Identifying Environmental Factors Affecting BspA Expression in Tannerella forsythia

Objective:

We investigated the effects of iron availability and temperature on the expression of human periodontopathogen Tannerella forsythia virulence factor BspA.  This study was initiated based on an earlier finding that showed several-fold induction in the expression of a BspA homolog during the T. forsythia growth in the host environment.

Method:

For temperature regulation, T. forsythia were incubated under anaerobic conditions at 35, 37 and 39°C for 8-12 hours to early- and late log growth phases. Western blots using an antibody specific for BspA were done to assess BspA expression. To test the effects of iron, T. forsythia cells were cultured in BF broth alone, or BF broth supplemented with either 30μM FeSO₄, as iron supplement, or 0.25 mM 2,2’-dipyridyl, an iron chelator.

Result:

BspA levels were similar in the cells cultured in the presence of iron chelator 2,2’-dipyridyl, or iron supplement 30μM FeSO₄, when compared to the cells cultured in broth alone.  In addition, BspA expression was similar in cells grown at different temperatures (32, 37 and 42 ⁰C).

Conclusion:

These data indicate that iron availability as well as temperature changes do not play a role in regulating BspA expression.  Studies are ongoing to identify other environmental factors that might regulate BspA expression in the host.