Cloning and sequence analysis of genes encoding Fasciola hepatica immunodominant antigens

ABSTRACT

An immuno-screening of fusion protein produced in lambda plaques was done using IPAb. Two clones were isolated and identified as Fh lambda 400 and Fh lambda 800. Both clones were sequenced, Fh lambda 400 contained 305 translated bases encoding 11.509 kDa and designated as SFh12, while Fh lambda 800 contained 311 translated bases encoding protein of 11.058 kDa designated as SFh11. The DNA sequence homology search of Fh lambda 400 revealed a relatively high degree of identity with F. hepatica amoebapore-like protein mRNA. However, Fh lambda 800 revealed the highest similarity with F. hepatica tegumental antigen [T1] mRNA. The protein homology search of SFh12 gave 100% identity with amoebapore-like protein [APLP], while SFh11 showed 75% identity with F. hepatica tegumental antigen [TA]. The biochemical analysis of the deduced proteins was identified. In addition, the predicted T- and B- cell epitopes were also evaluated. However, a histological localization of the identified antigens was achieved using the IPAb in an indirect immunofluorescent antibody assay [FA]. The results revealed that the IPAb labeled the outer glycocalyx in a characteristic pattern, which proved that the identified antigens were tegumental in origin and the infected fasciola subjects induced antibodies directed mainly against tegumental components