ANTIGENIC CHARACTERIZATION OF HUMAN ISOLATES OF CRYPTOSPORIDIA

Isolates of cryptosporidia from immunodeficient patients and from immu nocompetent children suffering from diarrhoea were sources for prepara tion of antigens. Altogether, antigens from 21 isolates were obtained, 19 from children and 2 from AIDS patients. With one exception, all ch ildren were under 4 years old and most of them were between 1 and 2 ye ars old. The probable source of infection was found in 11 cases. In 8 cases, as well as in both AIDS patients, the source of infection was n ot determined. The same groups of persons and the control group of hea lthy blood donors were examined serologically using ELISA with the ant igen of bovine origin and positive sera were used for following experi ments. Soluble and membrane-enriched antigens from oocysts were compar ed using polyacrylamide gel electrophoresis and electroimmunotransfer blots developed by human immune sera. While no differences were record ed in soluble antigens, two of the membrane-enriched antigens were mis sing (15.5 and 33 kD bands). While all isolates with a pattern typical for Cryptosporidium parvum were infective for neonatal mice, both iso lates with missing bands were not infective for newborn mice in repeat ed experiments. The first of them was infective for chickens and was o riginally determined to be Cryptosporidium baileyi (Ditrich et al. 199 1). However, the antigenic pattern differs from pattern of this specie s. The second isolate was infective for guinea pigs and its species cl assification remains uncertain.