A comparison of endogenous development of three isolates of Cryptosporidium in suckling mice

Transcriptional control of the Cryptosporidium life cycle

The parasite Cryptosporidium is a leading agent of diarrhoeal disease in young children, and a cause and consequence of chronic malnutrition1,2. There are no vaccines and only limited treatment options3. The parasite infects enterocytes, in which it engages in asexual and sexual replication4, both of which are essential to continued infection and transmission. However, their molecular mechanisms remain largely unclear5. Here we use single-cell RNA sequencing to reveal the gene expression programme of the entire Cryptosporidium parvum life cycle in culture and in infected animals. Diverging from the prevailing model6, we find support for only three intracellular stages: asexual type-I meronts, male gamonts and female gametes. We reveal a highly organized program for the assembly of components at each stage. Dissecting the underlying regulatory network, we identify the transcription factor Myb-M as the earliest determinant of male fate, in an organism that lacks genetic sex determination. Conditional expression of this factor overrides the developmental program and induces widespread maleness, while conditional deletion ablates male development. Both have a profound impact on the infection. A large set of stage-specific genes now provides the opportunity to understand, engineer and disrupt parasite sex and life cycle progression to advance the development of vaccines and treatments.

Mendelian segregation and high recombination rates facilitate genetic analyses in Cryptosporidium parvum

Very little is known about the process of meiosis in the apicomplexan parasite Cryptosporidium despite the essentiality of sex in its life cycle. Most cell lines only support asexual growth of Cryptosporidium parvum (C. parvum), but stem cell derived intestinal epithelial cells grown under air-liquid interface (ALI) conditions support the sexual cycle. To examine chromosomal dynamics during meiosis in C. parvum, we generated two transgenic lines of parasites that were fluorescently tagged with mCherry or GFP on chromosomes 1 or 5, respectively. Infection of ALI cultures or Ifngr1-/- mice with mCherry and GFP parasites resulted in cross-fertilization and the formation of "yellow" oocysts, which contain 4 haploid sporozoites that are the product of meiosis. Recombinant oocysts from the F1 generation were purified and used to infect HCT-8 cultures, and phenotypes of the progeny were observed by microscopy. All possible phenotypes predicted by independent segregation were represented equally (~25%) in the population, indicating that C. parvum chromosomes exhibit a Mendelian inheritance pattern. The most common pattern observed from the outgrowth of single oocysts included all possible parental and recombinant phenotypes derived from a single meiotic event, suggesting a high rate of crossover. To estimate the frequency of crossover, additional loci on chromosomes 1 and 5 were tagged and used to monitor intrachromosomal crosses in Ifngr1-/- mice. Both chromosomes showed a high frequency of crossover compared to other apicomplexans with map distances (i.e., 1% recombination) of 3-12 kb. Overall, a high recombination rate may explain many unique characteristics observed in Cryptosporidium spp. such as high rates of speciation, wide variation in host range, and rapid evolution of host-specific virulence factors.

Prevalence of Cryptosporidium and microsporidial infection in HIV-infected individuals

BACKGROUND

Microsporidia and Cryptosporidium are obligate intracellular protozoa. These medically important species are recognized as opportunistic organisms in intestinal complications in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome patients.

METHODS

The current cross-sectional study was designed and conducted from August 2016 to August 2017 to determine intestinal Cryptosporidium and microsporidia spp. in HIV-infected individuals from the Behavioral Diseases Counseling Center, Tabriz, Iran, by modified acid-fast and modified trichrome staining and nested polymerase chain reaction (PCR) and real-time PCR.

RESULTS

Of 100 HIV-infected persons, 21.0% (95% confidence interval [CI] 13.0 to 30.0) and 18.0% (95% CI 11.0 to 26.0) were identified as Cryptosporidium and microsporidia, respectively, by the microscopic method. Of these 100 HIV-infected persons, 18.0% (95% CI 11.0 to 26.0) and 14.0% (95% CI 7.0 to 22.0) were positive for Cryptosporidium and microsporidia, respectively, by the molecular method. The predominant species of microsporidia in patients was Enterocytozoon bieneusi (85.7% [95% CI 57.0 to 98.0]) and Encephalitozoon cuniculi (14.3% [95% CI 1.7 to 42.0]), which were found by quantitative real-time PCR and its high-resolution melting tool.

CONCLUSIONS

As far as we know, this study is the first to estimate the prevalence of infection with Cryptosporidium and microsporidia among HIV-infected persons in northwest of Iran. The prevalence of intestinal microsporidiosis and cryptosporidiosis in this area in HIV-infected people was higher than the global prevalence of infection among immunocompromised patients. In addition to the need for further studies to prove protozoan pathogenicity in the aforementioned group, preventive measures should be considered.

Requirement of microtubules for secretion of a micronemal protein CpTSP4 in the invasive stage of the apicomplexan Cryptosporidium parvum

The zoonotic Cryptosporidium parvum is a global contributor to infantile diarrheal diseases and opportunistic infections in immunocompromised or weakened individuals. Like other apicomplexans, it possesses several specialized secretory organelles, including micronemes, rhoptry, and dense granules. However, the understanding of cryptosporidial micronemal composition and secretory pathway remains limited. Here, we report a new micronemal protein in C. parvum, namely, thrombospondin (TSP)-repeat domain-containing protein-4 (CpTSP4), providing insights into these ambiguities. Immunostaining and enzyme-linked assays show that CpTSP4 is prestored in the micronemes of unexcysted sporozoites but secreted during sporozoite excystation, gliding, and invasion. In excysted sporozoites, CpTSP4 is also distributed on the two central microtubules unique to Cryptosporidium. The secretion and microtubular distribution could be completely blocked by the selective kinesin-5 inhibitors SB-743921 and SB-715992, resulting in the accumulation of CpTSP4 in micronemes. These support the kinesin-dependent microtubular trafficking of CpTSP4 for secretion. We also localize γ-tubulin, consistent with kinesin-dependent anterograde trafficking. Additionally, recombinant CpTSP4 displays nanomolar binding affinity to the host cell surface, for which heparin acts as one of the host ligands. A novel heparin-binding motif is identified and validated biochemically for its contribution to the adhesive property of CpTSP4 by peptide competition assays and site-directed mutagenesis. These findings shed light on the mechanisms of intracellular trafficking and secretion of a cryptosporidial micronemal protein and the interaction of a TSP-family protein with host cells.IMPORTANCECryptosporidium parvum is a globally distributed apicomplexan parasite infecting humans and/or animals. Like other apicomplexans, it possesses specialized secretory organelles in the zoites, in which micronemes discharge molecules to facilitate the movement and invasion of zoites. Although past and recent studies have identified several proteins in cryptosporidial micronemes, our understanding of the composition, secretory pathways, and domain-ligand interactions of micronemal proteins remains limited. This study identifies a new micronemal protein, namely, CpTSP4, that is discharged during excystation, gliding, and invasion of C. parvum sporozoites. The CpTSP4 secretion depends on the intracellular trafficking on the two Cryptosporidium-unique microtubes that could be blocked by kinesin-5/Eg5 inhibitors. Additionally, a novel heparin-binding motif is identified and biochemically validated, which contributes to the nanomolar binding affinity of CpTSP4 to host cells. These findings indicate that kinesin-dependent microtubular trafficking is critical to CpTSP4 secretion, and heparin/heparan sulfate is one of the ligands for this micronemal protein.

Mendelian segregation and high recombination rates facilitate genetic analyses in Cryptosporidium parvum

Very little is known about the process of meiosis in the apicomplexan parasite Cryptosporidium despite the essentiality of sex in its life cycle. Most cell lines only support asexual growth of Cryptosporidium parvum (C. parvum), but stem cell derived intestinal epithelial cells grown under air-liquid interface (ALI) conditions support the sexual cycle. To examine chromosomal dynamics during meiosis in C. parvum, we generated two transgenic lines of parasites that were fluorescently tagged with mCherry or GFP on chromosomes 1 or 5, respectively. Infection of ALI cultures or Ifngr1-/- mice with mCherry and GFP parasites produced "yellow" oocysts generated by cross-fertilization. Outcrossed oocysts from the F1 generation were purified and used to infect HCT-8 cultures, and phenotypes of the progeny were observed by microscopy. All possible phenotypes predicted by independent segregation were represented equally (~25%) in the population, indicating that C. parvum chromosomes exhibit a Mendelian inheritance pattern. Unexpectedly, the most common pattern observed from the outgrowth of single oocysts included all possible parental and recombinant phenotypes derived from a single meiotic event, suggesting a high rate of crossover. To estimate the frequency of crossover, additional loci on chromosomes 1 and 5 were tagged and used to monitor intrachromosomal crosses in Ifngr1-/- mice. Both chromosomes showed a high frequency of crossover compared to other apicomplexans with map distances (i.e., 1% recombination) of 3-12 kb. Overall, a high recombination rate may explain many unique characteristics observed in Cryptosporidium spp. such as high rates of speciation, wide variation in host range, and rapid evolution of host-specific virulence factors.

