New Method for Differentiation of Granuloviruses (Betabaculoviruses) Based on Real-Time Polymerase Chain Reaction (Real-Time PCR)

Baculoviridae is a highly diverse family of rod-shaped viruses with double-stranded DNA. To date, almost 100 species have had their complete genomic sequences deposited in the GenBank database, a quarter of which comprises granuloviruses (GVs). Many of the genomes are sequenced using next-generation sequencing, which is currently considered the best method for characterizing new species, but it is time-consuming and expensive. Baculoviruses form a safe alternative to overused chemical pesticides and therefore there is a constant need for identifying new species that can be active components of novel biological insecticides. In this study, we have described a fast and reliable method for the detection of new and differentiation of previously analyzed granulovirus species based on a real-time polymerase chain reaction (PCR) technique with melting point curve analysis. The sequences of highly conserved baculovirus genes, such as granulin and late expression factors 8 and 9 (lef-8 and lef-9), derived from GVs available to date have been analyzed and used for degenerate primer design. The developed method was tested on a representative group of eight betabaculoviruses with comparisons of melting temperatures to allow for quick and preliminary granulovirus detection. The proposed real-time PCR procedure may be a very useful tool as an easily accessible screening method in a majority of laboratories.