Cryptosporidium excystation and invasion: getting to the guts of the matter

Smith, H. V.; Nichols, R.A.B.; Grimason, Anthony

doi:10.1016/j.pt.2005.01.007

Cited by 133 publications

(113 citation statements)

References 73 publications

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“…A Cryptosporidium infection is initiated when the host ingests oocysts, from which invasive sporozoites emerge and infect the intestinal mucosa (35). It is likely that establishment of the infection and severity of the disease depends upon early events associated with the interaction of the parasite with the intestinal mucosa, suggesting that an effective vaccine should combine mucosal and systemic immunity.…”

Section: Discussionmentioning

confidence: 99%

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Identification and Immunological Characterization of Three Potential Vaccinogens against Cryptosporidium Species

Manque

Tenjo

Woehlbier

et al. 2011

Clin Vaccine Immunol

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Cryptosporidiosis is a ubiquitous infectious disease, caused by the protozoan parasites Cryptosporidium hominis and Cryptosporidium parvum, leading to acute, persistent, and chronic diarrhea with life-threatening consequences in immunocompromised individuals. In developing countries, cryptosporidiosis in early childhood has been associated with subsequent significant impairment in growth, physical fitness, and intellectual abilities. Currently, vaccines are unavailable and chemotherapeutics are toxic and impractical, and agents for immunoprophylaxis or treatment of cryptosporidiosis are a high priority. Availability of the genome sequences for C. hominis and C. parvum provides new opportunities to procure and examine novel vaccine candidates. Using the novel approach of "reverse vaccinology," we identified several new potential vaccine candidates. Three of these antigens-Cp15, profilin, and a Cryptosporidium apyrase-were delivered in heterologous prime-boost regimens as fusions with cytolysin A (ClyA) in a Salmonella live vaccine vector and as purified recombinant antigens, and they were found to induce specific and potent humoral and cellular immune responses, suggesting their potential as new vaccinogens against Cryptosporidium infection.

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Section: Discussionmentioning

confidence: 99%

“…Transmission occurs by ingestion of infective oocysts, from which invasive sporozoites emerge and invade the intestinal epithelium (35). Proliferation of the parasite in the gastrointestinal (GI) tract often results in acute, persistent, and chronic diarrhea.…”

mentioning

confidence: 99%

Identification and Immunological Characterization of Three Potential Vaccinogens against Cryptosporidium Species

Manque

Tenjo

Woehlbier

et al. 2011

Clin Vaccine Immunol

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“…(20) and (21). For the case of r ¼ 0:1 S/m and V ¼ 10 Vpp (peak to peak voltage), localized recirculation flows are noticed, with an enhancement of flow velocity in the vicinity of the electrodes.…”

Section: A Microfluidic Design and Operating Parametersmentioning

confidence: 94%

“…(11) and (12), e 1 ; r 1 ð Þ and e 2 ; r 2 ð Þ are the unknowns to be calculated as the medium permittivity e 3 ; r 3 ð Þ is a known quantity. The thickness of the Cryptosporidium cell membrane layer can be assumed to be nearly 50 nm, 20 while the membrane thickness of Giardia cells are larger and assumed to be 400 nm. 21 Therefore, the radius ratio of the cells can be calculated.…”

Section: -10mentioning

confidence: 99%

Characterization and separation of Cryptosporidium and Giardia cells using on-chip dielectrophoresis

et al. 2012

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Dielectrophoresis (DEP) has been shown to have significant potential for the characterization of cells and could become an efficient tool for rapid identification and assessment of microorganisms. The present work is focused on the trapping, characterization, and separation of two species of Cryptosporidium (C. parvum and C. muris) and Giardia lambia (G. lambia) using a microfluidic experimental setup. Cryptosporidium oocysts, which are 2-4 lm in size and nearly spherical in shape, are used for the preliminary stage of prototype development and testing. G. lambia cysts are 8-12 lm in size. In order to facilitate effective trapping, simulations were performed to study the effects of buffer conductivity and applied voltage on the flow and cell transport inside the DEP chip. Microscopic experiments were performed using the fabricated device and the real part of Clausius-Mossotti factor of the cells was estimated from critical voltages for particle trapping at the electrodes under steady fluid flow. The dielectric properties of the cell compartments (cytoplasm and membrane) were calculated based on a single shell model of the cells. The separation of C. muris and G. lambia is achieved successfully at a frequency of 10 MHz and a voltage of 3 Vpp (peak to peak voltage).

