Dataset Information

Effect of daily temperature fluctuation during the cool season on the infectivity of Cryptosporidium parvum.

ABSTRACT: The present work calculated the rate of inactivation of Cryptosporidium parvum oocysts attributable to daily oscillations of low ambient temperatures. The relationship between air temperature and the internal temperature of bovine feces on commercial operations was measured, and three representative 24-h thermal regimens in the approximately 15 degrees C, approximately 25 degrees C, and approximately 35 degrees C ranges were chosen and emulated using a thermocycler. C. parvum oocysts suspended in deionized water were exposed to the temperature cycles, and their infectivity in mice was tested. Oral inoculation of 10(3) treated oocysts per neonatal BALB/c mouse (approximately 14 times the 50% infective dose) resulted in time- and temperature-dependent reductions in the proportion of infected mice. Oocysts were completely noninfectious after 14 24-h cycles with the 30 degrees C regimen and after 70 24-h cycles with the 20 degrees C regimen. In contrast, oocysts remained infectious after 90 24-h cycles with the 10 degrees C regimens. The estimated numbers of days needed for a 1-log(10) reduction in C. parvum oocyst infectivity were 4.9, 28.7, and 71.5 days for the 30, 20, and 10 degrees C thermal regimens, respectively. The loss of infectivity of oocysts induced by these thermal regimens was due in part to partial or complete in vitro excystation.

SUBMITTER: Li X

PROVIDER: S-EPMC2820980 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Effect of daily temperature fluctuation during the cool season on the infectivity of Cryptosporidium parvum.

Li Xunde X Atwill Edward R ER Dunbar Lissa A LA Tate Kenneth W KW

Applied and environmental microbiology 20091218 4

The present work calculated the rate of inactivation of Cryptosporidium parvum oocysts attributable to daily oscillations of low ambient temperatures. The relationship between air temperature and the internal temperature of bovine feces on commercial operations was measured, and three representative 24-h thermal regimens in the approximately 15 degrees C, approximately 25 degrees C, and approximately 35 degrees C ranges were chosen and emulated using a thermocycler. C. parvum oocysts suspended i ...[more]

PMID: 20023095

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Project description:Cryptosporidium parvum is a causative agent of cryptosporidiosis, an infectious gastroenteritis in neonatal ruminants, which can be fatal in severe cases. The aim of this study was to determine the prevalence of infections in dairy cattle/calves during the early stages of a calving season and the species/genotypes of the Cryptosporidium present. Faecal samples collected from pre- and post-partum dams (n = 224) as well as calves from age ∼1 day onwards (n = 312) were examined. Oocysts were concentrated, DNA extracted and tested by Cryptosporidium 18S rRNA gene PCR and sequencing, while genotypes of C. parvum were determined by gp60 and VNTR analysis. Results showed that 31.3% and 30.4% of pre- and post-partum dams tested positive for Cryptosporidium, respectively. In the adults, C. parvum (n = 52), C. bovis (n = 4) and C. andersoni (n = 19) were identified, while in the calves 248 out of 312 (79.5%) were PCR-positive for C. parvum. The proportion of positive calf samples was significantly higher (P < 0.0001) than the proportion of positive adult cattle during the first seven weeks of the calving season. In adult cattle, three distinct gp60 genotypes were identified, a predominant genotype IIaA15G2R1 (n = 36) and genotypes IIaA15R1 (n = 2) and IIaA14G2R1 (n = 1). In the calves, only genotype IIaA15G2R1 was detected (n = 125). Although C. parvum was observed in adult cattle two weeks after the start of the calving season, the predominant genotypes were not detected until Week 4 in both adults and calves, meaning it is still unclear whether adult cattle are the initial source of C. parvum infections on the farm. Historically calves on this dairy farm demonstrated the IIaA19G2R1 genotype, which, has now clearly been replaced with the IIaA15G2R1 genotype that is now found in both adults and calves. During the study season, significantly higher levels of neonatal calf mortality were observed compared to the seasons before (P = 0.046) and after (P = 0.0002). This study has shown comparable levels of C. parvum infection in both pre- and post-partum dams but higher levels of infection in neonatal calves.

Project description:BackgroundHundreds of millions of people are infected with cryptosporidiosis annually, with immunocompromised individuals suffering debilitating symptoms and children in socioeconomically challenged regions at risk of repeated infections. There is currently no effective drug available. In order to facilitate the pursuit of anti-cryptosporidiosis targets and compounds, our study spans the classification of the Cryptosporidium parvum kinome and the structural and biochemical characterization of representatives from the CDPK family and a MAP kinase.ResultsThe C. parvum kinome comprises over 70 members, some of which may be promising drug targets. These C. parvum protein kinases include members in the AGC, Atypical, CaMK, CK1, CMGC, and TKL groups; however, almost 35% could only be classified as OPK (other protein kinases). In addition, about 25% of the kinases identified did not have any known orthologues outside of Cryptosporidium spp. Comparison of specific kinases with their Plasmodium falciparum and Toxoplasma gondii orthologues revealed some distinct characteristics within the C. parvum kinome, including potential targets and opportunities for drug design. Structural and biochemical analysis of 4 representatives of the CaMK group and a MAP kinase confirms features that may be exploited in inhibitor design. Indeed, screening CpCDPK1 against a library of kinase inhibitors yielded a set of the pyrazolopyrimidine derivatives (PP1-derivatives) with IC₅₀ values of < 10 nM. The binding of a PP1-derivative is further described by an inhibitor-bound crystal structure of CpCDPK1. In addition, structural analysis of CpCDPK4 identified an unprecedented Zn-finger within the CDPK kinase domain that may have implications for its regulation.ConclusionsIdentification and comparison of the C. parvum protein kinases against other parasitic kinases shows how orthologue- and family-based research can be used to facilitate characterization of promising drug targets and the search for new drugs.

Dataset Information

Effect of daily temperature fluctuation during the cool season on the infectivity of Cryptosporidium parvum.

Publications

Effect of daily temperature fluctuation during the cool season on the infectivity of Cryptosporidium parvum.

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