Coxiella burnetii phase I lipopolysaccharide O-antigen epitope (CbLPS O-antigen)

The Coxiella burnetii phase I lipopolysaccharide (LPS) O-antigen epitope is a critical virulence factor and the primary protective antigen of the causative agent of Q fever. Unlike the truncated LPS found in avirulent Phase II variants, the Phase I LPS contains a full-length O-polysaccharide chain characterized by unique and rare sugars, such as virenose and dihydrohydroxystreptose. This complex glycan structure allows the bacterium to evade the host's innate immune system by preventing complement-mediated lysis and masking underlying toll-like receptor ligands. In clinical practice, the presence of antibodies against this specific epitope is a hallmark of chronic Q fever, whereas acute infections typically show a higher initial response to Phase II antigens. As a therapeutic and prophylactic target, the Phase I LPS is the essential component of whole-cell vaccines like Q-Vax, which provide long-lasting immunity but are limited by high reactogenicity in individuals with prior exposure. Research into subunit vaccines and monoclonal antibodies specifically targets these O-antigen epitopes to develop safer alternatives for preventing Coxiella burnetii infection. The structural complexity of the O-antigen, particularly its unique terminal sugars, makes it a highly specific biomarker for diagnostic assays and a focal point for neutralizing antibody development. Understanding the interaction between this epitope and the host immune system is vital for managing both acute outbreaks and the severe complications associated with chronic Q fever endocarditis.

Other names

Phase I lipopolysaccharideC. burnetii O-polysaccharideVirulent lipopolysaccharidev-LPSCoxiella burnetii O-antigen

Induction of protective humoral immunity through B-cell activation and antibody production; neutralization of bacterial entry and intracellular survival by monoclonal antibodies.