Identification and characterization of odv-e25 of Spodoptera litura multicapsid nucleopolyhedrovirus

Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) odv-e25 is 684 bp long, potentially encoding 227 amino acids with a predicted molecular weight of 24.9 kDa. Homology analysis indicated that SpltMNPV ODV-E25 has 35-65% amino acid identity with that of other known baculoviruses. RT-PCR results revealed that the odv-e25 is transcribed actively at the late stage of infection and the mRNA start site was mapped within a consensus baculovirus late promoter sequence (TTAAG). Western blot analysis of odv-e25 expression with an antiserum made against 6 x His tagged ODV-E25 expressed in Escherichia coli indicated that it was present as a doublet of approximately 27 kDa from 24 h through 96 h in SpltMNPV-infected Spli-221 cells. Similar results were seen on Western blots of Spodoptera exigua (Se)MNPV-infected Se301 cells. Immunofluorescence analysis showed that ODV-E25 was predominantly present in the cytoplasm of SpltMNPV-infected cells and localized to the envelopes of occlusion-derived virus.