Immunodiagnosis of swine trichinellosis.

A rapid, sensitive and specific serologic test has been developed for the diagnosis of swine trichinellosis. The ELISA based test utilizes L1 stichosome antigens recovered as excretory-secretory (ES) products from in vitro cultivated muscle larvae. Field studies conducted with 20,000 commercial swine using crude ES antigen demonstrated that the test could detect 98% of the medically significant infections. The test had a false-positive rate of less than 3%. Because of difficulties in regulating the quality and quantity of ES antigen and the need to continually maintain infected laboratory animals for producing the diagnostic reagent, efforts have been made to clone and express the gene(s) encoding the immunodominant ES antigens. To date a cDNA sequence, designated TsA-12, which codes in part for a 53-kDa ES antigen, has been identified and expressed in bacteria. Results demonstrate that TsA-12 is recognized by immune sera and further suggest that the immunodominant 45-, 48- and 53-kDa ES proteins which share antigenic epitopes are distinct glycoproteins.

The differentiation of a newly described Asian taeniid from Taenia saginata using enzymatically amplified non-transcribed ribosomal DNA repeat sequences.

A newly described Asian taeniid which is morphologically indistinguishable from adult Taenia saginata has been identified in the aboriginal population of Taiwan. Hybridization patterns of restriction enzyme digested genomic DNA isolated from "Taiwan" Taenia and Taenia saginata revealed distinct variations between these cestodes. We have demonstrated by Southern blot analysis of ribosomal DNA fragments that Taiwan Taenia and T. saginata differ in a 2.4 kb fragment present in Bam HI digested DNA from T. saginata but absent from Taiwan Taenia DNA. The unique 2.4 kb sequence from T. saginata, as well as a partially homologous 3.1 kb fragment found in both Taiwan Taenia and T. saginata, contain sequences shown to be complementary to the 3'-end of the large ribosomal DNA subunit and to a large portion of the non-transcribed ribosomal DNA repeat. These fragments were subcloned into pUC 13 plasmid DNA, restriction enzyme mapped and partially sequenced. Two oligonucleotides complementary to regions on both the 2.4 kb and the 3.1 kb fragments were synthesized which generate 1.0 kb and 0.29 kb fragments specific for Taiwan Taenia and T. saginata, respectively, when used as primers during enzymatic amplification of cestode genomic DNA. Using this technique, we have been able to determine the identify of either cestode from a single proglottid with less than 200 ng of genomic DNA per reaction and further demonstrate that Taiwan Taenia exists in other parts of Eastern Asia.

A recombinant immunodiagnostic antigen for bovine cysticercosis.

The 70% ammonium sulfate-soluble fraction of the cyst fluid of Taenia hydatigena (designated ThFAS) was previously shown to have potential as an immunodiagnostic reagent for bovine cysticercosis. Western blot analysis indicated that the specific reactivity with antibodies in sera of T. saginata-infected cattle was associated with a 10 kDa component. Rabbit antiserum to ThFAS identified a homologous antigenic protein from the cestode Taenia crassiceps. Consequently, a cDNA expression library was constructed in lambda gt11 using poly A mRNA purified from T. crassiceps metacestodes and screened with rabbit antiserum to ThFAS. One strongly reactive clone (designated lambda TCA-2) produced a 123 kDa beta-galactosidase fusion protein which reacted in Western blot with sera from calves experimentally-infected with T. saginata and did not react with sera from uninfected calves or from cattle infected with Fasciola hepatica or with common gastrointestinal cattle parasites.