Outer Surface Protein B Is Critical for Borrelia burgdorferi Adherence and Survival within Ixodes Ticks

Abstract

Survival of Borrelia burgdorferi in ticks and mammals is facilitated, at least in part, by the selective expression of lipoproteins. Outer surface protein (Osp) A participates in spirochete adherence to the tick gut. As ospB is expressed on a bicistronic operon with ospA, we have now investigated the role of OspB by generating an OspB-deficient B. burgdorferi and examining its phenotype throughout the spirochete life cycle. Similar to wild-type isolates, the OspB-deficient B. burgdorferi were able to readily infect and persist in mice. OspB-deficient B. burgdorferi were capable of migrating to the feeding ticks but had an impaired ability to adhere to the tick gut and survive within the vector. Furthermore, the OspB-deficient B. burgdorferi bound poorly to tick gut extracts. The complementation of the OspB-deficient spirochete in trans, with a wild-type copy of ospB gene, restored its ability to bind tick gut. Taken together, these data suggest that OspB has an important role within Ixodes scapularis and that B. burgdorferi relies upon multiple genes to efficiently persist in ticks.

Transcriptional interplay among the regulators Rrp2, RpoN and RpoS in Borrelia burgdorferi

“…Several plasmids, such as lp25, lp28-1 and lp36, are essential for borrelial infectivity (Jewett et al, 2007;Purser & Norris, 2000;Stewart et al, 2005). Plasmid lp54 has been implicated as being important for the survival of B. burgdorferi in both tick and mammalian hosts, largely because of the presence of the ospAB and dbpBA operons (Caimano et al, 2005;Hagman et al, 1998;Neelakanta et al, 2007;Shi et al, 2008;Yang et al, 2004). Many other genes encoded on lp54 have been found to be differentially regulated in response to temperature, pH and other mammalian-derived signals, which are presumed to be mediated, at least in part, by RpoS (Caimano et al, 2005;Clifton et al, 2006;Ojaimi et al, 2003;Revel et al, 2002).…”

“…bba16 (ospB), which belongs to the ospAB operon that is essential for B. burgdorferi colonization and survival within tick midguts (Neelakanta et al, 2007;Yang et al, 2004), was downregulated 3.6-, 2.1 and 1.8-fold, respectively, by Rrp2, RpoN and RpoS. In our test, we also found that bba15 (ospA) was downregulated 1.8-, 1.3-and 1.3-fold, respectively, by Rrp2, RpoN and RpoS.…”

“…These data suggest that it is difficult to draw definitive conclusions about regulatory events based on microarray data that exhibit only slight fold changes in individual gene expression patterns. (Caimano et al, 2004(Caimano et al, , 2005(Caimano et al, , 2007Fisher et al, 2005;He et al, 2007;Neelakanta et al, 2007;Yang et al, 2004), but its recognition has prompted many new questions and has spawned a number of controversies. For example, the results of Fisher et al (2005) have called into question the linearity of the RpoNRpoS pathway.…”

A manganese transporter, BB0219 (BmtA), is required for virulence by the Lyme disease spirochete, Borrelia burgdorferi

“…In recent years, extensive efforts have been directed toward elucidating the mechanisms by which Bb cycles, adapts, and sustains itself in these diverse niches. It is now well established that outer surface (lipo)protein C (OspC), OspA/B, decorin-binding protein B/A (DbpB/A), PncA, and BptA are required by Bb for efficient infection of ticks or mammalian hosts (4)(5)(6)(7)(8)(9)(10). It is also generally accepted that the recently discovered Rrp2-RpoN ( 54 )-RpoS ( S ) regulatory pathway plays prominently in Bb's virulence expression (11)(12)(13)(14).…”

Biology of Infection with Borrelia burgdorferi

“…Subsequent studies suggest that OspA is an adhesin, important for retaining spirochetes in the tick midgut until feeding [161][162][163]. OspB, another potential midgut adhesin [164], BptA, a lipoprotein of unknown function, and the product of the BB0690 gene, which is probably involved in resistance to oxidative stress [165], also appear to contribute to bacterial survival in ticks [166][167][168]. The RpoN-RpoS regulatory cascade appears to be required for migration of spirochetes to the salivary glands during transmission, but not for survival within the tick environment [153].…”