Seib Group

Supervisors: Dr Evgeny Semchenko, Dr Taha & Prof Kate Seib

Molecular Biology, Microbiology, Vaccine Development, Immunology

There are >100 million cases of gonorrhoea per year, and infection can cause severe sequelae including pelvic inflammatory disease, adverse pregnancy outcomes, neonatal complications, infertility, and increased risk of HIV. Gonorrhoea disproportionally impacts women, particularly in the developing world, and has been recognised by the World Health Organization (WHO), USA Centers for Disease Control (CDC), and Australian National Antimicrobial Resistance Strategy as an urgent threat to global health. There is currently no gonococcal vaccine, and due to multidrug resistance there are concerns that N. gonorrhoeae may become untreatable in the near future.

A recent retrospective case-control study found that individuals vaccinated with the meningococcal serogroup B (MenB) outer membrane vesicle (OMV) vaccine MeNZB were significantly less likely to contract gonorrhoea compared with unvaccinated controls. We have shown that a newer MenB vaccine, induced antibodies in humans that are cross-reactive with N. gonorrhoeae. A randomised control trial is now underway to test the efficacy of 4CMenB against gonorrhoea. Human serum samples from this trial will be assessed to understand the vaccine-induced immune response and determine whether antibodies raised to 4CMenB can kill N. gonorrhoeae or block its adherence to host epithelial cells.

Techniques: Cloning, protein expression and purification, Western analysis, ELISA, serum bactericidal assays, cell adherence assays, opsonophagocytosis assays.

Supervisors: Dr Evgeny Semchenko, Dr Taha & Prof Kate Seib

Molecular Biology, Microbiology, Vaccine Development

Neisseria gonorrhoeae, the causative agent of gonorrhoea, is a significant health problem worldwide. The control of gonorrhoea depends on the development of a vaccine due to the continuing increase of antibiotic resistance and the staggering outcomes of infection, including infertility and increased transmission of HIV. This project aims to characterise potential vaccine candidates to aid in the development of a gonococcal vaccine. The distribution of the identified vaccine candidates will be investigated in a diverse range of N. gonorrhoeae strains. The functions of candidates will be examined by generating a mutant strain of N. gonorrhoeae that does not express the vaccine candidate and comparing the wild type and mutant strains in a panel of antimicrobial stress assays.

The vaccine potential of these candidates will be assessed by expressing and purifying the protein from Escherichia coli, immunising mice to generate antibodies to the protein, and then testing the ability of these antibodies to mediate killing of N. gonorrhoeae in various assays (e.g., serum bactericidal assays and neutrophil opsonophagocytic assays to measure killing of the bacteria; adherence assays to test if the antibodies can inhibit association and invasion of human epithelial cells).

Techniques: Cloning, protein expression and purification, construction of gene deletions in N. gonorrhoeae, Western analysis, ELISA, serum bactericidal assays, cell adherence assays, opsonophagocytosis assays.

Supervisors: Dr Evgeny Semchenko, Dr Taha & Prof Kate Seib

Microbiology, Glycobiology, Molecular Biology

Human mucosal surfaces, such as the airway, contain a range of carbohydrate structures (glycans) and many bacteria have evolved carbohydrate-binding proteins (lectins) that enable cell attachment, colonisation and invasion of host cells. Our aim is to identify glycans that host-adapted bacterial pathogens bind to during colonisation and disease. This project will focus on bacteria including Moraxella catarrhalis (causes middles ear infections and exacerbations of chronic obstructive pulmonary disease), Neisseria gonorrhoeae (causes gonorrhoea) and Neisseria meningitidis (causes sepsis and meningitis). We will probe Glycan Arrays (consisting of >400 sugars immobilised onto glass-slides) using recombinant proteins and wild type bacteria and a series of mutant strains lacking key outer membrane structures. The affinity and kinetics of interactions will be investigated using surface plasmon resonance. We will also use epithelial cell adherence and invasion assays to investigate the functional role of glycan-based host-pathogen interactions. These findings will contribute to understanding key bacterial and host factors involved in colonisation and disease and may direct development of new drugs and vaccines for these bacteria.

Techniques: Cloning, protein expression and purification, construction of gene deletions in bacteria, array technology, surface plasmon resonance, cell adherence assays.