Phylogenetic relationships of Cryptosporidium parasites based on the 70-kilodalton heat shock protein (HSP70) gene

Abstract

We have characterized the nucleotide sequences of the 70-kDa heat shock protein (HSP70) genes of Cryptosporidium baileyi, C. felis, C. meleagridis, C. muris, C. serpentis, C. wrairi, and C. parvum from various animals. Results of the phylogenetic analysis revealed the presence of several genetically distinct species in the genus Cryptosporidium and eight distinct genotypes within the species C. parvum. Some of the latter may represent cryptic species. The phylogenetic tree constructed from these sequences is in agreement with our previous results based on the small-subunit rRNA genes of Cryptosporidium parasites. The Cryptosporidium species formed two major clades: isolates of C. muris and C. serpentis formed the first major group, while isolates of C. felis, C. meleagridis, C. wrairi, and eight genotypes of C. parvum formed the second major group. Sequence variations were also observed between C. muris isolates from ruminants and rodents. The HSP70 gene provides another useful locus for phylogenetic analysis of the genus Cryptosporidium.

FIG. 1

Variation in the HSP70 gene nucleotide sequences in the primer regions of diagnostic tools by Rochelle et al. (29) (A and B), Di Giovanni et al. (7) (A and B), and Stinear et al. (33) (C).

FIG. 2

Phylogenetic relationship of Cryptosporidium parasites to other apicomplexan parasites inferred from neighbor-joining analysis of HSP70 gene nucleotide sequences.

FIG. 3

Phylogenetic relationships among Cryptosporidium parasites inferred from neighbor-joining analysis of nucleotide sequences (A) and deduced amino acid sequences (B).