Immunity Commons^™

Characterization Of The Ompl1 Gene Of Pathogenic Leptospira Species In China And Cross-Immunogenicity Of The Ompl1 Protein, Haiyan Dong, Ye Hu, Feng Xue, Dexter Sun, David M. Ojcius, Yafei Mao, Jie Yan

All Dugoni School of Dentistry Faculty Articles

Background: The usefulness of available vaccine and serological tests for leptospirosis is limited by the low cross-reactivity of antigens from numerous serovars of pathogenic Leptospira spp. Identification of genus-specific protein antigens (GP-Ag) of Leptospira would be important for development of universal vaccines and serodiagnostic methods. OmpL1, a transmembrane porin of pathogenic leptospires, was identified as a possible GP-Ag, but its sequence diversity and immune cross-reactivity among different serovars of pathogenic leptospires remains largely unknown.

Results: PCR analysis demonstrated that the ompL1 gene existed in all 15 official Chinese standard strains as well as 163 clinical strains of pathogenic leptospires isolated …

Critical Involvement Of The Atm-Dependent Dna Damage Response In The Apoptotic Demise Of Hiv-1-Elicited Syncytia, Jean-Luc Perfettini, Roberta Nardacci, Mehdi Bourouba, Frederic Subra, Laurent Gros, Claire Séror, Gwenola Manic, Filippo Rosselli, Alessandra Amendola, Peggy Masdehors, Luciana Chessa, Giuseppe Novelli, David M. Ojcius, Jan Konrad Siwicki, Magdalena Chechlinska, Christian Auclair, Jose R. Regueiro, Hughes De Thé, Marie-Lise Gougeon, Mauro Piacentini, Guido Kroemer

All Dugoni School of Dentistry Faculty Articles

DNA damage can activate the oncosuppressor protein ataxia telangiectasia mutated (ATM), which phosphorylates the histone H2AX within characteristic DNA damage foci. Here, we show that ATM undergoes an activating phosphorylation in syncytia elicited by the envelope glycoprotein complex (Env) of human immunodeficiency virus-1 (HIV-1) in vitro. This was accompanied by aggregation of ATM in discrete nuclear foci that also contained phospho-histone H2AX. DNA damage foci containing phosphorylated ATM and H2AX were detectable in syncytia present in the brain or lymph nodes from patients with HIV-1 infection, as well as in a fraction of blood leukocytes, correlating with viral status. Knockdown …

Susceptibility Of Chlamydia Trachomatis To The Excipient Hydroxy-Ethylcellulose: Ph And Concentration Dependence Of Antimicrobial Activity, Ali A. Abdul-Sater, David M. Ojcius, M. P. Meyer

All Dugoni School of Dentistry Faculty Articles

Hydroxyethyl cellulose (HEC) is used as a neutral excipient in microbicides used against sexually transmitted pathogens. However, HEC inhibits the infection of cervical epithelial cells by Chlamydia trachomatis at pH 5 in a concentration-dependent manner. At pH 7, infection is inversely dependent on the concentration of HEC, possibly due to pH-dependent calcium sequestration.

Louis Pasteur’S Views On Creation, Evolution, And The Genesis Of Germs, Alan L. Gillen, Frank Sherwin

Faculty Publications and Presentations

“There is no remembrance of men of old, and even those who are yet to come will not be remembered by those who follow.” Ecclesiastes 1:11 (NIV)

In past years revisionist historians have been rewriting the worldview of Christians who have made some of the major discoveries in biology and medicine. It appears that postmodern revisionists are rewriting history to support their agenda of a more “secular” explanation to science. The Judeo-Christian worldview is not politically correct in most universities. This is true in regard to past scientists such as Louis Pasteur who believed in creation. According to reliable, primary …

Atp Activates A Reactive Oxygen Species-Dependent Oxidative Stress Response And Secretion Of Pro-Inflammatory Cytokines In Macrophages, Christiane M. Cruz, Alessandra Rinna, Henry Jay Forman, Ana L. M. Ventura, Pedro M. Persechini, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Secretion of the proinflammatory cytokines, interleukin (IL)-1β and IL-18, usually requires two signals. The first, due to microbial products such as lipopolysaccharide, initiates transcription of the cytokine genes and accumulation of the precursor proteins. Cleavage and secretion of the cytokines is mediated by caspase-1, in association with an inflammasome containing Nalp3, which can be activated by binding of extracellular ATP to purinergic receptors. We show that treatment of macrophages with ATP results in production of reactive oxygen species (ROS), which stimulate the phosphatidylinositol 3-kinase (PI3K) pathway and subsequent Akt and ERK1/2 activation. ROS exerts its effect through glutathionylation of PTEN …