Multiple pathways for glucose phosphate transport and utilization support growth of Cryptosporidium parvum

Cryptosporidium parvum is an obligate intracellular parasite with a highly reduced mitochondrion that lacks the tricarboxylic acid cycle and the ability to generate ATP, making the parasite reliant on glycolysis. Genetic ablation experiments demonstrated that neither of the two putative glucose transporters CpGT1 and CpGT2 were essential for growth. Surprisingly, hexokinase was also dispensable for parasite growth while the downstream enzyme aldolase was required, suggesting the parasite has an alternative way of obtaining phosphorylated hexose. Complementation studies in E. coli support a role for direct transport of glucose-6-phosphate from the host cell by the parasite transporters CpGT1 and CpGT2, thus bypassing a requirement for hexokinase. Additionally, the parasite obtains phosphorylated glucose from amylopectin stores that are released by the action of the essential enzyme glycogen phosphorylase. Collectively, these findings reveal that C. parvum relies on multiple pathways to obtain phosphorylated glucose both for glycolysis and to restore carbohydrate reserves.

Dispersal and invasive stages of Urospora eugregarines (Apicomplexa) from brown bodies of a polychaete host

Urosporid eugregarines (Apicomplexa: Urosporidae) are unicellular eukaryotic parasites inhabiting the coelom or the intestine of marine invertebrates such as annelids, molluscs, nemerteans, and echinoderms. Despite the availability of published morphological and phylogenetical analyses of coelomic gregarines, their long-term survival in the host body cavity and dispersal routes into the marine environment remain unclear. Here, we focus on Urospora gametocysts and oocysts with sporozoites, which were found viable inside the so-called brown bodies floating in the body cavity of the polychaete Travisia forbesii. Brown bodies form as a result of host defence where coelomocytes encapsulate dead host cells and foreign objects including potential pathogens. We hypothesise the long-term persistence of Urospora eugregarines in brown bodies through evasion of the host immunity and outline possible pathways for their egress into the marine environment, applicable as dispersal routes for other parasites as well. Unique features revealed by detailed ultrastructural analysis of detected eugregarine stages include asynchronous sporogony, a massive sporozoite secretion apparatus, as well as the presence of free (possibly autoinfective) sporozoites within the gametocyst. The assignment to the genus Urospora and the complete identity with U. ovalis and U. travisiae were confirmed by analysing 18S rDNA sequences obtained from isolated gametocysts. The 18S rDNA phylogeny confirmed the affiliation of Urosporidae to Lecudinoidea and the grouping of all Urospora sequences with Difficilina from nemerteans and environmental sequences from the Artic region. We also enriched the Apicomplexa set by partial 28S rDNA sequences of two Urospora species enabling more complex phylogenetic analyses prospectively.

Genetic Ablation of a Female-Specific Apetala 2 Transcription Factor Blocks Oocyst Shedding in Cryptosporidium parvum

The apicomplexan parasite Cryptosporidium is a leading global cause of diarrheal disease, and the infection poses a particularly grave threat to young children and those with weakened immune function. Infection occurs by ingestion of meiotic spores called oocysts, and transmission relies on fecal shedding of new oocysts. The entire life cycle thus occurs in a single host and features asexual as well as sexual forms of replication. Here, we identify and locus tag two Apetala 2-type (AP2) transcription factors and demonstrate that they are exclusively expressed in male and female gametes, respectively. To enable functional studies of essential genes in Cryptosporidium parvum, we develop and validate a small-molecule-inducible gene excision system, which we apply to the female factor AP2-F to achieve conditional gene knockout. Analyzing this mutant, we find the factor to be dispensable for asexual growth and early female fate determination in vitro but to be required for oocyst shedding in infected animals in vivo. Transcriptional analyses conducted in the presence or absence of AP2-F revealed that the factor controls the transcription of genes encoding crystalloid body proteins, which are exclusively expressed in female gametes. In C. parvum, the organelle is restricted to sporozoites, and its loss in other apicomplexan parasites leads to blocked transmission. Overall, our development of conditional gene ablation in C. parvum provides a robust method for genetic analysis in this parasite that enabled us to identify AP2-F as an essential regulator of transcription required for oocyst shedding and transmission. IMPORTANCE The parasite Cryptosporidium infects millions of people worldwide each year, leading to life-threatening diarrheal disease in young children and immunosuppressed individuals. There is no vaccine and only limited treatment. Transmission occurs via the fecal-oral route by an environmentally resilient spore-like oocyst. Infection takes place in the intestinal epithelium, where parasites initially propagate asexually before transitioning to male and female gametes, with sex leading to the formation of new oocysts. The essential role of sexual development for continuous infection and transmission makes it an attractive target for therapy and prevention. To study essential genes and potential drug targets across the life cycle, we established inducible gene excision for C. parvum. We determined that the female-specific transcription factor AP2-F is not required for asexual growth and early female development in vitro but is necessary for oocyst shedding in vivo. This work enhances the genetic tools available to study Cryptosporidium gene function.

Apical Secretory Glycoprotein Complex Contributes to Cell Attachment and Entry by Cryptosporidium parvum

Cryptosporidium parvum is an enteric pathogen that invades epithelial cells in the intestine, where it resides at the apical surface in a unique epicellular location. Compared with those of related apicomplexan parasites, the processes of host cell attachment and invasion by C. parvum are poorly understood. The streamlined C. parvum genome contains numerous mucin-like glycoproteins, several of which have previously been shown to mediate cell attachment, although the majority are unstudied. Here, we identified the antigens recognized by monoclonal antibody (MAb) 1A5, which stains the apical end of sporozoites and mature merozoites. Immunoprecipitation with MAb 1A5 followed by mass spectrometry identified a heterodimer comprised of paralogous proteins which are related to additional orthologs in the genome of C. parvum and related species. Paralogous glycoproteins recognized by MAb 1A5 heterodimerize as a complex displayed on the parasite surface, and they also interact with lectins that suggest that they contain mucin-like, O-linked oligosaccharides. Although the gene encoding one of the paralogs was readily disrupted by CRISPR/Cas9 gene editing, its partner, which contains a mucin-like domain related to GP900, was refractory to deletion. Combined with the ability of MAb 1A5 to partially neutralize host cell attachment by sporozoites, these findings define a new family of secretory glycoproteins that participate in cell invasion by Cryptosporidium spp. IMPORTANCE Although Cryptosporidium is extremely efficient at penetrating mucus and invading epithelial cells in the intestine, the mechanism of cell attachment is poorly understood. To expand our understanding of this process, we characterized the antigens recognized by a monoclonal antibody that stains the apical end of invasive stages called sporozoites and merozoites. Our studies identify a family of glycoproteins that form heterodimers on the parasite cell surface to facilitate host cell attachment and entry. By further defining the role of mucin-like glycoproteins in host cell attachment, our studies may lead to strategies to disrupt cell adhesion and thereby decrease infection.

Early immune and host cell responses to Cryptosporidium infection

Cryptosporidium spp. are opportunistic protozoan parasites that infect epithelial cells of the small intestine and cause diarrheal illness in both immunocompetent and immunodeficient individuals. These infections may be more severe in immunocompromised individuals and young children, especially in children under 2 in developing countries. The parasite has a global distribution and is an important cause of childhood diarrhea where it may result in cognitive impairment and growth deficits. Current therapies are limited with nitazoxanide being the only FDA-approved drug. However, it is not efficacious in immunocompromised patients. Additionally, there are no vaccines for cryptosporidiosis available. While acquired immunity is needed to clear Cryptosporidium parasites completely, innate immunity and early responses to infection are important in keeping the infection in check so that adaptive responses have time to develop. Infection is localized to the epithelial cells of the gut. Therefore, host cell defenses are important in the early response to infection and may be triggered through toll receptors or inflammasomes which induce a number of signal pathways, interferons, cytokines, and other immune mediators. Chemokines and chemokine receptors are upregulated which recruit immune cells such neutrophils, NK cells, and macrophages to the infection site to help in host cell defense as well as dendritic cells that are an important bridge between innate and adaptive responses. This review will focus on the host cell responses and the immune responses that are important in the early stages of infection.

Past, current, and potential treatments for cryptosporidiosis in humans and farm animals: A comprehensive review

The intracellular protozoan parasite of the genus Cryptosporidium is among the leading causes of waterborne diarrheal disease outbreaks throughout the world. The parasite is transmitted by ingestion of infective oocysts that are highly stable in the environment and resistant to almost all conventional disinfection methods and water treatments. Control of the parasite infection is exceedingly difficult due to the excretion of large numbers of oocysts in the feces of infected individuals that contaminate the environment and serve as a source of infection for susceptible hosts including humans and animals. Drug development against the parasite is challenging owing to its limited genetic tractability, absence of conventional drug targets, unique intracellular location within the host, and the paucity of robust cell culture platforms for continuous parasite propagation. Despite the high prevalence of the parasite, the only US Food and Drug Administration (FDA)-approved treatment of Cryptosporidium infections is nitazoxanide, which has shown moderate efficacy in immunocompetent patients. More importantly, no effective therapeutic drugs are available for treating severe, potentially life-threatening cryptosporidiosis in immunodeficient patients, young children, and neonatal livestock. Thus, safe, inexpensive, and efficacious drugs are urgently required to reduce the ever-increasing global cryptosporidiosis burden especially in low-resource countries. Several compounds have been tested for both in vitro and in vivo efficacy against the disease. However, to date, only a few experimental compounds have been subjected to clinical trials in natural hosts, and among those none have proven efficacious. This review provides an overview of the past and present anti-Cryptosporidium pharmacotherapy in humans and agricultural animals. Herein, we also highlight the progress made in the field over the last few years and discuss the different strategies employed for discovery and development of effective prospective treatments for cryptosporidiosis.

