Identification of insertion and deletion genes in Autographa californica nucleopolyhedrovirus variants isolated from Galleria mellonella, Spodoptera exigua, Spodoptera litura and Xestia c-nigrum
T. Yanase et al., Identification of insertion and deletion genes in Autographa californica nucleopolyhedrovirus variants isolated from Galleria mellonella, Spodoptera exigua, Spodoptera litura and Xestia c-nigrum, VIRUS GENES, 21(3), 2000, pp. 167-177
The genomic DNA of four Autographa californica multinucleocapsid nucleopoly
hedrovirus (AcMNPV) variants isolated from Galleria mellonella, Spodoptera
exigua, Spodoptera litura and Xestia c-nigrum was analyzed in comparison wi
th the AcMNPV E2 strain. Restriction endonuclease analysis revealed a delet
ion and an insertion in collinear regions of the four variants. Polymerase
chain reaction analysis indicated that, in the four variants, the deletion
occurred in the region corresponding to AcMNPV C6 ORF86 (pnk/pnl). Also the
insertion, with a length of approximately 1.1 kb, was commonly identified
in the fragments corresponding to the PstI-J fragment (18.5 m.u.-21.2 m.u.)
of AcMNPV E2. Sequencing analysis of the variant from S. litura showed tha
t the insertion contains an additional open reading frame encoding 322 amin
o acids between homologues of AcMNPV ORF30 and ORF31 (the superoxide dismut
ase gene). This ORF has 82.8% amino acid identity to Bombyx mori NPV T3 ORF
22 (bro-a, one of the baculovirus repeated ORFs) and thus, it was named Sp
lt-bro-a. Southern blot hybridization study indicated that the other three
variants also contain Splt-bro-a homologue. In addition, the labeled Splt-b
ro-a gene weakly hybridized to the PstI-D fragment (99.0 m.u.-8.0 m.u.) of
AcMNPV E2. This fragment contains AcMNPV ORF2, a member of bro family. The
signal was also observed on the corresponding fragment of the four variants
. This result suggested that two bro genes are present in the four variants
, although AcMNPV E2 and C6 are known to contain a single bro gene.