Reciprocal infectivity of nuclear polyhedrosis viruses of the cabbage looper and alfalfa looper

Abstract

The cross-infectivity of two distinct nuclear polyhedrosis viruses, one isolated from the cabbage looper, Trichoplusia ni, which has the virions embedded singly in the polyhedral matrix; and one isolated from the alfalfa looper, Autographa californica, in which the virions are embedded multiply, was investigated. The multiply embedded virus was at least four times more pathogenic than the singly embedded virus to the cabbage looper and was also highly infective to the alfalfa looper. In contrast, the singly embedded cabbage looper virus was less infective to both the original and the alternate hosts. Cross-infectivity of the viruses was confirmed with both light and electron microscopes.