Mr. Strand et al., 2 MICROPLITIS-DEMOLITOR POLYDNAVIRUS MESSENGER-RNA EXPRESSED IN HEMOCYTES OF PSEUDOPLUSIA-INCLUDENS CONTAIN A COMMON CYSTEINE-RICH DOMAIN, Journal of virology, 71(3), 1997, pp. 2146-2156
Microplitis demolitor is a polydnavirus-carrying wasp that parasitizes
the larval stage of Pseudoplusia includens. A previous study indicate
d that ICI. demolitor polydnavirus (MdPDV) infects primarily hemocytes
in parasitized hosts. Thereafter, several alterations that compromise
the immune response of P. includens toward the developing parasitoid
occur in hemocytes. In this study, we identified two MdPDV mRNAs (1.0
and 1.5 kh) expressed in P. includens hemocytes that have homology; to
the viral genomic clone pMd-2. Corresponding 1.0- and 1.5-kb cDNA clo
nes (MdPi455 and MdPi59) were isolated from an MdPDV-infected hemocyte
cDNA library. Nucleotide sequence analysis of the cDNA clones confirm
ed that the 1.5- and 1.0-kb mRNAs have significant regions of homology
. Sequence alignment revealed that the gene, OMd1.0, encoding the 1.0-
kb mRNA is present in pMd-2. This gene contains mo introns and three e
xons that agree with the sequence for MdPi455. In contrast, the 1.5-kb
mRNA is likely encoded by a related gene located on the same MdPDV ge
nomic DNA as is OMd1.0. The predicted peptide sequences for the 1.0- a
nd 1.5 kb transcripts contain a cysteine-rich region at their 5' ends
that have some similarity with epidermal growth factor-like motifs. Hy
bridization studies revealed that both mRNAs are expressed in granular
cells and plasmatocytes, the primary classes of hemocytes involved in
defense against M. demolitor and other parasites.