BORRELIA-BURGDORFERI ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DISCRIMINATION OF OSPA VACCINATION FROM SPIROCHETE INFECTION

Recombinant Lyme disease vaccines based on purified preparations of ou ter surface protein A (OspA) have been shown to be effective in preven ting transmission of Borrelia burgdorferi in experimental animal model s and are now being tested in humans, Since the most widely used scree ning tests for Lyme disease are based on a whole-cell sonicate of B. b urgdorferi, serologic false positivity in vaccinated persons could res ult from reactivity to OspA within the antigen preparation, In order t o avoid serologic false positivity in vaccinated subjects, we develope d an immunoassay based on a low-passage-number, naturally occurring va riant of B. burgdorferi which lacks the plasmid encoding OspA and OspB . The use of an antigen preparation derived from this organism provide d sensitive and specific detection of B. burgdorferi seropositivity in experimental animals and in human Lyme disease cases, The OspA-B-nega tive enzyme-linked immunosorbent assay (ELISA) also appeared to be cap able of discriminating the vaccinated state from vaccine failure and n atural infection in experimental animals, Sera from human subjects par ticipating in a vaccine trial gave false-positive results with an ELIS A based on an OspA-containing strain, but no such reactivity was obser ved when the OspA-negative ELISA was used. We conclude that low-passag e-number OspA-B-negative isolates in immunoassays may become useful fo r the immunologic discrimination of the vaccinated state, natural infe ction, and vaccine failure.