Characterization Of Host Cell Death Induced By Chlamydia Trachomatis, Songmin Ying, Silke F. Fischer, Matthew A. Pettengill, Debye Conte, Stefan A. Paschen, David M. Ojcius, Georg Hacker

All Dugoni School of Dentistry Faculty Articles

Chlamydia are obligate intracellular bacteria that modulate apoptosis of the host cell. Strikingly, chlamydial infection has been reported both to inhibit and to induce apoptosis. Although the ability to inhibit apoptosis has been corroborated by the identification of cellular targets, confirmation of cell death induction has been complicated by a mixture of apoptotic features and atypical cell death during infection, as well as by differences in the experimental techniques used to measure cell death. Here we use a panel of well-established approaches in the study of apoptosis to define the form of cell death induced by Chlamydia trachomatis infection. Infected …

Recruitment Of Bad By The Chlamydia Trachomatis Vacuole Correlates With Host-Cell Survival, Philippe Verbeke, Lynn Welter-Stahl, S. Ying, J. Hansen, Georg Hacker, Toni Darville, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Chlamydiae replicate intracellularly in a vacuole called an inclusion. Chlamydial-infected host cells are protected from mitochondrion-dependent apoptosis, partly due to degradation of BH3-only proteins. The host-cell adapter protein 14-3-3β can interact with host-cell apoptotic signaling pathways in a phosphorylation-dependent manner. In Chlamydia trachomatis-infected cells, 14-3-3β co-localizes to the inclusion via direct interaction with a C. trachomatis-encoded inclusion membrane protein. We therefore explored the possibility that the phosphatidylinositol-3 kinase (PI3K) pathway may contribute to resistance of infected cells to apoptosis. We found that inhibition of PI3K renders C. trachomatis-infected cells sensitive to staurosporine-induced apoptosis, which is accompanied by mitochondrial cytochrome c …

Fms-Like Tyrosine Kinase 3 Ligand Recruits Plasmacytoid Dendritic Cells To The Brain, James Curtin, Gwendalyn King, Carlos Barcia, Chunyan Liu, Francois Hubert, Carole Guillonneau, Regis Josien, Ignacio Anegon, Pedro Lowenstein, Maria Castro

Articles

The lack of professional afferent APCs in naive brain parenchyma contributes to the systemic immune ignorance to Ags localized exclusively within the brain. Dendritic cells (DCs) appear within the brain as a consequence of inflammation, but no molecular mechanisms accounting for this influx have been described. In this study we demonstrate that Fms-like tyrosine kinase 3 ligand (Flt3L) recruits plasmacytoid DCs (pDCs; >50-fold; p < 0.001) to the brain parenchyma. These pDCs expressed IFN-alpha, the hallmark cytokine produced by pDCs, indicating recruitment and activation in situ of bona fide pDCs within the brain parenchyma. Flt3L did not increase the numbers of conventional DCs, macrophages, or B, T, NK, NKT, or microglial cells within the brain. Our data demonstrate that Flt3L reconstitutes a crucial afferent component of the immune response, namely, professional APCs within the brain parenchyma, and this could counteract the intrinsic systemic immune ignorance to Ags localized exclusively within the brain.

Intercellular Spreading Of Porphyromonas Gingivalis Infection In Primary Gingival Epithelial Cells, Özlem Yilmaz, Philippe Verbeke, Richard J. Lamont, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Porphyromonas gingivalis, an important periodontal pathogen, is an effective colonizer of oral tissues. The organism successfully invades, multiplies in, and survives for extended periods in primary gingival epithelial cells (GECs). It is unknown whether P. gingivalis resides in the cytoplasm of infected cells throughout the infection or can spread to adjacent cells over time. We developed a technique based on flow cytofluorometry and fluorescence microscopy to study propagation of the organism at different stages of infection of GECs. Results showed that P. gingivalis spreads cell to cell and that the amount of spreading increases gradually over time. There was a …

Premature Induction Of An Immunosuppressive Regulatory T Cell Response During Acute Simian Immunodeficiency Virus Infection, Jacob D. Estes, Qingsheng Li, Matthew R. Reynolds, Stephen W. Wietgrefe, Lijie Duan, Timothy Schacker, Louis J. Picker, David I. Watkins, Jeffrey D. Lifson, Cavan Reilly, John V. Carlis, Ashley T. Haase

