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Phillips S, Quigley BL, Timms P. Seventy Years of Chlamydia Vaccine Research - Limitations of the Past and Directions for the Future. Front Microbiol 2019; 10:70. [PMID: 30766521 PMCID: PMC6365973 DOI: 10.3389/fmicb.2019.00070] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/15/2019] [Indexed: 11/30/2022] Open
Abstract
Chlamydia is a major bacterial pathogen that infects humans, as well as a wide range of animals, including marsupials, birds, cats, pigs, cattle, and sheep. Antibiotics are the only treatment currently available, however, with high rates of re-infection, there is mounting pressure to develop Chlamydia vaccines. In this review, we analyzed how Chlamydia vaccine trials have developed over the past 70 years and identified where future trials need to be focused. There has been a strong bias toward studies targeting C. muridarum and C. trachomatis within mice and a lack of studies matching chlamydial species to their end target host. Even though a large number of specific antigenic targets have been studied, the results from whole-cell vaccine targets show slightly more promising results overall. There has also been a strong bias toward systemic vaccine delivery systems, despite the finding that mucosal delivery systems have shown more promising outcomes. However, the only successful vaccines with matched chlamydial species/infecting host are based on systemic vaccine delivery methods. We highlight the extensive work done with mouse model trials and indicate that whole cell antigenic targets are capable of inducing an effective response, protecting from disease and reducing shedding rates. However, replication of these results using antigen preparations more conducive to commercial vaccine production has proven difficult. To date, the Major Outer Membrane Protein (MOMP) has emerged as the most suitable substitute for whole cell targets and its delivery as a combined systemic and mucosal vaccine is most effective. Finally, although mouse model trials are useful, differences between hosts and infecting chlamydial strains are preventing vaccine formulations from mouse models to be translated into larger animals or intended hosts.
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Affiliation(s)
- Samuel Phillips
- Genecology Research Centre, The University of the Sunshine Coast, Maroochydore, QLD, Australia
| | - Bonnie L Quigley
- Genecology Research Centre, The University of the Sunshine Coast, Maroochydore, QLD, Australia
| | - Peter Timms
- Genecology Research Centre, The University of the Sunshine Coast, Maroochydore, QLD, Australia
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Eko FO, Mania-Pramanik J, Pais R, Pan Q, Okenu DMN, Johnson A, Ibegbu C, He C, He Q, Russell R, Black CM, Igietseme JU. Vibrio cholerae ghosts (VCG) exert immunomodulatory effect on dendritic cells for enhanced antigen presentation and induction of protective immunity. BMC Immunol 2014; 15:584. [PMID: 25551828 PMCID: PMC4312469 DOI: 10.1186/s12865-014-0056-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Accepted: 11/14/2014] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND We previously showed that the Vibrio cholerae ghost platform (VCG; empty V. cholerae cell envelopes) is an effective delivery system for vaccine antigens promoting the induction of substantial immunity in the absence of external adjuvants. However, the mechanism by which these cell envelopes enhance immunity and stimulate a predominantly Th1 cellular and humoral immune response has not been elucidated. We hypothesized that the immunostimulatory ability of VCG involves dendritic cell (DC) activation. OBJECTIVE The aims of this study were: a) to investigate the ability of DCs [using mouse bone marrow-derived DCs (BMDCs) as a model system] to take up and internalize VCGs; b) to evaluate the immunomodulatory effect of internalized VCGs on DC activation and maturation and their functional capacity to present chlamydial antigen to naïve and infection-sensitized CD4+ T cells and; c) to evaluate the ability of VCGs to enhance the protective immunity of a chlamydial antigen. RESULTS VCGs were efficiently internalized by DCs without affecting their viability and modulated DC-mediated immune responses. VCG-pulsed DCs showed increased secretion of proinflammatory cytokines and expression of co-stimulatory molecules associated with DC maturation in response to stimulation with UV-irradiated chlamydial elementary bodies (UV-EBs). Furthermore, this interaction resulted in effective chlamydial antigen presentation to infection-sensitized but not naïve CD4+ T cells and enhancement of protective immunity. CONCLUSIONS The present study demonstrated that VCGs activate DCs leading to the surface expression of co-stimulatory molecules associated with DC activation and maturation and enhancement of protective immunity induced by a chlamydial antigen. The results indicate that the immunoenhancing activity of VCG for increased T-cell activation against antigens is mediated, at least in part, through DC triggering. Thus, VCGs could be harnessed as immunomodulators to target antigens to DCs for enhancement of protective immunity against microbial infections.
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Affiliation(s)
| | | | - Roshan Pais
- Morehouse School of Medicine, Atlanta, GA, USA.
| | - Qing Pan
- Morehouse School of Medicine, Atlanta, GA, USA. .,College of Veterinary Medicine, China Agricultural University, Beijing, 100094, China.
| | | | | | - Chris Ibegbu
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA, USA.
| | - Cheng He
- College of Veterinary Medicine, China Agricultural University, Beijing, 100094, China.
| | - Qing He
- Morehouse School of Medicine, Atlanta, GA, USA.
| | | | | | - Joseph U Igietseme
- Morehouse School of Medicine, Atlanta, GA, USA. .,Centers for Disease Control (CDC), Atlanta, GA, USA.
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Eko FO, Okenu DN, Singh UP, He Q, Black C, Igietseme JU. Evaluation of a broadly protective Chlamydia-cholera combination vaccine candidate. Vaccine 2011; 29:3802-10. [PMID: 21421002 DOI: 10.1016/j.vaccine.2011.03.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 02/18/2011] [Accepted: 03/05/2011] [Indexed: 12/21/2022]
Abstract
The need to simultaneously target infections with epidemiological overlap in the population with a single vaccine provides the basis for developing combination vaccines. Vibrio cholerae ghosts (rVCG) offer an attractive approach for developing vaccines against a number of human and animal pathogens. In this study, we constructed a multisubunit vaccine candidate co-expressing the serovar D-derived Porin B and polymorphic membrane protein-D proteins of Chlamydia trachomatis and evaluated its ability to simultaneously induce broad-based chlamydial immunity and elicit a vibriocidal antibody response to the Vibrio carrier envelope. Intramuscular (IM) immunization with the vaccine candidate elicited high levels of antigen-specific genital mucosal and systemic Th1 cell-mediated and humoral immune responses against heterologous serovars and strains, including serovars E-H and L. Also, in addition to the multisubunit vaccine, the single subunit constructs conferred significant cross protection against the heterologous mouse strain, Chlamydia muridarum. Furthermore, all mice immunized with rVCG vaccine constructs responded with a significant rise in vibriocidal antibody titer, the surrogate marker for protection in cholera. These findings demonstrate the ability of the multisubunit vaccine to induce cross protective chlamydial as well as vibriocidal immunity and establish the possibility of developing a broadly efficacious Chlamydia-cholera combination vaccine.
