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Cardenas AJ, Thomas KS, Broden MW, Ferraro NJ, Pires MM, John CM, Jarvis GA, Criss AK. Neisseria gonorrhoeae scavenges host sialic acid for Siglec-mediated, complement-independent suppression of neutrophil activation. mBio 2024; 15:e0011924. [PMID: 38587424 PMCID: PMC11078009 DOI: 10.1128/mbio.00119-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 03/12/2024] [Indexed: 04/09/2024] Open
Abstract
Gonorrhea, caused by the bacterium Neisseria gonorrhoeae (Gc), is characterized by neutrophilic influx to infection sites. Gc has developed mechanisms to resist killing by neutrophils that include modifications to its surface lipooligosaccharide (LOS). One such LOS modification is sialylation: Gc sialylates its terminal LOS sugars with cytidine-5'-monophosphate-N-acetylneuraminic acid, which is scavenged from the host using LOS sialyltransferase (Lst) since Gc cannot make its sialic acid. Sialylation enables sensitive strains of Gc to resist complement-mediated killing in a serum-dependent manner. However, little is known about the contribution of sialylation to complement-independent, direct Gc-neutrophil interactions. In the absence of complement, we found sialylated Gc expressing opacity-associated (Opa) proteins decreased the oxidative burst and granule exocytosis from primary human neutrophils. In addition, sialylated Opa+ Gc survived better than vehicle treated or Δlst Gc when challenged with neutrophils. However, Gc sialylation did not significantly affect Opa-dependent association with or internalization of Gc by neutrophils. Previous studies have implicated sialic acid-binding immunoglobulin-type lectins (Siglecs) in modulating neutrophil interactions with sialylated Gc. Blocking neutrophil Siglecs with antibodies that bind to their extracellular domains eliminated the ability of sialylated Opa+ Gc to suppress the oxidative burst and resist neutrophil killing. These findings highlight a new role for sialylation in Gc evasion of human innate immunity, with implications for the development of vaccines and therapeutics for gonorrhea. IMPORTANCE Neisseria gonorrhoeae, the bacterium that causes gonorrhea, is an urgent global health concern due to increasing infection rates, widespread antibiotic resistance, and its ability to thwart protective immune responses. The mechanisms by which Gc subverts protective immune responses remain poorly characterized. One way N. gonorrhoeae evades human immunity is by adding sialic acid that is scavenged from the host onto its lipooligosaccharide, using the sialyltransferase Lst. Here, we found that sialylation enhances N. gonorrhoeae survival from neutrophil assault and inhibits neutrophil activation, independently of the complement system. Our results implicate bacterial binding of sialic acid-binding lectins (Siglecs) on the neutrophil surface, which dampens neutrophil antimicrobial responses. This work identifies a new role for sialylation in protecting N. gonorrhoeae from cellular innate immunity, which can be targeted to enhance the human immune response in gonorrhea.
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Affiliation(s)
- Amaris J. Cardenas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Keena S. Thomas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Mary W. Broden
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
| | - Noel J. Ferraro
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Marcos M. Pires
- Department of Chemistry, University of Virginia, Charlottesville, Virginia, USA
| | - Constance M. John
- VA Medical Center and University of California, San Francisco, San Francisco, California, USA
| | - Gary A. Jarvis
- VA Medical Center and University of California, San Francisco, San Francisco, California, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, USA
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Colón Pérez J, Villarino Fernández RA, Domínguez Lago A, Treviño Castellano MM, Pérez del Molino Bernal ML, Sánchez Poza S, Torres-Sangiao E. Addressing Sexually Transmitted Infections Due to Neisseria gonorrhoeae in the Present and Future. Microorganisms 2024; 12:884. [PMID: 38792714 PMCID: PMC11124187 DOI: 10.3390/microorganisms12050884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/16/2024] [Accepted: 04/22/2024] [Indexed: 05/26/2024] Open
Abstract
It was in the 1800s when the first public publications about the infection and treatment of gonorrhoea were released. However, the first prevention programmes were only published a hundred years later. In the 1940s, the concept of vaccination was introduced into clinical prevention programmes to address early sulphonamide resistance. Since then, tons of publications on Neisseria gonorrhoeae are undisputed, around 30,000 publications today. Currently, the situation seems to be just as it was in the last century, nothing has changed or improved. So, what are we doing wrong? And more importantly, what might we do? The review presented here aims to review the current situation regarding the resistance mechanisms, prevention programmes, treatments, and vaccines, with the challenge of better understanding this special pathogen. The authors have reviewed the last five years of advancements, knowledge, and perspectives for addressing the Neisseria gonorrhoeae issue, focusing on new therapeutic alternatives.
