New Borrelia burgdorferi antigenic variant isolated from Ixodes dammini from upstate New York.

A previously undescribed Borrelia burgdorferi antigenic variant was isolated from each of four Ixodes dammini larvae removed from white-footed mice, Peromyscus leucopus, captured in Millbrook, N.Y. This site is in the northern range of the known distribution of the tick in the northeastern United States. The molecular weights of approximately 32,500 and 35,500 for outer surface A and outer surface B proteins, respectively, were distinctly higher than those for previously characterized isolates from North American ticks, humans, and wild mammals. A prominent low-molecular-weight protein of about 23,500 was also present. All four isolates infected Syrian hamsters and retained their antigenicity after passage through these rodent hosts. Serum samples from patients with Lyme disease tended to have immunoglobulin M, immunoglobulin G, and immunoglobulin antibodies to Connecticut B. burgdorferi 2591 at titers slightly higher than or equal to those recorded for an antigenically different strain of B. burgdorferi from Millbrook, N.Y.