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Affiliation(s)
- F O Eko
- Morehouse School of Medicine, Atlanta, GA, United States.
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Induction of immune memory by a multisubunit chlamydial vaccine. Vaccine 2010; 29:1472-80. [PMID: 21184858 DOI: 10.1016/j.vaccine.2010.12.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 11/23/2010] [Accepted: 12/09/2010] [Indexed: 01/03/2023]
Abstract
We tested the hypothesis that intramuscular immunization with a multisubunit chlamydial vaccine candidate will induce long lasting immune responses in mice. Accordingly, groups of female C57BL/6 mice were immunized intramuscularly with Vibrio cholerae ghosts (VCG) expressing the Poring B and polymorphic membrane protein-D proteins of Chlamydia trachomatis or a control antigen. Humoral and cell-mediated immune responses were evaluated following immunization and after live chlamydial infection. Immunization induced an anamnestic response characterized by chlamydial-specific IgG2a and IgA antibodies in sera and vaginal lavage as well as specific genital and splenic T cell responses. The results also revealed that the local mucosal and systemic cellular and humoral immune effectors induced in mice following immunization with the vaccine candidate are long lasting. Vaccinated mice cleared intravaginal challenge with 10(5) chlamydial inclusion forming units within 12 days compared to control mice, which shed up to 2 × 10(3) IFUs at this time point. Moreover, rechallenge of mice 98 days after resolution of the primary infection resulted in the recall and retention of a relatively high frequency of chlamydial-specific Th1 cells and IgG2a in the genital mucosa. These results provide the first evidence that a VCG-based multisubunit chlamydial vaccine is capable of effectively stimulating anamnestic systemic and mucosal immune responses in mice. The data support further vaccine evaluation and testing for induction of long-term protective immunity.
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Jiang X, Shen C, Yu H, Karunakaran KP, Brunham RC. Differences in innate immune responses correlate with differences in murine susceptibility to Chlamydia muridarum pulmonary infection. Immunology 2009; 129:556-66. [PMID: 20102413 DOI: 10.1111/j.1365-2567.2009.03157.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We investigated the phenotypic basis for genetically determined differences in susceptibility and resistance to Chlamydia muridarum pulmonary infection using BALB/c and C57BL/6 mice. Following C. muridarum intranasal inoculation, the intensity of infection was very different between BALB/c and C57BL/6 beginning as early as 3 days post-infection. Intrapulmonary cytokine patterns also differed at early time-points (days 2 and 4) between these two strains of mice. The early recruitment of neutrophils to lung tissue was greater in BALB/c than in C57BL/6 mice and correlated with a higher number of inclusion forming units (IFU) of C. muridarum. At day 12 post-infection, BALB/c mice continued to demonstrate a greater burden of infection, significantly higher lung cytokine levels for tumour necrosis factor-alpha and interleukin-17 (IL-17) and a significantly lower level for interferon-gamma than did C57BL/6 mice. In vitro, bone-marrow-derived dendritic cells (BMDCs) from BALB/c mice underwent less functional maturation in response to C. muridarum infection than did BMDCs from C57BL/6 mice. The BMDCs of BALB/c mice expressed lower levels of activation markers (CD80, CD86, CD40 and major histocompatibility complex class II) and secreted less IL-12 and more IL-23 than BMDCs from C57BL/6 mice. Overall, the data demonstrate that the differences exhibited by BALB/c and C57BL/6 mice following C. muridarum pulmonary infection are associated with differences in early innate cytokine and cellular responses that are correlated with late differences in T helper type 17 versus type 1 adaptive immune responses.
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Affiliation(s)
- Xiaozhou Jiang
- British Columbia Centre for Disease Control, University of British Columbia, Vancouver, BC, Canada
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Ekong EE, Okenu DN, Mania-Pramanik J, He Q, Igietseme JU, Ananaba GA, Lyn D, Black C, Eko FO. A Vibrio cholerae ghost-based subunit vaccine induces cross-protective chlamydial immunity that is enhanced by CTA2B, the nontoxic derivative of cholera toxin. ACTA ACUST UNITED AC 2008; 55:280-91. [PMID: 19040663 DOI: 10.1111/j.1574-695x.2008.00493.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The Vibrio cholerae ghost (rVCG) platform is an effective carrier and delivery system for designing efficacious Chlamydia vaccines. We investigated whether CTA2B, the nontoxic derivative of cholera toxin, can augment protective immunity conferred by an rVCG-based chlamydial vaccine and enhance cross-protection against heterologous chlamydial strains. An rVCG vaccine coexpressing chlamydial major outer membrane protein and CTA2B was genetically constructed and antigens were targeted to the inner membrane of V. cholerae before ghost production by gene E-mediated lysis. Effective immunomodulation by CTA2B was demonstrated by the ability of the vaccine construct to enhance the activation and maturation of dendritic cells in vitro. Also, C57BL/6 mice immunized via mucosal and systemic routes showed increased specific mucosal and systemic antibody and T-helper type-1 (Th1) responses, irrespective of the route. The enhanced production of IFN-gamma, but not IL-4 by genital mucosal and splenic T cells, indicated a predominantly Th1 response. Clearance of the Chlamydia muridarum vaginal infection was significantly enhanced by codelivery of the vaccine with CTA2B, with the intravaginal route showing a moderate advantage. These results indicate that the rVCG-based vaccine is capable of inducing cross-protection against heterologous chlamydial serovars and that incorporation of mucosal adjuvants, such as CTA2B in the rVCG delivery platform, may enhance protective immunity.
