Novel real-time PCR assays for the specific detection of human infective Cryptosporidium species

Serum IgG Responses to gp15 and gp40 Protein-Derived Synthetic Peptides From Cryptosporidium parvum

Cryptosporidium spp. are responsible for moderate to severe diarrhea, mainly in children and immunocompromised patients. Using ELISA, the recognition of synthetic peptides generated from the sequences of the Cryptosporidium parvum gp40 and gp15 proteins by serum IgM and IgG antibodies from patients infected (cases) with Cryptosporidium hominis, C. parvum, and Cryptosporidium canis, and uninfected individuals (controls) was evaluated. A statistically significant difference (p = 0.0025) was found in terms of the recognition of peptides A133 and A32 between cases and controls. Additional studies are necessary to understand the potential of these peptides as vaccine candidates.

The profile of inflammatory factors in dairy calves with Cryptosporidium infection

The present study was conducted to investigate the detection and identification of Cryptosporidium species via molecular techniques and evaluate the serum concentrations of inflammatory factors in Cryptosporidium species. The fecal samples (n = 256) were collected from pre-weaned (≤ 2.00 months) calves and the positive samples were identified utilizing Ziehl-Neelsen staining. Nested species-specific multiplex PCR (nssm-PCR) and restriction fragment length polymorphism (RFLP) were used to identify the species and sub-species. The serum concentrations of IL-1β, IL-6, IL-12, TNF-α, and IFN-γ were also assessed. The results revealed that 10.54% of samples were positive. The results of Nested-PCR showed that 92.59% of the samples were positive for C. parvum while 7.41% were positive for C. andersoni. The results of RFLP confirmed 92.59% of the samples for C. parvum, 3.70% for C. muris / C. andersoni, and 3.70% for C. muris. The serum concentrations of IL-1β, IL-6, IL-12, TNF-α, and IFN-γ were significantly higher in the infected calves compared to those in healthy calves. However, the serum concentration of IFN-γ was significantly higher in the calves infected with C. parvum while the serum concentrations of TNF-α and IL-6 were significantly higher in those infected with C. andersoni . In conclusion, C. parvum was prevalent in the region and the calves demonstrated inflammatory responses to Cryptosporidium species.

Comparison of Three Real-Time PCR Assays Targeting the SSU rRNA Gene, the COWP Gene and the DnaJ-Like Protein Gene for the Diagnosis of Cryptosporidium spp. in Stool Samples

As qualified microscopy of enteric parasitoses as defined by high diagnostic accuracy is difficult to maintain in non-endemic areas due to scarce opportunities for practicing with positive sample materials, molecular diagnostic options provide less investigator-dependent alternatives. Here, we compared three molecular targets for the real-time PCR-based detection of Cryptosporidium spp. From a population of 1000 individuals comprising both Ghanaian HIV (human immunodeficiency virus) patients and military returnees after deployment in the tropics, stool samples were assessed for Cryptosporidium spp. by real-time PCR targeting the small subunit ribosomal RNA (SSU rRNA) gene, the Cryptosporidium oocyst wall (COWP) gene, and the DnaJ-like protein gene (DnaJ), respectively. In declining order, sensitivity of 100% for the SSU rRNA gene PCR, 90.0% for the COWP PCR and 88.8% for the DnaJ PCR, respectively, as well as specificity of 99.6% for the COWP PCR and 96.9% for both the SSU rRNA gene PCR and the DnaJ PCR, respectively, were recorded. Substantial agreement (kappa value 0.663) between the three assays was observed. Further, an accuracy-adjusted Cryptosporidium spp. prevalence of 6.0% was calculated for the study population. In conclusion, none of the assessed real-time PCR assays were associated with perfect test accuracy. However, a combination of highly sensitive SSU rRNA gene PCR for screening purposes and more specific COWP PCR for confirmatory testing should allow reliable diagnosis of Cryptosporidium spp. in stool samples even in low prevalence settings.

