FIG. 1.

Genome organization and transcription strategy of SARS-CoV HK-39. Genomic and mRNA transcripts are capped (black circles), carry leader sequences (vertical lines) at the 5′-proximal end, and are polyadenylated (A¹⁵). Arrows point to the positions of the intergenic sequence (CTAAACGAAC). After the release of the positive-sense genomic RNA into the cytoplasm of the host cell, the viral RNA-dependent RNA polymerase, encoded by ORF1a and -1b, is synthesized. It performs transcription of a full-length complementary (negative-sense) RNA, from which new genomic RNA, an overlapping set of subgenomic mRNA transcripts, and leader RNAs are synthesized. Note that all transcripts are preceded with common 5′ leader sequences and common 3′ ends. ORF1a and -1b, RNA-dependent RNA polymerase; S, the major peplomer glycoprotein; M, transmembrane glycoprotein; N, nucleocapsid protein; X1, X2, and X3, putative uncharacterized proteins.