TLR7 and viral infectious disease: The specific PAMPs recognized by the TLR family members have been well-characterized: TLR2 homodimers and TLR2–TLR1 and TLR2–TLR6 heterodimers mediate responses to bacterial lipoproteins, peptidoglycan, lipoteichoic acid, and zymosan; TLR3 to double-stranded RNA, a marker of viral infection; TLR4 to bacterial lipopolysaccharide (LPS); TLR5 to bacterial flagellin; TLR7 and 8 to imidazoquinolines and single stranded RNA, respectively; and TLR9 to bacterial DNA [26].