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Contamination of drinking water, food, and recreational water by C. parvum has resulted in numerous outbreaks of cryptosporidiosis. It has been demonstrated that C. parvum is composed of two distinct genotypes: a "anthroponotic" genotype (genotype 1) which has so far been found only in humans and primates; and a "zoonotic" genotype (genotype 2) which is found in domestic livestock such as cattle, sheep, and goats but which can also infect humans. Despite genetic and biological differences between these genotypes, little is known about differences in infectivity, viability, and environmental stresses. Differences in growth and virulence may also affect testing of drugs and disinfectants. Propagation of genotype 1 in laboratory animals has proven to be extremely difficult and inefficient, thus limiting the type of studies that can be performed with type 1. Since viability of the parasite decreases with age, there is a limited time frame for biological experimentation. This paper will review studies in the literature that described the growth of genotype 1 and genotype 2 in vitro and possible in vivo models. Both genotypes 1 and 2 can be grown for short periods of time (up to 96 hours) in vitro using a number of cell lines. These cell lines, derived from human and animal sources, include Caco2, HCT8 and MDCK cells. Several animal models have also been employed to either demonstrate infectivity, host specificity, or to propagate genotypes. Animal models include neonatal and immunodeficient mice, calves, gnotobiotic and conventional piglets. Human and bovine genotypes of C. parvum, have been identified and differentiated by isoenzyme analysis and confirmed by RAPD, RFLP, and sequence analysis, both of which are infectious for immunocompetent persons. Genotyping has been accomplished by a number of methods. Genetic analyses based on COWP, TRAP-C1, ssrRNA restriction fragment length polymorphisms (RFLP) profiles or by polymerase chain reaction (PCR) amplification of sequences such as the B-tubulin gene is most commonly used. Includes 9 references.

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Edition: Vol. - No. Published: 01/01/2001 Number of Pages: 3File Size: 1 file , 150 KB