Baculovirus nucleocapsid aggregation (MNPV vs SNPV): an evolutionary strategy, or a product of replication conditions?

Lepidopteran nucleopolyhedroviruses are members of the Baculoviridae and have been categorized as having two morphotypes of occluded virions: multiple nucleocapsids or single nucleocapsids within the virion envelope. Although it is a definitive characteristic of specific viruses, it appears to lack a defined genetic basis and is independent of virus phylogeny. This review summarizes the factors that appear to influence this trait and the role that it may play in virus biology.