Trichinella spiralis: murine strain variation in response to monoclonally defined, protective, nonstage-specific antigens.

Nine hybridoma cell lines secreting monoclonal antibodies (mAbs) against Trichinella spiralis muscle larvae (ML) excretory/secretory antigens (ESA) were developed. Two mAbs, 6-D8-E3 (6D8) and 6-B1-G10 (6B1), were studied in detail. Western blot analysis using ML ESA showed that 6D8 recognized 35- and 40-kDa constituents whereas 6B1 identified a doublet of 33 kDa. However, Western blots of SDS-PAGE of crude ML homogenate showed that 6D8 identified proteins of approximately 35 and 43-60 kDa, whereas 6B1 recognized bands of 42-50 kDa. These results indicated substantial apparent MW differences between secreted and nonsecreted proteins recognized by both mAbs. Neither 6D8 nor 6B1 reacted with adult worm ESA, but both recognized antigens in aqueous extracts of homogenates of whole adult worms. Competitive inhibition experiments using ML ESA as a target demonstrated that the antigen epitopes recognized by monoclonals 6D8, 6B1, a rat mAb, 9D4, and a 37-kDa antigen previously defined were noncross-reactive. MAbs 6D8, 6B1, and 9D4 were used to isolate proteins possessing target determinants by affinity chromatography from crude ML homogenates. Each mAb isolated distinct protein species as determined by SDS-PAGE (6B1, approximately 42 kDa; 6D8, approximately 28, 37, and 61 kDa; 9D4, approximately 29, 33, 38-57, 80, and 86 kDa). NFS mice responded in a dose-dependent manner to affinity-purified antigens and were 25-fold more effective (by weight of antigen) than either C3Heb/Fe(C3H) or B10.BR mice. Immunization of mice with 6D8, 6B1, or 9D4 antigens induced strong protection against a subsequent challenge infection in NFS mice as indicated by accelerated intestinal adult worm expulsion, reduced fecundity of the female worms, and reduction of ML burden. Affinity-isolated antigens stimulated in vitro proliferation of spleen and MLN cells from immune mice; however, the mitogenic response to these antigens barely varied among NFS, C3H, and B10.BR strains.