Morphologic, host specificity, and molecular characterization of a Hungarian Cryptosporidium meleagridis isolate

Abstract

This study was undertaken in order to characterize Cryptosporidium meleagridis isolated from a turkey in Hungary and to compare the morphologies, host specificities, organ locations, and small-subunit RNA (SSU rRNA) gene sequences of this organism and other Cryptosporidium species. The phenotypic differences between C. meleagridis and Cryptosporidium parvum Hungarian calf isolate (zoonotic genotype) oocysts were small, although they were statistically significant. Oocysts of C. meleagridis were successfully passaged in turkeys and were transmitted from turkeys to immunosuppressed mice and from mice to chickens. The location of C. meleagridis was the small intestine, like the location of C. parvum. A comparison of sequence data for the variable region of the SSU rRNA gene of C. meleagridis isolated from turkeys with other Cryptosporidium sequence data in the GenBank database revealed that the Hungarian C. meleagridis sequence is identical to a C. meleagridis sequence recently described for a North Carolina isolate. Thus, C. meleagridis is a distinct species that occurs worldwide and has a broad host range, like the C. parvum zoonotic strain (also called the calf or bovine strain) and Cryptosporidium felis. Because birds are susceptible to C. meleagridis and to some zoonotic strains of C. parvum, these animals may play an active role in contamination of surface waters not only with Cryptosporidium baileyi but also with C. parvum-like parasites.

FIG. 1

Alignment of the Cryptosporidium SSU rRNA gene diagnostic fragments obtained with primers CPBDIAGF and CPBDIAGR for C. parvum anthroponotic genotype 1, C. meleagridis, C. parvum zoonotic genotype 2, and C. wrairi. Only the first 300 columns of the alignments are shown, as the remaining columns were identical for all of the genotypes. Dashes indicate gaps, and dots indicate bases that are identical to the C. parvum genotype 1 bases. The GenBank accession numbers for the C. parvum genotype 1, C. meleagridis, C. parvum genotype 2, and C. wrairi sequences shown are L16997, AJ242472, AJ242471, and U11440, respectively. In the complete SSU rRNA coding sequence for the anthroponotic genotype of C. parvum (GenBank accession no. L16997), the region shown corresponds to positions 602 to 901.