Elimination of A7 MNRs of AcMNPV fp25k delayed FP development and
improved virion occlusion
Abstract
Background: Insect specific DNA baculoviruses have been widely used for
biological control of insect pests to reduce cancers caused by chemical
application in agriculture and forestry and as vectors for high yield
exogenous protein expression. The most extensively studied and widely
used baculovirus is the Autographa californica multicapsid
nucleopolyhedrovirus (AcMNPV) due to its ability to replicate in many
permissive cells with high virus titer. During serial passage of AcMNPV
in permissive insect cells at high MOI, the fp25k mutates at a high
frequency leading to the development of the few polyhedra (FP) phenotype
with reduced polyhedra production and few virion occlusions in polyhedra
resulting in poor infectivity to insects. Method and results: We used
site-directed mutagenesis on wild type AcMNPV (AcP3) fp25k gene to
eliminate these hypermutable sites and produced a recombinant virus
AcP3-FPSDM and performed restriction fragment length polymorphism (RFLP,
as well as Western blot analysis to understand virion occlusion
efficacy. We compared fp25k stability between AcP3 and AcP3-FPSDM in Hi5
cells. Our experimental results showed that AcP3-FPSDM performed better
in virion occlusion efficiency. Conclusion: We showed that AcP3-FPSDM is
a better virus for researchers to apply in agriculture and forestry to
reduce chemical usage, thus cancer cases.