Examination of streptococcal gene expression in the mammalian environment

Laboratory studies of bacterial gene expression have not allowed the investigation of in vivo factors crucial to pathogenesis. Recently, genetic tools have been used to identify in vivo-activated genes. These tools, however, have not allowed the measurement of specific expression levels of virulence-associated bacterial genes in vivo, This report describes a system, previously tested utilizing the fructosyltransferase (ftf) gene of Streptococcus mutans, that allows the measurement of activity of specific virulence-associated streptococcal genes while bacteria are living in the animal environment.