Adeno-SV40 hybrid virus

View more Health videos

A type of defective virus particle in which part of the genetic material of papovavirus SV40 is encased within an adenovirus protein coat (capsid). Adenovirus progeny possesses properties different from those of the original parent adenovirus. It produces tumors in newborn hamsters; it replicates in monkey cell cultures; and although it does not produce infectious SV40, it causes monkey cells in culture to produce a new cellular antigen known to be specifically induced by SV40—the SV40 tumor, or T, antigen. The new virus stock therefore behaves like a hybrid. It has proved to be a population of two distinct kinds of virus particles. One kind of particle is a true adenovirus. The other particle is the adeno-SV40 hybrid, which has an adenovirus coat, but whose genetic material appears to consist of defective adenovirus type 7 DNA, representing about 85% of the adenovirus genome, covalently linked to a portion (about 50%) of an SV40 genome.

In this virus population the particle carrying the SV40 genetic material has been termed PARA (particle aiding replication of adenovirus). The PARA is considered an unconditionally defective virus, since under no known conditions can it reproduce itself except in a cell coinfected with adenovirus. The adenovirus is considered conditionally defective, since it can reproduce independently in human cells but not in monkey cells. See also Adenoviridae; Animal virus.