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

The gene encoding M(2), the ion channel-forming protein of influenza v irus ii was expressed under the control of an inducible promoter in Sa ccharomyces cerevisiae. By using single and multicopy plasmids contain ing GAL promoter-M(2) fusions, a correlation was observed between plas mid copy number and growth in medium inducing M(2) expression. Cells e xpressing M(2) from multicopy plasmids have reduced growth rates, sugg esting that high levels of M(2) are toxic to growth. The addition of a mantadine, a compound known to block the ion channel activity of certa in M(2) alleles, restores the growth rates to wild-type levels in cell s expressing an amantadine-susceptible allele of M(2) but not an amant adine-resistant allele of M(2), suggesting that M(2) expression in S. cerevisiae results in the formation of functional M(2) ion channels. M easurements of extracellular acidification by microphysiometry suggest that proton efflux in M(2)-expressing cells is altered and that the a ddition of amantadine permits the reestablishment of the proton gradie nt. The growth impairment phenotype resulting from M(2) expression was used to develop a high-capacity screening assay which identified a na vel inhibitor possessing an antiviral profile similar to that of amant adine.