The Lyme disease agent exploits a tick protein to infect the mammalian host

Nature 436:573-7, 2005

Speaker:洪惠雯                         Date:2005/12/14

Commentator: 辛致煒  教授             Time:13:10~14:00  Room:601

Abstract:

     Lyme disease, or Lyme borreliosis, was recognized as an important emerging infection in the late 20^th century. The Lyme disease agent, Borrelia burgdorferi, is maintained in a complex enzootic cycle. It is now the most commonly reported arthropod-borne illness in the US and Europe and is also found in Asia. Tick salivary proteins that enter the host during feeding have multiple effects, including the ability to inhibit the complement cascade and repress production of cytokines. Here we describe a feeding-inducible protein in Ixodes scapularis saliva, Salp15, is the first protein associated with the immunosuppressive activity of tick saliva that was shown to protect B. burgdorferi from antibody-mediated killing both in vitro and in vivo. RNA interference-mediated repression of Salp15 in I. scapularis reduced the capacity of tick-borne spirochaetes to infect naïve mice and in mice that had an immune response. Studies were also performed with Peromyscus leucopus, a natural reservoir ofB. burgdorferi, and similar results were obtained. Salp15 plays a crucial role between ticks and B. burgdorferi, perhaps B. burgdorferi-induced enhancement of Salp15, might inhibit CD4⁺ T cell activation and enable ticks to more effectively engorge and/or avoid rejection by the host. For future vaccine development, the selection of a common invariable epitope is of vital importance, Salp15 may be a novel candidate vaccine.      

Reference:

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