Microbial Pathogenesis of Oral Organisms

ASHU SHARMA, PhD  personal profile

The paths of pathogenic bacteria

The human oral cavity is a highly diverse ecosystem containing more than 500 species of bacteria, including both cultivable and non-cultivable species.  It is believed that infection with a select few Gram-negative anaerobes, called the red-complex, is responsible for causing periodontitis or gum disease, which if not treated leads to tooth loss. My lab studies the pathogenic mechanisms of the red-complex bacteria by utilizing molecular-genetic and biochemical approaches. The red-complex bacteria of the include Porphyromonas gingivalis, Tannerella forsythia (formerly Bacteroides forsythus) and Treponema denticola (a spirochete). 

Our overall objectives are to gain a better understanding of how these pathogenic bacteria initiate colonization, form biofilms, and initiate tissue destructive host immune responses critical for disease progression.  The research focuses on identifying virulence factors these bacteria produce and host-cell receptors involved in their recognition.  Identification of these virulence factors and their receptor should pave the way for developing intervention strategies, such as vaccines, against periodontal bacteria. In this regard, we have developed genetic systems whereby non-pathogenic oral streptococci (Streptococci gordonii) can be engineered to expression vaccine antigens of choice.  These genetically modified streptococcal vectors can be utilized for vaccine delivery by oral route.