Qingsheng Li Publications

Here we report the results of an investigation into the possibility that one mechanism responsible for the establishment of persistent human immunodeficiency virus infection is an early regulatory T (T_reg) cell response that blunts virus- specific responses. Using the simian immunodeficiency virus (SIV)–infected rhesus macaque model, we show that, indeed, viral replication and immune activation in lymphatic tissue drive a premature immunosuppressive response, with dramatic increases in the frequencies of CD4⁺CD25⁺FOXP3⁺ Treg cells, transforming growth factor–β1⁺ cells, interleukin–10+ cells, and indoleamine 2,3-dioxygenase+CD3⁺ cells.When we compared SIV infection with rhesus cytomegalovirus (RhCMV) …

A Role For Mitogen-Activated Protein Kinase (Erk1/2) Activation And Non-Selective Pore Formation In P2x7 Receptor-Mediated Thymocyte Death, Rodolphe Auger, Iris Motta, Karim Benihoud, David M. Ojcius, Jean M. Kanellopoulos

All Dugoni School of Dentistry Faculty Articles

Extracellular ATP (ATPe) binds to P2X7 receptors (P2X7R) expressed on the surface of cells of hematopoietic lineage, including murine thymocytes. Activation of P2X7R by ATPe results in the opening of cation-specific channels, and prolonged ATPe exposure leads to the formation of non-selective pores enabling transmembrane passage of solutes up to 900 Da. In the presence of ATPe, P2X7R-mediated thymocyte death is due primarily to necrosis/lysis and not apoptosis, as measured by the release of lactate dehydrogenase indicative of a loss of plasma membrane integrity. The present study is focused on the identification of P2X7R signaling mediators in ATP-induced thymocyte necrosis/lysis. …

Association Between Coinfection Of Porphyromonas Gingivalis, Actinobacillus Actinomycetemcomitans And Treponema Denticola And Periodontal Tissue Destruction In Chronic Periodontitis, L. L. Chen, Y. M. Wu, J. Yan, W. L. Sun, Y. Z. Sun, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

No abstract provided.

Defensin In Ticks: Molecular Characterization, Expression, And Role In Innate Immunity, Daniel E. Sonenshine, Wayne L. Hynes, Shane M. Ceraul, Michelle Todd

Biological Sciences Faculty Publications

No abstract provided.

Activation Of The Phosphatidylinositol 3-Kinase/Akt Pathway Contributes To Survival Of Primary Epithelial Cells Infected With The Periodontal Pathogen Porphyromonas Gingivalis, Özlem Yilmaz, Thomas Jungas, Philippe Verbeke, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Porphyromonas gingivalis, an important periodontal pathogen, infects primary gingival epithelial cells (GECs). Despite the large number of bacteria that replicate inside the GECs, the host cell remains viable. We demonstrate that P. gingivalis triggers rapid and reversible surface phosphatidylserine exposure through a mechanism requiring caspase activation. However, after 1 day of infection, the bacteria no longer induce phosphatidylserine externalization and instead protect infected cells against apoptosis. Infection exerts its effect at the level of mitochondria, as P. gingivalis also blocks depolarization of the mitochondrial transmembrane potential and cytochrome c release. Interestingly, protein kinase B/Akt is phosphorylated during infection, which can …

Tolerance Of The Fetus By The Maternal Immune System: Role Of Inflammatory Mediators At The Feto-Maternal Interface, Colette Kanellopoulos-Langevin, Stephane M. Caucheteux, Philippe Verbeke, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

The adaptive immune system of placental mammals has evolved to tolerate the fetus. Rejection of the fetus by adaptive immune responses is therefore a rare event, with abortion being caused more frequently by inflammation in the placenta. This review will cover recent aspects of immune privilege and the innate immune system at the feto-maternal interface, citing examples of the role played by microbial infections in fetal demise.

