Virus envelope acquisition of nuclear polyhedrosis virus in vitro

There have been several reports concerned with the replication and morphogenesis of insect baculoviruses during the past decade [1--7]. While there is general agreement as to the assembly of the virus on the basis of electron microscopic studies, there are still questions regarding the details of the replicative mechanisms, such as the acquisition of the virus envelope. Three possible ways have been proposed to describe envelope formation of nuclear polyhedrosis virus: (i) acquisition of budding through the nuclear membrane; (ii) acquisition of budding through the plasma membrane, and (iii) de novo formation within the nucleus. This paper briefly describes the observations made on the acquisition of a virus envelope by the cotton bollworm virus (Heliothis armigera), a nuclear polyhedrosis virus, in primary hemocyte cultures. Swirling hair-like clusters, hitherto unreported, were observed in association with virogenic stroma and nucleocapsids in the nuclei of infected cells. It is postulated that the formation of the hair-like structure may be involved in the process of envelopment of the virus.