Cryptosporidiosis: From Prevention to Treatment, a Narrative Review

Cryptosporidiosis is a water- and food-borne zoonotic disease caused by the protozoon parasite of the genus Cryptosporidium. C. hominis and C. parvum are the main two species causing infections in humans and animals. The disease can be transmitted by the fecal-oral route as well as the respiratory route. The infective stage (sporulated oocysts) is resistant to different disinfectants including chlorine. Currently, no effective therapeutic drugs or vaccines are available to treat and control Cryptosporidium infection. To prevent cryptosporidiosis in humans and animals, we need to understand better how the disease is spread and transmitted, and how to interrupt its transmission cycle. This review focuses on understanding cryptosporidiosis, including its infective stage, pathogenesis, life cycle, genomics, epidemiology, previous outbreaks, source of the infection, transmission dynamics, host spectrum, risk factors and high-risk groups, the disease in animals and humans, diagnosis, treatment and control, and the prospect of an effective anti-Cryptosporidium vaccine. It also focuses on the role of the One Health approach in managing cryptosporidiosis at the animal-human-environmental interface. The summarized data in this review will help to tackle future Cryptosporidium infections in humans and animals and reduce the disease occurrence.

Evaluation of a vaccine candidate isolated from Cryptosporidium parvum oocyst in mice

Background and Aim

Cryptosporidiosis is a leading cause of diarrheal disease worldwide and is an animal and public health burden. This study aimed to evaluate the protective potential of affinity-purified Cryptosporidium parvum oocyst antigen as a vaccine candidate according to fecal oocyst shedding, humoral and cellular immune responses, histopathological changes, and the number of parasite developmental stages in ileal and hepatic tissues.

Materials and Methods

We isolated oocysts from naturally infected buffalo calves and identified them molecularly as C. parvum isolates (GenBank: ON730707 and ON730708) by targeting the Cryptosporidium oocyst wall protein gene. We propagated the C. parvum oocysts in mice. In addition, we prepared crude antigen from the isolated oocysts by purification using cyanogen bromide-activated Sepharose-4B affinity chromatography coupled with rabbit hyperimmune serum. Then, we divided 81 parasite-free mice into three groups: (1) non-vaccinated non-infected mice, (2) mice orally infected with 1 × 10⁵ C. parvum oocysts on week 4 of the experiment, and (3) mice immunized twice with 40 μg/kg of the purified fraction at 2-week intervals. Then, we challenged the vaccinated group with C. parvum oocysts after 2 weeks, and the positive control group was infected at the same time.

Results

We observed a prolonged prepatent period and decreased oocyst shedding in the vaccinated infected mice compared with the non-vaccinated infected mice (t < 0.001). The vaccinated mice had significantly higher immunoglobulin G levels than those in the other two groups at all examined weeks. In addition, the production of cytokines interferon-gamma, interleukin (IL)-10, IL-12, and IL-15 was activated post-vaccination. After the challenge, all tested cytokines were significantly increased (p < 0.001) in the two infected groups compared with the non-vaccinated non-infected group, with the highest levels in the vaccinated infected group. Vaccinated infected mice exhibited significantly fewer pathological lesions in the ileum and liver than non-vaccinated infected mice, which showed prominent histopathological lesions. Endogenous developmental stages of C. parvum indicated that the ileum was more parasitized than the liver and that vaccination resulted in a lower number of oocysts in ileal and hepatic tissues (p < 0.05).

Conclusion

Our prepared affinity-purified vaccine candidate could be promising in protecting against cryptosporidiosis.

Efficacy of clofazimine and nitazoxanide combination in treating intestinal cryptosporidiosis and enhancing intestinal cellular regeneration in immunocompromised mice

Cryptosporidium is a widely distributed food and water-borne enteric protozoan that affects a wide range of vertebrates, resulting in life-threatening consequences, particularly in immunocompromised hosts. The lack of effective anti-cryptosporidial drugs may be related to the parasite's unique intestinal location, plus the lack of studies on the process by which the protozoan is able to impair intestinal cellular function. The present work aimed to assess the effect of clofazimine (CFZ), an FDA-approved drug for the treatment of leprosy, as an anti-cryptosporidial drug, using transmission electron microscopy (TEM) and an immunocompromised mouse model. The affected intestinal mucosa with parasitic stages in the infected non-treated group showed signs of severe cellular degeneration, including the loss of tight junctions, deformed and damaged microvilli and irregularly distributed nuclei with a severely vacuolated cytoplasm. Comparatively, nitazoxanide (NTZ) monotherapy showed the lowest efficacy as the drug was associated with the lowest rate of oocyst shedding. In addition, NTZ treatment failed to achieve the return of complete cellular function; abnormalities were evident in the microvilli, cytoplasmic organelles and nuclear features. Clofazimine demonstrated an improvement of the mucosal cellular components, including mitochondria and significantly reduced oocyst shedding. Combined treatment with low-dose CFZ and half-dose NTZ resulted in a significant improvement in the enterocyte cellular structures with an absence of intracellular parasitic stages. These results indicate that CFZ, a safe and readily prescribed drug, effectively reduces cryptosporidiosis when used in combination with only half the dose of NTZ. Used in combination, these drugs were shown to be efficient in regaining intestinal cellular activity following Cryptosporidium-induced functional damage in an immunocompromised mouse model.

A genetic screen identifies a protective type III interferon response to Cryptosporidium that requires TLR3 dependent recognition

Cryptosporidium is a leading cause of severe diarrhea and diarrheal-related death in children worldwide. As an obligate intracellular parasite, Cryptosporidium relies on intestinal epithelial cells to provide a niche for its growth and survival, but little is known about the contributions that the infected cell makes to this relationship. Here we conducted a genome wide CRISPR/Cas9 knockout screen to discover host genes that influence Cryptosporidium parvum infection and/or host cell survival. Gene enrichment analysis indicated that the host interferon response, glycosaminoglycan (GAG) and glycosylphosphatidylinositol (GPI) anchor biosynthesis are important determinants of susceptibility to C. parvum infection and impact on the viability of host cells in the context of parasite infection. Several of these pathways are linked to parasite attachment and invasion and C-type lectins on the surface of the parasite. Evaluation of transcript and protein induction of innate interferons revealed a pronounced type III interferon response to Cryptosporidium in human cells as well as in mice. Treatment of mice with IFNλ reduced infection burden and protected immunocompromised mice from severe outcomes including death, with effects that required STAT1 signaling in the enterocyte. Initiation of this type III interferon response was dependent on sustained intracellular growth and mediated by the pattern recognition receptor TLR3. We conclude that host cell intrinsic recognition of Cryptosporidium results in IFNλ production critical to early protection against this infection.

Live imaging of the Cryptosporidium parvum life cycle reveals direct development of male and female gametes from type I meronts

Cryptosporidium is a leading infectious cause of diarrhea around the world associated with waterborne outbreaks, community spread, or zoonotic transmission. The parasite has significant impact on early childhood mortality, and infection is both a consequence and cause of malnutrition and stunting. There is currently no vaccine, and treatment options are very limited. Cryptosporidium is a member of the Apicomplexa, and, as typical for this, protist phylum relies on asexual and sexual reproduction. In contrast to other Apicomplexa, including the malaria parasite Plasmodium, the entire Cryptosporidium life cycle unfolds in a single host in less than 3 days. Here, we establish a model to image life cycle progression in living cells and observe, track, and compare nuclear division of asexual and sexual stage parasites. We establish the length and sequence of the cell cycles of all stages and map the developmental fate of parasites across multiple rounds of invasion and egress. We propose that the parasite executes an intrinsic program of 3 generations of asexual replication, followed by a single generation of sexual stages that is independent of environmental stimuli. We find no evidence for a morphologically distinct intermediate stage (the tetraploid type II meront) but demonstrate direct development of gametes from 8N type I meronts. The progeny of each meront is collectively committed to either asexual or sexual fate, but, importantly, meronts committed to sexual fate give rise to both males and females. We define a Cryptosporidium life cycle matching Tyzzer’s original description and inconsistent with the coccidian life cycle now shown in many textbooks.

The Long and Short of Next Generation Sequencing for Cryptosporidium Research

The intestinal parasite Cryptosporidium is a significant cause of severe diarrhoeal disease that can have long term effects. Therapeutic options remain limited despite a significant impact on public health, partly due to various challenges in the field of Cryptosporidium research, including the availability of genomic and transcriptomic data from environmental and clinical isolates. In this review we explore how long read DNA and RNA sequencing technologies have begun to provide novel insights into the biology of the parasite. The increased deployment of these technologies will help researchers address key gaps in the understanding of Cryptosporidium biology, and ultimately drive translational research and better parasite control.

Comparative proteomics reveals Cryptosporidium parvum manipulation of the host cell molecular expression and immune response

Cryptosporidium is a life-threating protozoan parasite belonging to the phylum Apicomplexa, which mainly causes gastroenteritis in a variety of vertebrate hosts. Currently, there is a re-emergence of Cryptosporidium infection; however, no fully effective drug or vaccine is available to treat Cryptosporidiosis. In the present study, to better understand the detailed interaction between the host and Cryptosporidium parvum, a large-scale label-free proteomics study was conducted to characterize the changes to the proteome induced by C. parvum infection. Among 4406 proteins identified, 121 proteins were identified as differentially abundant (> 1.5-fold cutoff, P < 0.05) in C. parvum infected HCT-8 cells compared with uninfected cells. Among them, 67 proteins were upregulated, and 54 proteins were downregulated at 36 h post infection. Analysis of the differentially abundant proteins revealed an interferon-centered immune response of the host cells against C. parvum infection and extensive inhibition of metabolism-related enzymes in the host cells caused by infection. Several proteins were further verified using quantitative real-time reverse transcription polymerase chain reaction and western blotting. This systematic analysis of the proteomics of C. parvum-infected HCT-8 cells identified a wide range of functional proteins that participate in host anti-parasite immunity or act as potential targets during infection, providing new insights into the molecular mechanism of C. parvum infection.

