Abstract
As Ixodes ticks spread to new regions, the incidence of Lyme disease (LD) in companion animals and humans will increase. Preventive strategies for LD in canines center on vaccination and tick control (acaricides). Both subunit and bacterin based LD veterinary vaccines are available. Outer surface protein C (OspC), a potent immunogen and dominant early antigen, has been demonstrated to elicit protective antibody (Ab) responses. However, a single OspC protein elicits a relatively narrow range of protection. There are conflicting reports as to whether the immunodominant epitopes of OspC reside within variable or conserved domains. A detailed understanding of the antigenic determinants of OspC is essential for understanding immune responses to this essential virulence factor and vaccinogen. Here, we investigate the contribution of the conserved C-terminal C10 motif in OspC triggered Ab responses. Using a panel of diverse recombinant full length OspC proteins and their corresponding C10 deletion variants (OspCΔC10), we demonstrate that the C10 motif does not significantly contribute to immunization or infection induced Ab responses in rabbits, rats, canines, horses and non-human primates. Furthermore, the C10 motif is not required to trigger potent bactericidal Ab responses. This study provides insight into the antigenic structure of OspC. The results enhance our understanding of immune responses that develop during infection or upon vaccination and have implications for interpretation of LD diagnostic assays that employ OspC.
Highlights
Lyme disease (LD) is a growing public health threat in N
To add to our understanding of the antigenic structure of OspC, we investigated the potential contribution of the conserved C10 [33] motif in OspC directed Ab responses during natural infection and upon immunization
To determine if the C10 motif contributes to bactericidal Ab responses elicited by immunization with recombinant OspC, hyperimmune antisera were generated to OspC type A and OspCDC10
Summary
Lyme disease (LD) is a growing public health threat in N. Current subunit vaccines consist of Outer surface protein (Osp) A or OspA in combination with a modified form of OspC. These proteins are produced during different stages of the enzootic cycle [15]. Understanding the antigenic structure of OspC and its inherent diversity is essential for interpreting Ab responses induced by vaccination or during infection. To develop a broadly protective OspC based subunit vaccine antigen, Earnhart and Marconi developed unique recombinant proteins, referred to as chimeritopes (chimeric epitope based proteins), that consist of diverse L5 and H5 epitopes. The data suggest that a single OspC protein delivered in the context of either a bacterin or subunit vaccine is insufficient to convey protection against diverse strains. To generate an OspC based antigen that elicits broad protection, the diversity and antigenic structure of OspC must be considered
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