LOCATION AND NUCLEOTIDE-SEQUENCE OF THE GENE ENCODING THE VIRAL ENHANCING FACTOR OF THE TRICHOPLUSIA-NI GRANULOSIS-VIRUS

The gene encoding the viral enhancing factor (VEF) of Trichoplusia ni granulosis virus has been cloned from a lambda-gt 11 expression library, and the complete nucleotide sequence determined. The VEF gene encodes a protein with a predicted M(r) of 104K which does not share homology with any previously reported proteins. A possible promoter is located four nucleotides upstream of the initiation codon and represents a consensus baculovirus late promoter (ATAAG). This has been confirmed by the identification of VEF mRNA in Northern blots of infected larvae 6 days but not 3 days post-infection. Using an anti-VEF-TrpE polyclonal antiserum in Western blots of dissolved viral occlusion bodies, related proteins have been identified in both Pseudaletia unipuncta granulosis virus Hawaiian strain (PuGV-H) and Heliothis armigera GV (HaGV), but not in Erinnyis ello GV (EeGV), T. ni singly enveloped nuclear polyhedrosis virus (TnSNPV) or Autographa californica multiply enveloped NPV (AcMNPV). Similar results were obtained with Southern blots of genomic digests. DNA fragments homologous to an internal portion of the VEF gene were found in PuGV-H and HaGV but not in EeGV, TnSNPV or AcMNPV.