Cryptosporidium parvum is an emerging zoonotic pathogen transmitted via the fecal–oral route, and is considered a leading cause of moderate-to-severe diarrheal disease in young children in resource limited areas. After infection, C. parvum parasitizes intestinal epithelial cells and evokes an inflammatory immune response, leading to severe damage of the intestinal mucosa. The infection can be lethal to immunosuppressed individuals. However, no fully effective drug or vaccine is available for cryptosporidiosis, and the pathogenesis and immune mechanisms during C. parvum infection are obscure. Thus, an in-depth understanding of host-parasite interaction is needed. Hence, we established a C. parvum-infected HCT-8 cell model and performed comparative quantitative proteomic analyses to profile global host-parasite interactions and determine the molecular mechanisms that are activated during infection, aiming to offer new insights into the treatment of Cryptosporidium.

Commensal Cryptosporidium colonization elicits a cDC1-dependent Th1 response that promotes intestinal homeostasis and limits other infections

Cryptosporidium can cause severe diarrhea and morbidity, but many infections are asymptomatic. Here, we studied the immune response to a commensal strain of Cryptosporidium tyzzeri (Ct-STL) serendipitously discovered when conventional type 1 dendritic cell (cDC1)-deficient mice developed cryptosporidiosis. Ct-STL was vertically transmitted without negative health effects in wild-type mice. Yet, Ct-STL provoked profound changes in the intestinal immune system, including induction of an IFN-γ-producing Th1 response. TCR sequencing coupled with in vitro and in vivo analysis of common Th1 TCRs revealed that Ct-STL elicited a dominant antigen-specific Th1 response. In contrast, deficiency in cDC1s skewed the Ct-STL CD4 T cell response toward Th17 and regulatory T cells. Although Ct-STL predominantly colonized the small intestine, colon Th1 responses were enhanced and associated with protection against Citrobacter rodentium infection and exacerbation of dextran sodium sulfate and anti-IL10R-triggered colitis. Thus, Ct-STL represents a commensal pathobiont that elicits Th1-mediated intestinal homeostasis that may reflect asymptomatic human Cryptosporidium infection.

Anticryptosporidium Efficacy of Olea europaea and Ficus carica Leaves Extract in Immunocompromised Mice Associated with Biochemical Characters and Antioxidative System

Cryptosporidiosis is caused by an opportunistic protozoan parasite (Cryptosporidium parvum and C. hominis) known as a parasite of humans, especially children and immunocompromised patients. The current study was designed to evaluate the therapeutic efficacy of a mixture of fig and olive leaf extracts as an alternative medicinal plant. Parasitological examination for oocysts in the stool and histopathological alterations in the small intestines were examined. Additionally, biochemical analyses of liver and kidney functions in addition to antioxidant parameters such as superoxide dismutase (SOD), glutathione peroxidase (GSH) and catalase (CAT) in the plasma were evaluated. Our results showed that marked reduction in oocysts shedding and amelioration in intestinal histopathological changes and hepatic or renal functions were detected in all treated groups compared to the control infected group. Additionally, the treated groups with tested extracts at ratios 1:3 and 1:5 showed a significant decrease in the number of oocysts compared to the other treated groups. Results exhibited a significant increase in the plasma SOD, CAT and GSH levels in treated groups compared to the infected control one. This study suggested that a mixture of fig and olive leaf extracts is a convenient promising therapeutic agent for Cryptosporidiosis.

Challenges for Cryptosporidium Population Studies

Cryptosporidiosis is ranked sixth in the list of the most important food-borne parasites globally, and it is an important contributor to mortality in infants and the immunosuppressed. Recently, the number of genome sequences available for this parasite has increased drastically. The majority of the sequences are derived from population studies of Cryptosporidium parvum and Cryptosporidium hominis, the most important species causing disease in humans. Work with this parasite is challenging since it lacks an optimal, prolonged, in vitro culture system, which accurately reproduces the in vivo life cycle. This obstacle makes the cloning of isolates nearly impossible. Thus, patient isolates that are sequenced represent a population or, at times, mixed infections. Oocysts, the lifecycle stage currently used for sequencing, must be considered a population even if the sequence is derived from single-cell sequencing of a single oocyst because each oocyst contains four haploid meiotic progeny (sporozoites). Additionally, the community does not yet have a set of universal markers for strain typing that are distributed across all chromosomes. These variables pose challenges for population studies and require careful analyses to avoid biased interpretation. This review presents an overview of existing population studies, challenges, and potential solutions to facilitate future population analyses.

The Efficacy of Citrus maxima Peels Aqueous Extract Against Cryptosporidiosis in Immunecompromised Mice

INTRODUCTION

 Cryptosporidiosis is an opportunistic globally distributed parasitic disease caused by protozoan Cryptosporidium where its development is closely related to the host's immune status. New therapeutic agents are a high priority as chemotherapeutics are impractical and vaccines are unavailable for young as well as immune-compromised patients or animals. The current study was designed to evaluate the therapeutic effect of the internal white (albedo) and external yellow (flavedo) peels of Citrus maxima (C. maxima) as an alternative medicinal plant. MATERIALS AND METHODS : Parasitological examination for oocysts in the stool was determined. Histopathological alterations and immunohistochemical expression of APC and cyclin D1 as well as an assessment of interferon-γ (IFN-γ) and interleukin 1β (IL-1β) in ileal tissues was carried out. In addition, the biochemical examination of serum albumin, globulin and liver enzymes were evaluated. Results revealed a significant decrease of oocysts count correlated with an amelioration of histopathological and immunohistochemical changes in ileal tissue with an enhancement of liver enzymes and inflammatory cytokines levels.

CONCLUSION

 It could be concluded that treatment with C. maxima peel extracts have a potential therapeutic and an immunoregulatory efficacy against Cryptosporidiosis. Obtained results showed that the white peel was found to have more immunological effect that could significantly enhance inflammatory cytokines response towards normal status. Hence, it can be used in the daily animal diet to give protective effects against infection.

Opportunities and Challenges in Developing a Cryptosporidium Controlled Human Infection Model for Testing Antiparasitic Agents

Cryptosporidiosis is a leading cause of moderate-to-severe diarrhea in low- and middle-income countries, responsible for high mortality in children younger than two years of age, and it is also strongly associated with childhood malnutrition and growth stunting. There is no vaccine for cryptosporidiosis and existing therapeutic options are suboptimal to prevent morbidity and mortality in young children. Recently, novel therapeutic agents have been discovered through high-throughput phenotypic and target-based screening strategies, repurposing malaria hits, etc., and these agents have a promising preclinical in vitro and in vivo anti-Cryptosporidium efficacy. One key step in bringing safe and effective new therapies to young vulnerable children is the establishment of some prospect of direct benefit before initiating pediatric clinical studies. A Cryptosporidium controlled human infection model (CHIM) in healthy adult volunteers can be a robust clinical proof of concept model for evaluating novel therapeutics. CHIM could potentially accelerate the development path to pediatric studies by establishing the safety of a proposed pediatric dosing regimen and documenting preliminary efficacy in adults. We present, here, perspectives regarding the opportunities and perceived challenges with the Cryptosporidium human challenge model.

Insulinase-like Protease 1 Contributes to Macrogamont Formation in Cryptosporidium parvum

The apicomplexan parasite Cryptosporidium parvum contains an expanded family of 22 insulinase-like proteases (INS), a feature that contrasts with their otherwise streamlined genome. Here, we examined the function of INS1, which is most similar to the human insulinase protease that cleaves a variety of small peptide substrates. INS1 is an M16A clan member and contains a signal peptide, an N-terminal domain with the HXXEH active site, followed by three inactive domains. Unlike previously studied C. parvum INS proteins that are expressed in sporozoites and during merogony, INS1 was expressed exclusively in macrogamonts, where it was localized in small cytoplasmic vesicles. Although INS1 did not colocalize with the oocyst wall protein recognized by the antibody OW50, immune-electron microscopy indicated that INS1 resides in small vesicles in the secretory system. Notably, these small INS1-positive vesicles were often in close proximity to large OW50-positive vacuoles resembling wall-forming bodies, which contain precursors for oocyst wall formation. Genetic deletion of INS1, or replacement with an active-site mutant, resulted in lower formation of macrogamonts in vitro and reduced oocyst shedding in vivo Our findings reveal that INS1 functions in the formation or maturation of macrogamonts and that its loss results in attenuated virulence in immunocompromised mice.IMPORTANCE Cryptosporidiosis is a debilitating diarrheal disease in young children in developing countries. The absence of effective treatments or vaccines makes this infection very difficult to manage in susceptible populations. Although the oral dose of oocysts needed to cause infection is low, infected individuals shed very high numbers of oocysts, readily contaminating the environment. Our studies demonstrate that the protease INS1 is important for formation of female sexual stages and that in its absence, parasites produce fewer oocysts and are attenuated in immunocompromised mice. These findings suggest that mutants lacking INS1, or related proteases, are useful for further characterizing the pathway that leads to macrogamont maturation and oocyst wall formation.

