SARS-CoV RdRp

The SARS coronavirus, sometimes shortened to SARS-CoV, is the virus that causes severe acute respiratory syndrome (SARS). SARS coronavirus is a positive and single stranded RNA virus belonging to a family of enveloped coronaviruses. Its genome is about 29.7kb, which is one of the largest among RNA viruses. The SARS virus has 13 known genes and 14 known proteins. There are 265 nucleotides in the 5'UTR and 342 nucleotides in the 3'UTR. SARS is similar to other coronaviruses in that its genome expression starts with translation of two large ORFs, 1a and 1b, both of which are polyproteins. Genome replication and transcription in most RNA viruses are catalyzed by RNA-dependent RNA polymerase (RdRp). RdRp, an enzyme, is an important protein encoded in the genomes of viruses containing RNA because it can catalyze the synthesis of the RNA strand complementary to a given RNA template. Coronavirus replication and transcription are mediated by a protein complex with RdRP as a main component of the viral particles. Furthermore, RdRP and other replicase proteins have been speculated to act as a starting replication machinery in the synthesis of CoV RNA by amplifying the genome before genome translation to improve the efficiency of virus infection.