Multiplicity-dependent kinetics and murine leukemia virus infection in Fv-1-sensitive and Fv-1-resistant cells.

Viral growth curves of N- and B-tropic murine leukemia viruses (MuLVs) were measured at varying multiplicities of infection (m.o.i.) on Fv-1-sensitive and -resistant cells. Both Fv-1-dependent and Fv-1-independent effects on the appearance of progeny virus were observed. At low m.o.i., growth curves in productively infected Fv-1-resistant cells were identical to those in Fv-1-sensitive cells with a latent period of 24–30 hr; under these conditions the virus-releasing Fv-1-resistant cells are doubly infected and show growth kinetics similar to those of the singly infected Fv-1-sensitive cells. The length of the viral latent period in both Fv-1-sensitive and -resistant cells was inversely related to m.o.i. and appeared to correlate with the fraction of multiply infected cells in a given population. The average yield per infected cell increased stoichiometrically as a function of m.o.i.