Acid-shock ofCampylobacter jejuniinduces flagellar gene expression and host cell invasion

ABSTRACT During its intraerythrocytic development, the malaria parasite Plasmodium falciparum exposes variant surface antigens (VSAs) on infected erythrocytes to establish and maintain an infection. One family of small VSAs is the polymorphic STEVOR proteins, which are marked for export to the host cell surface through their PEXEL signal peptide. Interestingly, some STEVORs have also been reported to localize to the parasite plasma membrane and apical organelles, pointing toward a putative function in host cell egress or invasion. Using deep RNA sequencing analysis, we characterized P. falciparum stevor gene expression across the intraerythrocytic development cycle, including free merozoites, in detail and used the resulting stevor expression profiles for hierarchical clustering. We found that most stevor genes show biphasic expression oscillation, with maximum expression during trophozoite stages and a second peak in late schizonts. We selected four STEVOR variants, confirmed the expected export of these proteins to the host cell membrane, and tracked them to a secondary location, either to the parasite plasma membrane or the secretory organelles of merozoites in late schizont stages. We investigated the function of a particular STEVOR that showed rhoptry localization and demonstrated its role at the parasite-host interface during host cell invasion by specific antisera and targeted gene disruption. Experimentally determined membrane topology of this STEVOR revealed a single transmembrane domain exposing the semiconserved as well as variable protein regions to the cell surface. IMPORTANCE Malaria claims about half a million lives each year. Plasmodium falciparum, the causative agent of the most severe form of the disease, uses proteins that are translocated to the surface of infected erythrocytes for immune evasion. To circumvent the detection of these gene products by the immune system, the parasite evolved a complex strategy that includes gene duplications and elaborate sequence polymorphism. STEVORs are one family of these variant surface antigens and are encoded by about 40 genes. Using deep RNA sequencing of blood-stage parasites, including free merozoites, we first established stevor expression of the cultured isolate and compared it with published transcriptomes. We reveal a biphasic expression of most stevor genes and confirm this for individual STEVORs at the protein level. The membrane topology of a rhoptry-associated variant was experimentally elucidated and linked to host cell invasion, underlining the importance of this multifunctional protein family for parasite proliferation.

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Shigella flexneri Diguanylate Cyclases Regulate Virulence

Journal of Bacteriology ◽

10.1128/jb.00242-21 ◽

2021 ◽

Author(s):

Ruchi Ojha ◽

Ashley A. Dittmar ◽

Geoffrey B. Severin ◽

Benjamin J. Koestler

Keyword(s):

Host Cell ◽

Cell Invasion ◽

Biofilm Formation ◽

Shigella Flexneri ◽

Acid Resistance ◽

Host Cell Invasion ◽

Plaque Size ◽

Human Pathogen ◽

Signaling System ◽

Acid Shock

Shigella flexneri is an intracellular human pathogen that invades colonic cells and causes bloody diarrhea. S. flexneri evolved from commensal Escherichia coli , and genome comparisons reveal that S. flexneri has lost approximately 20% of its genes through the process of pathoadaptation, including a disproportionate number of genes associated with the turnover of the nucleotide-based second messenger cyclic di-guanosine monophosphate (c-di-GMP); however, the remaining c-di-GMP turnover enzymes are highly conserved. C-di-GMP regulates many behavioral changes in other bacteria in response to changing environmental conditions, including biofilm formation, but this signaling system has not been examined in S. flexneri . In this study, we expressed VCA0956, a constitutively active c-di-GMP synthesizing diguanylate cyclase (DGC) from Vibrio cholerae , in S. flexneri to determine if virulence phenotypes were regulated by c-di-GMP. We found that expressing VCA0956 in S. flexneri increased c-di-GMP levels, and this corresponds with increased biofilm formation, and reduced acid resistance, host cell invasion, and plaque size. We examined the impact of VCA0956 expression on the S. flexneri transcriptome, and found that genes related to acid resistance were repressed, and this corresponded with decreased survival to acid shock. We also found that individual S. flexneri DGC mutants exhibit reduced biofilm formation, reduced host cell invasion and plaque size, as well as increased resistance to acid shock. This study highlights the importance of c-di-GMP signaling in regulating S. flexneri virulence phenotypes Importance The intracellular human pathogen Shigella causes dysentery, resulting in as many as one million deaths per year. Currently, there is no approved vaccine for the prevention of shigellosis, and the incidence of antimicrobial resistance amongst Shigella species is on the rise. Here, we explore how the widely conserved c-di-GMP bacterial signaling system alters Shigella behaviors associated with pathogenesis. We find that expressing or removing enzymes associated with c-di-GMP synthesis results in changes in Shigella ’s ability to form biofilms, invade host cells, form lesions in host cell monolayers, and resist acid stress.

