| In oder to study the biological and molecular character of Cryptosporidium mouse genotypeâ… . The fecal samples were collected from 17-20 days old mice in the Laboratory Animal Centre in Basic Medical College of Zhengzhou Uiversity (Zhengzhou, China). The samples were concentrated and examined by microscopy of fecal smear stained with acid-fast stain and sugar floatation method. The Cryptopsoridium-positive samples were stored in 2.5% potassium dichromate solution at 4℃. Purified oocysts were confirmed as mouse genotype I by sequence analysis of the SSU rRNA gene. Three lambs (1 male and 2 female), three calves and twelve mice were given 1×105 oocysts per animal. Oocysts shedding in stool were calculated by counting the number of oocysts per gram of faeces by light microscope using hemacytometer after oocysts concentration by sugar flotation. The lengths and widths (to the nearest micrometer) of oocysts (n=50) were measured and the shape index (the ratio of length and width) of each oocyst was calculated. Fragments of the SSU rRNA and GP60 genes were amplified by PCR, and PCR products were sequenced. Oocysts are smaller than Cryptosporidium parvum. This species has been reported to be prevalent in mice and rodents widely. Oocysts obtained from laboratory mice for the present study measured 4.81-4.84μm×4.05-4.13μm, with a mean size of 4.83μm×4.09μm and a mean shape index of 1.18. Pre-patent period was 5 days in neonatal mice, and 6 days in adult mice. Patent period was 24-28 days in neonatal mice, and 28-29 days in adult mice. Oocysts were not infectious for lambs and calves. Cryptosporidia were attached to the microvillar brush border of the small intestine of mice. However, infection of parasites were mostly extensive in the ileum. No parasites were seen in the large intestine of mice. Cryptosporidia were not detected in the gastrointestinal tract of both lamb and calve inoculated with Cryptosporidium mouse genotypeâ… oocysts. Analysis of SSU rRNA locus demonstrated the new species to be distinct from all other species, and analysis of GP60 gene showed identical subtype from narturally infected mice, passaged mice and infected animals. Based on morphological, molecular and biological data, this species geographically widespread parasite found in rodents, is consider as a new species and is named C. tyzzeri. |
