Oocysts, IgG levels and immunoblot patterns determined for Cryptosporidiumparvum in bovine examined during a visit to a farm (northeastern Spain)

Single fecal and serum samples were individually collected from 101 bovines selected at random during a visit to a farm in northeastern Spain (Group I , 26 animals aged 2-36 days; Group II, 34 animals aged 1.5-4.5 months; Grou p III, 41 animals aged 20-24 months). Testing for the presence of Cryptospo ridium parvum oocysts in feces (Monofluo Kit Cryptosporidium, Diagnostics p asteur, France) indicated that 26% animals were infected (81% of Group I, 1 5% of Group II and 0% of Group III). Serological testing (ELISA for detecti on of specific anti-C, parvum IgG) indicated that 59% animals were seroposi tive (12% of Group I, 74% of Group II and 78% of Group III). Immunoblotting results indicate that cattle sera recognize C. parvum antigens of widely v arying molecular weights and that the number of antigens recognized increas es with age. Immunoblots revealed that some of the sera belonging to the Gr oup I reacted with protein fractions between 15 and 20 kDa but none recogni zed the 21-23 kDa antigen. Only few sera in the Group II recognized the pro tein fraction between 15 and 20 kDa. The recognition of 21-23 kDa fraction was observed by four sera from uninfected and seropositive animals. Sera fr om all the seronegative Group II animals recognized few antigens and always with molecular weight greater than 50 kDa. Serum samples from both seropos itive and seronegative animals belonging to the Group III recognized antige ns with molecular weight ranging 15-20 kDa. Surprisingly, the protein fract ions between 21 and 28 kDa reacted with approximately 30% of the sera from seropositive animals and only one of the nine sera from seronegative animal s. The recognition of 42-46 kDa antigens increased with the age and only re acted with the sera from uninfected animals. (C) 1999 Elsevier Science B.V. All rights reserved.