Multi-locus analysis of human infective Cryptosporidium species and subtypes using ten novel genetic loci.
BACKGROUND
Cryptosporidium is a protozoan parasite that causes diarrheal illness in a wide range of hosts including humans. Two species, C. parvum and C. hominis are of primary public health relevance. Genome sequences of these two species are available and show only 3-5% sequence divergence. We investigated this sequence variability, which could correspond either to sequence gaps in the published genome sequences or to the presence of species-specific genes. Comparative genomic tools were used to identify putative species-specific genes and a subset of these genes was tested by PCR in a collection of Cryptosporidium clinical isolates and reference strains.


RESULTS
The majority of the putative species-specific genes examined were in fact common to C. parvum and C. hominis. PCR product sequence analysis revealed interesting SNPs, the majority of which were species-specific. These genetic loci allowed us to construct a robust and multi-locus analysis. The Neighbour-Joining phylogenetic tree constructed clearly discriminated the previously described lineages of Cryptosporidium species and subtypes.


CONCLUSIONS
Most of the genes identified as being species specific during bioinformatics in Cryptosporidium sp. are in fact present in multiple species and only appear species specific because of gaps in published genome sequences. Nevertheless SNPs may offer a promising approach to studying the taxonomy of closely related species of Cryptosporidia.
Bouzid
Maha
M
Biomedical Research Centre, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK.
Tyler
Kevin M
KM
Christen
Richard
R
Chalmers
Rachel M
RM
Elwin
Kristin
K
Hunter
Paul R
PR
D001483:Base Sequence; D003457:Cryptosporidiosis / Q000469:parasitology*; D003458:Cryptosporidium / Q000737:chemistry / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D056426:Genetic Loci; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment
D015800:Protozoan Proteins