Characterization of a virus isolated from a case of human infectious hepatitis

A new viral agent, isolated from the serum of an infectious hepatitis patient and designated as Agent II-B, was extensively studied in in vitro and in vivo systems. Agent II-B multiplied well in primary and serial animal cell cultures and in embryonated hen's eggs. Quantal and quantitative infectivity assays were performed in monolayers of African green monkey kidney cells. Effective concentrations of 5-iodo-2-deoxyuridine and guanidine hydrochloride did not inhibit the multiplication of Agent II-B, although 2-hydroxybenzyl-benzimidazole was an effective inhibitor. Essential lipids were not detected. The diameter of the agent is 16-25 nm and its buoyant density in CsCl equilibrium density gradients was 1.35 gm/ml. Neutralization test results did not reveal antigenic relatedness between Agent II-B and known human picornaviruses. Apparently, this new viral agent is a picornavirus which possesses the capacity to multiply in unexpectedly diverse cell types.