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Protection elicited by native outer membrane protein Oms66 (p66) against host-adapted Borrelia burgdorferi:
1Division of Infectious Diseases, Department of Medicine, UCLA School of Medicine, Los Angeles, California 90095, USA. mexner@ucla.edu
Abstract:
Oms66 is a Borrelia burgdorferi outer membrane porin protein whose role in Lyme disease pathogenesis and immunity has not been well established. Oms66 was solubilized from whole-cell lysates of strain B313 (which is derived from B31 but lacks OspA, -B, -C, and -D) and purified to homogeneity by fast-protein liquid chromatography. Purified native Oms66 (nOms66), which retained the ability to form large channels in a planar lipid bilayer model membrane system, and denatured Oms66 (hOms66) were used to immunize New Zealand White rabbits. The resulting Oms66 antisera were tested in a complement-dependent borreliacidal assay in parallel with basal serum and with serum from rabbits immune to reinfection with B. burgdorferi (IRS). IRS showed high-titer complement-dependent killing of both strains B31 and B313. Sera from animals immunized with nOms66 showed high-titer complement-dependent killing activity against strain B313 but exhibited no killing of B31. By comparison, serum generated from immunizations with hOms66 showed no killing activity against either strain. Following adsorption of antiserum to nOms66 with recombinant Oms66 (rOms66), the serum antibodies no longer bound to rOms66 or to nOms66 that had been denatured with 8 M urea. However, the antibodies still bound to nOms66 and killing activity against B313 was retained, thus suggesting that native, conformational epitopes are targets of this bactericidal activity. Six C3H HeJ mice were immunized with nOms66 and were challenged using "host-adapted" B. burgdorferi B31 by skin implantation of infected mouse ear tissue. Four of the six mice were protected against both localized and disseminated infection. These findings indicate that native Oms66 can elicit potent bactericidal activity and significant protective immunity against host-adapted organisms.
Insights
Native Oms66, a Borrelia burgdorferi outer membrane protein, elicits strong bactericidal activity and protective immunity against Lyme disease in mice. This suggests Oms66 is a promising target for Lyme disease vaccines.
Area of Science:
- Microbiology and Immunology
- Bacterial Pathogenesis
- Vaccine Development
Background:
- The role of Borrelia burgdorferi outer membrane protein Oms66 in Lyme disease pathogenesis and immunity is not well understood.
- Outer membrane proteins are crucial for bacterial survival and interaction with the host immune system.
Purpose of the Study:
- To investigate the immunogenicity and protective potential of native Oms66 (nOms66) from Borrelia burgdorferi.
- To determine if antibodies against nOms66 can mediate complement-dependent killing and confer protection against Lyme disease.
Main Methods:
- Purification of native Oms66 (nOms66) from Borrelia burgdorferi strain B313.
- Immunization of rabbits with nOms66 and testing of resulting antisera in complement-dependent borreliacidal assays.
- Immunization of mice with nOms66 and subsequent challenge with host-adapted Borrelia burgdorferi B31.
Main Results:
- Antisera generated against nOms66 showed high-titer complement-dependent killing activity against Borrelia burgdorferi strain B313, but not strain B31.
- Antibodies targeting native, conformational epitopes of nOms66 were responsible for the bactericidal activity.
- Four out of six mice immunized with nOms66 were protected against both localized and disseminated infection following challenge.
Conclusions:
- Native Oms66 elicits potent bactericidal activity mediated by antibodies recognizing conformational epitopes.
- Immunization with native Oms66 confers significant protective immunity against host-adapted Borrelia burgdorferi.
- Oms66 represents a potential target for developing effective vaccines against Lyme disease.