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Alugupalli KR. A TLR4 ligand-based adjuvant for promoting the immunogenicity of typhoid subunit vaccines. Front Immunol 2024; 15:1383476. [PMID: 38799439 PMCID: PMC11116679 DOI: 10.3389/fimmu.2024.1383476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/19/2024] [Indexed: 05/29/2024] Open
Abstract
None of the typhoid Vi Polysaccharide (ViPS) subunit vaccines incorporate adjuvants, and the immunogenicity of ViPS vaccines (e.g. Typbar TCV® and Typhim Vi®) is in part due to associated TLR4 ligands such as endotoxin present in these vaccines. Since endotoxin content in vaccines is variable and kept very low due to inherent toxicity, it was hypothesized that incorporating a defined amount of a non-toxic TLR4-ligand such as monophosphoryl lipid A in ViPS vaccines would improve their immunogenicity. To test this hypothesis, a monophosphoryl lipid A-based adjuvant formulation named Turbo was developed. Admixing Turbo with Typbar TCV® (ViPS-conjugated to tetanus toxoid) increased the levels of anti-ViPS IgM, IgG1, IgG2b, IgG2a/c, and IgG3 in inbred and outbred mice. In infant mice, a single immunization with Turbo adjuvanted Typbar TCV® resulted in a significantly increased and durable IgG response and improved the control of bacterial burden compared to mice immunized without Turbo. Similarly, when adjuvanted with Turbo, the antibody response and control of bacteremia were also improved in mice immunized with Typhim Vi®, an unconjugated vaccine. The immunogenicity of unconjugated ViPS is inefficient in young mice and is lost in adult mice when immunostimulatory ligands in ViPS are removed. Nevertheless, when adjuvanted with Turbo, poorly immunogenic ViPS induced a robust IgG response in young and adult mice, and this was observed even under antigen-limiting conditions. These data suggest that incorporation of Turbo as an adjuvant will make typhoid vaccines more immunogenic regardless of their intrinsic immunogenicity or conjugation status and maximize the efficacy across all ages.
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Affiliation(s)
- Kishore R. Alugupalli
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA, United States
- TurboVax Inc, Philadelphia, PA, United States
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Alugupalli KR. TLR4 Ligands in Typhoid Vi Polysaccharide Subunit Vaccines Contribute to Immunogenicity. Immunohorizons 2024; 8:29-34. [PMID: 38180344 PMCID: PMC10832388 DOI: 10.4049/immunohorizons.2300085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/11/2023] [Indexed: 01/06/2024] Open
Abstract
Activation of B cells and T cells requires the engagement of costimulatory signaling pathways in addition to Ag receptor signaling for efficient immune responses. None of the typhoid Vi polysaccharide (ViPS) subunit vaccines contains adjuvants that could activate costimulatory signaling pathways, yet these vaccines are very immunogenic. I hypothesized that residual TLR ligands present in the ViPS preparation used for making typhoid subunit vaccines account for the robust immune response generated by these vaccines. I show the presence of endotoxin, a potent agonist of TLR4, in ViPS preparations and ViPS vaccines. Furthermore, I found that ViPS obtained from various sources induces the production of proinflammatory cytokines such as IL-6 from mouse peritoneal exudate cells. Unconjugated and tetanus toxoid-conjugated ViPS vaccines activate human and mouse TLR4. Mice deficient in TLR4 or the signaling adaptors MyD88 and Trif (Toll/IL-1R domain-containing adapter inducing IFN-β) are severely impaired in generating anti-ViPS responses to these vaccines. Elimination of the TLR4 agonist in ViPS preparation resulted in the loss of immunogenicity, and addition of lipid A, a known TLR4 agonist, restored the immunogenicity. These data highlight the importance of associated TLR ligands in the immunogenicity of ViPS subunit vaccines.
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Affiliation(s)
- Kishore R. Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
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Alugupalli AS, Cravens MP, Walker JA, Gulandijany D, Dickinson GS, Debes GF, Schifferli DM, Bäumler AJ, Alugupalli KR, Alugupalli KR. The Lack of Natural IgM Increases Susceptibility and Impairs Anti-Vi Polysaccharide IgG Responses in a Mouse Model of Typhoid. Immunohorizons 2022; 6:807-816. [PMID: 36480484 DOI: 10.4049/immunohorizons.2200088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 12/13/2022] Open
Abstract
Circulating IgM present in the body prior to any apparent Ag exposure is referred to as natural IgM. Natural IgM provides protective immunity against a variety of pathogens. Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of typhoid fever in humans. Because mice are not permissive to S. Typhi infection, we employed a murine model of typhoid using S. enterica serovar Typhimurium expressing the Vi polysaccharide (ViPS) of S. Typhi (S. Typhimurium strain RC60) to evaluate the role of natural IgM in pathogenesis. We found that natural mouse IgM binds to S. Typhi and S. Typhimurium. The severity of S. Typhimurium infection in mice is dependent on presence of the natural resistance-associated macrophage protein 1 (Nramp1) allele; therefore, we infected mice deficient in secreted form of IgM (sIgM) on either a Nramp1-resistant (129S) or -susceptible (C57BL/6J) background. We found that the lack of natural IgM results in a significantly increased susceptibility and an exaggerated liver pathology regardless of the route of infection or the Nramp1 allele. Reconstitution of sIgM-/- mice with normal mouse serum or purified polyclonal IgM restored the resistance to that of sIgM+/+ mice. Furthermore, immunization of sIgM-/- mice with heat-killed S. Typhi induced a significantly reduced anti-ViPS IgG and complement-dependent bactericidal activity against S. Typhi in vitro, compared with that of sIgM+/+ mice. These findings indicate that natural IgM is an important factor in reducing the typhoid severity and inducing an optimal anti-ViPS IgG response to vaccination.
