Abstract: In order to provide the theory base for the utilizing of SpltMNPV isolates, the homologous analysis of gene sequences among Spodoptera litura multinucleocapsid nucleopolyhedrovirus (SpltMNPV) isolates or between SpltMNPV and S. littoralis nucleopoly hedrovirus (SpliNPV) were studied. According to the complete genome sequence (AF527603) of SpltMNPV and the sequence (AF527603) of SpliNPV Not I-D fragment deposited in GenBank, five pairs of primers were designed and used. ORF39-ORF42 and ORF119-ORF124 of SpltMNPV three isolates, i.e., Fukuoka (Fu), Egypt (Eg) and Ogasawara (Og), were amplified by PCR. The comparison of ORF39-ORF42 and ORF119-ORF124 nucleotide and amino acid sequences of SpltMNPV isolates, i.e., Chinese isolate (Zh), Eg, Fu and Og, with those of SpliNPV indicated that the similarity between Zh and Og, or between Eg, Fu and SpliNPV is as high as over 99%, but the similarity between Zh and Eg, Fu, SpliNPV or between Og and Eg, Fu, SpliNPV is as low as 74%. This means that among SpltMNPV three genotypes, the homology between B and C is high, A and B or C is low, but the homology between A and SpliNPV is high. The homology of the isolates within the same genotype is high too. The neighbor-joining tree based on amino acid sequences of the ecdysteroid UDP-glucosyltransferase (EGT) in 29 nucleopolyhedroviruses and 10 granuloviruses was established. In the phylogenetic tree, EGTs of Eg and Fu clustered into one clade with SpliNPV, which belonged to a larger clade that included the other SpltMNPV isolates. Based on the sequence alignment and the phylogenetic tree of baculovirus EGTs, it is inferred that Eg and Fu are the isolates of SpliNPV, but Og is the isolate of SpltMNPV.

Key words: Spodoptera litura multinucleocapsid nucleopolyhedrovirus, isolate, gene, sequence analysis, homology, phylogenetic development