Lysosomal Membrane Permeabilization Induces Cell Death In A Mitochondrion-Dependent Fashion, Patricia Boya, Karine Andreau, Delphine Poncet, Naoufal Zamzami, Jean-Luc Perfettini, Didier Metivier, David M. Ojcius, Marja Jäättelä, Guido Kroemer

All Dugoni School of Dentistry Faculty Articles

A number of diseases are due to lysosomal destabilization, which results in damaging cell loss. To investigate the mechanisms of lysosomal cell death, we characterized the cytotoxic action of two widely used quinolone antibiotics: ciprofloxacin (CPX) or norfloxacin (NFX). CPX or NFX plus UV light (NFX*) induce lysosomal membrane permeabilization (LMP), as detected by the release of cathepsins from lysosomes. Inhibition of the lysosomal accumulation of CPX or NFX suppresses their capacity to induce LMP and to kill cells. CPX- or NFX-triggered LMP results in caspase-independent cell death, with hallmarks of apoptosis such as chromatin condensation and phosphatidylserine exposure on …

Role Of Proapoptotic Bax In Propagation Of Chlamydia Muridarum (The Mouse Pneumonitis Strain Of Chlamydia Trachomatis) And The Host Inflammatory Response, Jean-Luc Perfettini, David M. Ojcius, Charles W. Andrews Jr., Stanley J. Korsmeyer, Roger G. Rank, Toni Darville

All Dugoni School of Dentistry Faculty Articles

The BCL-2 family member BAX plays a critical role in regulating apoptosis. Surprisingly, bax-deficient mice display limited phenotypic abnormalities. Here we investigate the effect of BAX on infection by the sexually transmitted pathogen,Chlamydia muridarum (the mouse pneumonitis strain ofChlamydia trachomatis). Bax −/−cells are relatively resistant to Chlamydia-induced apoptosis, and fewer bacteria are recovered after two infection cycles from Bax −/− cells than from wild-type cells. These results suggest that BAX-dependent apoptosis may be used to initiate a new round of infection, most likely by releasingChlamydia-containing apoptotic bodies from infected cells that could be internalized by neighboring uninfected cells. Nonetheless, infected …

Characterization Of A Gene Encoding Two Isoforms Of A Mitochondrial Protein Upregulated By Cyclosporin A In Activated T Cells, Laurent Mascarell, Rodolphe Auger, Andres Alcover, David M. Ojcius, Thomas Jungas, Veronique Cadet-Daniel, Jean M. Kanellopoulos, Paolo Truffa-Bacchi

All Dugoni School of Dentistry Faculty Articles

Cyclosporin A (CSA) is an immunosuppressor used in organ transplantation. A recent proteomic analysis has revealed that activation of T cells in the presence of CSA induces the synthesis of hundreds of new proteins. Here we used representational difference analysis to characterize some of the corresponding induced genes. After cDNA bank screening we focused on one of these genes, which we named CSA-conditional, T cell activation-dependent (CSTAD) gene. This gene produces two mRNAs resulting from alternative splicing events. They encode two proteins of 104 and 141 amino acids, CSTADp-S and CSTADp-L, for the short and long forms, respectively. FK506 had …

Glutathione Levels And Bax Activation During Apoptosis Due To Oxidative Stress In Cells Expressing Wild-Type And Mutant Cystic Fibrosis Transmembrane Conductance Regulator, Thomas Jungas, Iris Motta, Francis Duffieux, Pascale Fanen, Veronique Stoven, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Cystic fibrosis is characterized by chronic inflammation and an imbalance in the concentrations of alveolar and lung oxidants and antioxidants, which result in cell damage. Modifications in lung glutathione concentrations are recognized as a salient feature of inflammatory lung diseases such as cystic fibrosis, and glutathione plays a major role in protection against oxidative stress and is important in modulation of apoptosis. The cystic fibrosis transmembrane conductance regulator (CFTR) is permeable to Cl−, larger organic ions, and reduced and oxidized forms of glutathione, and the ΔF508 CFTR mutation found in cystic fibrosis patients has been correlated with impaired glutathione transport …

The Development Of A Bluetongue Virus Diagnostic Assay Using Peptides Derived From The Structural Protein Vp7 And Nonstructural Protein Ns2, Yi Lu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Several peptides derived from viral proteins, VP7 and NS2 of bluetongue virus (BTV), were synthesized for an immunologic detection assay: distinguishing between bluetongue virus infected, vaccinated, and noninfected animals (ruminants) with dot blot analysis. The School of Veterinary Medicine, University of California, Davis, supplied the serum samples from 24 bovine, 18 caprine, 23 ovine. Another 205 bison serum samples were obtained in Utah. The serum samples of BTV-infected animals revealed detectable antibodies to both VP7 and NS2 peptides, whereas vaccinated animals only exhibited antibodies against VP7. Noninfected animals did not display antibody against either viral peptide. These data confirmed the …

