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Wang X, Tang D, Wang F, Jin G, Wang L, Liu Q, Liu J. Microneme Protein 6 Is Involved in Invasion and Egress by Neospora caninum. Pathogens 2021; 10:pathogens10020201. [PMID: 33668497 PMCID: PMC7918358 DOI: 10.3390/pathogens10020201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 02/04/2021] [Accepted: 02/10/2021] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Neospora caninum, is the etiological agent of neosporosis, an infection that causes abortions in cattle and nervous system dysfunction in dogs. Invasion and egress are the key steps of the pathogenesis of N. caninum infection. Microneme proteins (MICs) play important roles in the recognition, adhesion, and invasion of host cells in other apicomplexan parasites. However, some MICs and their functions in N. caninum infection have rarely been reported. METHODS The homologous recombination strategy was used to investigate the function of MIC6 in N. caninum infection. RESULTS ΔNcMIC6 showed a smaller plaque size and weakened capacities of invasion and egress than Nc1. Transcription levels of the egress-related genes CDPK1, PLP1, and AMA1 of ΔNcMIC6 were downregulated. Due to the lack of NcMIC6, virulence of the pathogen in the infected mouse was weakened. The subcellular localization of NcMIC1 and NcMIC4 in ΔNcMIC6, however, did not change. Nevertheless, the transcription levels of MIC1 and MIC4 in ΔNcMIC6 were downregulated, and the expression and secretion of MIC1 and MIC4 in ΔNcMIC6 were reduced compared with that in Nc1. Furthermore, the absence of NcMIC6 weakened the virulence in mice and lower parasite load detected in mice brains. CONCLUSIONS NcMIC6 is involved in host cell invasion and egress in N. caninum and may work synergistically with other MICs to regulate the virulence of the pathogen. These data lay a foundation for further research into the function and application of NcMIC6.
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Chao AT, Lee BH, Wan KF, Selva J, Zou B, Gedeck P, Beer DJ, Diagana TT, Bonamy GMC, Manjunatha UH. Development of a Cytopathic Effect-Based Phenotypic Screening Assay against Cryptosporidium. ACS Infect Dis 2018; 4:635-645. [PMID: 29341586 DOI: 10.1021/acsinfecdis.7b00247] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cryptosporidiosis is a diarrheal disease predominantly caused by Cryptosporidium parvum ( Cp) and Cryptosporidium hominis ( Ch), apicomplexan parasites which infect the intestinal epithelial cells of their human hosts. The only approved drug for cryptosporidiosis is nitazoxanide, which shows limited efficacy in immunocompromised children, the most vulnerable patient population. Thus, new therapeutics and in vitro infection models are urgently needed to address the current unmet medical need. Toward this aim, we have developed novel cytopathic effect (CPE)-based Cp and Ch assays in human colonic tumor (HCT-8) cells and compared them to traditional imaging formats. Further model validation was achieved through screening a collection of FDA-approved drugs and confirming many previously known anti- Cryptosporidium hits as well as identifying a few novel candidates. Collectively, our data reveals this model to be a simple, functional, and homogeneous gain of signal format amenable to high throughput screening, opening new avenues for the discovery of novel anticryptosporidials.
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Affiliation(s)
- Alexander T. Chao
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Boon Heng Lee
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Kah Fei Wan
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Jeremy Selva
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Bin Zou
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Peter Gedeck
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - David John Beer
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
| | - Thierry T. Diagana
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Ghislain M. C. Bonamy
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore, 138669, Singapore
| | - Ujjini H. Manjunatha
- Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore, 138670, Singapore
- Novartis Institute for Tropical Diseases, 5300 Chiron Way, Emeryville, California 94608, United States
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Karanis P, Aldeyarbi HM. Evolution of Cryptosporidium in vitro culture. Int J Parasitol 2011; 41:1231-42. [PMID: 21889507 DOI: 10.1016/j.ijpara.2011.08.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/03/2011] [Accepted: 08/04/2011] [Indexed: 02/07/2023]
Abstract
This overview discusses findings from culturing Cryptosporidium spp. in cell and axenic cultures as well as factors limiting the development of this parasite in cultivation systems during recent years. A systematic review is undertaken of findings regarding the life cycle of the parasite, taking into account physiological, biochemical and genetic aspects, in the hope that this attempt will facilitate future approaches to research and developments in the understanding of Cryptosporidium biology.
