The plasmid-deficient strain also functioned as a successful live attenuated vaccine in mice, whereby infection (vaccination) with the plasmid-negative strain limited the pathology usually associated with subsequent infections [121]. Importantly, Kari Linsitinib concentration et al. [80] showed a similar phenomenon with C. trachomatis, whereby they

generated a plasmid-free, attenuated strain of ocular C. trachomatis and showed that it could protect against trachoma in a nonhuman primate model. These plasmid-free strains could be our best chance of a vaccine that can generate sufficiently strong immunity, involving both B and T cell responses, to an array of important antigens, in Bosutinib price the absence of adverse pathology. Of course, the regulatory requirements involved with the use of live attenuated vaccines means that it will be essential to fully understand the molecular mechanisms underpinning these plasmid-free “vaccine” strains. In this respect, the other recent breakthrough that could significantly accelerate vaccine research is that we now have the ability to genetically

manipulate Chlamydia [122]. This major achievement that still has some technical challenges, means that potentially we can delete, or inactivate, key genes to understand their role in pathogenesis, and this should eventually result in a controlled means to produce a live attenuated vaccine strain that is unable to cause adverse pathology. These exciting advances, combined with rapid developments in vaccine adjuvants and delivery mechanisms, means that the previously elusive C. trachomatis vaccine goal may soon be within our reach. The authors alone are responsible for the views expressed in this article and do not necessarily represent the views, decisions or policies of the institutions with

which they are affiliated. Many thanks to Sami Gottlieb for suggested editorial changes. Thanks to Chris Barker for discussions regarding animal models and reviewing ADAMTS5 of the manuscript. Chlamydia vaccine research in the authors’ laboratories is supported by funding from NHMRC, NIRAP and ARC Schemes. “
“Chlamydia trachomatis (Ct) is the commonest bacterial sexually transmitted infection [1]. Because a high proportion of infected people have no symptoms, screening programmes for those at risk have been the mainstay of control programmes in countries where it is prioritised and economically sustainable. However, these programmes have failed to reduce the number of reported cases, and it has even been suggested that early detection and treatment of chlamydial infection increases its incidence by preventing the development of protective immunity [2]. A vaccine against Ct would be of great public health benefit.