TLR9 and infectious disease: Polymorphisms in the studied genes CD209, DDX58, MBL2, TLR2, TLR3, and TLR9 have been reported to influence a number of infectious diseases, including HIV-1 (Koizumi et al. 2007; Pine et al. 2009), cytomegalovirus (Mezger et al. 2008), tuberculosis (Vannberg et al. 2008; Velez et al. 2010), hepatitis C virus (Koutsounaki et al. 2008; Ryan et al. 2010), and dengue virus (Sakuntabhai et al. 2005; Acioli-Santos et al. 2008; Wang et al. 2011) infection among others, revealing their potential role in host defense against pathogens.