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Affiliation(s)
- Eno E Ekong
- Morehouse School of Medicine, Atlanta, GA 30310, USA
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7
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Immunization with chlamydial plasmid protein pORF5 DNA vaccine induces protective immunity against genital chlamydial infection in mice. ACTA ACUST UNITED AC 2008; 51:973-80. [PMID: 18989639 DOI: 10.1007/s11427-008-0130-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 08/28/2008] [Indexed: 10/21/2022]
Abstract
To validate the immune protective efficacy of pORF5 DNA vaccine and to analyze potential mechanisms related to this protection. In this study, pORF5 DNA vaccine was constructed and evaluated for its protective immunity in a mouse model of genital chlamydial infection. Groups of BALB/c mice were immunized intranasally with pORF5 DNA vaccine. Humoral and cell mediated immune responses were evaluated. The clearance ability of chlamydial challenge from the genital tract and the chlamydia-induced upper genital tract gross pathology and histopathological characterization were also detected. The results showed that the total and the IgG2a anti-pORF5 antibody levels in serum were significantly elevated after pcDNA3.1-pORF5 vaccination, as were the total antibody and IgA levels in vaginal fluids. pcDNA3.1-pORF5 induced a significantly high level of Th1 response as measured by robust gamma interferon (IFN-gamma). Minimal IL-4 was produced by immune T cells in response to the re-stimulation with pORF5 protein or the inactive elementary body in vitro. pcDNA3.1-pORF5-vaccinated mice displayed significantly reduced bacterial shedding upon a chlamydial challenge and an accelerated resolution of infection. 100% of pcDNA3.1-pORF5 vaccinated mice successfully resolved the infection by day 24. pcDNA3.1-pORF5-immunized mice also exhibited protection against pathological consequences of chlamydial infection. The stimulated index was significantly higher than that of mice immunized with pcDNA3.1 and PBS (P<0.05). Together, these results demonstrated that immunization with pORF5 DNA vaccine is a promising approach for eliciting a protective immunity against a genital chlamydial challenge.
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Abstract
The discovery that genes can be functionally transferred from bacteria to mammalian cells has suggested the possible use of bacterial vectors as gene delivery vehicles for vaccines. Attenuated invasive human intestinal bacteria, such as Salmonella and Shigella, have been used as plasmid DNA vaccine carriers and their potency has been evaluated in several animal models. This delivery system allows the administration of DNA vaccines together with associated bacterial immunostimulators directly to professional antigen presenting cells via human mucosal surfaces. Various strategies have been taken to improve the use of this delivery system to achieve robust immune responses at both mucosal and systemic sites of the immunized animals.
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Affiliation(s)
- F Xu
- Vaccine Research Department, Chiron Corporation, Emeryville, CA 94608, USA.
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9
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Abstract
Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.
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Igietseme J, Eko F, He Q, Bandea C, Lubitz W, Garcia-Sastre A, Black C. Delivery of Chlamydia vaccines. Expert Opin Drug Deliv 2005; 2:549-62. [PMID: 16296774 DOI: 10.1517/17425247.2.3.549] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The plethora of ocular, genital and respiratory diseases of Chlamydia, including nongonococcal urethritis, cervicitis pelvic inflammatory disease, ectopic pregnancy, tubal factor infertility, conjunctivitis, blinding trachoma and interstitial pneumonia, and chronic diseases that may include atherosclerosis, multiple sclerosis, adult onset asthma and Alzheimer's disease, still pose a considerable public health challenge to many nations. Although antibiotics are effective against Chlamydia when effectively diagnosed, asymptomatic infections are rampart, making clinical presentation of complications often the first evidence of an infection. Consequently, the current medical opinion is that an effective prophylactic vaccine would constitute the best approach to protect the human population from the most severe consequences of these infections. Clinical and experimental studies have demonstration that Chlamydia immunity in animals and humans is mediated by T cells and a complementary antibody response, and the completion of the genome sequencing of several isolates of Chlamydia is broadening our knowledge of the immunogenic antigens with potential vaccine value. Thus, major advances have been made in defining the essential elements of a potentially effective subunit vaccine design and parameters for evaluation. However, the challenge to develop effective delivery systems and human compatible adjuvants that would boost the immune response to achieve long-lasting protective immunity remains an elusive objective in chlamydial vaccine research. In response to evolving molecular and cellular technologies and novel vaccinology approaches, considerable progress is being made in the construction of novel delivery systems, such as DNA and plasmid expression systems, viral vectors, living and nonliving bacterial delivery systems, the use of chemical adjuvants, lipoprotein constructs and the codelivery of vaccines and specific immuno-modulatory biological agonists targeting receptors for chemokines, Toll-like receptors, and costimulatory molecules. The application of these novel delivery strategies to Chlamydia vaccine design could culminate in timely achievement of an efficacious vaccine.
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Affiliation(s)
- Joseph Igietseme
- National Center for Infectious Disease/CDC, Atlanta, GA 30333, USA.
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11
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Abstract
The use of live attenuated bacterial vaccine strains allows the targeted delivery of macromolecules to mammalian cells and tissues via the mucosal route. Depending on their specific virulence mechanisms and inherent metabolic preferences, bacteria invade certain cell types and body niches where they consequently deliver their cargo. Recently, the ability of attenuated strains of Salmonella, Shigella and Yersinia spp., as well as Listeria monocytogenes and invasive Escherichia coli, to deliver eukaryotic expression plasmids into mammalian cells in vitro and in vivo has been discovered. The great potential of bacteria-mediated transfer of plasmid DNA encoding vaccine antigens and/or therapeutic molecules was demonstrated in experimental animal models of infectious diseases, tumours and gene deficiencies. The exact mechanism of DNA transfer from the bacterial vector into the mammalian host is not yet completely known. The understanding of molecular events during bacterial DNA transfer, however, will further the development of bacterial vector systems with great promise for various clinical applications.
