Sequence Analysis Of Helicase Gene And Subcloning Of Hrs Of Helicoverpa Armigera Single-nucleocapsid Nucleopolyhedrovirus

In order to investigate the genomic organization of the single-nucleocapid nucleopolyhedrovirus of Helicoverpa armigera, the EcoRI-N fragment located at 54.8-59.3 kbp of the viral genome was sequenced. The fragment contained 3762 bp helicase gene potentially encoding a protein with a molecular mass of 146 kDa. A late transcriptional motif, ATAAG, was found at -50nt upstream of the translational start codon ATG, while two TATA box was located at -112nt and -189nt upstream of ATG. A typical poly(A) signal was found at 12nt downstream of the translational stop codon. Compared HaSNPV helicase with the helicases of Autographa colifornica MNPV (AcMNPV), (Bombyx bori NPV (BmNPV), Lymantria dispar MNPV (LdMNPV)Spodoptera exigue MNPV (SeMNPV), Orgyia pseudotsugata MNPV (OpMNPV), and Xestia c-nigrum granuloviurs (XcGV), only 5 motifs (I, la, II, III, IV) were found conserved in baculovirus. The homology of the other two motifs (V and VI), which are also quite conserved in other helicases, were lower than 30%. The HaSNPV helicase protein had considerable amino acid sequence similarity with other baulovirus helicases (58%), and the highest (66%) with SeMNPV and the lowest with XcGV.(43%). HaSNPV helicase was the first helicase reported in single-nucleocapsid nucleopolyhedrovirusThere are 5 homologue regions (hrs) in HaSNPV genome which may play important roles in the viral replication. These 5 hrs were subcloned into plasmids which forms a base line for future functional study of HaSNPV hrs.