How the host 'sees' pathogens: global gene expression responses to infection

Innate immune responses to pathogens are believed to be patterned and stere otyped. Adaptive responses display variety but in relatively few types of p roducts and with limited numbers of mechanisms. Is this apparent disparity between microbial pathogen diversity and a restricted set of host responses an accurate picture of infection or is it the result of a limited collecti on of analytic tools? DNA microarray technology permits one to address simp le descriptive questions about global gene expression inside cells. In part icular, it offers an opportunity to examine the relationship between host a cid pathogen in much greater detail than has been possible previously. One can now ask, firstly, how a host cell or organism 'sees' a microbial pathog en from the viewpoint of gene expression responses and, secondly, at what l evel it is able to discriminate between different agents. Other potential i nsights to be reaped include the identification of microbial determinants o f the host response, the temporal features of the 'conversation' between ho st and pathogen, novel strategies for therapeutic and prophylactic interven tion and prognostic markers of outcome.