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Affiliation(s)
- P Karanis
- University of Cologne, Center for Anatomy, Institute II, Molecular and Medical Parasitology, Joseph-Stelzmann-Street 9, Geb.35, 50937 Köln, Germany.
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Enhanced egress of intracellular Eimeria tenella sporozoites by splenic lymphocytes from coccidian-infected chickens. Infect Immun 2011; 79:3465-70. [PMID: 21628515 DOI: 10.1128/iai.01334-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Egress, which describes the mechanism that some intracellular parasites use to exit from parasitophorous vacuoles and host cells, plays a very important role in the parasite life cycle and is central to Eimeria propagation and pathogenesis. Despite the importance of egress in the intracellular parasite's life cycle, very little information is known on this process compared to other steps, e.g., invasion. The present study was conducted to investigate the interplay between the host adaptive immune system and Eimeria egression. Splenic lymphocytes or soluble immune factors were incubated with parasite-infected host cells for 3 or 5 h, and the percentage of egress was calculated according to an established formula. Viability of egressed parasites and host cells was tested using trypan blue exclusion and annexin V and propidium iodide staining, respectively. We found that premature egression of sporozoites from Eimeria tenella-infected primary chicken kidney cells or from chicken peripheral blood mononuclear cells occurred when the cells were cocultured in vitro with spleen lymphocytes from E. tenella-infected chickens but not when they were cocultured with splenocytes from uninfected chickens. Eimeria-specific antibodies and cytokines (gamma interferon [IFN-γ], interleukin-2 [IL-2], and IL-15), derived from E. tenella-primed B and T lymphocytes, respectively, were capable of promoting premature egress of sporozoites from infected host cells. Both egressed parasites and host cells were viable, although the latter showed reduced reinvasion ability. These results suggest a novel, immune-mediated mechanism that the host exploits to interrupt the normal Eimeria life cycle in vivo and thereby block the release of mature parasites into the environment.
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Wyatt CR, Riggs MW, Fayer R. Cryptosporidiosis in Neonatal Calves. Vet Clin North Am Food Anim Pract 2010; 26:89-103, table of contents. [DOI: 10.1016/j.cvfa.2009.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Biphasic modulation of apoptotic pathways in Cryptosporidium parvum-infected human intestinal epithelial cells. Infect Immun 2008; 77:837-49. [PMID: 19075026 DOI: 10.1128/iai.00955-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The impact of Cryptosporidium parvum infection on host cell gene expression was investigated by microarray analysis with an in vitro model using human ileocecal HCT-8 adenocarcinoma cells. We found changes in 333 (2.6%) transcripts at at least two of the five (6, 12, 24, 48, and 72 h) postinfection time points. Fifty-one of the regulated genes were associated with apoptosis and were grouped into five clusters based on their expression patterns. Early in infection (6 and 12 h), genes with antiapoptotic roles were upregulated and genes with apoptotic roles were downregulated. Later in infection (24, 48, and 72 h), proapoptotic genes were induced and antiapoptotic genes were downregulated, suggesting a biphasic regulation of apoptosis: antiapoptotic state early and moderately proapoptotic state late in infection. This transcriptional profile matched the actual occurrence of apoptosis in the infected cultures. Apoptosis was first detected at 12 h postinfection and increased to a plateau at 24 h, when 20% of infected cells showed nuclear condensation. In contrast, experimental silencing of Bcl-2 induced apoptosis in 50% of infected cells at 12 h postinfection. This resulted in a decrease in the infection rate and a reduction in the accumulation of meront-containing cells. To test the significance of the moderately proapoptotic state late in the infection, we inhibited apoptosis using pancaspase inhibitor Z-VAD-FMK. This treatment also affected the progression of C. parvum infection, as reinfection, normally seen late (24 h to 48 h), did not occur and accumulation of mature meronts was impaired. Control of host apoptosis is complex and crucial to the life of C. parvum. Apoptosis control has at least two components, early inhibition and late moderate promotion. For a successful infection, both aspects appear to be required.
