Fig. 3.

Flowchart of three methods for constructing coronavirus infectious cloning. (A) Targeted RNA recombination scheme used to make interspecies chimeric viruses: mIBV (Stage 1) and recombinant IBV (Stage 2). (B) In vitro ligation. The SARS-CoV full-length genome is divided into seven segments, named A-F, with type II restriction endonucleases Bgl1 at both ends. (C) Bacterial artificial chromosome system. Restriction enzyme sites in the MERS-CoV genome were employed to ligate the full-length MERS-CoV genome into pBeloBAC11.