sybr-green-i and Cryptosporidiosis

Cow's milk, which is one of today's most important food sources, can be a reservoir for many pathogens that create a risk to public health. One of these pathogens is Cryptosporidium parvum. The oocysts of C.parvum, an obligate intracellular parasite, cause infection when ingested orally. The oocysts scattered around with the feces of infected cows or calves can contaminate raw milk and this is frequently seen in dairy farms. The aim of this study was to investigate the viability of C.parvum by propidium monoazide (PMA)-quantitative polymerase chain reaction (qPCR) method after heat treatment applied to contaminated raw cow's milk. For the study, 50 ml of unpasteurized cow's milk was contaminated with 5 X 105 C.parvum oocysts and portioned into 1.5 ml microcentrifuge tubes. Three groups, namely the control group, pasteurization group and boiling group were formed. No warming procedure was applied to the control group. In the pasteurization group, the milks in microcentrifuge tubes were poured into the wells of the dry block heater set to 71.7 °C and incubated for five seconds. At the end of the period, the milks were transferred to the wells of the cold metal tube, which was removed at -20 °C with the help of a micropipette, and incubated for five seconds. The milks in the boiling group were incubated for two minutes in a dry block heater set to 95 °C. After the heat treatment, the milks in microcentrifuge tubes were transferred to 10 ml centrifuge tubes, PBS was added to make the final volume 10 ml, and centrifuged at 4000 rpm for 20 minutes. After this process was repeated twice, 400 µl of PBS was added to the precipitate remaining at the bottom, and the precipitate was homogenized. One sample of each group was applied with PMA, while PMA was not applied to the other sample. PMA-applied samples were incubated for five minutes at room temperature and in the dark, and then exposed to UV light for five minutes in the device with cooling feature. The oocysts were collected by centrifugation at 5000 g for five minutes. After DNA isolation from oocysts, SYBR Green real time PCR (Rt-PCR) was performed using primers amplifying the COWP gene region. As a result of SYBR Green Rt-PCR, the mean Ct values of the control without PMA, pasteurization and boiling groups were determined as 25 ± 1.24, 23 ± 0.98 and 26 ± 1.03, respectively. While no peak was obtained in the boiling group after PMA application, the mean Ct values of the control and pasteurization groups were

Topics: Animals; Cattle; Cryptosporidiosis; Cryptosporidium; Cryptosporidium parvum; Female; Milk; Oocysts; Pasteurization

To detect a wide range of Cryptosporidium species from human faeces by analysis of the Cryptosporidium oocyst wall protein gene by PCR.. The nested-assay comprised an initial amplification using a conventional thermocycler followed by real time PCR using a LightCycler with SYBR Green I for the characterization of the amplicons. The technique uses four sets of primers composed of five to six oligonucleotides with one to six base differences corresponding to the inter-species sequence differences of the gene fragment. Restriction fragment length polymorphism analysis identified Cryptosporidium hominis and C. parvum. The assay was evaluated using DNA extracted from purified material and faecal specimens containing a range of potential pathogens (including Cryptosporidium). The assay was specific, sensitive, reproducible and rapid.. This unique technique enables the rapid detection of a range of polymorphic COWP gene sequences directly from faeces using real time PCR.. This study demonstrates a novel approach to identification of Cryptosporidium species and the identification of C. hominis and C. parvum. The technique may be especially useful for the analysis of environmental samples which are likely to contain heterogeneous mixtures of Cryptosporidium species.

Topics: Animals; Benzothiazoles; Clinical Laboratory Techniques; Cryptosporidiosis; Cryptosporidium; Diamines; DNA Primers; DNA, Protozoan; Feces; Genes, Protozoan; Humans; Organic Chemicals; Polymerase Chain Reaction; Polymorphism, Genetic; Polymorphism, Restriction Fragment Length; Protozoan Proteins; Quinolines; Reproducibility of Results; Sensitivity and Specificity

Several real-time PCR procedures for the detection and genotyping of oocysts of Cryptosporidium parvum were evaluated. A 40-cycle amplification of a 157-bp fragment from the C. parvum beta-tubulin gene detected individual oocysts which were introduced into the reaction mixture by micromanipulation. SYBR Green I melting curve analysis was used to confirm the specificity of the method when DNA extracted from fecal samples spiked with oocysts was analyzed. Because C. parvum isolates infecting humans comprise two distinct genotypes, designated type 1 and type 2, real-time PCR methods for discriminating C. parvum genotypes were developed. The first method used the same beta-tubulin amplification primers and two fluorescently labeled antisense oligonucleotide probes spanning a 49-bp polymorphic sequence diagnostic for C. parvum type 1 and type 2. The second genotyping method used SYBR Green I fluorescence and targeted a polymorphic coding region within the GP900/poly(T) gene. Both methods discriminated between type 1 and type 2 C. parvum on the basis of melting curve analysis. To our knowledge, this is the first report describing the application of melting curve analysis for genotyping of C. parvum oocysts.

Topics: Animals; Benzothiazoles; Cattle; Cryptosporidiosis; Cryptosporidium parvum; Diamines; Fluorescent Dyes; Genotype; Humans; Organic Chemicals; Polymerase Chain Reaction; Quinolines; Sensitivity and Specificity; Temperature; Tubulin