that proton efflux in M(2)-expressing cells is altered and that the addition of amantadine permits the reestablishment of the proton gradient. The growth impairment phenotype resulting from M(2) expression was used to develop a high-capacity screening assay which identified a navel inhibitor possessing an antiviral profile similar to that of amantadine.