Envelope gene capture and insect retrovirus evolution: The relationship between errantivirus and baculovirus envelope proteins

In this report the evolution of insect retroviruses (errantiviruses) is reviewed with particular emphasis on the relationship between their env protein and a baculovirus envelope fusion protein. In addition, selected features of the env protein from the errantivirus Dme17.6V are examined. These include characterization of the 21 amino acid predicted fusion peptide sequence that is highly homologous to a region of baculovirus envelope fusion proteins. We found that, although this sequence could not substitute for the homologous sequence in the baculovirus LD130 envelope fusion protein, by changing four amino acids, the hybrid construct became active for low-pH induced cell fusion. In addition, a Dme17.6V env-egfp construct was found to localize to cell membranes.