SARS Coronavirus - SARS Coronavirus Biology

SARS Coronavirus Biology

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. SARS is similar to other coronaviruses in that its genome expression starts with translation of two large ORFs 1a and 1b, which are two polyproteins. The SARS virus has 13 known genes and 14 known proteins. There are 265bp in the 5'UTR and 342bp in the 3'UTR.

Coronaviruses usually express pp1a (the ORF1a polyprotein) and the PP1ab polyprotein with joins ORF1a and ORF1b. The polyproteins are then processed by enzymes that are encoded by ORF1a. Product proteins from the processing includes various replicative enzymes such as RNA dependent polymerase, RNA helicase, and proteinase. The replication complex in coronavirus is also responsible for the synthesis of various mRNAs downstream of ORF 1b, which are structural and accessory proteins. Two different proteins, 3CLpro and PL2pro, cleave the large polyproteins into 16 smaller subunits.

SARS-Coronavirus follows the replication strategy typical of the Coronavirus genus.