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Affiliation(s)
- Holger Loessner
- Molecular Immunology, GBF, German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
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12
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Manoj S, Babiuk LA, van Drunen Littel-van den Hurk S. Approaches to enhance the efficacy of DNA vaccines. Crit Rev Clin Lab Sci 2004; 41:1-39. [PMID: 15077722 DOI: 10.1080/10408360490269251] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
DNA vaccines consist of antigen-encoding bacterial plasmids that are capable of inducing antigen-specific immune responses upon inoculation into a host. This method of immunization is advantageous in terms of simplicity, adaptability, and cost of vaccine production. However, the entry of DNA vaccines and expression of antigen are subjected to physical and biochemical barriers imposed by the host. In small animals such as mice, the host-imposed impediments have not prevented DNA vaccines from inducing long-lasting, protective humoral, and cellular immune responses. In contrast, these barriers appear to be more difficult to overcome in large animals and humans. The focus of this article is to summarize the limitations of DNA vaccines and to provide a comprehensive review on the different strategies developed to enhance the efficacy of DNA vaccines. Several of these strategies, such as altering codon bias of the encoded gene, changing the cellular localization of the expressed antigen, and optimizing delivery and formulation of the plasmid, have led to improvements in DNA vaccine efficacy in large animals. However, solutions for increasing the amount of plasmid that eventually enters the nucleus and is available for transcription of the transgene still need to be found. The overall conclusions from these studies suggest that, provided these critical improvements are made, DNA vaccines may find important clinical and practical applications in the field of vaccination.
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Affiliation(s)
- Sharmila Manoj
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada
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Schoen C, Stritzker J, Goebel W, Pilgrim S. Bacteria as DNA vaccine carriers for genetic immunization. Int J Med Microbiol 2004; 294:319-35. [PMID: 15532991 DOI: 10.1016/j.ijmm.2004.03.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Genetic immunization with plasmid DNA vaccines has proven to be a promising tool in conferring protective immunity in various experimental animal models of infectious diseases or tumors. Recent research focuses on the use of bacteria, in particular enteroinvasive species, as effective carriers for DNA vaccines. Attenuated strains of Shigella flexneri, Salmonella spp., Yersinia enterocolitica or Listeria monocytogenes have shown to be attractive candidates to target DNA vaccines to immunological inductive sites at mucosal surfaces. This review summarizes recent progress in bacteria-mediated delivery of plasmid DNA vaccines in the field of infectious diseases and cancer.
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Affiliation(s)
- Christoph Schoen
- Department of Microbiology, Biocenter of the University, D-97074 Würzburg, Germany
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Eko FO, He Q, Brown T, McMillan L, Ifere GO, Ananaba GA, Lyn D, Lubitz W, Kellar KL, Black CM, Igietseme JU. A novel recombinant multisubunit vaccine against Chlamydia. THE JOURNAL OF IMMUNOLOGY 2004; 173:3375-82. [PMID: 15322201 DOI: 10.4049/jimmunol.173.5.3375] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The administration of an efficacious vaccine is the most effective long-term measure to control the oculogenital infections caused by Chlamydia trachomatis in humans. Chlamydia genome sequencing has identified a number of potential vaccine candidates, and the current challenge is to develop an effective delivery vehicle for induction of a high level of mucosal T and complementary B cell responses. Vibrio cholerae ghosts (VCG) are nontoxic, effective delivery vehicles with potent adjuvant properties, and are capable of inducing both T cell and Ab responses in mucosal tissues. We investigated the hypothesis that rVCG could serve as effective delivery vehicles for single or multiple subunit chlamydial vaccines to induce a high level of protective immunity. rVCG-expressing chlamydial outer membrane proteins were produced by a two-step genetic process, involving cloning of Omp genes in V. cholerae, followed by gene E-mediated lysis of the cells. The immunogenicity and vaccine efficacy of rVCG-expressing single and multiple subunits were compared. Immunologic analysis indicated that i.m. immunization of mice with either vaccine construct induced a strong mucosal and systemic specific Th1 response against the whole chlamydial organism. However, there was an immunogenic advantage associated with the multiple subunit vaccine that induced a higher frequency of Th1 cells and a relatively greater ability to confer protective immunity, compared with the single subunit construct. These results support the operational theory that the ability of a vaccine to confer protective immunity against Chlamydia is a function of the level of Th1 response elicited.
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Affiliation(s)
- Francis O Eko
- Department of Microbiology, Biochemistry, and Immunology, Morehouse School of Medicine, Atlanta, GA 30310, USA.
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15
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Eko FO, Lubitz W, McMillan L, Ramey K, Moore TT, Ananaba GA, Lyn D, Black CM, Igietseme JU. Recombinant Vibrio cholerae ghosts as a delivery vehicle for vaccinating against Chlamydia trachomatis. Vaccine 2003; 21:1694-703. [PMID: 12639492 DOI: 10.1016/s0264-410x(02)00677-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An efficacious vaccine is needed to control the morbidity and burden of rising healthcare costs associated with genital Chlamydia trachomatis infection. Despite considerable efforts, the development of reliable chlamydial vaccines using conventional strategies has proven to be elusive. The 40kDa major outer membrane protein (MOMP) of C. trachomatis is so far the most promising candidate for a subunit vaccine. The lack of satisfactory protective immunity with MOMP-based vaccine regimens to date would suggest that either MOMP alone is inadequate as a vaccine candidate or better delivery systems are needed to optimize the effect of MOMP. Recombinant Vibrio cholerae ghosts (rVCG) are attractive for use as non-living vaccines because they possess strong adjuvant properties and are excellent vehicles for delivery of antigens of vaccine relevance to mucosal sites. The suitability of the ghost technology for designing an anti-chlamydial vaccine was evaluated by constructing a rVCG vector-based candidate vaccine expressing MOMP (rVCG-MOMP) and assessing vaccine efficacy in a murine model of C. trachomatis genital infection. Intramuscular delivery of the rVCG-MOMP vaccine induced elevated local genital mucosal as well as systemic Th1 responses. In addition, immune T cells from immunized mice could transfer partial protection against a C. trachomatis genital challenge to nai;ve mice. These results suggest that rVCG expressing chlamydial proteins may constitute a suitable subunit vaccine for inducing an efficient mucosal T cell response that protects against C. trachomatis infection. Altogether, the potency and relatively low production cost of rVCG offer a significant technical advantage as a chlamydial vaccine.
