SARS-CoV-2 replication proteins (RTC) (RTC)

SARS-CoV-2 replication proteins are a group of 16 non-structural proteins (nsp1-16) that collectively facilitate the replication and transcription of the viral genome within host cells [9, 10]. These proteins are initially translated as two large polyproteins (pp1a and pp1ab), which are subsequently cleaved into individual functional units by two viral proteases: the main protease (Mpro, also known as 3CLpro or nsp5) and the papain-like protease (PLpro or nsp3) [1, 14]. Once released, these proteins assemble into a membrane-associated replication-transcription complex (RTC), centered around the RNA-dependent RNA polymerase (RdRp or nsp12), which synthesizes new genomic and subgenomic RNA [8, 15]. Other components of the complex include the helicase (nsp13), exonuclease (nsp14) for proofreading, and methyltransferases (nsp14/nsp16) for RNA capping [10, 12]. These proteins are primary therapeutic targets because they are essential for viral survival and lack direct human homologs, minimizing off-target effects [8, 15]. Clinically approved drugs like remdesivir and molnupiravir act as nucleoside analogs that inhibit the RdRp, while nirmatrelvir (part of Paxlovid) and ensitrelvir target the Mpro to halt polyprotein processing [1, 2, 8]. Targeting the replication machinery effectively reduces viral load and prevents the progression of COVID-19 [4, 16]. However, challenges such as the emergence of resistance mutations and significant drug-drug interactions, particularly with ritonavir-boosted regimens, remain critical considerations in therapeutic development [2, 11].

Other names

Non-structural proteinsnspsReplicase proteinsViral replicaseReplication-Transcription ComplexSARS-CoV-2 non-structural proteinsReplicase polyprotein 1ab

Inhibition of the viral RNA-dependent RNA polymerase (RdRp) to terminate RNA chain elongation and inhibition of viral proteases (Mpro and PLpro) to prevent the cleavage of polyproteins into functional non-structural proteins.