Cryptosporidium: Host-Parasite Interactions and Pathogenesis

Purpose of Review

Cryptosporidium spp. (C. hominis and C. parvum) are a major cause of diarrhea-associated morbidity and mortality in young children globally. While C. hominis only infects humans, C. parvum is a zoonotic parasite that can be transmitted from infected animals to humans. There are no treatment or control measures to fully treat cryptosporidiosis or prevent the infection in humans and animals. Our knowledge on the molecular mechanisms of Cryptosporidium-host interactions and the underlying factors that govern infectivity and disease pathogenesis is very limited.

Recent Findings

Recent development of genetics and new animal models of infection, along with progress in cell culture platforms to complete the parasite lifecycle in vitro, is greatly advancing the Cryptosporidium field.

Summary

In this review, we will discuss our current knowledge of host-parasite interactions and how genetic manipulation of Cryptosporidium and promising infection models are opening the doors towards an improved understanding of parasite biology and disease pathogenesis.

A review of Cryptosporidium spp. and their detection in water

Cryptosporidium spp. are one of the most important waterborne pathogens worldwide and a leading cause of mortality from waterborne gastrointestinal diseases. Detection of Cryptosporidium spp. in water can be very challenging due to their low numbers and the complexity of the water matrix. This review describes the biology of Cryptosporidium spp. and current methods used in their detection with a focus on C. parvum and C. hominis. Among the methods discussed and compared are microscopy, immunology-based methods using monoclonal antibodies, molecular methods including PCR (polymerase chain reaction)-based assays, and emerging aptamer-based methods. These methods have different capabilities and limitations, but one common challenge is the need for better sensitivity and specificity, particularly in the presence of contaminants. The application of DNA aptamers in the detection of Cryptosporidium spp. oocysts shows promise in overcoming these challenges, and there will likely be significant developments in aptamer-based sensors in the near future.

Neonatal Mouse Gut Metabolites Influence Cryptosporidium parvum Infection in Intestinal Epithelial Cells

Cryptosporidium sp. occupies a unique intracellular niche that exposes the parasite to both host cell contents and the intestinal lumen, including metabolites from the diet and produced by the microbiota. Both dietary and microbial products change over the course of early development and could contribute to the changes seen in susceptibility to cryptosporidiosis in humans and mice.

The protozoan parasite Cryptosporidium sp. is a leading cause of diarrheal disease in those with compromised or underdeveloped immune systems, particularly infants and toddlers in resource-poor localities. As an enteric pathogen, Cryptosporidium sp. invades the apical surface of intestinal epithelial cells, where it resides in close proximity to metabolites in the intestinal lumen. However, the effect of gut metabolites on susceptibility to Cryptosporidium infection remains largely unstudied. Here, we first identified which gut metabolites are prevalent in neonatal mice when they are most susceptible to Cryptosporidium parvum infection and then tested the isolated effects of these metabolites on C. parvum invasion and growth in intestinal epithelial cells. Our findings demonstrate that medium or long-chain saturated fatty acids inhibit C. parvum growth, perhaps by negatively affecting the streamlined metabolism in C. parvum, which is unable to synthesize fatty acids. Conversely, long-chain unsaturated fatty acids enhanced C. parvum invasion, possibly by modulating membrane fluidity. Hence, gut metabolites, either from diet or produced by the microbiota, influence C. parvum growth in vitro and may also contribute to the early susceptibility to cryptosporidiosis seen in young animals.

Copro-microscopical and immunological diagnosis of cryptosporidiosis in Egyptian buffalo-calves with special reference to their cytokine profiles

Cryptosporidiosis is considered to be one of the most devasting gastrointestinal diseases in calves. The aim of this study was to investigate Cryptosporidium parvum infection (C. parvum) in buffalo-calves with both copro-microscopic examination and enzyme linked immunosorbent assay (ELISA) using two C. parvum prepared antigens with regards to their cytokines profile; interferon- γ (IFN-γ), interleukin (IL)-12 and IL-14 to achieve a proper diagnosis. All collected buffalo- calves' fecal samples were examined by modified Ziehl-Neelsen staining technique. ELISA was performed to evaluate the diagnostic accuracy of the two C. parvum prepared antigens; crude whole oocyst (CWO) and crude sonicated oocyst (CSO) in detection of anti-C. parvum IgG in buffalo-calves' sera. As well, concentrations of INF-γ, IL-12 and IL-14 in the buffalo-calves' serum samples were estimated. The results revealed that the overall parasitological incidence of cryptosporidiosis was 40%. However, the serological diagnosis by ELISA assay showed 53.75% and 27.5% when using CWO and CSO antigen, respectively. Also, the diagnostic efficacy parameters of both antigens; CWO and CSO showed a significant high specificity (83.3%) achieved by CSO antigen and a high sensitivity (71.8%) by CWO antigen. The levels of INF-γ, IL-12 and IL-14 were significantly increased in positive Cryptosporidium infected group by both coprological and serological assays followed by the group which was positive for cryptosporidiosis by copro-microscopic examination only. The present study concluded that a combination of coprological and serological examination with reference to the cytokines profile is needed for proper diagnosis of cryptosporidiosis in buffalo-calves.

Life cycle progression and sexual development of the apicomplexan parasite Cryptosporidium parvum

The apicomplexan parasite Cryptosporidium is a leading global cause of severe diarrhoeal disease and an important contributor to early childhood mortality. Currently, there are no fully effective treatments or vaccines available. Parasite transmission occurs through ingestion of oocysts, through either direct contact or consumption of contaminated water or food. Oocysts are meiotic spores and the product of parasite sex. Cryptosporidium has a single-host life cycle in which both asexual and sexual processes occur in the intestine of infected hosts. Here, we genetically engineered strains of Cryptosporidium to make life cycle progression and parasite sex tractable. We derive reporter strains to follow parasite development in culture and in infected mice and define the genes that orchestrate sex and oocyst formation through mRNA sequencing of sorted cells. After 2 d, parasites in cell culture show pronounced sexualization, but productive fertilization does not occur and infection falters. By contrast, in infected mice, male gametes successfully fertilize female parasites, which leads to meiotic division and sporulation. To rigorously test for fertilization, we devised a two-component genetic-crossing assay using a reporter that is activated by Cre recombinase. Our findings suggest obligate developmental progression towards sex in Cryptosporidium, which has important implications for the treatment and prevention of the infection.

Infection with Cryptosporidium parvum is a leading cause of severe diarrhoeal disease and childhood mortality worldwide. Using tools they recently developed to genetically engineer Cryptosporidium, the authors define life cycle stage-specific markers and generate reporter parasites, making life cycle progression and parasite sex tractable.

A Stem-Cell-Derived Platform Enables Complete Cryptosporidium Development In Vitro and Genetic Tractability

Despite being a frequent cause of severe diarrheal disease in infants and an opportunistic infection in immunocompromised patients, Cryptosporidium research has lagged due to a lack of facile experimental methods. Here, we describe a platform for complete life cycle development and long-term growth of C. parvum in vitro using “air-liquid interface” (ALI) cultures derived from intestinal epithelial stem cells. Transcriptomic profiling revealed that differentiating epithelial cells grown under ALI conditions undergo profound changes in metabolism and development that enable completion of the parasite life cycle in vitro. ALI cultures support parasite expansion > 100-fold and generate viable oocysts that are transmissible in vitro and to mice, causing infection and animal death. Transgenic parasite lines created using CRISPR/Cas9 were used to complete a genetic cross in vitro, demonstrating Mendelian segregation of chromosomes during meiosis. ALI culture provides an accessible model that will enable innovative studies into Cryptosporidium biology and host interactions.

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Air-liquid interface (ALI) cultivation of Cryptosporidium supports robust parasite growth

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Both asexual and sexual phases of the parasite complete development in ALI cultures

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ALI culture supports the production of de novo oocysts that can trigger an infection in mice

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In vitro crossing in ALI cultures opens up forward genetics for Cryptosporidium

A suite of phenotypic assays to ensure pipeline diversity when prioritizing drug-like Cryptosporidium growth inhibitors

Cryptosporidiosis is a leading cause of life-threatening diarrhea in children, and the only currently approved drug is ineffective in malnourished children and immunocompromised people. Large-scale phenotypic screens are ongoing to identify anticryptosporidial compounds, but optimal approaches to prioritize inhibitors and establish a mechanistically diverse drug development pipeline are unknown. Here, we present a panel of medium-throughput mode of action assays that enable testing of compounds in several stages of the Cryptosporidium life cycle. Phenotypic profiles are given for thirty-nine anticryptosporidials. Using a clustering algorithm, the compounds sort by phenotypic profile into distinct groups of inhibitors that are either chemical analogs (i.e. same molecular mechanism of action (MMOA)) or known to have similar MMOA. Furthermore, compounds belonging to multiple phenotypic clusters are efficacious in a chronic mouse model of cryptosporidiosis. This suite of phenotypic assays should ensure a drug development pipeline with diverse MMOA without the need to identify underlying mechanisms.

