User:Marvin O'Neal/OspA: Difference between revisions

<span style="color:red">The membrane composition of <i>Borrelia</i> is abundant in both OspA and OspB, and the two proteins share a 53% similarity in their primary sequences. Both OspA and OspB are expressed in the tick's gut and downregulated during feeding and aid in its survivability; however, OspA is overall less varied and reactive than OspB, which has greater variability.<ref name="becker">PMID: 15713683</ref> The relatively conserved sequence of OspA thus lends itself better to study and application toward the development of a vaccine for a broader range of <i>Borrelia</i> strains in the treatment of Lyme disease than that of OspB. The first vaccine used a purified recombinant form of OspA and functioned in blocking transmission of the spirochetes expressing OspA from tick to host during feeding, killing them while still attached to the tick's gut.<ref name="connolly">PMID: 15864264</ref><ref name="battisti">PMID: 18779341</ref> The vaccine, Lymerix, had shown 76% and 92% effectiveness in separate clinical trials in which patients were treated for two years following a three-dose schedule. However, the vaccination was suspended from use in 2002 when opponents claimed the [http://en.wikipedia.org/wiki/Immunoglobulin_G IgG antibodies] for OspA were associated with the onset of severe chronic arthritis, as well as other side effects affecting immunity.<ref name="connolly">PMID: 15864264</ref><ref name="plotkin">PMID: 21217175</ref> In conjunction with the desire for a more widespread vaccine treating multiple strains, research towards a new vaccine has already begun.