Fig. 2.

Immune Control of Papillomavirus Infections. A) The balance between viral gene expression and the immune response to infection is shown in a see-saw format at the different stages of the papillomavirus infection cycle. In a naïve host with no immunological memory of the infecting papillomavirus types, lesion formation proceeds unchecked. As the immune response develops, viral gene expression (and cells expressing viral genes) declines. Transient immune depletion or more prolonged immune suppression can change immune surveillance status to allow the redetection of papillomavirus DNA. B) Summary of infection and regression data obtained using the rabbit model of mucosal epithelial infection [19,22]. In this system, experimental infection leads to the rapid appearance of palpable lesions over the course of 5 weeks with papillomavirus DNA readily detectable in surface swabs (single green star). Following immune regression, detectable copies decline by approximately seven orders of magnitude (orange star; note log scale), but increase following sustained immune suppression (double green star). The images beneath show tissue histology and disease pathology during the course of lesion formation and regression (following H&E staining), as well as the appearance of the experimentally-induced palpable lesions on the tongue. Following lesions regression, the animals showed no symptoms. The right-most histology image shows the sites of tissue fragments that have been removed following laser-capture microdissection for the quantitation of papillomavirus DNA as described in Refs. [19,22]. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)