Figure 1. The external (A) and interior (B) structures of hantaviruses with three genomic RNA segments (L, M, and S).
Like most members of Bunyavirales , hantaviruses genome encompasses large (L), medium (M), and small (S) single-stranded negative-sense RNA (−ssRNA) segments, consisting of about 10,000−15,000 nucleotides in total (Figure 2 ).33 The L segment encodes RdRp that mediates the transcription and replication of viral genomic RNA. The M segment encodes a glycoprotein precursor (GPC), which is co-translated and cleaved by host cell signal peptidases to Gn and Gc.34 Gn and Gc bind to cell receptors, regulate immune responses, and induce protective antibodies.4The S segment encodes the N protein, which binds to and protects the viral RNA molecules. The S segment of some orthohantaviruses(e.g., ANDV, PUUV, SNV, TULV, and LANV) encodes a nonstructural protein (NS), which inhibit the production of interferon in host cells.35
The terminal untranslated region (UTR) sequences of the genomic segments of hantaviruses are highly conserved and complementary. They form stalk structures and participate in the replication and transcription of viral genomic RNA (vRNA).36,37