it appears that OSP A really IS expressed in mammalian hosts

[Guest guest]

As I recall, more than one member here has asserted flatly that the

Bb spirochete's OSP A is not expressed in mammals. This finding

seems to state otherwise.

Any thoughts?

Infect Immun. 2003 Jul;71(7):4003-10. Related Articles, Links

Host-adapted Borrelia burgdorferi in mice expresses OspA during

inflammation.

Crowley H, Huber BT.

Department of Pathology, Tufts University School of Medicine,

Boston, Massachusetts 02111, USA.

Antibody responses to outer surface protein A (OspA) of Borrelia

burgdorferi may occur during periods of arthritis late in the

clinical course of untreated Lyme disease. These antibody responses

are paradoxical, given the conclusive evidence demonstrating that B.

burgdorferi transmitted to the mammalian host expresses little or no

OspA. The parallel occurrence of OspA antibodies and arthritic

episodes suggests that OspA expression is upregulated during

infection with B. burgdorferi. We hypothesized that this was due to

the inflammatory environment caused by the immune response to the

spirochete. To test our hypothesis, we adapted an in vivo model that

mimics the host-pathogen interaction. Dialysis chambers containing

B. burgdorferi were implanted into the peritoneal cavities of mice

in the presence or absence of zymosan, a yeast cell wall extract

that induces inflammation. Spirochetes were harvested 2 days later,

and OspA expression was assessed at the protein and transcription

level by Western blotting and real-time reverse transcription-PCR,

respectively. Flow cytometry was also utilized to evaluate OspA

protein expression on individual spirochetes. B. burgdorferi

maintained in an inflammatory in vivo environment show an increased

OspA expression relative to B. burgdorferi kept under normal in vivo

conditions. Furthermore, host-adapted B. burgdorferi with a low OspA

phenotype upregulates OspA expression when transferred to an

inflammatory in vivo environment. The results obtained by these

techniques uniformly identify inflammation as a mediator of in vivo

OspA expression in host-adapted B. burgdorferi, providing insights

into the behavior of live spirochetes in the mammalian host.

PMID: 12819088 [PubMed - indexed for MEDLINE]