Abstract
The stability of the in vitro infectivity of the non-occluded virions (NOV) of the A. californica nuclear polyhedrosis virus (Ac-NPV) was tested. Exposure of Ac-NPV NOV to solutions ranging from pH 7.5-11.4 with molarities of 0.1-0.001 showed that infectivity was most stable in 0.001 M, pH 7.5, Tris(hydroxymethyl)aminomethane (Tris)-HCl buffer. Infectious NOV could be concentrated by precipitation with 50% saturated (NH4)2SO4 or 9% (wt/wt) polyethylene glycol 4000. Treatment of concentrated preparations with 1 M-urea did not affect infectivity or the centrifugal properties of the NOV. NOV were partially purified by centrifugation through a sucrose underlay. [Trichoplusia ni ovarian cells were used].