Vaccine needed to beat emerging ‘superbug’

By Dr Kate Seib

Bacterial pathogens cause significant levels of disease worldwide and the control of many of these pathogens depends on vaccine development due to increasing antibiotic resistance and the serious outcomes of infection.

Of particular concern is the sexually transmitted infection (STI) gonorrhoeae, caused by the bacteria Neisseria gonorrhoeae. It is estimated that there are as many as 88 million cases of gonorrhoeae each year worldwide. Ascending reproductive tract infections causes 1/3 of the cases of female infertility and 1/8 of low birth weight babies and leads to annual medical costs exceeding $1.1 billion in the USA. N. gonorrhoeae is also associated with significantly increased susceptibility to, and transmission of, HIV.

In Australia in 2011 there were 12,116 notifications of gonococcal infection (~40/100,000 population; 19% increase from 2010) (2), with extremely high rates in indigenous populations (~800/100,000) (3). Furthermore, a concerning level of antibiotic resistance has emerged and it is feared that N. gonorrhoeae may become an untreatable ‘superbug’ in the near future (1).

There is currently no licensed vaccine to prevent infection by N. gonorrhoeae. This is largely due to two issues, firstly this organism only naturally infects humans and as such is not easily studied in animal models, and secondly it has numerous mechanisms that mediate variable gene expression, allowing it to adapt to different host environments and to evade the human immune system. Despite the difficulties in generating mucosal immunity and vaccines for STIs, the development of a gonococcal vaccine should be made a priority in order to reduce HIV transmission, decrease infertility and improve newborn health.

Work in my group aims to discover and characterise novel virulence factors and vaccine antigens of Neisseria gonorrhoeae, based on a combination of genome based analysis, and screening of gonococcal outer membrane proteins to identify proteins that are involved in association and colonisation of human epithelial cells.

1. Unemo M, et al. Ann N Y Acad Sci. 2011;1230:E19-28.

2. NNDSS. Gonococcal infection, Australia. 2011 http://www9.health.gov.au/cda/source/Rpt_3.cfm

3. NCHECR. Bloodborne viral and sexually transmitted infections in Aboriginal and Torres Strait Islander people. 2011. http://www.med.unsw.edu.au/NCHECRweb.nsf/page/AboriginalSurvRep

Dr Kate Seib leads her own research group within the Institute for Glycomics, at the Griffith University’s Gold Coast campus. She recently received a Career Development Fellowship from the Australian NHMRC to aid in the identification of virulence factors and vaccine antigens for human pathogens including Neisseria gonorrhoeae.