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Affiliation(s)
- Francis O Eko
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, 720 Westview Dr. Atlanta, GA 30310, USA.
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Weiss S. Transfer of eukaryotic expression plasmids to mammalian hosts by attenuated Salmonella spp. Int J Med Microbiol 2003; 293:95-106. [PMID: 12755370 DOI: 10.1078/1438-4221-00248] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transkingdom transfer of DNA from bacteria to other organisms, well established for bacteria, yeast and plants, was recently also extended to mammalian host cells. Attenuated intracellular bacteria or non-pathogenic bacteria equipped with adhesion and invasion properties have been demonstrated to transfer eukaryotic expression plasmids in vitro and in vivo. Here the mucosal application of attenuated Salmonella enterica spp. as DNA carrier for the induction of immune responses towards protein antigens encoded by expression plasmids, their use to complement genetic defects or deliver immunotherapeutic proteins is reviewed. Plasmid transfer has been reported for Salmonella typhimurium, S. typhi and S. choleraesuis so far but clearly other Salmonella strains should be able to transfer expression plasmids as well. Transfer of DNA is effected most likely by bacterial death within the host cell resulting from metabolic attenuation. Since these bacteria remain in the phagocytic vacuole it is unclear how the DNA from such dying bacteria is delivered to the nucleus of infected cells. Nevertheless, the efficiency that has been observed was astonishingly high, reaching close to 100% under certain conditions. Gene transfer in vivo was mainly directed towards vaccination strategies either as vaccination against infectious microorganisms or model tumors. Interestingly, in some cases tolerance against autologous antigens could be broken. In general, this type of immunization was more efficacious than either direct application of antigen, vaccination with naked DNA or using the same bacterium as a heterologous carrier expressing the antigen via a prokaryotic promoter. The ease of generating such vehicles for gene transfer combined with technology validated for mass vaccination programs and the efficacy of induction of protective immune responses makes Salmonella as carrier for mucosal DNA vaccination a highly attractive area for further research and development.
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Affiliation(s)
- Siegfried Weiss
- Molecular Immunology, GBF, German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124 Braunschweig, Germany.
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Igietseme JU, Eko FO, Black CM. Contemporary approaches to designing and evaluating vaccines against Chlamydia. Expert Rev Vaccines 2003; 2:129-46. [PMID: 12901604 DOI: 10.1586/14760584.2.1.129] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The clinically relevant pathologic consequences of primary ocular, genital, or respiratory human infection by members of the genus Chlamydia are conjunctivitis, cervicitis, urethritis and sinusitis. The major complications and sometimes debilitating evolutionary outcomes of these infections include: trichiasis and cicatrizing trachoma, endometritis or pelvic inflammatory disease and involuntary tubal factor infertility and bronchopulmonary pneumonia. These diseases, in addition to other chlamydia-associated chronic syndromes (e.g., artherosclerosis, multiple sclerosis and Alzheimer's disease), pose serious public healthcare and huge budgetary concerns. The current medical opinion is that an efficacious prophylactic vaccine is a sine qua non--to control the morbidity of chiamydial infection in the human population. The research goal for an efficacious human chlamydial vaccine has faced key challenges to define the elements of protective immunity to facilitate vaccine evaluation, the judicious selection of appropriate vaccine candidates that possess stable antigenic and immunologic properties and the development of effective delivery vehicles and adjuvants to boost immune effectors to achieve long-term protective immunity. Progress in the functional immunobiology of Chlamydia has established the essential immunologic paradigms for vaccine selection and evaluation, including the obligatory requirement for a vaccine to induce T-helper Type 1 immune response that controls chlamydiae. Recent advances in chlamydial genomics and proteomics should enhance the identification of likely chlamydial gene products that fulfill the antigenic requirements of putative vaccine candidates. Major inroads are however needed in the construction and development of novel and effective delivery systems, such as vectors and adjuvants. This review summarizes the status of contemporary chlamydial vaccine research and promising trends fueling the growing optimism for an efficacious vaccine. The unified approach to vaccines for the genus Chlamydia is validated by the several conserved genes and common immunogenic proteins among member species and the similarity of immune effectors controlling Chlamydia species in animals and humans.
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Affiliation(s)
- Joseph U Igietseme
- Molecular Pathogenesis Laboratory, National Center for Infectious Disease, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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18
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Pasetti MF, Levine MM, Sztein MB. Animal models paving the way for clinical trials of attenuated Salmonella enterica serovar Typhi live oral vaccines and live vectors. Vaccine 2003; 21:401-18. [PMID: 12531639 DOI: 10.1016/s0264-410x(02)00472-3] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Attenuated Salmonella enterica serovar Typhi (S. Typhi) strains can serve as safe and effective oral vaccines to prevent typhoid fever and as live vectors to deliver foreign antigens to the immune system, either by the bacteria expressing antigens through prokaryotic expression plasmids or by delivering foreign genes carried on eukaryotic expression systems (DNA vaccines). The practical utility of such live vector vaccines relies on achieving a proper balance between minimizing the vaccine's reactogenicity and maximizing its immunogenicity. To advance to clinical trials, vaccine candidates need to be pre-clinically evaluated in relevant animal models that attempt to predict what their safety and immunogenicity profile will be when administered to humans. Since S. Typhi is a human-restricted pathogen, a major obstacle that has impeded the progress of vaccine development has been the shortcomings of the animal models available to assess vaccine candidates. In this review, we summarize the usefulness of animal models in the assessment of the degree of attenuation and immunogenicity of novel attenuated S. Typhi strains as vaccine candidates for the prevention of typhoid fever and as live vectors in humans.
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Affiliation(s)
- Marcela F Pasetti
- Center for Vaccine Development, University of Maryland School of Medicine, Room 480, 685 West Baltimore Street, Baltimore, MD 21201, USA.
