ISG15 and infection: Infection of macrophages with wild type M. tuberculosis CDC1551 results in increased expression of pro-inflammatory cytokines and chemokines, specifically, upregulation of pro-IL-1B, several interferon-inducible proteins (ISG15, IFIT1, IFIT2, IFIT3, IFIH1 and MX1) and rapid recycling of components associated with IL-12 signalling.