Subtyping Cryptosporidium ryanae: A Common Pathogen in Bovine Animals

Abstract

Cryptosporidium ryanae is one of the most common species for cryptosporidiosis in cattle. However, little is known of the genetic characteristics of C. ryanae due to the lack of subtyping tools. In the present study, the 60-kDa glycoprotein (gp60) gene of C. ryanae was identified in whole genome sequence data and analyzed for sequence characteristics using bioinformatics tools. The protein it encodes had some of the typical characteristics of GP60 proteins, with a signal peptide, a furin cleavage site, and a glycosylphosphatidylinositol anchor at the C terminus of the protein, and numerous O-glycosylation sites. The gene sequence was used in the development of a subtyping tool, which was used in characterizing C. ryanae from 110 specimens from dairy cattle, 2 from beef cattle, 6 from yaks, and 4 from water buffaloes in China. Altogether, 17 subtypes from 8 subtype families were recognized, namely XXIa to XXIh. Possible host adaption was identified within this species, reflected by the unique occurrence of XXIa, XXIc, and XXIh in dairy cattle, yaks, and water buffaloes, respectively. Some geographical differences were detected in the distribution of subtype families in dairy cattle; specimens from southern China showed higher genetic diversity than from northern China, and the XXIa subtype family was only seen in dairy cattle in southern and eastern China. The gp60-based subtyping tool should be useful in molecular epidemiological studies of the transmission of C. ryanae.

Subtyping Cryptosporidium xiaoi, a Common Pathogen in Sheep and Goats

“…The gene was 1437 bp in length and encoded 478 amino acids. Although it shared sequence similarities with the gp60 gene of C. parvum (AF022929), C. hominis (FJ839883), C. ubiquitum [ 12 ], and C. ryanae [ 17 ] in the 5′ and 3′ regions at the amino acid level, the full sequence similarity was only 19.9 to 41.6% between C. xiaoi and the other four species ( Figure 1 ). The GP60 protein of C. xiaoi had classic features of Cryptosporidium GP60 proteins, including an N-terminal signal peptide, a furin cleavage site (RSRR), two potential N-glycosylation sites, nearly 100 O-glycosylation sites in the GP40 region, and a GPI anchor at the C terminus.…”

“…This may explain the inability of the commonly used gp60 primers to amplify DNA of C. xiaoi [ 23 ]. Similar to C. ubiquitum , C. canis , C. felis , and C. ryanae , the trinucleotide repeats of TCA/TCG/TCT encoding a polyserine tract at the 5′ end of the gp60 gene and widely used to differentiate subtypes within subtype families, were absent in the gp60 sequence of C. xiaoi [ 12 , 13 , 17 , 24 ]. However, a polyserine tract encoded by AGC/AGT repeats was observed in the gp60 gene of the subtype family XXIIIl, and subtypes within XXIIIl differed mostly in the number of AGC/AGT repeats.…”

“…Thus, genetic recombination might be responsible for high sequence heterogeneity in the gp60 gene of C. xiaoi . Genetic recombination at the gp60 locus was observed in C. parvum , C. hominis , C. ubiquitum, and C. ryanae [ 2 , 12 , 17 ].…”

“…[ 2 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Recently, gp60 gene-based subtyping tools have been developed for molecular epidemiological studies of some non-human pathogenic Cryptosporidium spp., such as the bovine-adapted C. ryanae and the marsupial-adapted C. fayeri [ 16 , 17 ]. However, such a tool is not available for C. xiaoi , which is occasionally found in humans [ 18 ].…”

Editorial for the Special Issue: Epidemiology, Transmission, Cell Biology and Pathogenicity of Cryptosporidium

“…In the current paper, phylogenetic analysis of these same genotypes at the actin locus confirmed that these two clusters were representative of potential novel Cryptosporidium fish species. In their paper, Yang et al [ 5 ] described the identification of the 60-kDa glycoprotein ( gp60) gene of C. ryanae in a whole-genome sequence for the further development of a subtyping tool. The use of this tool in the characterization of isolates from dairy cattle, beef cattle, yaks, and water buffaloes highlighted a high genetic diversity in C. ryanae .…”