Effect of pH on Cytopathogenicity of Orphan Viruses.

Abstract

The cytopatho-genic titer of certain orphan viruses in monkey kidney tissue culture was depressed or delayed when grown in the presence of a medium which developed an acid pH. This phenomenon was termed the "pH effect". Sensitivity to the "pH effect" appeared to be strain characteristic. Neutralization of tissue culture acidity with an excess of NaHCO3, or prevention of acid formation by omission of glucose restored optimal viral cytopathogenicity. The "pH effect" tended to be less evident with rapidly cytopathogenic agents or in the presence of large inocula. Rate of primary isolation of orphan virus from stool suspensions was substantially decreased when acid producing tissue culture medium was used.