Comparison of three diagnostic methods in the diagnosis of cryptosporidiosis and gp 60 subtyping of Cryptosporidium parvum in diarrheic calves in Central Anatolia Region of Turkey

The aim of this study was to compare three diagnostic methods for the diagnosis of cryptosporidiosis and to detect subtypes ofCryptosporidium parvum by sequences analyses of gp60 gene in diarrheic calves in several herds in Konya province located in Central Anatolia Region of Turkey. Fecal samples were collected from a total of 194 pre-weaned calves (n=158, ≤15 days old, and n=36, 15 to 40 days old), with diarrhoea. For comparative diagnosis, all samples were examined by modified Ziehl-Neelsen staining of fecal smears for the presence of oocyst, nested PCR-RFLP of SSU rRNA and TaqMan qPCR for the detection of Cryptosporidium DNA. A total of 92 (47.4%) and 104 (53.6%) out of the examined samples were found positive by microscopic examination and molecular tools, respectively. The diagnostic sensitivity and specificity of microscopic identification were determined as 88.5% and 100.0%, respectively compared to molecular assays. Cryptosporidium parvum was the only detected species in all positive samples by species-specific qPCR and nested PCR-RFLP assays. Species identifications were further confirmed by sequence analyses of the SSU rRNA PCR products. There was no statistically significant difference in C. parvum prevalence between early pre-weaned calves and calves older than 15 days. The sequence analyses of the gp60 gene of C. parvum isolates revealed a one subtype IIaA13G2R1 belonging to zoonotic family IIa in diarrheic calves

Prevalence and genotyping of bovine Cryptosporidium species in the Mediterranean and Central Anatolia Region of Turkey

The prevalence of Cryptosporidium species in calves and heifers with relation to diarrhea from several herds was investigated in this study. Fecal samples were collected from 135 and 120 pre-weaned calves and 79 and 130 heifers raised in the Central Anatolia (CAR) and Mediterranean Regions (MR) of Turkey, respectively. A total of 86 post-weaned calves in CAR were also included in the study. For diagnostic comparison, all samples were examined by microscopic examination, SSU rRNA nested PCR and TaqMan real-time PCR for the presence of oocyst and Cryptosporidium DNA. In total, 102 (34.0 %) and 93 (37.2 %) of the examined samples from CAR and MR were found positive for Cryptosporidium DNA with both nested PCR and real-time PCR analyses, respectively with an overall prevalence of 35.5 %. The diagnostic sensitivity and specificity of microscopic examination were determined as 68.7 % and 100.0 % compared to molecular tools, respectively. RFLP and sequence analyses of the SSU rRNA from the PCR products revealed that 138 (70.8 %) out of 195 positive isolates were C. parvum further confirming the species-specific real-time PCR results. Among the remaining 57 (29.2 %) positive isolates, 30 (15.4 %) and 27 (13.8 %) were characterized as C. ryanae and C. bovis, respectively. C. parvum was the dominant species in pre-weaned calves especially with diarrhea while C. bovis and C. ryanae were mostly found in post-weaned calves and heifers. The sequence analyses of the gp60 gene of C. parvum isolates revealed two subtypes (IIaA13G2R1, IIaA14G1R1) belonging to zoonotic family IIa, with IIaA13G2R1 being the most common in diarrheic calves.

Fast and Highly Sensitive Detection of Pathogens Wreathed with Magnetic Nanoparticles Using Dark-Field Microscopy

Cryptosporidium parvum ( C. parvum) is a highly potent zoonotic pathogen, which can do significant harm to both human beings and livestock. However, existing technologies or methods are deficient for rapid on-site detection of water contaminated with C. parvum. Better detection approaches are needed to allow water management agencies to stop major breakouts of the pathogen. Herein, we present a novel detection method for cryptosporidium in a tiny drop of sample using a magnetic nanoparticle (MNP) probe combined with dark-field microscopy in 30 min. The designed MNP probes bind with high affinity to C. parvum, resulting in the formation of a golden garland-like structure under dark-field microscopy. This MNP-based dark-field counting strategy yields an amazing PCR-like sensitivity of 8 attomolar (aM) (5 pathogens in 1 μL). Importantly, the assay is very rapid (∼30 min) and is very simple to perform as it involves only one step of mixing and magnetic separation, followed by dropping on a slide for counting under dark-field microscope. By combining the advantages of the specific light-scattering characteristic of MNP probe under dark field and the selective magnetic separation ability of functionalized MNP, the proposed MNP-based dark-field enumeration method offers low cost and significant translational potential.

