Abstract
Chronological changes in the immune responses of 3 groups of neonatal calves naturally infected with cryptosporidia were studied, using sequential samples from Idaho calves from 1 to 27 days of age, single samples from Idaho calves that ranged in age from 3 to 45 days, and samples from Texas calves obtained at 1, 7, 14, and 21 days of age. The indirect fluorescent antibody (IFA) assay was used to evaluate antibody activity in sera and colostrum, and in sera and feces (copra-antibody) from dams and calves, respectively, from the Idaho and Texas dairies. Both tissue and oocyst antigens were used in some assays. IgG1 was the predominant isotype responsible for antibody activity in the calves sera, as well as the dams sera and colostral whey. IgG1 and IgA were the most active isotypes identified from the copra-antibody preparations. The IgG1 and IgA copra-antibody activity mirrored the rise and fall of the cryptosporidia oocyst shedding pattern. IgM and the serum protein C3 were also detectable in the copra-antibody preparations on many of the same sampling days. The IgG in the colostral whey reacted well with all antigens, regardless of origin, with the same relative intensity whether tested by IFA or immunoblotting. The very young calves sera and copra-antibody also reacted with all Cryptosporidia isolates. Some cross reactions were noted when the older calves sera and copra-antibodies were tested with heterologous antigens, but higher titers were obtained with homologous antigens. The possibility of strain differences indicated by IFA results were further supported by scanning electron microscopic ultrastructure studies. Additional electron microscopic studies failed to demonstrate the 4 merozoite meront. Intact oocysts were often seen leaving their attachment sites, but excysting oocysts were never seen still attached. The results suggest that the immune response in neonatal calves infected with cryptosporidia is similar to that observed following the infection of young ruminants with other gastro-intestinal infections.
Mamer, Beth Eunice (1988). The serology and ultrastructure of Cryptosporidium sp. Tyzzer 1907 (Protozoa: Cryptosporidiidae). Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -32310.