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Affiliation(s)
- Julia Colón Pérez
- Servicio de Microbiología y Parasitología Clínica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain; (J.C.P.); (A.D.L.); (M.M.T.C.); (M.L.P.d.M.B.)
- Grupo Microbiología, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), 15706 Santiago de Compostela, Spain
| | - Rosa-Antía Villarino Fernández
- Departamento de Microbiología, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain;
| | - Adrián Domínguez Lago
- Servicio de Microbiología y Parasitología Clínica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain; (J.C.P.); (A.D.L.); (M.M.T.C.); (M.L.P.d.M.B.)
- Grupo Microbiología, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), 15706 Santiago de Compostela, Spain
| | - María Mercedes Treviño Castellano
- Servicio de Microbiología y Parasitología Clínica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain; (J.C.P.); (A.D.L.); (M.M.T.C.); (M.L.P.d.M.B.)
- Grupo Microbiología, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), 15706 Santiago de Compostela, Spain
| | - María Luisa Pérez del Molino Bernal
- Servicio de Microbiología y Parasitología Clínica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain; (J.C.P.); (A.D.L.); (M.M.T.C.); (M.L.P.d.M.B.)
- Grupo Microbiología, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), 15706 Santiago de Compostela, Spain
| | - Sandra Sánchez Poza
- Departamento de Microbiología, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain;
| | - Eva Torres-Sangiao
- Servicio de Microbiología y Parasitología Clínica, Complexo Hospitalario Universitario de Santiago de Compostela, 15706 Santiago de Compostela, Spain; (J.C.P.); (A.D.L.); (M.M.T.C.); (M.L.P.d.M.B.)
- Grupo Microbiología, Instituto de Investigación Sanitaria de Santiago de Compostela (IDIS), 15706 Santiago de Compostela, Spain
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Jones RA, Jerse AE, Tang CM. Gonococcal PorB: a multifaceted modulator of host immune responses. Trends Microbiol 2024; 32:355-364. [PMID: 37891023 DOI: 10.1016/j.tim.2023.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023]
Abstract
Neisseria gonorrhoeae is a human-specific pathogen responsible for the sexually transmitted infection, gonorrhoea. N. gonorrhoeae promotes its survival by manipulating both innate and adaptive immune responses. The most abundant gonococcal outer-membrane protein is PorB, an essential porin that facilitates ion exchange. Importantly, gonococcal PorB has several immunomodulatory properties. To subvert the innate immune response, PorB suppresses killing mechanisms of macrophages and neutrophils, and recruits negative regulators of complement to the gonococcal cell surface. For manipulation of adaptive immune responses, gonococcal PorB suppresses the capability of dendritic cells to stimulate proliferation of T cells. As gonococcal PorB is highly abundant in outer-membrane vesicles, consideration of the immunomodulatory properties of this porin is critical when designing gonococcal vaccines.
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Affiliation(s)
- Rebekah A Jones
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Ann E Jerse
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, MD, USA
| | - Christoph M Tang
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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Zhang H, Qiu Q, Li Q, Feng L, Li D, Zhang M, Wang J, Ma S, Xu L. Proteomics Clustering Research of ITRAQ Markers in Plasma of AIDS Patients with Different Chinese Medicine Syndromes. IRANIAN JOURNAL OF PUBLIC HEALTH 2024; 53:376-386. [PMID: 38894847 PMCID: PMC11182475 DOI: 10.18502/ijph.v53i2.14922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 09/19/2023] [Indexed: 06/21/2024]
Abstract
Background We aimed to distinguish the different Chinese medicine (CM) syndromes of acquired immune deficiency syndrome (AIDS) patients at the proteomics level. Methods We collected AIDS patients diagnosed with different CM syndromes from Weishi County, Kaifeng City, Henan Province, China, including Qi-deficiency syndrome (named QD group) and dampness-heat syndrome (named DH group). Healthy people were collected as controls from Weishi County, Kaifeng city, Henan Province, China. The plasma from three groups were labeled with ITRAQ, LC/MC was used for protein quantitative analysis. Finally, sequence search and cluster analysis were performed. Results Overall, 27 different proteins were found. Three proteins were up-regulated and 2 proteins down-regulated in the QD group, 11 proteins up-regulated and 13 proteins down-regulated in the DH group. Compared with DH group, there were 7 different proteins in QD group, among which 5 proteins were down-regulated and 2 proteins were up-regulated. When the target protein of DH group was up-regulated, the protein of HC group was down-regulated correspondingly. Conclusion The significance analysis and clustering of protein results showed that DH group was significantly different from QD group and HC group at the protein level (P<0.05). However, the QD group could not be effectively distinguished from the HC group. AAT, PF4, C-reactive protein and c4bp may be used as potential biomarkers in DH group. Mass spectrometry based on feature selection can be used to classify different CM syndromes.
