Previous reports have indicated that p34.8 (gp37) may be essential for the
replication of Autographa californica nucleopolyhedrovirus (AcMNPV) because
no virus with inactivated p34.8 was isolated. We have ascertained the requ
irement for this gene by attempting to inactivate it with a large insertion
[the gene encoding GFP (green fluorescent protein)] or by deleting all the
conserved domains from the open reading frame (ORF). The gene encoding GFP
was inserted into the Nod site of the p34.8 ORF and a viral plaque contain
ing the insertion was propagated in SF-21 cells. Similarly, 531 bp (Notl-Xb
al) containing all conserved domains were deleted from the ORF, All mutants
were authenticated by PCR amplification, restriction endonuclease analysis
, DNA sequencing, and Southern and Northern blot analysis. It was found tha
t inactivation of p34.8 of AcUW1-LacZ (AcMNPV containing a lacZ gene in the
p10 locus) had no effect on the biological property of virus, such as viru
lence and kinetics. These two independent methods showed that p34.8 is not
essential for replication and that this locus could provide another site fo
r the engineering of baculoviruses.