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Castellanos-Gonzalez A, Yancey LS, Wang HC, Pantenburg B, Liscum KR, Lewis DE, White AC. Cryptosporidium infection of human intestinal epithelial cells increases expression of osteoprotegerin: a novel mechanism for evasion of host defenses. J Infect Dis 2008; 197:916-23. [PMID: 18288900 DOI: 10.1086/528374] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Cryptosporidium parasites are pathogens of human intestinal epithelial cells. To determine which genes are regulated during early infection, human ileal mucosa cultured as explants was infected with C. parvum or C. hominis, and gene expression was analyzed by microarray. The gene for osteoprotegerin (OPG) was up-regulated by both parasites. OPG mRNA was also significantly increased in biopsy specimens obtained from a volunteer experimentally infected with C. meleagridis, compared with levels in a prechallenge biopsy specimen. After in vitro infection of HCT-8 cells, there was an early peak in production of OPG mRNA protein. Treatment of infected cells with the OPG ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induced epithelial cell apoptosis and reduced parasite numbers, and recombinant OPG blocked these effects. These results suggest a novel TRAIL-mediated pathway for elimination of Cryptosporidium infection and a role for OPG in modulating this host response.
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Inhibition of apoptosis in Cryptosporidium parvum-infected intestinal epithelial cells is dependent on survivin. Infect Immun 2008; 76:3784-92. [PMID: 18519556 DOI: 10.1128/iai.00308-08] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cryptosporidium parvum is an obligate intracellular protozoan capable of causing severe diarrheal disease in a wide variety of mammals, including humans. C. parvum infection has been associated with induction of apoptosis in exposed epithelial cells, and we now demonstrate that apoptosis is restricted to a subset of cells actively infected with C. parvum. Approximately 20% of the infected cells underwent apoptosis within 48 h of infection, suggesting that the majority of the infected cells are rescued from apoptosis. C. parvum infection resulted in low-level activation of multiple members of the caspase family, including caspase-2, -3, -4, -6, -8, and -9. The kinetics of caspase activation correlated with apoptosis over a 48-h time course. Pan caspase inhibitors reduced apoptosis of epithelial cells infected by C. parvum. Furthermore, C. parvum infection inhibited staurosporine-induced apoptosis and caspase-3/7 activation at 24 h and 48 h. Infection with C. parvum led to upregulation of genes encoding inhibitors of apoptosis proteins (IAPs), including c-IAP1, c-IAP2, XIAP, and survivin. Knockdown of survivin gene expression, but not that of c-IAP1, c-IAP2, or XIAP expression, increased caspase-3/7 activity as well as apoptosis of infected cells and decreased C. parvum 18S rRNA levels. These data suggest that the apoptotic response of infected intestinal epithelial cells is actively suppressed by C. parvum via upregulation of survivin, favoring parasite infection.
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Exit from host cells by the pathogenic parasite Toxoplasma gondii does not require motility. EUKARYOTIC CELL 2007; 7:131-40. [PMID: 17993573 DOI: 10.1128/ec.00301-07] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The process by which the intracellular parasite Toxoplasma gondii exits its host cell is central to its propagation and pathogenesis. Experimental induction of motility in intracellular parasites results in parasite egress, leading to the hypothesis that egress depends on the parasite's actin-dependent motility. Using a novel assay to monitor egress without experimental induction, we have established that inhibiting parasite motility does not block this process, although treatment with actin-disrupting drugs does delay egress. However, using an irreversible actin inhibitor, we show that this delay is due to the disruption of host cell actin alone, apparently resulting from the consequent loss of membrane tension. Accordingly, by manipulating osmotic pressure, we show that parasite egress is delayed by releasing membrane tension and promoted by increasing it. Therefore, without artificial induction, egress does not depend on parasite motility and can proceed by mechanical rupture of the host membrane.
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Leirião P, Rodrigues CD, Albuquerque SS, Mota MM. Survival of protozoan intracellular parasites in host cells. EMBO Rep 2005; 5:1142-7. [PMID: 15577928 PMCID: PMC1299194 DOI: 10.1038/sj.embor.7400299] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2004] [Accepted: 10/25/2004] [Indexed: 12/30/2022] Open
Abstract
The most common human diseases are caused by pathogens. Several of these microorganisms have developed efficient ways in which to exploit host molecules, along with molecular pathways to ensure their survival, differentiation and replication in host cells. Although the contribution of the host cell to the development of many intracellular pathogens (particularly viruses and bacteria) has been unequivocally established, the study of host-cell requirements during the life cycle of protozoan parasites is still in its infancy. In this review, we aim to provide some insight into the manipulation of the host cell by parasites through discussing the hurdles that are faced by the latter during infection.
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Affiliation(s)
- Patrícia Leirião
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | | | - Sónia S. Albuquerque
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | - Maria M. Mota
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
- Tel: +351 21 446 4517; Fax: +351 21 440 7970;
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