Inhibition Of Apoptosis By Gamma Interferon In Cells And Mice Infected With Chlamydia Muridarum (The Mouse Pneumonitis Strain Of Chlamydia Trachomatis), Jean-Luc Perfettini, Toni Darville, Alice Dautry-Varsat, Roger G. Rank, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

The effect of gamma interferon (IFN-γ) on apoptosis due to infection by Chlamydia muridarum (the mouse pneumonitis strain of Chlamydia trachomatis) was studied in epithelial cells in culture and in the genital tracts of mice. IFN-γ concentrations that induce the formation of aberrant, persistent chlamydiae inhibit apoptosis due to C. muridarum infection. In cells treated with an IFN-γ concentration that leads to the development of a heterogenous population of normal and aberrant Chlamydia vacuoles, apoptosis was inhibited preferentially in cells that contained the aberrant vacuoles. The inhibitory effect of IFN-γ appears to be due in part to expression of host …

Role Of Bcl-2 Family Members In Caspase-Independent Apoptosis Due To Chlamydia Infection, Jean-Luc Perfettini, John C. Reed, Nicole Israel, Jean-Claude Martinou, Alice Dautry-Varsat, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Infection with an obligate intracellular bacterium, the Chlamydia trachomatis lymphogranuloma venereum (LGV/L2) strain or the guinea pig inclusion conjunctivitis serovar of Chlamydia psittaci, leads to apoptosis of host cells. The apoptosis is not affected by a broad-spectrum caspase inhibitor, and caspase-3 is not activated in infected cells, suggesting that apoptosis mediated by these two strains of Chlamydia is independent of known caspases. Overexpression of the proapoptotic Bcl-2 family member, Bax, was previously shown to induce caspase-independent apoptosis, and we find that Bax is activated and translocates from the cytosol to the mitochondria in C. psittaci-infected cells. C. psittaci-induced apoptosis is …

La Notion De Danger, Jean M. Kanellopoulos, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Pendant de nombreuses années, les recherches en immunologie ont été centrées sur la réponse immunitaire adaptative, et la plupart des immunologistes considéraient que sa fonction principale était de faire la distinction entre soi et non soi. Plus récemment, plusieurs équipes ont proposé que la fonction principale du système immunitaire est en réalité d’éliminer les agents pathogènes. Or, c’est le système immunitaire inné, longtemps négligé, qui joue un rôle essentiel dans l’induction d’une réponse contre les microorganismes. Ce système réagit précocement aux infections, voire instantanément, puis il induit et oriente la réponse du système adaptatif. Plusieursthéories ont été élaborées pour expliquer …

Effect Of Chlamydia Trachomatis Infection And Subsequent Tnfa Secretion On Apoptosis In The Murine Genital Tract, Jean-Luc Perfettini, Toni Darville, Gabriel Gachelin, Philippe Souque, Michel Huerre, Alice Dautry-Varsat, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

The pathology observed during Chlamydia infection is due initially to localized tissue damage caused by the infection itself, followed by deleterious host inflammatory responses that lead to permanent scarring. We have recently reported that the infection byChlamydia in vitro results in apoptosis of epithelial cells and macrophages and that infected monocytes secrete the proinflammatory cytokine interleukin-1β. At the same time, proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α) can also trigger apoptosis of susceptible cells. To study the possible relationship between Chlamydia trachomatis infection and apoptosis in vivo, we used the terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling technique to …

Enhancement Of Atp Levels And Glucose Metabolism During An Infection By Chlamydia: Nmr Studies Of Living Cells, David M. Ojcius, H. Degani, Joel Mispelter, Alice Dautry-Varsat

All Dugoni School of Dentistry Faculty Articles

The Chlamydia species are obligate intracellular bacteria that proliferate only within the infected cell. Since the extracellular bacteria are metabolically inert and there are no cell-free systems for characterizingChlamydia metabolism, we studied metabolic changes related to ATP synthesis and glycolysis in HeLa cells infected withChlamydia psittaci during the course of the 2-day infection cycle using noninvasive 31P and 13C NMR methods. We find that the infection stimulates ATP synthesis in the infected cell, with a peak of ATP levels occurring midway through the infection cycle, when most of the metabolically active bacteria are proliferating. The infection also stimulates synthesis of …

Distribution Of Endosomal, Lysosomal And Mhc Markers In A Monocytic Cell Line Infected With Chlamydia Psittaci, David M. Ojcius, Raymond Hellio, Alice Dautry-Varsat

