The effect of inoculum concentration on the development of the nuclear polyhedrosis virus of Autographa californica in TN-368 cells

A multiplicity of infection (m.o.i.) of 25 or 50 mean tissue culture-infective doses (TCID₅₀) of Autographa californica NPV per cell of a TN-368 cell line initially infected >90% of attached cells whereas an m.o.i. of 1 or 5 TCID₅₀/cell initially infected <50% of the cells. An immunoperoxidase technique first detected nucleocapsid antigens at 6–12 hr postinfection (PI) and polyhedral protein antigen 12–18 hr PI, which was followed 4–6 hr later by polyhedra formation. At a m.o.i. of 50, the extracellular virus titer (nonoccluded progeny virus) increased between 6 and 12 hr PI while at m.o.i. of 25, 5, and 1, the titer increased at 12–18 hr PI. Antisera to nucleocapsids and polyhedral protein were specific and also failed to react with viral envelope antigens.