Practice question

RNA replicase denotes multiprotein complex combining RNA-dependent RNA polymerase with cofactors that copies viral RNA genome. Commonly encountered in positive-strand RNA bacteriophage Qβ, plant viruses like tobacco mosaic virus, and animal pathogens such as poliovirus, SARS coronavirus, hepatitis C virus. Upon entry, viral replicase recognizes conserved cis-acting elements at genome termini, synthesizes complementary negative strand intermediate, then abundant progeny positive strands packaged into virions. Because cellular machinery lacks broad RdRp activity, these replicases are virus encoded and often error-prone, driving rapid evolution and quasi-species diversity enabling immune escape in RNA viral populations.