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Affiliation(s)
- Akhil S Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA.,Department of Microbiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA
| | - Matthew P Cravens
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Justin A Walker
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Dania Gulandijany
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Gregory S Dickinson
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Gudrun F Debes
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA
| | - Dieter M Schifferli
- Department of Microbiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, Davis, CA; and
| | - Kishore R Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA
| | - Kishore R Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA
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Terminal Deoxynucleotidyl Transferase Is Not Required for Antibody Response to Polysaccharide Vaccines against Streptococcus pneumoniae and Salmonella enterica Serovar Typhi. Infect Immun 2018; 86:IAI.00211-18. [PMID: 29967094 DOI: 10.1128/iai.00211-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/26/2018] [Indexed: 11/20/2022] Open
Abstract
B cell antigen receptor (BCR) diversity increases by several orders of magnitude due to the action of terminal deoxynucleotidyl transferase (TdT) during V(D)J recombination. Unlike adults, infants have limited BCR diversity, in part due to reduced expression of TdT. Since human infants and young mice respond poorly to polysaccharide vaccines, such as the pneumococcal polysaccharide vaccine Pneumovax23 and Vi polysaccharide (ViPS) of Salmonella enterica serovar Typhi, we tested the contribution of TdT-mediated BCR diversity in response to these vaccines. We found that TdT+/- and TdT-/- mice generated comparable antibody responses to Pneumovax23 and survived Streptococcus pneumoniae challenge. Moreover, passive immunization of B cell-deficient mice with serum from Pneumovax23-immunized TdT+/- or TdT-/- mice conferred protection. TdT+/- and TdT-/- mice generated comparable levels of anti-ViPS antibodies and antibody-dependent, complement-mediated bactericidal activity against S Typhi in vitro To test the protective immunity conferred by ViPS immunization in vivo, TdT+/- and TdT-/- mice were challenged with a chimeric Salmonella enterica serovar Typhimurium strain expressing ViPS, since mice are nonpermissive hosts for S Typhi infection. Compared to their unimmunized counterparts, immunized TdT+/- and TdT-/- mice challenged with ViPS-expressing S Typhimurium exhibited a significant reduction in the bacterial burden and liver pathology. These data suggest that the impaired antibody response to the Pneumovax23 and ViPS vaccines in the young is not due to limited TdT-mediated BCR diversification.
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Pandya KD, Palomo-Caturla I, Walker JA, K Sandilya V, Zhong Z, Alugupalli KR. An Unmutated IgM Response to the Vi Polysaccharide of Salmonella Typhi Contributes to Protective Immunity in a Murine Model of Typhoid. THE JOURNAL OF IMMUNOLOGY 2018; 200:4078-4084. [PMID: 29743315 DOI: 10.4049/jimmunol.1701348] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 04/16/2018] [Indexed: 11/19/2022]
Abstract
T cell-dependent B cell responses typically develop in germinal centers. Abs generated during such responses are isotype switched and have a high affinity to the Ag because of somatic hypermutation of Ab genes. B cell responses to purified polysaccharides are T cell independent and do not result in the formation of bona fide germinal centers, and the dominant Ab isotype produced during such responses is IgM with very few or no somatic mutations. Activation-induced cytidine deaminase (AID) is required for both somatic hypermutation and Ig isotype switching in humans and mice. To test the extent to which unmutated polysaccharide-specific IgM confers protective immunity, we immunized wildtype and AID-/- mice with either heat-killed Salmonella enterica serovar Typhi (S. Typhi) or purified Vi polysaccharide (ViPS). We found that wildtype and AID-/- mice immunized with heat-killed S. Typhi generated similar anti-ViPS IgM responses. As expected, wildtype, but not AID-/- mice generated ViPS-specific IgG. However, the differences in the Ab-dependent killing of S. Typhi mediated by the classical pathway of complement activation were not statistically significant. In ViPS-immunized wildtype and AID-/- mice, the ViPS-specific IgM levels and S. Typhi bactericidal Ab titers at 7 but not at 28 d postimmunization were also comparable. To test the protective immunity conferred by these immunizations, mice were challenged with a chimeric S. Typhimurium strain expressing ViPS. Compared with their naive counterparts, immunized wildtype and AID-/- mice exhibited significantly reduced bacterial burden regardless of the route of infection. These data indicate that an unmutated IgM response to ViPS contributes to protective immunity to S. Typhi.
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Affiliation(s)
- Kalgi D Pandya
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Isabel Palomo-Caturla
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Justin A Walker
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Vijay K Sandilya
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Zhijiu Zhong
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
| | - Kishore R Alugupalli
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107; and .,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107
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Starr M. Paediatric travel medicine: vaccines and medications. Br J Clin Pharmacol 2014; 75:1422-32. [PMID: 23163285 DOI: 10.1111/bcp.12035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 10/31/2012] [Indexed: 12/15/2022] Open
Abstract
The paediatric aspects of travel medicine can be complex, and individual advice is often required. Nonetheless, children are much more likely to acquire common infections than exotic tropical diseases whilst travelling. Important exceptions are malaria and tuberculosis, which are more frequent and severe in children. Overall, travellers' diarrhoea is the most common illness affecting travellers. This review discusses vaccines and medications that may be indicated for children who are travelling overseas. It focuses on immunizations that are given as part of the routine schedule, as well as those that are more specific to travel. Malaria and travellers' diarrhoea are also discussed.
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Affiliation(s)
- Mike Starr
- The Royal Children's Hospital Melbourne, Parkville, Victoria, Australia.
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