Formation and Function of Liquid-Like Viral Factories in Negative-Sense Single-Stranded RNA Virus Infections.

Liquid-liquid phase separation (LLPS) represents a major physiochemical principle to organize intracellular membrane-less structures. Studies with non-segmented negative-sense (NNS) RNA viruses have uncovered a key role of LLPS in the formation of viral inclusion bodies (IBs), sites of viral protein concentration in the cytoplasm of infected cells. These studies further reveal the structural and functional complexity of viral IB factories and provide a foundation for their future research.

Measles Virus Forms Inclusion Bodies with Properties of Liquid Organelles.

Nonsegmented negative-strand RNA viruses, including measles virus (MeV), a member of the family, are assumed to replicate in cytoplasmic inclusion bodies. These cytoplasmic viral factories are not membrane bound, and they serve to concentrate the viral RNA replication machinery. Although inclusion bodies are a prominent feature in MeV-infected cells, their biogenesis and regulation are not well understood.