Genetic characterization of Cryptosporidium parvum from calves by mutation scanning and targeted sequencing--zoonotic implications.

This study explored the genetic make-up of Cryptosporidium in fecal samples from 268 individual calves on pasture-based dairy farms in three regions of Victoria, Australia. An integrated approach, using PCR-coupled single-strand conformation polymorphism, targeted sequencing and phylogenetic analysis, was employed to classify the genetic variants (i.e. genotypes and subgenotypes) of Cryptosporidium parvum present in 124 (46.3%) samples and to infer their zoonotic potential. Genotypic and subgenotypic classification was achieved using a portion of the 60 kDa glycoprotein gene (designated pgp60); specific identity was verified using a region within the small subunit of the nuclear ribosomal RNA (pSSU). Twelve sequence types representing ten distinct subgenotypes were defined within genotype IIa, namely IIaA16G3R1 (n=7), IIaA17G2R1 (1), IIaA18G2R1a (2), IIaA18G2R1b (1), IIaA18G4R1 (1), IIaA19G3R1a (80), IIaA19G3R1b (1), IIaA20G2R1 (9), IIaA20G3R1 (1), IIaA20G4R1 (9), IIaA21G3R1 (1) and IIaA23G3R1 (9), of which IIaA18G2R1b, IIaA18G4R1 and IIaA19G3R1b are new records. All of the subgenotypes, except IIaA16G3R1, IIaA18G4R1 and IIaA20G4R1, have been detected previously in humans and are thus considered to be of zoonotic relevance. (Nucleotide sequences reported in this paper are available in the GenBank database under accession numbers FJ825018-FJ825029).