Biology subjects

Zielke, R. A.

Publications and source records attributed to Zielke, R. A..

3 recordsLinked to original sources

bioRxiv2026

An mRNA-Lipid Nanoparticle Platform Encoding the Conserved Outer Membrane Protein BamA Elicits Broadly Cross-Reactive Systemic and Mucosal Antibodies Against Antimicrobial-Resistant Neisseria gonorrhoeae

Neisseria gonorrhoeae (Ng) is the causative agent of gonorrhea, and the global spread of antimicrobial-resistant strains makes vaccine development a public health priority. Although messenger RNA (mRNA) vaccines have transformed protection against viral diseases, the platform remains in its infancy against pathogenic bacteria. Here, we evaluated the immunogenicity and protective efficacy of an mRNA-lipid nanoparticle (LNP) vaccine encoding the highly conserved outer membrane antigen BamA in the female mouse model of lower genital tract infection. We delivered BamA mRNA-LNPs via intramuscular (IM) or intranasal (IN) routes, with or without CpG ODN 2395, and measured antigen-specific antibody responses in serum and vaginal lavage samples. Both routes elicited robust BamA-specific antibodies that recognized diverse Ng isolates, including ceftriaxone-resistant strains. However, neither route accelerated bacterial clearance nor reduced bioburden, nor did either generate serum bactericidal activity. These findings show that BamA mRNA-LNPs are immunogenic but, as formulated, are not protective, and they pave the way for modifications to the construct, adjuvant, and route. To our knowledge, this is the first evaluation of an mRNA vaccine against Ng, establishing the platform as an amenable approach for gonococcal antigen testing. ImportanceNeisseria gonorrhoeae is a high-priority public health threat, and no licensed gonococcal vaccine exists. mRNA-lipid nanoparticle vaccines have transformed antiviral immunization but remain largely untested against bacterial pathogens. This study is the first to evaluate an mRNA vaccine against N. gonorrhoeae, using the conserved, essential outer membrane antigen BamA. We show that BamA mRNA-LNPs delivered by intramuscular or intranasal routes elicit robust, broadly cross-reactive antibodies that recognize diverse isolates, including ceftriaxone-resistant strains, even though the tested formulations did not confer protection in mice. By establishing mRNA-LNPs as a viable platform for gonococcal antigen testing, this work lays the foundation for optimizing constructs, adjuvants, and routes for developing mRNA-based vaccines against gonorrhea and other antimicrobial-resistant bacteria.

microbiology↗

bioRxiv2020

A novel gonorrhea vaccine composed of MetQ lipoprotein formulated with CpG shortens experimental murine infection

Bacterial surface lipoproteins are emerging as attractive vaccine candidates due to their biological importance and the feasibility of their large-scale production for vaccine manufacturing. The global prevalence of gonorrhea, resistance to antibiotics, and serious consequences to reproductive and neonatal health necessitate development of effective vaccines. Reverse vaccinology identified the surface-displayed L-methionine binding lipoprotein MetQ (NGO2139) and its homolog GNA1946 (NMB1946) as gonococcal and meningococcal vaccine candidates, respectively. Here, we assessed the suitability of MetQ for inclusion in a gonorrhea vaccine by examining MetQ conservation, its function in Neisseria gonorrhoeae (Ng) pathogenesis, and its ability to induce protective immune responses using a female murine model of lower genital tract infection. In-depth bioinformatics, phylogenetics and mapping the most prevalent Ng polymorphic amino acids to the GNA1946 crystal structure revealed remarkable MetQ conservation: ~97% Ng isolates worldwide possess a single MetQ variant. Mice immunized with rMetQ-CpG (n=40), a vaccine containing a tag-free version of MetQ formulated with CpG, exhibited robust, antigen-specific antibody responses in serum and at the vaginal mucosae including secretory IgA. Consistent with the activity of CpG as a Th1-stimulating adjuvant, the serum IgG1/IgG2a ratio of 0.38 indicated a Th1 bias. Combined data from two independent challenge experiments demonstrated that rMetQ-CpG immunized mice cleared infection faster than control animals (vehicle, p<0.0001; CpG, p=0.002) and had lower Ng burden (vehicle, p=0.03; CpG, p<0.0001). We conclude rMetQ-CpG induces a protective immune response that accelerates bacterial clearance from the murine lower genital tract and represents an attractive component of a gonorrhea subunit vaccine.

microbiology↗

bioRxiv2018

Quantitative proteomics of the 2016 WHO Neisseria gonorrhoeae reference strains surveys vaccine candidates and antimicrobial resistance determinants

The sexually transmitted disease gonorrhea (causative agent: Neisseria gonorrhoeae) remains an urgent public health threat globally due to the repercussions on reproductive health, high incidence, widespread antimicrobial resistance (AMR), and absence of a vaccine. To mine gonorrhea antigens and enhance our understanding of gonococcal AMR at the proteome level, we performed the first large-scale proteomic profiling of a diverse panel (n=15) of gonococcal strains, including the 2016 World Health Organization (WHO) reference strains. These strains show all existing AMR profiles, previously described in regard to phenotypic and reference genome characteristics, and are intended for quality assurance in laboratory investigations. Herein, these isolates were subjected to subcellular fractionation and labeling with tandem mass tags coupled to mass spectrometry and multi-combinatorial bioinformatics. Our analyses detected 901 and 723 common proteins in cell envelope and cytoplasmic subproteomes, respectively. We identified nine novel gonorrhea vaccine candidates. Expression and conservation of new and previously selected antigens were investigated. In addition, established gonococcal AMR determinants were evaluated for the first time using quantitative proteomics. Six new proteins, WHO_F_00238, WHO_F_00635, WHO_F_00745, WHO_F_01139, WHO_F_01144, and WHO_F_01226, were differentially expressed in all strains, suggesting that they represent global proteomic AMR markers, indicate a predisposition toward developing or compensating gonococcal AMR, and/or act as new antimicrobial targets. Finally, phenotypic clustering based on the isolates defined antibiograms and common differentially expressed proteins yielded seven matching clusters between established and proteome-derived AMR signatures. Together, our investigations provide a reference proteomics databank for gonococcal vaccine and AMR research endeavors, which enables microbiological, clinical, or epidemiological projects and enhances the utility of the WHO reference strains.

microbiology↗