The mechanism by which human immunodeficiency virus type 1 (HIV-1) causes CD4+ T cell depletion has until now remained largely unexplained. In July Genome Research, Jacques Corbeil and colleagues from the University of California San Diego, demonstrate the molecular events triggered by invasion of the HIV, creating a detailed account of the cellular injury progression following HIV infection.

Using chip technology Corbeil et al. measured the simultaneous mRNA expression at eight distinct time points, of 6800 genes in a CD4+ T cell line during the course of HIV infection. They found that responses to infection included a decrease in overall host cell mRNA synthesis, with the replacement of host cell mRNA by viral mRNA, a suppression of mitochondrial and DNA repair gene transcripts and an increased expression of the pro-apoptotic gene and its p53-induced product Bax with the activation of the apoptotic proteins caspase 2, 3 and...