The Genetic Polymorphism Analysis Of Gp64 And Hr5 Sequences Of Bombyx Mori Nuclearpolyhedrosis Virus In Guangxi

Bombyx mori nucleopolyhedrovirus(BmNPV)can cause blood-type abscess in silkworm and cause serious loss in silkworm industry.At the same time,BmNPV has been used in modern medical research and biotechnology as a good exogenous gene expression material.The homologous repeat region of BmNPV can be used as origin of replication of the virus genome,and it can be used as an enhancer to enhance gene expression efficiency,and is of great significance for the proliferation of BmNPV.Glycoprotein GP64,a receptor on the surface of the cell membrane,is an important structure for the virus to invade the host cell,which plays a key role in the spread of the virus in the host.In this study,BMNPV polyhedrons were purified from the samples collected from Guangxi,and the whole genome of BmNPV in Guangxi was extracted.The hr5 and gp64 gene from the homologous repeat region of the genome were cloned by sequencing and sequence analysis,the results were:1.The hr5 nucleotide sequence of 19 BmNPV strains in Guangxi showed different degrees of variation in the sequence length,which was mainly due to the absence and insertion of large segments.This difference occurs not only among different strains but also in the sequence of the two objectives of the same strain.Hr5 of 19 strains ranged from 165 bp to 999 bp,of which 10 strains had two different lengths and 2 strains absent all of thire homologous repeat sequence.The results indicated that hr5 was an unnecessary factor in virus replication,other hrs have functional compensation for the missing hr5 palindrome sequence.2.In this experiment,gp64 gene of 18 BmNPV strains was cloned and analyzed.The length of gp64 gene in two strains was the same as that of the T3 strain gp64 gene.There were 3 nucleotide deletions in 94-96 site of gp64 gene of two strains,the gp64 gene ORF of 10 strains was inserted into 6 nucleotides at 97-102 sites.It was found that the mutation site was located in the N-terminal signal peptide sequence of GP64 protein,and the amino acid of deletion and insertion is hydrophobic amino acid.The effect of the mutation on the structure and function of the region is still to be studied.3.According to the genetic evolution tree constructed by gp64 ORF of BmNPV strain,it is shown that the isolates from abroad are not in the same subpopulation as the isolates in the region,indicating that the gp64 gene has geographical characteristics to adapt to different living environment.4.The homology of nucleotide sequences between gp64 gene and hr5 sequence of BmNPV isolate was compared.The homology of gp64 gene sequence was above 97.5%,and the nucleotide homology of hr5 sequence was only above 66%.It can be concluded that gp64 is more conservative,but hr5 is not.