title: Trichinella spiralis: major histocompatibility complex-associated elimination of encysted muscle larvae in swine.
abstract: A heretofore undescribed host-mediated reactivity against encapsulated muscle larvae (ML) of the nematode Trichinella spiralis is reported. Inbred miniature swine (NIH minipigs) of three independent SLA phenotypes, which received a primary oral dose of 300 T. spiralis ML, successfully resisted a secondary infection of 10,000 ML; however, only pigs of the SLAa/a phenotype exhibited an unusual and highly significant reduction in the numbers of encysted ML from the primary infection (P less than 0.0003). This initial anti-encysted ML reactivity was confirmed in subsequent trials by comparing the prechallenge ML burdens with the reduced ML numbers in primary-infected aa pigs after challenge. Analyses of inbred strains of mice, selected for major histocompatibility type and for resistance or susceptibility to infection with T. spiralis, showed no such anti-encysted ML response. Because elimination of encysted T. spiralis ML had been accomplished previously only through selected drug regimens, our demonstration of a nonpharmacological, host-mediated reactivity against this stage of the parasite in swine highlights the importance of MHC genes in regulating disease resistance in a livestock species.
authors.affiliation: Helminthic Diseases Laboratory, U.S. Department of Agriculture, Beltsville, Maryland 20705.
authors.forename: K B
authors.initials: KB
authors.lastname: Madden
authors.forename: K D
authors.initials: KD
authors.lastname: Murrell
authors.forename: J K
authors.initials: JK
authors.lastname: Lunney
mesh_terms: D000818:Animals; D006649:Histocompatibility Antigens / Q000276:immunology; D007814:Larva / Q000276:immunology; D016018:Least-Squares Analysis; D008285:Major Histocompatibility Complex / Q000276:immunology*; D009132:Muscles / Q000469:parasitology; D010641:Phenotype; D013552:Swine; D013553:Swine Diseases / Q000276:immunology*; D013556:Swine, Miniature / Q000469:parasitology*; D014059:Tongue / Q000469:parasitology; D014234:Trichinella / Q000276:immunology*; D014235:Trichinellosis / Q000276:immunology / Q000662:veterinary*
chemical_list: D006649:Histocompatibility Antigens