Detection of Borrelia burgdorferi OspA in Ixodes scapularis larvae by an antigen-capture enzyme-linked immunosorbent assay.

The Borrelia burgdorferi outer surface protein A (OspA) was quantified by an antigen-capture ELISA. The test detected 0.156 ng OspA/B, using purified rabbit IgG as a detection system. Dose-response relationship was described by a three-parameter equation and second degree polynomials. The estimated amount of OspA in host-attached Ixodes scapularis larvae was positively correlated with the tick's engorgement status, whereas the presence of blood in OspA-negative larvae reduced test absorbance. The antigen-capture ELISA can be effectively used in the ecology and epidemiology of Lyme borreliosis. However, host attached larvae should be matched by engorgement level to remove the effect of this variable on test results.