Cellular immune response and scanning electron microscopy in the evaluation of Moringa leaves aqueous extract effect on Cryptosporidium parvum in buffalo intestinal tissue explants

Cryptosporidium is an apicomplexan parasite of human and animals and is considered as an important co-factor in neonatal diarrhea. In this study, an explant culture was used as an in vitro model of buffalo intestine to evaluate the effect of Moringa leaves extract on Cryptosporidium parvum (C. parvum) oocysts using light and scanning electron microscopy and measuring IFN-γ, IL-12 and IL-14 in the culture supernatants. C. parvum oocysts were collected from naturally-infected calf feces, isolated, excysted and then co-inoculated with ileal tissue explants culture medium. The prepared Moringa leaves extract was then introduced to the infected tissues in the concentrations of 100 mg/ml and 300 mg/ml. After 24 h, tissues were collected and processed for light and scanning electron microscopy. Also, culture supernatants were collected for cytokines measurement. C. parvum parasitophorous vacuoles were found attached to the surface of tissue in Cryptosporidium-infected ileal tissue explants. High magnification imaging of ileal tissue explants using scanning electron microscopy showed that Moringa leaves extracts had a great effect on Cryptosporidium-infected ileal tissue explants. There was a high significant (P < 0.001) increase in IFN-γ, IL-12 and IL-14 (375, 275 and 90 pg/ml, respectively) in the supernatants of infected non-treated ileal tissue explant culture plate wells compared to the control non-infected ones (74.66, 75 and 50 pg/ml, respectively). A concentration of 100 mg/ml Moringa extract exhibited the highest anticryptosporidial effect causing a significant decrease in IFN-γ, IL-12 and IL-14 levels (225, 150 and 65 pg/ml, respectively) compared with supernatants of infected non-treated ileal explant culture plate wells. In this study, explant culturing of buffalo ileal tissues allowed investigating the pathogenesis of cryptosporidiosis using light and scanning electron microscopy and studying changes in cytokine levels in tissues with and without Moringa leaves extract treatment. This model could help to understand the regulation of intestinal secretory and inflammatory responses, and could be useful for the screening of potential anticryptosporidial candidate compounds.

Anticryptosporidial effect of pomegranate peels water extract in experimentally infected mice with special reference to some biochemical parameters and antioxidant activity

Cryptosporidiosis is a zoonotic disease caused by a well-known parasitic protozoan called Cryptosporidium. Infection in livestock causes important economic losses among farm animals and its control has a global concern. In this study, internal white and external red layers were separated from pomegranate peels (Punica granatum) then; they were grinded to reach Nano form. Anticryptosporidial effect of their water extracts was investigated in experimentally infected mice. Also, their antioxidant activity, biochemical and histopathological changes were studied. Briefly, hot aqueous extracts of pomegranate peels were prepared regarding its good sensory attributes at concentration of 10% W/V. Analysis of total phenolics, individual phenolics by HPLC-DAD and antioxidant activities have been done. Forty-five mice were divided into five groups each one containing nine mice. The first group was healthy mice and the 2nd one was infected orally with 10⁴ Cryptosporidium parvum (C. parvum) oocysts/mice and not treated. The other 3 groups were infected and orally treated with Nitazoxanide (NTZ) for the 3rd group, pomegranate red peel extract for the 4th group and pomegranate white peel extract for the 5th group. Blood samples were collected after 1 and 2 weeks post treatment for protein profile, liver enzymes and antioxidant activity evaluation. After 3 weeks, all animals were sacrificed and ileal tissues were embedded in paraffin for histopathological examination. The results showed that pomegranate peel extracts were rich in phenolic compounds, had high antioxidant activity and therapeutic effect on C. parvum in experimentally infected mice. Red peel extract diminished C. parvum oocysts count significantly in experimentally infected mice than white peel and NTZ treatments. Also, the histopathological examination revealed that red peel treated mice ileal sections showed a great enhancement in the shape and structure of villi towards normal structure than other treated groups. Most of the measured biochemical parameters after 2 weeks' treatment with red pomegranate peel and NTZ were enhanced in their concentrations towards the healthy normal status. In conclusion, this study showed the effectiveness of Nano-form of pomegranate white and red peel extracts against C. parvum oocysts. Pomegranate red peel extract was found to have antioxidant activity that could significantly enhance the serum biochemical parameters and oxidative stress towards the healthy normal status. Furthermore, it is suggested that pomegranate peel should be separated and used in the daily animal diet or as a functional beavarage for human as accepted from the panelists to give protective effects against this parasite as well as to improve health benefits.

First report and molecular characterization of Cryptosporidium spp. in humans and animals in Khartoum state, Sudan

BACKGROUND AND AIM

Cryptosporidium is recognized to infect several mammalian species as well as humans, causing substantial economic losses and serious public health concern. Infected animals can be a source of environmental contamination and human infections. In general, the occurrence of Cryptosporidium species in animals and human in Sudan and zoonotic importance is not well documented. This study aimed to identify Cryptosporidium spp. infecting different animal species and humans and to compare between different isolates obtained.

MATERIALS AND METHODS

To provide molecular information about Cryptosporidium in animals and humans, both modified Ziehl-Neelsen (MZN) specific stain and molecular assay were used. Concentration techniques followed by three protocols of DNA extraction were carried out. After microscopic screening of 263 fecal samples (goats [n=197], cattle [n=12], sheep [n=12], and human [n=42]), 61 positive and 30 negative, randomly selected samples were used in nested polymerase chain reaction (PCR) targeting part of the 18S RNA.

RESULTS

Nested PCR amplification confirmed 91.8% (56/61) of microscopic-positive samples. 8.2% (5/61) of negative samples by PCR (positive by microscopy) were considered false negatives. Sequencing followed by alignment of the 14 isolates indicated that all samples were identical (100%) and belonged to Cryptosporidium parvum.

CONCLUSION

MZN staining procedure is reliable for the routine diagnosis of Cryptosporidium; cetyltrimethylammonium bromide extraction buffer and nested PCR targeting 18S rRNA gene are reliable and useful in epidemiological studies of this parasite.

Widespread occurrence of Cryptosporidium infections in patients with HIV/AIDS: Epidemiology, clinical feature, diagnosis, and therapy

Cryptosporidium infection is a serious threat for HIV/AIDS patients, causing severe diarrhea and even death. The overall prevalence of Cryptosporidium in HIV/AIDS patients was calculated as approximately 8.69% (7,799/89,724), with higher prevalence observed in individuals with diarrhea, individuals with low CD4⁺ T-lymphocyte counts, and antiretroviral therapy-naïve individuals. Cryptosporidium infection was not significantly associated with patient age or gender, national development levels, or continent of residence. Over the period from 2007 to 2017, Cryptosporidium prevalence was 10.09% (3,282/32,517); this figure was higher than that observed in each of the previous observation periods (1985-1995 and 1996-2006), suggesting that the prevalence of cryptosporidiosis has been increasing over time in HIV/AIDS patients. Ten Cryptosporidium species and genotypes have been identified from 1,252 isolates, with C. hominis, C. parvum, and C. meleagridis accounting for 93.53% of infections. Five subtypes each of C. hominis (Ia, Ib, Id, Ie, and If), C. parvum (IIa to IIe), and C. meleagridis (IIIa to IIIe) have been described by sequence analyses of the 60-kDa glycoprotein (gp60) gene. Variation in the clinical manifestations observed in HIV/AIDS patients might be attributed to infection by different Cryptosporidium species, genotypes and subtypes, as well as different sites of infection. New molecular and immunological diagnostic techniques are in development or already commercially available. High-throughput screening methods for development of new or repurposed therapeutics as well as novel parasite genetic manipulation strategies offer hope for improving human cryptosporidiosis therapies. Painstaking efforts by researchers as well as support from governments and funding agencies will be required to make lasting achievements in this field.

Limitations in the screening of potentially anti-cryptosporidial agents using laboratory rodents with gastric cryptosporidiosis

The emergence of cryptosporidiosis, a zoonotic disease of the gastrointestinal and respiratory tract caused by Cryptosporidium Tyzzer, 1907, triggered numerous screening studies of various compounds for potential anti-cryptosporidial activity, the majority of which proved ineffective. Extracts of Indonesian plants, Piper betle and Diospyros sumatrana, were tested for potential anti-cryptosporidial activity using Mastomys coucha (Smith), experimentally inoculated with Cryptosporidium proliferans Kváč, Havrdová, Hlásková, Daňková, Kanděra, Ježková, Vítovec, Sak, Ortega, Xiao, Modrý, Chelladurai, Prantlová et McEvoy, 2016. None of the plant extracts tested showed significant activity against cryptosporidia; however, the results indicate that the following issues should be addressed in similar experimental studies. The monitoring of oocyst shedding during the entire experimental trial, supplemented with histological examination of affected gastric tissue at the time of treatment termination, revealed that similar studies are generally unreliable if evaluations of drug efficacy are based exclusively on oocyst shedding. Moreover, the reduction of oocyst shedding did not guarantee the eradication of cryptosporidia in treated individuals. For treatment trials performed on experimentally inoculated laboratory rodents, only animals in the advanced phase of cryptosporidiosis should be used for the correct interpretation of pathological alterations observed in affected tissue. All the solvents used (methanol, methanol-tetrahydrofuran and dimethylsulfoxid) were shown to be suitable for these studies, i.e. they did not exhibit negative effects on the subjects. The halofuginone lactate, routinely administered in intestinal cryptosporidiosis in calves, was shown to be ineffective against gastric cryptosporidiosis in mice caused by C. proliferans. In contrast, the control application of extract Arabidopsis thaliana, from which we had expected a neutral effect, turned out to have some positive impact on affected gastric tissue.

