Influence of host cells on the infectivity and neutralizability echovirus type 4 (Pesascek)

The heterogeneity of echovirus type 4 (strain Pesascek) is documented. This strain had a higher EOP on RD cells than on GMK-AH1 or primary green monkey kidney cells. It was more effectively neutralized in tests on RD cells than on GMK-AH1 cells. The latter phenomenon was analyzed on materials of Pesascek virus after banding in density gradients. A minor fraction was found that resisted neutralization as tested on either RD or GMK-AH1 cells. Another fraction containing the main peak of infectivity was rendered almost harmless to RD cells by neutralizing antibody, while still infecting GMK-AH1 cells. Filtration diminished the non-neutralizable fraction of virus, as did treatment of virus with disrupted membranes. The validity of the theory which holds aggregation of virus responsible for the non-neutralizable fractions, as well as the role played by different host cells for neutralizability, are discussed.