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19
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Lu H, Xing Z, Brunham RC. GM-CSF transgene-based adjuvant allows the establishment of protective mucosal immunity following vaccination with inactivated Chlamydia trachomatis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6324-31. [PMID: 12444139 DOI: 10.4049/jimmunol.169.11.6324] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cellular and humoral immune responses induced following murine Chlamydia trachomatis infection confer almost sterile protection against homologous reinfection. On the other hand, immunization with inactivated organism induces little protective immunity in this model system. The underlying mechanism(s) that determines such divergent outcome remains unclear, but elucidating the mechanism will probably be important for chlamydial vaccine development. One of the distinct differences between the two forms of immunization is that chlamydia replication in epithelial cells causes the secretion of a variety of proinflammatory cytokines and chemokines, such as GM-CSF, that may mobilize and mature dendritic cells and thereby enhance the induction of protective immunity. Using a murine model of C. trachomatis mouse pneumonitis lung infection and intrapulmonary adenoviral GM-CSF transfection, we demonstrate that the expression of GM-CSF in the airway compartment significantly enhanced systemic Th1 cellular and local IgA immune responses following immunization with inactivated organisms. Importantly, immunized mice had significantly reduced growth of chlamydia and exhibited less severe pulmonary inflammation following challenge infection. The site of GM-CSF transfection proved important, since mice immunized with inactivated organisms after GM-CSF gene transfer by the i.p. route exhibited little protection against pulmonary challenge, although i.p. immunization generated significant levels of systemic Th1 immune responses. The obvious difference between i.p. and intrapulmonary immunization was the absence of lung IgA responses following i.p. vaccination. In aggregate, the findings demonstrate that the local cytokine environment is critical to the induction of protective immunity following chlamydial vaccination and that GM-CSF may be a useful adjuvant for a chlamydial vaccine.
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Affiliation(s)
- Hang Lu
- British Columbia Center for Disease Control and Department of Medicine, University of British Columbia, Vancouver, Canada
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20
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Garmory HS, Brown KA, Titball RW. Salmonella vaccines for use in humans: present and future perspectives. FEMS Microbiol Rev 2002; 26:339-53. [PMID: 12413664 DOI: 10.1111/j.1574-6976.2002.tb00619.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
In recent years there has been significant progress in the development of attenuated Salmonella enterica serovar Typhi strains as candidate typhoid fever vaccines. In clinical trials these vaccines have been shown to be well tolerated and immunogenic. For example, the attenuated S. enterica var. Typhi strains CVD 908-htrA (aroC aroD htrA), Ty800 (phoP phoQ) and chi4073 (cya crp cdt) are all promising candidate typhoid vaccines. In addition, clinical trials have demonstrated that S. enterica var. Typhi vaccines expressing heterologous antigens, such as the tetanus toxin fragment C, can induce immunity to the expressed antigens in human volunteers. In many cases, the problems associated with expression of antigens in Salmonella have been successfully addressed and the future of Salmonella vaccine development is very promising.
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Affiliation(s)
- Helen S Garmory
- Department of Biomedical Sciences, Dstl Chemical and Biological Sciences, Porton Down, Salisbury SP4 0JQ, UK.
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21
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Krusch S, Domann E, Frings M, Zelmer A, Diener M, Chakraborty T, Weiss S. Listeria monocytogenes mediated CFTR transgene transfer to mammalian cells. J Gene Med 2002; 4:655-67. [PMID: 12439857 DOI: 10.1002/jgm.313] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Several approaches for gene therapy of cystic fibrosis using viral and non-viral vectors are currently being undertaken. Nevertheless, the present data suggest that vectors currently being used will either have to be further modified or, alternatively, novel vector systems need to be developed. Recently, bacteria have been proven as suitable vehicles for DNA transfer to a wide variety of eukaryotic cells. In this study, we assessed the ability of the facultative intracellular pathogen Listeria monocytogenes to deliver a cDNA encoding the human cystic fibrosis transmembrane conductance regulator (CFTR) to CHO-K1 cells, since these cells have been extensively used for heterologous CFTR expression. METHODS An established in vitro gene transfer system based on antibiotic-mediated lysis of intracellular L. monocytogenes was exploited to transfer eukaryotic expression plasmids. Transient as well as stable CFTR transgene expression was analyzed by microscopical and biochemical methods; functionality was tested by whole-cell patch-clamp recordings. RESULTS L. monocytogenes mediated gene transfer to CHO-K1 cells was facilitated by an improved transfection protocol. In addition, the use of the isogenic mutant L. monocytogenes hlyW491A, engineered to produce a hemolysin variant with low toxigenic activity, greatly enhanced the efficiency of gene transfer. This strain allowed the transfer of functional CFTR to CHO-K1 cells. CONCLUSIONS This is the first demonstration of L. monoyctogenes mediated CFTR transgene transfer. The successful in vitro transfer suggests that L. monocytogenes might be a potential vector for cystic fibrosis gene therapy or alternative applications and deserves further investigation in vitro as well as in vivo.
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Affiliation(s)
- Stefan Krusch
- Division of Cell Biology and Immunology, GBF, German Research Centre for Biotechnology, Mascheroder Weg 1, 38124 Braunschweig, Germany.
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22
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Abstract
The ultimate goal of current chlamydial vaccine efforts is to utilise either conventional or modern vaccinology approaches to produce a suitable immunisation regimen capable of inducing a sterilising, long-lived heterotypic protective immunity at mucosal sites of infection to curb the severe morbidity and worldwide prevalence of chlamydial infections. This lofty goal poses tremendous challenges that include the need to clearly define the relevant effectors mediating immunity, the antigens responsible for inducing these effectors, the anti-chlamydial action(s) of effectors, and establishment of the most effective method of vaccine delivery. Tackling these challenges is further compounded by the biological complexity of chlamydia, the existence of multiple serovariants, the capacity to induce both protective and deleterious immune effectors, and the occurrence of asymptomatic and persistent infections. Thus, novel molecular, immunological and genetic approaches are urgently needed to extend the frontiers of current knowledge, and develop new paradigms to guide the production of an effective vaccine regimen. Progress made in the last 15 years has culminated in various paradigm shifts in the approaches to designing chlamydial vaccines. The dawn of the current immunological paradigm for antichlamydial vaccine design has its antecedence in the recognition that chlamydial immunity is mediated primarily by a T helper type1 (Th1) response, requiring the induction and recruitment of specific T cells into the mucosal microenvironment. Additionally, the ancillary role of humoral immune response in complementing the Th1-driven protective immunity, through ensuring adequate memory and optimal Th1 response during a reinfection, has been recognised. With continued progress in chlamydial genomics and proteomics, select chlamydial proteins, including structural, membrane and secretory proteins, are being targeted as potential subunit vaccine candidates. However, the development of an effective adjuvant, delivery vehicle or system for a potential subunit vaccine is still an elusive objective in these efforts. Promising delivery vehicles include DNA and virus vectors, bacterial ghosts and dendritic cells. Finally, a vaccine still represents the best approach to protect the greatest number of people against the ocular, pulmonary and genital diseases caused by chlamydial infections. Therefore, considering the urgency and the enormity of these challenges, a partially protective vaccine preventing certain severe sequelae would constitute an acceptable short-term goal to control Chlamydia. However, more research efforts and support are needed to achieve the worthy goal of protecting a significant number of the world's population from the devastating consequences of chlamydial invasion of the human mucosal epithelia.