Monoclonal Antibodies to Intracellular Stages of Cryptosporidium parvum Define Life Cycle Progression In Vitro

Cryptosporidium is a protozoan parasite that causes gastrointestinal disease in humans and animals. Currently, there is a limited array of antibodies available against the parasite, which hinders imaging studies and makes it difficult to visualize the parasite life cycle in different culture systems. In order to alleviate this reagent gap, we created a library of novel antibodies against the intracellular life cycle stages of Cryptosporidium. We identified antibodies that recognize specific life cycle stages in distinctive ways, enabling unambiguous description of the parasite life cycle. These MAbs will aid future investigation into Cryptosporidium biology and help illuminate growth differences between various culture platforms.

Among the obstacles hindering Cryptosporidium research is the lack of an in vitro culture system that supports complete life development and propagation. This major barrier has led to a shortage of widely available anti-Cryptosporidium antibodies and a lack of markers for staging developmental progression. Previously developed antibodies against Cryptosporidium were raised against extracellular stages or recombinant proteins, leading to antibodies with limited reactivity across the parasite life cycle. Here we sought to create antibodies that recognize novel epitopes that could be used to define intracellular development. We identified a mouse epithelial cell line that supported C. parvum growth, enabling immunization of mice with infected cells to create a bank of monoclonal antibodies (MAbs) against intracellular parasite stages while avoiding the development of host-specific antibodies. From this bank, we identified 12 antibodies with a range of reactivities across the parasite life cycle. Importantly, we identified specific MAbs that can distinguish different life cycle stages, such as trophozoites, merozoites, type I versus II meronts, and macrogamonts. These MAbs provide valuable tools for the Cryptosporidium research community and will facilitate future investigation into parasite biology.

IMPORTANCECryptosporidium is a protozoan parasite that causes gastrointestinal disease in humans and animals. Currently, there is a limited array of antibodies available against the parasite, which hinders imaging studies and makes it difficult to visualize the parasite life cycle in different culture systems. In order to alleviate this reagent gap, we created a library of novel antibodies against the intracellular life cycle stages of Cryptosporidium. We identified antibodies that recognize specific life cycle stages in distinctive ways, enabling unambiguous description of the parasite life cycle. These MAbs will aid future investigation into Cryptosporidium biology and help illuminate growth differences between various culture platforms.

Cryptosporidiosis: A zoonotic disease concern

Cryptosporidiosis is considered to be a crucial zoonotic disease caused by worldwide distributing parasitic protozoa called Cryptosporidium spp. Cryptosporidiosis becomes a major public health and veterinary concern by affecting in human and various host range species of animals. Essentially, its importance of infection is increasing because of the high incidence in young children, immunocompromised persons, or immunodeficiency syndrome patients, especially in HIV/AIDS, and it is also one of the most causes of mortality in those patients who infected with Cryptosporidium spp. as well as young animals. All domestic animal, livestock, wildlife, and human can be potential reservoirs that contribute Cryptosporidium spp. to food and surface waters and transmitted to other hosts through fecal-oral route. The oocyst stage of Cryptosporidium spp. can remain infective and resistant to various environmental exposure and also resistant to many general disinfecting agents including chlorination which normally used in water treatment. Therefore, the understanding of these zoonotic pathogens is very essential in both animal and human health. This review focuses on the biology, life cycle, transmission, diagnosis, treatment, prevention, and control of this protozoan infection to emphasize and remind as the significant One Health problem.

Morpholino-mediated in vivo silencing of Cryptosporidium parvum lactate dehydrogenase decreases oocyst shedding and infectivity

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An in vivo morpholino-based approach for targeted gene knockdown of genes in Cryptosporidium parvum was developed.

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Cryptosporidium parvum lactate dehydrogenase, and sporozoite 60K were knocked down sustainably in infected mice.

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Cryptosporidium parvum lactate dehydrogenase knockdown significantly decreased oocyst shedding and infectivity.

Cryptosporidium is a highly prevalent protozoan parasite that is the second leading cause of childhood morbidity and mortality due to diarrhoea in developing countries, and causes a serious diarrheal syndrome in calves, lambs and goat kids worldwide. Development of fully effective drugs against Cryptosporidium has mainly been hindered by the lack of genetic tools for functional characterization and validation of potential molecular drug targets in the parasite. Herein, we report the development of a morpholino-based in vivo approach for Cryptosporidium parvum gene knockdown to facilitate determination of the physiological roles of the parasite’s genes in a murine model. We show that, when administered intraperitoneally at non-toxic doses, morpholinos targeting C. parvum lactate dehydrogenase (CpLDH) and sporozoite 60K protein (Cp15/60) were able to specifically and sustainably down-regulate the expression of CpLDH and Cp15/60 proteins, respectively, in C. parvum-infected interferon-γ knockout mice. Over a period of 6 days of daily administration of target morpholinos, CpLDH and Cp15/60 proteins were down-regulated by 20- to 50-fold, and 10- to 20-fold, respectively. Knockdown of CpLDH resulted in approximately 80% reduction in oocyst load in the feces of mice, and approximately 70% decrease in infectivity of the sporozoites excysted from the shed oocysts. Cp15/60 knockdown did not affect oocyst shedding nor infectivity but, nevertheless, provided a proof-of-principle for the resilience of the morpholino-mediated C. parvum gene knockdown system in vivo. Together, our findings provide a genetic tool for deciphering the physiological roles of C. parvum genes in vivo, and validate CpLDH as an essential gene for the growth and viability of C. parvum in vivo.

A conserved ankyrin repeat-containing protein regulates conoid stability, motility and cell invasion in Toxoplasma gondii

Apicomplexan parasites are typified by an apical complex that contains a unique microtubule-organizing center (MTOC) that organizes the cytoskeleton. In apicomplexan parasites such as Toxoplasma gondii, the apical complex includes a spiral cap of tubulin-rich fibers called the conoid. Although described ultrastructurally, the composition and functions of the conoid are largely unknown. Here, we localize 11 previously undescribed apical proteins in T. gondii and identify an essential component named conoid protein hub 1 (CPH1), which is conserved in apicomplexan parasites. CPH1 contains ankyrin repeats that are required for structural integrity of the conoid, parasite motility, and host cell invasion. Proximity labeling and protein interaction network analysis reveal that CPH1 functions as a hub linking key motor and structural proteins that contain intrinsically disordered regions and coiled coil domains. Our findings highlight the importance of essential protein hubs in controlling biological networks of MTOCs in early-branching protozoan parasites.

Apicomplexan parasites such as Toxoplasma gondii possess a tubulin-rich structure called the conoid. Here, Long et al. identify a conoid protein that interacts with motor and structural proteins and is required for structural integrity of the conoid, parasite motility, and host cell invasion.

The truth about in vitro culture of Cryptosporidium species

Cryptosporidium research has focused on the development of infection control, and effective therapy that has thus far been hampered by the inability to culture Cryptosporidium in vitro. Other limitations include inadequate animal models, cumbersome screening procedures for chemotherapeutic approaches and a lack of tools for genetic manipulation. These limitations can, however, be eased by the improvement and focused development of in vitro cultivation. The ability to culture relevant Cryptosporidium isolates in vitro and to propagate the life cycle stages that are responsible for causing disease in an infected host is still a critical link. This ability will facilitate other relevant approaches, e.g., the ability to knockout genes and the application of broader screening for drug discoveries and vaccine developments, in combination with new discoveries on the parasite's basic biology, genetic manipulation and new life cycle stages. Success in this effort represents an essential step towards significant progress in the control of cryptosporidiosis.

Detection of Cryptosporidium and Cyclospora Oocysts from Environmental Water for Drinking and Recreational Activities in Sarawak, Malaysia

Cryptosporidiosis and cyclosporiasis are caused by waterborne coccidian protozoan parasites of the genera Cryptosporidium and Cyclospora, respectively. This study was conducted to detect Cryptosporidium and Cyclospora oocysts from environmental water abstracted by drinking water treatment plants and recreational activities in Sarawak, Malaysia. Water samples (12 each) were collected from Sungai Sarawak Kanan in Bau and Sungai Sarawak Kiri in Batu Kitang, respectively. In addition, 6 water samples each were collected from Ranchan Recreational Park and UNIMAS Lake at Universiti Malaysia Sarawak, Kota Samarahan, respectively. Water physicochemical parameters were also recorded. All samples were concentrated by the iron sulfate flocculation method followed by the sucrose floatation technique. Cryptosporidium and Cyclospora were detected by modified Ziehl-Neelsen technique. Correlation of the parasites distribution with water physicochemical parameters was analysed using bivariate Pearson correlation. Based on the 24 total samples of environmental water abstracted by drinking water treatment plants, all the samples (24/24; 100%) were positive with Cryptosporidium, and only 2 samples (2/24; 8.33%) were positive with Cyclospora. Based on the 12 total samples of water for recreational activities, 4 samples (4/12; 33%) were positive with Cryptosporidium, while 2 samples (2/12; 17%) were positive with Cyclospora. Cryptosporidium oocysts were negatively correlated with dissolved oxygen (DO).

