Genomic Cloning of Fasciola Hepatica Excretory - Secretory Antigenic Genes in E.coli

11-23 ABSTRACT A complementary DNA (cDNA) library was constructed from the mRNA of adult worms of Fasciola hepatica in the expression vector λgt11, the size of the library contained approximately 2.4 x 10 recombinants and the recombinant efficiency was 85%. The library was directedly screened with a rabbit antisera raised against a excretory-secretory (ES) antigen of Fasciola hepatica. Two positive clones of strong signal were selected from a group of 200 positive clones, named λFH3 and λFH7. The length of external fragments of two recombinants were 0.85Kb (λFH3) and 1.15Kb (λFH7). The E.coli 1089 host was infected by recombinants λFH3 and λFH7 respectively, through SDS PAGE (polyacrylamide gel electrophoresis) after induced by isopropyl-D-thiogalactopyranoside (IPTG) (final concentration 5mM), the results indicated that the molecular weight of fusion protein expressed (β-galactosidase fusion protein) of recombinant λFH3 was 138KD, and that of λFH7 was 156KD, the rate of fusion proteins expression was approximately 100mg/liter. Western blot showed that two hybrid proteins corresponded to 26.2KD protein band ((FH3) and 38.8KD protein band (λFH7) of Fasciola hepatica ES antigens.