G14secL04Tpc3: Difference between revisions
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Lyme disease is caused by the bacterial spirochete Borrelia burgdorferi sensu lato. Colonization and survival of Borrelia burgdorferi within ticks and mammals is facilitated, in part, by lipoproteins. OspB and OspA are two of the major lipoproteins present on the outer surface of the spirochete Borrelia Burgdoferi. Studies have shown that OspB is critical for the adherence of the spirochete to the gut wall of its tick vector. The free OspB structure consists of a barrel domain which might be the portion that interacts with a protein or a linear saccharide in the tick-gut (17368), promoting the attachment of spirochete on the tick gut. It’s believed that destroying these lipoproteins will cause bacterial death of spirochetes. Some antibody Fab fragments such as H6831 and CB2 have been shown to cause bacterial lysis of spirochetes by binding to these lipoproteins in the absence of phagocytes and without complement, which is normally part of the immune response to bacteria. However, it is unclear how binding of H6831 or CB2 can lead directly to lysis of the bacterium. | Lyme disease is caused by the bacterial spirochete Borrelia burgdorferi sensu lato. Colonization and survival of Borrelia burgdorferi within ticks and mammals is facilitated, in part, by lipoproteins. OspB and OspA are two of the major lipoproteins present on the outer surface of the spirochete Borrelia Burgdoferi. Studies have shown that OspB is critical for the adherence of the spirochete to the gut wall of its tick vector. The free OspB structure consists of a barrel domain which might be the portion that interacts with a protein or a linear saccharide in the tick-gut (17368), promoting the attachment of spirochete on the tick gut. It’s believed that destroying these lipoproteins will cause bacterial death of spirochetes. Some antibody Fab fragments such as H6831 and CB2 have been shown to cause bacterial lysis of spirochetes by binding to these lipoproteins in the absence of phagocytes and without complement, which is normally part of the immune response to bacteria. However, it is unclear how binding of H6831 or CB2 can lead directly to lysis of the bacterium. | ||
==Transmission of Spirochete== | |||
Selective expression of outer surface proteins are important for the colonization and persistence within the tick vector. | |||
It was observed that after entry into the ticks, B. burgdorferi replicates and persists within the gut, then during a subsequent blood meal, migrates through the vector and is transmitted to a new host. Other studies show that the expression of B. burgdorferi OspA and OspB is immediately turned on when the spirochetes enter and reside within the arthropod vector. However, during transmission from the arthropod vector to a vertebrate host, expression of B. burgdorferi are downregulate. Since OspA and OspB are critical for the adherence of the spirochete to the mid-gut of the tick, if this protein is down- regulated or expressed less, then it will attach less to the mid-gut of the tick and as a result be more likely to be excreted in some way into the host on which the tick is feeding. | |||
==Free OspB structure== | ==Free OspB structure== | ||
