Cryptosporidium parvum IId family: clonal population and dispersal from Western Asia to other geographical regions

Abstract

In this study, 111 Cryptosporidium parvum IId isolates from several species of animals in China, Sweden, and Egypt were subtyped by multilocus sequence typing (MLST). One to eleven subtypes were detected at each of the 12 microsatellite, minisatellite, and single nucleotide polymorphism (SNP) loci, forming 25 MLST subtypes. Host-adaptation and significant geographical segregation were both observed in the MLST subtypes. A clonal population structure was seen in C. parvum IId isolates from China and Sweden. Three ancestral lineages and the same RPGR sequence were shared by these isolates examined. Therefore, the present genetic observations including the higher nucleotide diversity of C. parvum IId GP60 sequences in Western Asia, as well as the unique distribution of IId subtypes (almost exclusively found in Asia, Europe, and Egypt) and in combination with the domestication history of cattle, sheep, and goats, indicated that C. parvum IId subtypes were probably dispersed from Western Asia to other geographical regions. More population genetic structure studies involving various C. parvum subtype families using high-resolution tools are needed to better elucidate the origin and dissemination of C. parvum in the world.

Figure 1. Phylogenetic relationship among MLST subtypes of C. parvum IId isolates at 12 genetic loci as assessed by a neighbor-joining analysis of the concatenated nucleotide sequences, using distance calculated by the Kimura 2-parameter model.

The figure was generated using the softwares of Microsoft PowerPoint 2003 and Adobe Photoshop 8.0.1 after by the cycle model in MEGA version 4 opening the tree file.

Figure 2. Population structure inferred by Bayesian clustering using multilocus subtype information.

Ancestral population size of 3 (K = 3) was chosen as the best fit for the current data (Fig. S2). Upper labels are the ancestral populations; the geographic locations, MLST subtypes, and hosts of the isolates are at the bottom. C = cattle, H = horse, M = mouse.

Figure 3. Ratio of the common C. parvum subtype families found in the world.

Numbers above bars represent numbers of samples subtyped at the GP60 locus. Data are based on studies published between 2004 and March 2013.

Figure 4. Distribution of C. parvum IId subtypes in the world.

The size of black circle indicates the number of isolates. Blue and red circles represent isolates from animals and humans, respectively. The figure was generated using the softwares of MapInfo Professional 7.0, Microsoft PowerPoint 2003 and Adobe Photoshop 8.0.1.