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Faculty Opinions recommendation of The IL-12 Response of Primary Human Dendritic Cells and Monocytes to Toxoplasma gondii Is Stimulated by Phagocytosis of Live Parasites Rather Than Host Cell Invasion.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725957291.793518980 ◽

2016 ◽

Author(s):

Frank Seeber

Keyword(s):

Dendritic Cells ◽

Toxoplasma Gondii ◽

Host Cell ◽

Cell Invasion ◽

Host Cell Invasion ◽

Human Dendritic Cells

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Faculty Opinions recommendation of Aspergillus fumigatus CalA binds to integrin α5β1 and mediates host cell invasion.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.727157720.793531362 ◽

2017 ◽

Author(s):

Leah Cowen ◽

Teresa O’Meara

Keyword(s):

Aspergillus Fumigatus ◽

Host Cell ◽

Cell Invasion ◽

Host Cell Invasion ◽

Integrin Α5β1

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A Genome-Wide siRNA Screen Implicates Spire1/2 in SipA-Driven Salmonella Typhimurium Host Cell Invasion

PLoS ONE ◽

10.1371/journal.pone.0161965 ◽

2016 ◽

Vol 11 (9) ◽

pp. e0161965 ◽

Cited By ~ 10

Author(s):

Daniel Andritschke ◽

Sabrina Dilling ◽

Mario Emmenlauer ◽

Tobias Welz ◽

Fabian Schmich ◽

...

Keyword(s):

Salmonella Typhimurium ◽

Host Cell ◽

Cell Invasion ◽

Host Cell Invasion ◽

Sirna Screen ◽

Genome Wide ◽

A Genome

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Characterisation of NcGRA7 and NcSAG4 proteins: Immunolocalisation and their role in the host cell invasion by Neospora caninum tachyzoites

Acta Parasitologica ◽

10.2478/s11686-010-0056-9 ◽

2010 ◽

Vol 55 (4) ◽

Cited By ~ 9

Author(s):

Adriana Aguado-Martínez ◽

Gema Álvarez-García ◽

Gereon Schares ◽

Verónica Risco-Castillo ◽

Aurora Fernández-García ◽

...

Keyword(s):

Monoclonal Antibody ◽

Host Cell ◽

Cell Invasion ◽

Neospora Caninum ◽

Parasitophorous Vacuole ◽

Membrane Surface ◽

Chronic Phase ◽

Host Cell Invasion ◽

Invasion Mechanisms ◽

The Matrix

AbstractNeospora caninum negatively impacts bovine reproductive performance around the world. Addressing this problem requires a greater understanding of the parasite’s molecular biology. In this study, monoclonal antibodies against recombinant proteins were successfully developed and employed to characterise two different proteins of N. caninum: the acute phase-associated NcGRA7 and the chronic phase-associated NcSAG4. Immunofluorescence with the anti-rNcGRA7 monoclonal antibody suggested that NcGRA7 trafficks from tachyzoite dense granules to the matrix of the parasitophorous vacuole and parasite’s surroundings. Furthermore, NcGRA7 is also expressed in the bradyzoite stage and localised on the matrix of bradyzoite-positive vacuoles. NcGRA7 appears to be partially involved in the tachyzoite-invasion mechanisms, as an anti-rNcGRA7 monoclonal antibody partially inhibited in vitro tachyzoite-invasion. A monoclonal antibody specific for NcSAG4 confirmed this protein’s bradyzoitespecific expression both by western blot and immunofluorescence. However, some bradyzoite-positive vacuoles only weakly expressed NcSAG4, if it was expressed at all. The specificity of the anti-rNcSAG4 monoclonal antibody was confirmed by the recognition of the NcSAG4 in the membrane surface of Nc-1SAG4c transgenic tachyzoites, which constitutively expresses NcSAG4. Blocking NcSAG4 of Nc-1SAG4c tachyzoites with the monoclonal antibody did not affect host cell invasion. However, its implication on the host cell adhesion or host immune evasion should not be discarded.

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1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Cells ◽

10.3390/cells10051053 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1053

Author(s):

Lidia Węglińska ◽

Adrian Bekier ◽

Katarzyna Dzitko ◽

Barbara Pacholczyk-Sienicka ◽

Łukasz Albrecht ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Cell Invasion ◽

Direct Action ◽

Human Fibroblasts ◽

Imidazole Ring ◽

Host Cells ◽

In Vitro Assays ◽

Host Cell Invasion

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b–12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b–12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

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