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Affiliation(s)
- Haiyan Zhang
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Quan Qiu
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Qingya Li
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Long Feng
- Department of Pathogenic Organism Biology, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Dongyang Li
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Miao Zhang
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Juan Wang
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Suna Ma
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
| | - Liran Xu
- Zhongjing Institute of Chinese Medicine, Henan University of Chinese Medicine, Zhengzhou city, Henan Province, China
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Cardenas AJ, Thomas KS, Broden MW, Ferraro NJ, John CM, Pires MM, Jarvis GA, Criss AK. Neisseria gonorrhoeae scavenges host sialic acid for Siglec-mediated, complement-independent suppression of neutrophil activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.576097. [PMID: 38293026 PMCID: PMC10827150 DOI: 10.1101/2024.01.17.576097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Gonorrhea, caused by the bacterium Neisseria gonorrhoeae (Gc), is characterized by neutrophil influx to infection sites. Gc has developed mechanisms to resist killing by neutrophils that include modifications to its surface lipooligosaccharide (LOS). One such LOS modification is sialylation: Gc sialylates its terminal LOS sugars with cytidine-5'-monophosphate-N-acetylneuraminic acid (CMP-NANA) scavenged from the host using LOS sialyltransferase (Lst), since Gc cannot make its own sialic acid. Sialylation enables sensitive strains of Gc to resist complement-mediated killing in a serum-dependent manner. However, little is known about the contribution of sialylation to complement-independent, direct Gc-neutrophil interactions. In the absence of complement, we found sialylated Gc expressing opacity-associated (Opa) proteins decreased the oxidative burst and granule exocytosis from primary human neutrophils. In addition, sialylated Opa+ Gc survived better than vehicle treated or Δlst Gc when challenged with neutrophils. However, Gc sialylation did not significantly affect Opa-dependent association with or internalization of Gc by neutrophils. Previous studies have implicated sialic acid-binding immunoglobulin-type lectins (Siglecs) in modulating neutrophil interactions with sialylated Gc. Blocking neutrophil Siglecs with antibodies that bind to their extracellular domains eliminated the ability of sialylated Opa+ Gc to suppress oxidative burst and resist neutrophil killing. These findings highlight a new role for sialylation in Gc evasion of human innate immunity, with implications for the development of vaccines and therapeutics for gonorrhea.
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Affiliation(s)
- Amaris J Cardenas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Keena S. Thomas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Mary W. Broden
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Noel J. Ferraro
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Constance M. John
- VA Medical Center and University of California, San Francisco, San Francisco, CA, USA
| | - Marcos M. Pires
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Gary A. Jarvis
- VA Medical Center and University of California, San Francisco, San Francisco, CA, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
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Gray MC, Thomas KS, Lamb ER, Werner LM, Connolly KL, Jerse AE, Criss AK. Evaluating vaccine-elicited antibody activities against Neisseria gonorrhoeae: cross-protective responses elicited by the 4CMenB meningococcal vaccine. Infect Immun 2023; 91:e0030923. [PMID: 37991382 PMCID: PMC10715150 DOI: 10.1128/iai.00309-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 09/27/2023] [Indexed: 11/23/2023] Open
Abstract
The bacterial pathogen Neisseria gonorrhoeae is an urgent global health problem due to increasing numbers of infections, coupled with rampant antibiotic resistance. Vaccines against gonorrhea are being prioritized to combat drug-resistant N. gonorrhoeae. Meningococcal serogroup B vaccines such as four-component meningococcal B vaccine (4CMenB) are predicted by epidemiology studies to cross-protect individuals from natural infection with N. gonorrhoeae and elicit antibodies that cross-react with N. gonorrhoeae. Evaluation of vaccine candidates for gonorrhea requires a suite of assays for predicting efficacy in vitro and in animal models of infection, including the role of antibodies elicited by immunization. Here, we present the development and optimization of assays to evaluate antibody functionality after immunization of mice: antibody binding to intact N. gonorrhoeae, serum bactericidal activity, and opsonophagocytic killing activity using primary human neutrophils [polymorphonuclear leukocytes (PMNs)]. These assays were developed with purified antibodies against N. gonorrhoeae and used to evaluate serum from mice that were vaccinated with 4CMenB or given alum as a negative control. Results from these assays will help prioritize gonorrhea vaccine candidates for advanced preclinical to early clinical studies and will contribute to identifying correlates and mechanisms of immune protection against N. gonorrhoeae.
