The RNA-dependent RNA polymerase of pandemic GII.4 human norovirus forms liquid-liquid phase condensates that serve as viral replication factories in infected human intestinal enteroid cultures.
Many viral proteins form biomolecular condensates via liquid-liquid phase separation (LLPS) to support viral replication and evade host antiviral responses, and thus, they are potential targets for designing antivirals. In the case of nonenveloped positive-sense RNA viruses, forming such condensates for viral replication is unclear and less understood. Human noroviruses (HuNoVs) are positive-sense RNA viruses that cause epidemic and sporadic gastroenteritis worldwide. Here, we show that the RNA-dependent RNA polymerase (RdRp) of pandemic GII.4 HuNoV forms distinct condensates that exhibit all the signature properties of LLPS with sustained polymerase activity and the capability of recruiting components essential for viral replication. We show that such condensates are formed in HuNoV-infected human intestinal enteroid cultures and are the sites for genome replication. Our studies demonstrate the formation of phase-separated condensates as replication factories in a positive-sense RNA virus, which plausibly is an effective mechanism to dynamically isolate RdRp replicating the genomic RNA from interfering with the ribosomal translation of the same RNA.
Kaundal et al. (Fri,) conducted a other in Human norovirus infection. RNA-dependent RNA polymerase (RdRp) of pandemic GII.4 HuNoV was evaluated on Formation of liquid-liquid phase condensates and viral replication. The RNA-dependent RNA polymerase of pandemic GII.4 human norovirus forms liquid-liquid phase condensates that serve as viral replication factories in infected human intestinal enteroid cultures.