Lateral Flow Loop-Mediated Isothermal Amplification Test with Stem Primers: Detection of Cryptosporidium Species in Kenyan Children Presenting with Diarrhea

Background. Cryptosporidium is a protozoan parasite and a major cause of diarrhea in children and immunocompromised patients. Current diagnostic methods for cryptosporidiosis such as microscopy have low sensitivity while techniques such as PCR indicate higher sensitivity levels but are seldom used in developing countries due to their associated cost. A loop-mediated isothermal amplification (LAMP) technique, a method with shorter time to result and with equal or higher sensitivity compared to PCR, has been developed and applied in the detection of Cryptosporidium species. The test has a detection limit of 10 pg/µl (~100 oocysts/ml) indicating a need for more sensitive diagnostic tools. This study developed a more sensitive lateral flow dipstick (LFD) LAMP test based on SAM-1 gene and with the addition of a second set of reaction accelerating primers (stem primers). Results. The stem LFD LAMP test showed analytical sensitivity of 10 oocysts/ml compared to 100 oocysts/ml (10 pg/ul) for each of the SAM-1 LAMP test and nested PCR. The stem LFD LAMP and nested PCR detected 29/39 and 25/39 positive samples of previously identified C. parvum and C. hominis DNA, respectively. The SAM-1 LAMP detected 27/39. On detection of Cryptosporidium DNA in 67 clinical samples, the stem LFD LAMP detected 16 samples and SAM-2 LAMP 14 and nested PCR identified 11. Preheating the templates increased detection by stem LFD LAMP to 19 samples. Time to results from master mix preparation step took ~80 minutes. The test was specific, and no cross-amplification was recorded with nontarget DNA. Conclusion. The developed stem LFD LAMP test is an appropriate method for the detection of C. hominis, C. parvum, and C. meleagridis DNA in human stool samples. It can be used in algorithm with other diagnostic tests and may offer promise as an effective diagnostic tool in the control of cryptosporidiosis.

Laboratory diagnosis of cryptosporidiosis

Cryptosporidiosis is a major etiology of persistent and chronic diarrhea in children and immunocompromised patients. In addition, it is also one of the important pathogens causing zoonotic or waterborne outbreaks. A number of conventional and molecular tests are available, but each test is riddled with few limitations. Further, there is a need to develop point of care tests and multiplexed tests for simultaneous detection of multiple pathogens.

Molecular epidemiologic tools for waterborne pathogens Cryptosporidium spp. and Giardia duodenalis

Molecular diagnostic tools have played an important role in improving our understanding of the transmission of Cryptosporidium spp. and Giardia duodenalis, which are two of the most important waterborne parasites in industrialized nations. Genotyping tools are frequently used in the identification of host-adapted Cryptosporidium species and G. duodenalis assemblages, allowing the assessment of infection sources in humans and public health potential of parasites found in animals and the environment. In contrast, subtyping tools are more often used in case linkages, advanced tracking of infections sources, and assessment of disease burdens attributable to anthroponotic and zoonotic transmission. More recently, multilocus typing tools have been developed for population genetic characterizations of transmission dynamics and delineation of mechanisms for the emergence of virulent subtypes. With the recent development in next generation sequencing techniques, whole genome sequencing and comparative genomic analysis are increasingly used in characterizing Cryptosporidium spp. and G. duodenalis. The use of these tools in epidemiologic studies has identified significant differences in the transmission of Cryptosporidium spp. in humans between developing countries and industrialized nations, especially the role of zoonotic transmission in human infection. Geographic differences are also present in the distribution of G. duodenalis assemblages A and B in humans. In contrast, there is little evidence for widespread zoonotic transmission of giardiasis in both developing and industrialized countries. Differences in virulence have been identified among Cryptosporidium species and subtypes, and possibly between G. duodenalis assemblages A and B, and genetic recombination has been identified as one mechanism for the emergence of virulent C. hominis subtypes. These recent advances are providing insight into the epidemiology of waterborne protozoan parasites in both developing and developed countries.