Infectivity, persistence and serological response of nine Trichinellagenotypes in rats

Domestic and sylvatic Trichinellagenotypes were evaluated for infectivity, muscle larvae persistence, and host antibody responses in rats. Groups of rats were inoculated with T. spiralis, T. nativa, T. britovi, three genotypes of T. pseudospiralis(from USSR, USA, and Australia), T. murrelli, TrichinellaT6, and T. nelsoni, respectively. The muscle larvae intensity (larvae per gram), total larval burden (Ipg x rat weight), and the antibody levels were determined at necropsy 5, 10, 20, and 40 weeks post inoculation. All Trichinellagenotypes were established in the rats, but infectivity and persistence differed significantly: T. spiralisestablished and persisted in high numbers, the three T. pseudospiralisgenotypes were also highly infective but differed significantly in persistence, T. britoviand T. nativahad limited infectivity and persistence, TrichinellaT6 had low infectivity and very low persistence, and T. murrelliand T. nelsoniwere almost non-infective. Except for T. spiralis, initial total muscle larval burdens declined significantly for other genotypes during the experiment. A high initial serological response was detected for all genotypes, but the antibody levels decreased rapidly in relation to decreasing larval burdens. After 20 w.p.i. the antibody levels I remained high only in T. spiralisand T. pseudospiralisinfected rats. The high infectivity and persistence of T. pseudospiralisin rats, suggests that in addition to T. spiralis, this species might be of significant importance in the domestic cycle of trichinellosis.