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Affiliation(s)
- Mary C. Gray
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Keena S. Thomas
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Evan R. Lamb
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Lacie M. Werner
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Kristie L. Connolly
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, Maryland, USA
| | - Ann E. Jerse
- Department of Microbiology and Immunology, Uniformed Services University, Bethesda, Maryland, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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Werner LM, Criss AK. Diverse Functions of C4b-Binding Protein in Health and Disease. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 211:1443-1449. [PMID: 37931209 PMCID: PMC10629839 DOI: 10.4049/jimmunol.2300333] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 05/26/2023] [Indexed: 11/08/2023]
Abstract
C4b-binding protein (C4BP) is a fluid-phase complement inhibitor that prevents uncontrolled activation of the classical and lectin complement pathways. As a complement inhibitor, C4BP also promotes apoptotic cell death and is hijacked by microbes and tumors for complement evasion. Although initially characterized for its role in complement inhibition, there is an emerging recognition that C4BP functions in a complement-independent manner to promote cell survival, protect against autoimmune damage, and modulate the virulence of microbial pathogens. In this Brief Review, we summarize the structure and functions of human C4BP, with a special focus on activities that extend beyond the canonical role of C4BP in complement inhibition.
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Affiliation(s)
- Lacie M. Werner
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Alison K. Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
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Belcher T, Rollier CS, Dold C, Ross JDC, MacLennan CA. Immune responses to Neisseria gonorrhoeae and implications for vaccine development. Front Immunol 2023; 14:1248613. [PMID: 37662926 PMCID: PMC10470030 DOI: 10.3389/fimmu.2023.1248613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 07/26/2023] [Indexed: 09/05/2023] Open
Abstract
Neisseria gonorrheoae is the causative agent of gonorrhea, a sexually transmitted infection responsible for a major burden of disease with a high global prevalence. Protective immunity to infection is often not observed in humans, possible due to high variability of key antigens, induction of blocking antibodies, or a large number of infections being relatively superficial and not inducing a strong immune response. N. gonorrhoeae is a strictly human pathogen, however, studies using mouse models provide useful insights into the immune response to gonorrhea. In mice, N. gonorrhoea appears to avoid a protective Th1 response by inducing a less protective Th17 response. In mouse models, candidate vaccines which provoke a Th1 response can accelerate the clearance of gonococcus from the mouse female genital tract. Human studies indicate that natural infection often induces a limited immune response, with modest antibody responses, which may correlate with the clinical severity of gonococcal disease. Studies of cytokine responses to gonococcal infection in humans provide conflicting evidence as to whether infection induces an IL-17 response. However, there is evidence for limited induction of protective immunity from a study of female sex workers in Kenya. A controlled human infection model (CHIM) has been used to examine the immune response to gonococcal infection in male volunteers, but has not to date demonstrated protection against re-infection. Correlates of protection for gonorrhea are lacking, which has hampered the progress towards developing a successful vaccine. However, the finding that the Neisseria meningitidis serogroup B vaccines, elicit cross-protection against gonorrhea has invigorated the gonococcal vaccine field. More studies of infection in humans, either natural infection or CHIM studies, are needed to understand better gonococcal protective immunity.
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Affiliation(s)
- Thomas Belcher
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Christina Dold
- The Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom
| | - Jonathan D. C. Ross
- Sexual Health and HIV, University Hospitals Birmingham NHS Trust, Birmingham, United Kingdom
| | - Calman A. MacLennan
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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Gray MC, Thomas KS, Lamb ER, Werner LM, Connolly KL, Jerse AE, Criss AK. Evaluating vaccine-elicited antibody activities against Neisseria gonorrhoeae: cross-protective responses elicited by the 4CMenB meningococcal vaccine. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.03.551882. [PMID: 37577557 PMCID: PMC10418180 DOI: 10.1101/2023.08.03.551882] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The bacterial pathogen Neisseria gonorrhoeae is an urgent global health problem due to increasing numbers of infections, coupled with rampant antibiotic resistance. Vaccines against gonorrhea are being prioritized to combat drug-resistant N. gonorrhoeae. Meningococcal serogroup B vaccines such as 4CMenB are predicted by epidemiology studies to cross-protect individuals from natural infection with N. gonorrhoeae and elicit antibodies that cross-react with N. gonorrhoeae. Evaluation of vaccine candidates for gonorrhea requires a suite of assays for predicting efficacy in vitro and in animal models of infection, including the role of antibodies elicited by immunization. Here we present assays to evaluate antibody functionality after immunization: antibody binding to intact N. gonorrhoeae, serum bactericidal activity, and opsonophagocytic killing activity using primary human neutrophils (polymorphonuclear leukocytes). These assays were developed with purified antibodies against N. gonorrhoeae and used to evaluate serum from mice that were vaccinated with 4CMenB or given alum as a negative control. Results from these assays will help prioritize gonorrhea vaccine candidates for advanced preclinical to early clinical study and will contribute to identifying correlates and mechanisms of immune protection against N. gonorrhoeae .
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