TLR7 and viral infectious disease: Isatoribine (Lee et al., 2003), 7-deazaguanosine (Lee et al., 2003), and loxoribine (Dzopalic et al., 2010) all are known Guanosine (G) analogs that can activate TLR7 and induce downstream immune responses to inhibit virus infection (Horsmans et al., 2005).