FIG. 1.

Diagram of the elements involved in coronavirus transcription. (A) The scheme represents all of the sequence elements probably involved in the discontinuous negative-strand synthesis model. CS-L, leader CS; CS-B, body CS. TRS-L and TRS-B, transcription-regulating sequences from the leader and body, respectively. An, poly(A). (B) Representation of the discontinuous transcription during negative-strand synthesis. cCS-B and cTRS-B represent the CS-B and TRS-B complementary sequences, respectively. Un, poly(U). (C) Leader and body sequences are probably located close to one another in higher-order structures maintained by RNA-protein and protein-protein interactions.