All Dugoni School of Dentistry Faculty Articles

The intracellular fate of Chlamydia psittaci during infection of a monocytic cell line, THP1, was characterized. Cytochalasin D inhibited phagocytosis of latex beads but had no effect on infection by C. psittaci, and vacuoles expressed the transferrin receptor, suggesting accessibility to the endocytic pathway. Early Chlamydia-containing vacuoles expressed major histocompatibility complex (MHC) class I molecules, and most vacuoles fused with host cell lysosomes, since they expressed LAMP-1 and had acidic pHs. In cells prestimulated with gamma interferon, vacuoles also expressed MHC class II molecules, suggesting that the monocytes might effectively process Chlamydia-derived antigens for presentation by MHC class I and …

Interleukin-10 Inhibits Tumor Metastasis Through An Nk-Cell Dependent Mechanism, Li-Mou Zheng, David M. Ojcius, F. Garaud, C. Roth, E. Maxwell, Z. Li, H. Rong, J. Chen, X. Y. Wang, J. J. Catino, I. King

All Dugoni School of Dentistry Faculty Articles

Interleukin-10 (IL-10) is a recently described pleiotropic cytokine secreted mainly by type 2 helper T cells. Previous studies have shown that IL-10 suppresses cytokine expression by natural killer (NK) and type 1 T cells, thus down-regulating cell-mediated immunity and stimulating humoral responses. We here report that injected IL-10 protein is an efficient inhibitor of tumor metastasis in experimental (B16-F10) and spontaneous (M27 and Lox human melanoma) metastasis models in vivo at doses that do not have toxic effects on normal or cancer cells. Histological characterization after IL-10 treatment confirmed the absence of CD8+ and CD4+ T cells and macrophages at …

The Effect Of The Mammalian Hormone Estrogen On The Yeast C̲A̲N̲D̲I̲D̲A̲ A̲L̲B̲I̲C̲A̲N̲S̲, Marcia Clifton Finucane

Theses, Dissertations and Capstones

Changes in the balance between commensal microbes and mammalian hosts can cause disease if the scales tip in favor of the microbe. Although usually caused by a defective host immune response, overgrowth of or changes in the microbe may also be responsible for opportunistic infections. Clinical and laboratory investigations have indicated that mammalian hormones, including estrogen, can influence the production of symptomatic disease and the virulence attributes of Candida albicans.

This study demonstrated enhanced growth of some strains of C. albicans when 17β-estradiol was added to the growth medium. Measurement of extracellular protein under the influence of estradiol did …

Ph And Calcium Dependence Of Hemolysis Due To Rickettsia Prowazekii: Comparison With Phospholipase Activity, David M. Ojcius, M. Thibon, C. Mounier, Alice Dautry-Varsat

All Dugoni School of Dentistry Faculty Articles

Rickettsia prowazekii invades nucleated cells through phagocytosis and subsequently proliferates in the cytoplasm of the host cell. Hemolysis and a phospholipase A2 (PLA2) activity at neutral pHs have previously been reported; even though the phagosomal environment is most likely acidic. We here show that R. prowazekii and R. typhi also lyse erythrocytes at mildly acidic pHs, compatible with an early phagosomal compartment. For R. prowazekii, hemolysis at an acidic pH but not a neutral pH is enhanced by Ca2+, raising the possibility that more than one membranolytic factor may be produced by the rickettsiae. The rickettsiae alone display PLA2 activity, …

Symptoms Six Weeks After Covid-19 Are Reduced Among Us Health Care Personnel Receiving Additional Vaccine Doses During The Omicron Period, December 2021-April 2022., Nicholas M. Mohr, Ian D. Plumb, Eliezer Santos León, Malea Pinckney, Karisa K. Harland, Anusha Krishnadasan, Karin F. Hoth, Fernand Rwamwejo, John P. Haran, Melissa Briggs-Hagen, Eric Kontowicz, David A. Talan

Jefferson Hospital Staff Papers and Presentations

BACKGROUND: The objective of this study was to test the hypothesis that subsequent doses of the coronavirus disease 2019 (COVID-19) vaccine are associated with lower incidence of COVID-19-like symptoms at 6 weeks after infection.

METHODS: This study was a case-control analysis of health care personnel in an ongoing multicenter COVID-19 vaccine effectiveness study. We enrolled participants at the time of COVID-19-like symptoms between December 19, 2021, and April 27, 2022, which corresponded to the early Omicron-predominant period after original monovalent severe acute respiratory syndrome coronavirus 2 additional vaccination doses became available. Our outcome was self-reported symptoms completed 6 weeks after …