Molecular and phylogenetic analysis of Cryptosporidium muris from various hosts

Isolates of Cryptosporidium muris and C. serpentis were characterized from different hosts using nucleotide sequence analysis of the rDNA 18S and ITS1 regions, and the heat-shock (HSP-70) gene. Phylogenetic analysis confirmed preliminary evidence that C. muris is not a uniform species. Two distinct genotypes were identified within C. muris; (1) C. muris genotype A; comprising bovine and camel isolates of C. muris from different geographical locations, and (2) C. muris genotype B comprising C. muris isolates from mice, a hamster, a rock hyrax and a camel from the same enclosure. These 2 genotypes may represent separate species but further biological and molecular studies are required for confirmation

Cryptosporidium andersoni n. sp. (Apicomplexa: Cryptosporiidae) from Cattle, Bos taurus

A new species of Cryptosporidium is described from the feces of domestic cattle, Bos taurus. Oocysts are structurally similar to those of Cryptosporidium muris described from mice but are larger than those of Cryptosporidium parvum. Oocysts of the new species are ellipsoidal, lack sporocysts, and measure 7.4 x 5.5 μm (range, 6.0-8.1 by 5.0-6.5 μm). The length to width ratio is 1.35 (range, 1.07-1.50). The colorless oocyst wall is < 1 μm thick, lacks a micropyle, and possesses a longitudinal suture at one pole. A polar granule is absent, whereas an oocyst residuum is present. Oocysts were passed fully sporulated and are not infectious to outbred, inbred immunocompetent or immunodeficient mice, chickens or goats. Recent molecular analyses of the RDNA 18S and ITS1 regions and heat-shock protein 70 (HSP-70) genes demonstrate this species to be distinct from C. muris infecting rodents. Based on transmission studies and molecular data, we consider the large form of Cryptosporidium infecting the abomasum of cattle to be a new species and have proposed the name Cryptoxporidium andersoni n. sp. for this parasite

Molecular and phylogenetic characterisation of Cryptosporidium from birds

Avian isolates of Cryptosporidium species from different geographic locations were sequenced at two loci, the 18S rRNA gene and the heat shock gene (HSP-70). Phylogenetic analysis of the sequence data provided support for the existence of a new avian species of Cryptosporidium infecting finches and a second species infecting a black duck. The identity of Cryptosporidium baileyi and Cryptosporidium meleagridis as valid species was confirmed. Also, C. baileyi was identified in a number of isolates from the brown quail extending the host range of this species

Determination of Cryptosporidium Parvum Oocyst viability by fluorescence in situ hybridization (FISH) using a ribosomal RNA-directed probes

Free to read from publisher website AIMS: Fluorescence in situ hybridization (FISH) has been proposed for species-specific detection, and viability determination of Cryptosporidium parvum oocysts. FISH-based viability determination depends on rRNA decay after loss of viability. We examined the effects of RNase(s) and RNase inhibitors on FISH of C. parvum. METHODS AND RESULTS: FISH was performed using a 5'-Texas red-labelled DNA oligonucleotide probe at 1 pM microl(-1). Intact and heat-permeabilized oocysts were treated with 1-100 microg ml(-1) RNase. FISH of intact oocysts appeared unaffected by exogenous RNase if this was neutralized before permeabilization. FISH fluorescence of heat-killed oocysts stored in phosphate-buffered saline at room temperature decayed by 1/2 after 55 h, but remained detectable after 6 days. Addition of vanadyl ribonucleoside complex (VRC) extended rRNA half-life of heat-permeabilized oocysts to 155 h. CONCLUSIONS: Extended rRNA half-life may result in viability overestimation using FISH. RNase pretreatment before FISH is recommended to destroy residual rRNA in recently killed oocysts. Incorporation of 1-10 mM l(-1) VRC before FISH permeabilization steps should neutralize RNase activity. SIGNIFICANCE AND IMPACT OF THE STUDY: Elimination of FISH fluorescence of nonviable C. parvum is desirable. Use of RNase and VRC is suggested to reduce numbers of false-positive 'viable' oocysts