Advances and Perspectives on the Epidemiology of Bovine Cryptosporidium in China in the Past 30 Years

Major progress has been made in understanding the epidemiology of bovine Cryptosporidium in China in the past 30 years. The overall infection rate in that period was 14.50% (5265/36316), with different prevalence being observed among dairy cattle, yaks, beef cattle, and buffalo. The infection rate declined as the animals' ages increased and the lowest prevalence occurred in winter. Ten Cryptosporidium species and two genotypes have been found in cattle, with Cryptosporidium parvum, C. andersoni, C. bovis, and C. ryanae being the commonest species. Cryptosporidium bovis rather than C. parvum predominated in preweaned dairy cattle, and C. parvum IIdA15G1 and IIdA19G1 were the only subtypes detected in dairy cattle. Two subtype families, IIa and IId, were found in yaks. Population genetic analysis detected an epidemic population structure in C. andersoni, which suggested that the prevalence of C. andersoni in China is not attributable to the introduction of dairy cattle. Moreover, C. parvum IId subtypes probably dispersed from western Asia to other geographic regions based on population genetic analysis of isolates from China, Sweden, and Egypt. Therefore, we hypothesize that Cryptosporidium was introduced into China in the past, and different populations formed progressively in various hosts in response to diverse factors, including the transmission dynamics, geographic isolation, host specificity, and large-scale farming. More epidemiological studies are required to test this hypothesis and to clarify the prevalence and transmission of Cryptosporidium species in China.

Novel Bioengineered Three-Dimensional Human Intestinal Model for Long-Term Infection of Cryptosporidium parvum

Cryptosporidium spp. are apicomplexan parasites of global importance that cause human diarrheal disease. In vitro culture models that may be used to study this parasite and that have physiological relevance to in vivo infection remain suboptimal. Thus, the pathogenesis of cryptosporidiosis remains poorly characterized, and interventions for the disease are limited. In this study, we evaluated the potential of a novel bioengineered three-dimensional (3D) human intestinal tissue model (which we developed previously) to support long-term infection by Cryptosporidium parvum Infection was assessed by immunofluorescence assays and confocal and scanning electron microscopy and quantified by quantitative reverse transcription-PCR. We found that C. parvum infected and developed in this tissue model for at least 17 days, the extent of the study time used in the present study. Contents from infected scaffolds could be transferred to fresh scaffolds to establish new infections for at least three rounds. Asexual and sexual stages and the formation of new oocysts were observed during the course of infection. Additionally, we observed ablation, blunting, or distortion of microvilli in infected epithelial cells. Ultimately, a 3D model system capable of supporting continuous Cryptosporidium infection will be a useful tool for the study of host-parasite interactions, identification of putative drug targets, screening of potential interventions, and propagation of genetically modified parasites.

Cryptosporidium: Identification and Genetic Typing

Cryptosporidium spp. are obligate protozoan parasites of the gastrointestinal tract of vertebrates, including humans. In the majority of human cases, the diarrheal disease cryptosporidiosis is caused by either the human-adapted species Cryptosporidium hominis or the zoonotic Cryptosporidium parvum 'bovine genotype' (also known as Cryptosporidium pestis). The infectious stage, environmentally resilient Cryptosporidium oocysts, are shed by the infected host. Cryptosporidium parasites are transmitted by the fecal-oral route and are one of the major water-borne pathogens. The cryptic nature of the microscopic Cryptosporidium oocysts coupled with the existence of several host-adapted and zoonotic species requires molecular tools to identify Cryptosporidium spp. in either fecal or environmental samples. This unit describes methods for Cryptosporidium identification and typing using genotyping based on nuclear loci. We also provide a protocol for morphological confirmation of Cryptosporidium oocysts based on antibody labeling of the Cryptosporidium oocyst wall and a protocol for purification of oocysts from fecal material. © 2017 by John Wiley & Sons, Inc.

The fine structure of sexual stage development and sporogony of Cryptosporidium parvum in cell-free culture

The sexual stages and new oocysts development of Cryptosporidium parvum were investigated in a cell-free culture system using transmission electron microscopy (TEM). Sexual development was extremely rapid after inoculation of oocysts into the medium. The process began within 1/2-12 h and was completed with new oocyst formation 120 h post-inoculation. The macrogamonts were bounded by two membranes and had amylopectin granules and two distinct types of wall-forming bodies. The microgamonts had a large nucleus showing lobe projections and condensation of chromatin, giving rise to peripherally budding microgametes. The microgametes contained a large area of granular substance containing groups of microtubules surrounding the electron-dense nucleus. In some instances, the dividing microgamy was observed in cell-free cultures with no preceding merogonic process. Fertilization was observed with the bullet-shaped microgamete penetrating an immature macrogamont at 24 and 216 h. The new thin- and thick-walled oocysts had a large residuum with polysaccharide granules and sporogony noted inside these oocysts. Novel immature four-layer walled thick oocysts with irregular knob-like protrusions on the outer layer resembling the immature Eimeria oocysts were also observed. The present study confirms the gametogony and sporogony of C. parvum in cell-free culture and describes their ultra-structure for the first time.

Use of aerobic spores as a surrogate for cryptosporidium oocysts in drinking water supplies

Waterborne illnesses are a growing concern among health and regulatory agencies worldwide. The United States Environmental Protection Agency has established several rules to combat the contamination of water supplies by cryptosporidium oocysts, however, the detection and study of cryptosporidium oocysts is hampered by methodological and financial constraints. As a result, numerous surrogates for cryptosporidium oocysts have been proposed by the scientific community and efforts are underway to evaluate many of the proposed surrogates. The purpose of this review is to evaluate the suitability of aerobic bacterial spores to serve as a surrogate for cryptosporidium oocysts in identifying contaminated drinking waters. To accomplish this we present a comparison of the biology and life cycles of aerobic spores and oocysts and compare their physical properties. An analysis of their surface properties is presented along with a review of the literature in regards to the transport, survival, and prevalence of aerobic spores and oocysts in the saturated subsurface environment. Aerobic spores and oocysts share many commonalities with regard to biology and survivability, and the environmental prevalence and ease of detection make aerobic spores a promising surrogate for cryptosporidium oocysts in surface and groundwater. However, the long-term transport and release of aerobic spores still needs to be further studied, and compared with available oocyst information. In addition, the surface properties and environmental interactions of spores are known to be highly dependent on the spore taxa and purification procedures, and additional research is needed to address these issues in the context of transport.

In vitro excystation of Cryptosporidium muris oocysts and viability of released sporozoites in different incubation media

This study aimed to evaluate and document the excystation process of Cryptosporidium muris oocysts in various incubation media, and to monitor the behaviour of excysting and freshly excysted sporozoites. A test of oocyst viability, using fluorescent double staining with fluorescein diacetate and propidium iodide, was performed prior to each experimental assay. Light microscope observations confirmed that relatively often only three sporozoites were released; the fourth one either left the oocyst later together with a residual body or remained trapped within the oocyst wall. These results suggest that successful oocyst excystation is not limited by the viability of all four sporozoites. Darkening of oocysts to opaque and their specific movement (the so-called "oocyst dancing") preceded the final excystation and liberation of sporozoites, while the dormant oocysts appeared refractive. The process of excystation in C. muris is not gradual as generally described in cryptosporidia but very rapid in an eruptive manner. Experiments were performed using oocysts stored at 4 °C for various time periods, as well as oocysts freshly shed from host rodents (Mastomys coucha) of different ages. The most suitable medium supporting high excystation rate (76 %) and prolonged motility of sporozoites was RPMI 1640, enriched with 5 % bovine serum albumin (BSA). Our results emphasize that to reliably evaluate the success of in vitro excystation of cryptosporidia, not only the number of released sporozoites in a set time period should be taken into consideration but also their subsequent activity (motility), as it is expected to be essential for the invasion of host cells.

Drug Development Against the Major Diarrhea-Causing Parasites of the Small Intestine, Cryptosporidium and Giardia

Diarrheal diseases are among the leading causes of morbidity and mortality in the world, particularly among young children. A limited number of infectious agents account for most of these illnesses, raising the hope that advances in the treatment and prevention of these infections can have global health impact. The two most important parasitic causes of diarrheal disease are Cryptosporidium and Giardia. Both parasites infect predominantly the small intestine and colonize the lumen and epithelial surface, but do not invade deeper mucosal layers. This review discusses the therapeutic challenges, current treatment options, and drug development efforts against cryptosporidiosis and giardiasis. The goals of drug development against Cryptosporidium and Giardia are different. For Cryptosporidium, only one moderately effective drug (nitazoxanide) is available, so novel classes of more effective drugs are a high priority. Furthermore, new genetic technology to identify potential drug targets and better assays for functional evaluation of these targets throughout the parasite life cycle are needed for advancing anticryptosporidial drug design. By comparison, for Giardia, several classes of drugs with good efficacy exist, but dosing regimens are suboptimal and emerging resistance begins to threaten clinical utility. Consequently, improvements in potency and dosing, and the ability to overcome existing and prevent new forms of drug resistance are priorities in antigiardial drug development. Current work on new drugs against both infections has revealed promising strategies and new drug leads. However, the primary challenge for further drug development is the underlying economics, as both parasitic infections are considered Neglected Diseases with low funding priority and limited commercial interest. If a new urgency in medical progress against these infections can be raised at national funding agencies or philanthropic organizations, meaningful and timely progress is possible in treating and possibly preventing cryptosporidiosis and giardiasis.