AN ABUNDANTLY EXPRESSED HEMOLYMPH GLYCOPROTEIN ISOLATED FROM NEWLY PARASITIZED MANDUCA-SEXTA LARVAE IS A POLYDNAVIRUS GENE-PRODUCT

Cotesia congregata polydnavirus (CcPDV) is essential for successful pa rasitism of Manduca sexta larvae by the braconid wasp C. congregata. C cPDV virions are present in large numbers in the oviducts of C. congre gata and injected with eggs into the hemocoel of M. sexta larvae durin g parasitization. Injection of sucrose density purified virions into n onparasitized larvae causes several of the parasitism-induced alterati ons in the physiology of host larvae that occur as a result of natural parasitism, including the synthesis of novel hemolymph proteins and a brogation of the host's immune response against the developing parasit es. One of these proteins, early-expressed protein 1 (EP1), is a 190-k Da molecule which constitutes up to 5% of the total hemolymph protein by 24 hr following oviposition by the wasp. Using N-terminal sequence data for EP1 to construct primers for use in the polymerase chain reac tion, we amplified and cloned a cDNA corresponding to the gene encodin g EP1. This cDNA hybridized to DNA of the CcPDV genome, but not to DNA isolated from M. serta larvae, suggesting that EP1 is a CcPDV gene pr oduct. A cDNA clone was isolated from an expression library generated from RNA extracted from newly parasitized M. serta larvae. Sequence an alysis of the cDNA clone revealed the presence of an open reading fram e of 819 bp encoding a protein of 30.7 kDa. in vitro transcription/tra nslation of the cDNA clone produced a protein of approximately 31 kDa, which was immunoprecipitated by EP1-specific polyclonal antiserum gen erated against purified deglycosylated EP1. EP1-like sequences also we re amplified from male wasp genomic DNA, suggestive of integration of EP1-like sequences in the genome. This report constitutes the first ev idence that a specific protein isolated from a parasitized host insect is a wasp polydnavirus gene product. (C) 1994 Academic Press, Inc.