Cloning and sequence analysis of gp64 gene in Bombyx mori nucleopolyhedrovirus Guangxi isolates

ObjectiveThis research aimed to understand gp64 gene conservation of Bombyx mori nucleopolyhedrovirus (BmNPV) Guangxi isolates and master the specific site of mutation, which could provide reference for study of intraspecific microevolution pattern of nucleopolyhedrovirus(NPV). MethodThe gp64 genes of 19 BmNPV strains collected from dif-ferent sericultural areas in Guangxi were cloned and sequenced. Homology and the mononucleotide polymorphisms of gp64 complete open reading frame(ORF) were analyzed, and phylogenetic tree of gp64 gene was established. ResultThe gp64 gene ORF sequences of Guangxi BmNPV strains were not consistent, showing three types as 1590 nt, 1593 nt and 1599 nt. The diversities were caused by GCG deletion in position 94-96, and GCGCCG insertion in position 97-102. inser-tion mutations of nucleotide only happened in Guangxi BmNPV strains. Only GXSL strain shared 100.0%homologies in nu-cleotide and deduced amino acid sequence with T3 strain. The other 18 strains shared 98.5%-99.2% homology in nu-cleotide sequence and 98.7%-99.6% homology in deduced amino acid sequence with T3 strain. All 19 Guangxi BmNPV strains were separated into two clades(clade Ⅰand clade Ⅱ). Among them, 11 strains were included in clade Ⅱ sep-arately and 7 strains were included in a sub-clade of cladeⅠ. Synonymous substitutions occurred in several positions of gp64 genes from Guangxi BmNPV strains, showing certain regularity.ConclusionThe gp64 genes of Guangxi BmNPV strains em-bodies genetic diversity and independent genetic evolution. The insertion mutation indicates territorial characteristic.