Vaccine containing outer-surface protein A protects against Lyme disease.

2003 APR 9 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - A Lyme disease vaccine (lipo-OspA) containing outer-surface protein A (OspA) effectively prevented the disease in individuals who experienced a strong immune response to the antigen, according to a report in Clinical Therapeutics.

"Lyme disease, which is caused by the spirochete Borrelia burgdorferi, is the most common vector-borne illness reported in the United States," reported Robert T. Schoen and colleagues at Yale University and GlaxoSmithKline Biologicals. "Despite efforts to increase public awareness of the disease and prevention techniques, the reported incidence of Lyme disease increased 1.7-fold from 1991 to 1999. Thus, we conducted an open-label, nonrandomized, single-center, prospective extension trial for the following reasons: (1) to compare the tolerability profile of a fourth or fifth vaccine dose given at 24 or 36 months after the end of the first vaccination of the primary immunization series (0, 1, and 12 months) and (2) to determine whether these booster injections at months 24 or 36 (or both) would attain an immune response similar to that obtained at month 13 (1 month after administration of the primary vaccine series at 0, 1, and 12 months)."

The investigators administered at least one booster dose of the vaccine to 318 subjects (173 women, 145 men), average age of 55 years, at 12 or 24 months after the third primary vaccination. A second booster at month 36 was administered to 88 of the subjects who received a 24-month booster.

"A total IgG anti-OspA antibody titer of greater than or equal to1400 EL.U/mL before the beginning of the tick season provides approximately 95% probability of protection against Lyme disease," said Schoen and his collaborators about a previous study involving this vaccine. "Nearly all subjects whose vaccine failed had IgG anti-OspA antibody titers

In this study, at least 96% of the subjects had titers greater than or equal to1400 EL.U/mL and over 99% had titers >400 EL.U/mL within a month after receiving a booster (An open-label, nonrandomized, single-center, prospective extension, clinical trial of booster dose schedules to assess the safety profile and immunogenicity of recombinant ...