Chlamydiavaccines: recent developments and the role of adjuvants in future formulations

Abstract

Bacteria of the genus Chlamydia cause a plethora of ocular, genital and respiratory diseases that continue to pose a considerable public health challenge worldwide. The major diseases are conjunctivitis and blinding trachoma, non-gonococcal urethritis, cervicitis, pelvic inflammatory disease, ectopic pregnancy, tubal factor infertility and interstitial pneumonia. The rampart asymptomatic infections prevent timely and effective antibiotic treatments, and quite often clinical presentation of sequelae is the first evidence of an infection. Besides, significant broad coverage in population screening and treatment is economically and logistically impractical, and mass education for public awareness has been ineffective. The current medical opinion is that an efficacious prophylactic vaccine is the best approach to protect humans from chlamydial infections. Unfortunately, a human vaccine has yet to be realized despite successful veterinary vaccines. Fortunately, recent advances in chlamydial immunobiology, cell biology, molecular pathogenesis, genomics, antigen discovery and animal models of infections are hastening progress toward an efficacious vaccine. Thus, it is established that Chlamydia immunity is mediated by T cells and a complementary antibody response, and several potential vaccine candidates have been identified. However, further advances are needed in effective vaccine delivery systems and safe potent adjuvants to boost and sustain immune responses for long-lasting protective immunity. This article focuses on the current status of human chlamydial vaccine research, specifically how application of new delivery systems and human compatible adjuvants could lead to a timely achievement of efficacious Chlamydia vaccines. The ranking of the candidate vaccine antigens for human vaccine development will await the availability of results from studies in which the antigens are tested by comparable experimental standards, such as antigen-adjuvant combination, route of delivery and possible toxicity.

A multi-epitope vaccine based on <italic>Chlamydia trachomatis</italic> major outer membrane protein induces specific immunity in mice

“…Although efforts have been made throughout the years to develop a protective vaccine, there are no vaccines available which effectively prevent C. trachomatis genital infections. Therefore, developing an effective vaccine capable of preventing and controlling C. trachomatis genital tract infections is urgently required [13,14].…”

Groove-type Recognition of Chlamydiaceae-specific Lipopolysaccharide Antigen by a Family of Antibodies Possessing an Unusual Variable Heavy Chain N-Linked Glycan

“…The structures of oligosaccharide bisphosphates were isolated from the LPS of a recombinant Escherichia coli strain expressing the gene gseA (Kdo transferase) of C. psittaci 6BC. The lack of an effective vaccine against Chlamydia has spurred considerable efforts to generate high affinity antibodies against the antigenic LPS (22)(23)(24).…”

Cloning and Expression of Truncated Chlamydial Major Outer Membrane Protein in E.coli: A Miniature Step Forward

“…This view is supported by A. Feher who writes "a prophylactic vaccine has long been sought against C.trachomatis but has yet to be obtained" [15]. Moreover, despite advancement in the field of veterinary currently there is, however, no human protective vaccine [16]. Also, orientations of newly strategies in "OMICS" technology like vaccinomics are trying to produce an effective vaccine that would serve immunity against genital chlamydiosis [17].…”