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“…Infection begins with the oral uptake of Cryptosporidium oocysts, the environmentally resistant form, which then pass through the acidic stomach before entering the small intestine, where they presumably excyst. Although the molecular and biochemical mechanisms involved in excystation are poorly understood, it is believed that host environmental factors, such as temperature, pH, proteases, bile salts, and possibly other unknown factors, trigger the excystation of ingested oocysts (19). The newly excysted sporozoites secrete adhesive molecules and other signaling proteins which have been demonstrated to play a key role in the initial attachment and cellular invasion (4,6).…”

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confidence: 99%

Bile Acids Enhance Invasiveness of Cryptosporidium spp. into Cultured Cells

et al. 2006

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Bile salts such as sodium taurocholate (NaTC) are routinely used to induce the excystation of Cryptosporidium oocysts. Here we show that NaTC significantly enhanced the invasion of several cultured cell lines by freshly excysted Cryptosporidium parvum and Cryptosporidium hominis sporozoites. A variety of purified bile salts or total bile from bovine also enhanced the invasion of cultured cells by C. parvum. Further studies demonstrated that NaTC increased protein secretion and gliding motility of sporozoites, the key processes for successful invasion. These observations may lead to improved Cryptosporidium infectivity of cultured cells and help future studies on the host-parasite interaction.As members of the phylum Apicomplexa, the enteric protozoa Cryptosporidium species share a common apical secreting apparatus that mediates locomotion during cellular invasion (5, 21). Cryptosporidium hominis and Cryptosporidium parvum, whose genomes were sequenced recently (1, 28), are the species most frequently linked with human cryptosporidiosis (21,27). Infection begins with the oral uptake of Cryptosporidium oocysts, the environmentally resistant form, which then pass through the acidic stomach before entering the small intestine, where they presumably excyst. Although the molecular and biochemical mechanisms involved in excystation are poorly understood, it is believed that host environmental factors, such as temperature, pH, proteases, bile salts, and possibly other unknown factors, trigger the excystation of ingested oocysts (19). The newly excysted sporozoites secrete adhesive molecules and other signaling proteins which have been demonstrated to play a key role in the initial attachment and cellular invasion (4, 6).The in vitro cell culture system, while limited to the asexual phase, has been a useful tool for investigating early parasite attachment and invasion and has been applied to measure Cryptosporidium infectivity and for screening of compounds for inhibitory activity (3,17). Several cell lines, including human ileocecal adenocarcinoma (HCT-8), human colonic adenocarcinoma (Caco-2), and Madin-Darby bovine kidney (MDBK) cell lines, are widely used for Cryptosporidium in vitro studies (12,22). To initiate in vitro infection, purified Cryptosporidium oocysts are often treated with sodium hypochlorite either alone or followed by sodium taurocholate (NaTC)-trypsin treatment before infecting cell monolayers. Several publications have dealt with assessment of the conditions and materials for optimal oocyst excystation and tissue culture infection by the excysted sporozoites (15,16,23,24). Upton et al. (24) investigated the optimization of infection of oocysts treated with bleach without prior excystation. Gold et al. showed that the presence of NaTC in the culture medium enhanced infection when oocysts were directly added to cell culture monolayers (11). However, the nature of this enhancement was not fully investigated, and it was assumed that the NaTC facilitated the excystation of oocysts in the culture medium (...

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Cryptosporidium excystation and invasion: getting to the guts of the matter

Cited by 133 publications

References 73 publications

Identification and Immunological Characterization of Three Potential Vaccinogens against Cryptosporidium Species

Identification and Immunological Characterization of Three Potential Vaccinogens against Cryptosporidium Species

Characterization and separation of Cryptosporidium and Giardia cells using on-chip dielectrophoresis

Bile Acids Enhance Invasiveness of Cryptosporidium spp. into Cultured Cells

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