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Affiliation(s)
- Joseph U Igietseme
- Microbiology & Immunology, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, Georgia 30310, USA.
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Devico AL, Fouts TR, Shata MT, Kamin-Lewis R, Lewis GK, Hone DM. Development of an oral prime-boost strategy to elicit broadly neutralizing antibodies against HIV-1. Vaccine 2002; 20:1968-74. [PMID: 11983256 DOI: 10.1016/s0264-410x(02)00080-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Given the increasing incidence of HIV-1 infection world-wide, an affordable, effective vaccine is probably the only way that this virus will be contained. Accordingly, our group is developing an oral prime-boost strategy with the primary goal of eliciting broadly neutralizing antibodies against HIV-1 to provide sterilizing immunity for this virus. Our secondary goal is to elicit broadly cross-reactive anti-viral CD8(+) T cells by this strategy to blunt any breakthrough infections that occur after vaccination of individuals who fail to develop sterilizing immunity. This article describes our progress in the use of the live attenuated intracellular bacteria, Salmonella and Shigella, as oral delivery vehicles for DNA vaccines and the development of conformationally constrained HIV-1 Env immunogens that elicit broadly neutralizing antibodies.
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MESH Headings
- AIDS Vaccines/administration & dosage
- AIDS Vaccines/immunology
- Administration, Oral
- Animals
- Bacterial Vaccines/administration & dosage
- Bacterial Vaccines/immunology
- CD4 Antigens/chemistry
- CD4 Antigens/metabolism
- CD8-Positive T-Lymphocytes/immunology
- HIV Antibodies/biosynthesis
- HIV Antibodies/immunology
- HIV Envelope Protein gp120/chemistry
- HIV Envelope Protein gp120/immunology
- HIV Envelope Protein gp120/metabolism
- HIV-1/immunology
- Humans
- Immunity, Mucosal
- Immunization, Secondary
- Macaca mulatta
- Mice
- Models, Molecular
- Protein Conformation
- Protein Interaction Mapping
- Protein Structure, Tertiary
- Receptors, CCR5/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/immunology
- Salmonella typhi/immunology
- Salmonella typhimurium/immunology
- Shigella flexneri/immunology
- Vaccination/methods
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/immunology
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/immunology
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Affiliation(s)
- Anthony L Devico
- Division of Vaccine Research, Institute of Human Virology, University of Maryland Biotechnology Institute, 725 W. Lombard Street, Baltimore, MD 21201, USA
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24
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Huang B, Subramaniam S, Frey J, Loh H, Tan HM, Fernandez CJ, Kwang J, Chua KL. Vaccination of ducks with recombinant outer membrane protein (OmpA) and a 41 kDa partial protein (P45N') of Riemerella anatipestifer. Vet Microbiol 2002; 84:219-30. [PMID: 11731174 DOI: 10.1016/s0378-1135(01)00456-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The generation of protective immunity against Riemerella anatipestifer infection in ducks were investigated by immunizations with recombinant glutathione sulfatransferase (GST) fusion's proteins of OmpA, a 42kDa major outer membrane protein, and P45N', a 41kDa N-terminal fragment of a newly identified 45kDa potential surface protein from R. anatipestifer. The DNA encoding OmpA and P45N' were isolated from R. anatipestifer serotype 15 (field strain 110/89) and serotype 19 (reference strain 30/90), respectively. Immunoblotting and ELISA results showed that the purified recombinant proteins induced the production of antibodies in immunized ducks. However, neither was protective against subsequent challenge with the virulent serotype 15 strain, 34/90. All the five ducks immunized with formalinized R. anatipestifer strain 34/90 survived the challenge with the homologous strain whereas six out of seven ducks in the non-immunized control group died within a week following the challenge.
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Affiliation(s)
- Bin Huang
- Institute of Molecular Agrobiology, National University of Singapore, Singapore
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25
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Weiss S, Chakraborty T. Transfer of eukaryotic expression plasmids to mammalian host cells by bacterial carriers. Curr Opin Biotechnol 2001; 12:467-72. [PMID: 11604322 DOI: 10.1016/s0958-1669(00)00247-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The concept of transkingom transfer of DNA from bacteria to other organisms has recently been extended to include eukaryotic host cells. Intracellular bacteria have been shown to transfer eukaryotic expression plasmids to mammalian host cells in vitro and in vivo. This can be used to induce immune responses towards protein antigens encoded by the plasmid, to complement genetic defects or even to direct the production of proteins in appropriate organs. The ease of generating such vehicles makes this a highly attractive area for further research.
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Affiliation(s)
- S Weiss
- Molecular Immunology, Gesellschaft für Biotechnologische Forschung mbH (GBF), German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124, Braunschweig, Germany.
