Caparon Lab Research

Research in my laboratory is directed at understanding the complex interactions that occur between pathogenic gram positive bacteria and their human hosts during infection. Of particular interest is the organism Streptococcus pyogenes, the causative agent of a number of serious diseases including, pharangytis ("strep throat"), impetigo, scarlet fever, rheumatic fever and acute glomerulonephritis.

Specific projects include the analysis of two surface proteins of S. pyogenes that direct its initial interaction with host cells. One protein, known as the M protein, functions to allow the bacterium to adhere to keratinocytes during infection of the skin; while protein F, fibronectin-binding protein, mediates the attachment of S. pyogenes to epidermal Langerhans cells. The capacity to control the expression of adhesins for specific cell types has allowed an examination of the effect of adherence to a host cell on the pathogen-host interaction. These studies have shown that these adhesive interactions coordinate the targeting of other secreted streptococcal molecules which then act in combination to influence the signaling pathways that these host cells use to orchestrate the inflammatory response.

Expression of the adhesins and the other secreted molecules is tightly regulated in response to several environment cues, including O2. Genes involved in regulation have been identified (mga, rofA, gasK1K2R, ropB, tig) and their role in regulation is under analysis using state of the art tools we are developing for S. pyogenes, including novel methods of transposon mutagenesis which can specifically identify gene products secreted from gram positive bacteria.