CONSTRUCTION OF A COMPLEMENTARY DNA LIBRARY OF PARELAPHOSTRONGYLUS TENUIS AND IDENTIFICATION OF A POTENTIALLY SERO-DIAGNOSTIC RECOMBINANT ANTIGEN

Newly developed serological tests for diagnosing parelaphostrongylosis in cervids, using the excretory-secretory products (ES) of the infective larvae of larvae of Parelaphostrongylus enzyme-linked immunosorbent assays (ELISAs), demonstrable Superiority over the traditional method of, larval recovery and microscopic identification. To generate a source of ELISA antigen by genetic engineering. we created it complementary DNA (cDNA) expression library by the reverse transcription of mRNA of P. tenuis adult worms and by ligation with the vector lambda-ZAP II. The library was screened using antisera produced in mice by immunization with a somatic antigen preparation of adult worms. Seventeen clones were isolated, sequenced, and checked for similarity to other DNA sequences in GenBank. A Previously identified parasite gene encoding an asparlyl protease inhibitor (API) was isolated front the cDNA library, subcloned and expressed using the pET expression vector to produce a glutathione S transferase (GSTI-His-S-tag-P. tenuis API fusion Protein (molecular weight = 63 kDa). An ELISA utilizing the API fusion protein as the coating antigen was used to serologically diagnose all white-tailed deer (WTD, Odocoileus virginianus 10 out of 10) that had been inoculated with a range of 6-150 L3 P. tenuis, indicating that the antigen may be useful serodiagnostic antigen for P. tenuis infection in this cervid species.