The comparative analysis of complete genome sequences from two South African betabaculoviruses: Phthorimaea operculella granulovirus and Plutella xylostella granulovirus

The complete genomes of two novel South African betabaculovirus isolates, namely Phthorimaea operculella granulovirus (PhopGV-SA) and Plutella xylostella granulovirus (PlxyGV-SA), were sequenced and compared to the respective reference isolates PhopGV-1346 and PlxyGV-K1. For both isolates, the genome size and guanine-cytosine (GC) content were similar to those of the respective reference genomes. However, numerous-single nucleotide polymorphisms (SNPs) and several insertions/deletions were observed, revealing the novelty of the isolates. Focus was placed on analysing the observed insertion/deletion events by conducting amino acid sequence alignments for all ORFs of each isolate against all respective ORFs in the corresponding reference isolate. Certain ORFs in each granulovirus genome contained significant insertion/deletion events. In addition, the PlxyGV-SA genome had single-nucleotide insertions/deletions in ORFs 38 and 49 that resulted in the extension and complete overlap of these two ORFs with the neighbouring ORFs 39 and 48, respectively. These novel isolates have significant potential for development and application as biopesticides in South Africa, and the genetic variations observed may have important implications for the biological activity and management of host resistance in the field.