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26
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Mollenkopf H, Dietrich G, Kaufmann SH. Intracellular bacteria as targets and carriers for vaccination. Biol Chem 2001; 382:521-32. [PMID: 11405217 DOI: 10.1515/bc.2001.066] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this review we discuss intracellular bacteria as targets and carriers for vaccines. For clarity and ease of comprehension, we focus on three microbes, Mycobacterium tuberculosis, Listeria monocytogenes and Salmonella, with an emphasis on tuberculosis, one of the leading causes of death from infectious disease. Novel vaccination strategies against these pathogens are currently being considered. One approach favors the use of live attenuated vaccines and vaccine carrier strains thereof, either for heterologous antigen presentation or DNA vaccine delivery. This strategy includes both the improvement of attenuated vaccine strains as well as the 'de novo' generation of attenuated variants of virulent pathogens. An alternative strategy relies on the application of subunit immunizations, either as nucleic acid vaccines or protein antigens of the pathogen. Finally, we present a short summary of the vaccination strategies against tuberculosis.
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Affiliation(s)
- H Mollenkopf
- Max-Planck-Institute for Infection Biology, Department of Immunology, Berlin, Germany
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27
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Weiss S, Krusch S. Bacteria-mediated transfer of eukaryotic expression plasmids into mammalian host cells. Biol Chem 2001; 382:533-41. [PMID: 11405218 DOI: 10.1515/bc.2001.067] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Invasive intracellular bacteria are able to transfer eukaryotic expression plasmids into mammalian host cells in vitro and in vivo. This can be used to induce immune responses toward protein antigens encoded by the plasmid or to complement genetic defects. Plasmid transfer takes place when the recombinant bacterium dies within the host cell, either due to metabolic attenuation or induction of autolysis. Alternatively, antibiotics can be used and spontaneous transfer has also been observed, indicating that this phenomenon might also occur under physiological conditions. Plasmid transfer has been reported for Shigella flexneri, Salmonella typhimurium and S. typhi, Listeria monocytogenes and recombinant Escherichia coli, but other invasive bacteria should also share this property. In vivo attempts were mainly directed toward vaccination using shigella and salmonella as carrier. So far a wide variety of antigens have been used succesfully in mice. Often this type of immunization was superior over direct application of antigen or using the same bacterium as a heterologous carrier expressing the antigen via a prokaryotic promoter. Characterization of the host cells revealed that macrophages and dendritic cells might be responsible for immune stimulation by either expressing the antigen or cross-presenting the antigen after uptake of apoptotic antigen expressing cells.
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Affiliation(s)
- S Weiss
- German Research Centre for Biotechnology (GBF), Molecular Immunology, Braunschweig
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28
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Gentschev I, Dietrich G, Spreng S, Kolb-Mäurer A, Brinkmann V, Grode L, Hess J, Kaufmann SH, Goebel W. Recombinant attenuated bacteria for the delivery of subunit vaccines. Vaccine 2001; 19:2621-8. [PMID: 11257401 DOI: 10.1016/s0264-410x(00)00502-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using attenuated intracellular bacteria as carriers, we have developed two different approaches for the delivery of subunit vaccines encoding heterologous antigens. The first system is based on the direct secretion of the heterologous antigens in Gram-negative bacteria via the hemolysin secretion system of Escherichia coli into either phagosome or cytosol of infected cells. The second approach is based on the transport of eukaryotic antigen expression vectors by intracellular bacteria like Listeria and Salmonella into the host cell and here, preferably, into the cytosolic compartment. After release of the plasmid DNA from the bacteria, the plasmid-encoded antigens can be expressed directly by the host cell. Finally, we combined both types of subunit vaccines in one live vector - we equipped Salmonella strains with a phagosomal escape function by utilization of the hemolysin secretion system and used this recombinant vaccine strain for the delivery of a eukaryotic antigen expression vector into the cytosol of macrophages.
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Affiliation(s)
- I Gentschev
- Department of Microbiology, University of Wuerzburg, D-97074, Wuerzburg, Germany
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29
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Drabner B, Guzmán CA. Elicitation of predictable immune responses by using live bacterial vectors. BIOMOLECULAR ENGINEERING 2001; 17:75-82. [PMID: 11222981 DOI: 10.1016/s1389-0344(00)00072-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There is an increasing need for novel vaccines able to stimulate efficient and long-lasting responses, which have also low production costs. To confer protective immunity following vaccination, the adequate type of response should be elicited. Vaccines based on attenuated bacterial carriers have contained production and delivery costs, and are able to stimulate more potent immune responses than non-replicating formulations. The improved knowledge on carrier physiology and host response, the availability of different mutants and highly sophisticated expression tools, and the possibility of co-administering modulators enable to trigger predictable responses according to the specific needs. Recent studies support the use of attenuated bacteria not only as conventional carriers, but also as a delivery system for DNA vaccines against infectious agents and tumors. In this review we discuss the most widely used bacterial carrier systems for either antigens or nucleic acid vaccines, and the strategies which have been successfully exploited to modulate the immune responses elicited.
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Affiliation(s)
- B Drabner
- Vaccine Research Group, Division of Microbiology, GBF-German Research Centre for Biotechnology, Mascheroder Weg 1, D-38124, Braunschweig, Germany
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30
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Dietrich G, Spreng S, Gentschev I, Goebel W. Bacterial systems for the delivery of eukaryotic antigen expression vectors. ANTISENSE & NUCLEIC ACID DRUG DEVELOPMENT 2000; 10:391-9. [PMID: 11079578 DOI: 10.1089/oli.1.2000.10.391] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Attenuated bacterial strains allow the administration of recombinant vaccines via the mucosal surfaces. Whereas attenuated bacteria are generally engineered to express heterologous antigens, a novel approach employs intracellular bacteria for the delivery of eukaryotic antigen expression vectors (so-called DNA vaccines). This strategy allows a direct delivery of DNA to professional antigen-presenting cells (APC), such as macrophages and dendritic cells (DC), through bacterial infection. The bacteria used for DNA vaccine delivery either enter the host cell cytosol after phagocytosis by the APC, for example, Shigella and Listeria, or they remain in the phagosomal compartment, such as Salmonella. Both intracellular localizations of the bacterial carriers seem to be suitable for successful delivery of DNA vaccine vectors.
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Affiliation(s)
- G Dietrich
- University of Würzburg, Lehrstuhl für Mikrobiologie, Germany
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31
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Nieto FJ. [Infections and arteriosclerosis: science or fiction?]. GACETA SANITARIA 2000; 14:185-8. [PMID: 10984981 DOI: 10.1016/s0213-9111(00)71465-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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