Development of highly sensitive assays for detection of genetic variation in key Helicoverpa armigera nucleopolyhedrovirus genes.

Information on the degree of genetic variation in key Helicoverpa armigera nucleopolyhedrovirus (HearNPV) genes is limited as the currently used techniques lack the detection sensitivity required to identify multiple genetic variants within a baculovirus population. To facilitate the detection and study of genetic variation within HearNPV populations, denaturing gradient gel electrophoresis (DGGE) assays were designed for a core baculovirus gene (DNA polymerase) and two core lepidopteran-specific baculovirus genes (dbp1 and me53). The gene-specific DGGE assays were capable of producing unique, sensitive and rapid genetic fingerprints of the genetic variants within a HearNPV population and were sensitive enough to detect as many as 26 genetic variants within a single portion (<500bp) of a HearNPV gene. In addition to enabling the detection of the genetic variation in key HearNPV genes, the DGGE assays allowed seven geographically distinct HearNPV populations to be differentiated on the basis of their DGGE profiles. The developed DGGE assays will be useful in studies that aim to elucidate the generation and maintenance of genetic diversity in HearNPV.