Intra-specific and inter-specific recombination of tortricid-specific granuloviruses during co-infection in insect larvae.

Intra-specific recombination between two genotypes of the Cryptophlebia leucotreta granulovirus (CrleGV), namely CV3 and CV4, was studied by mixed infection experiments of larvae of C. leucotreta, followed by in vivo cloning and DNA restriction enzyme analyses of isolated progeny viruses. As a prerequisite for these studies a comparative restriction map for of CV3 and CV4 was constructed for eight restriction enzymes. The mixed infection experiments resulted in the isolation of the recombinant CrleGV CVR, which contained restriction sites typical for both parental viruses. Inter-specific recombination between two different granulovirus species, namely CrleGV CV3 and Cydia pomonella granulovirus (CpGV), was analogously investigated by mixed infections of larvae of C. leucotreta. A survey of more than 300 isolated CrleGV and CpGV clones did not reveal any recombinant, which indicated an extremely low recombination frequency in these experiments. By using a specific PCR approach, however, chimerical fragments from the highly conserved granulin gene sequence could be observed in DNA preparations of virus progeny. Cloning and sequencing indicated recombination between CrleGV and CpGV DNA. Our results suggest that recombination between granulovirus genotypes and granulovirus species result in eventually viable viruses and may contribute to the genetic diversity in this virus group.