Coronavirus genomic RNA packaging

Abstract

RNA viruses carry out selective packaging of their genomes in a variety of ways, many involving a genomic packaging signal. The first coronavirus packaging signal was discovered nearly thirty years ago, but how it functions remains incompletely understood. This review addresses the current state of knowledge of coronavirus genome packaging, which has mainly been studied in two prototype species, mouse hepatitis virus and transmissible gastroenteritis virus. Despite the progress that has been made in the mapping and characterization of some packaging signals, there is conflicting evidence as to whether the viral nucleocapsid protein or the membrane protein plays the primary role in packaging signal recognition. The different models for the mechanism of genomic RNA packaging that have been prompted by these competing views are described. Also discussed is the recent exciting discovery that selective coronavirus genome packaging is critical for in vivo evasion of the host innate immune response.

Graphical abstract

Highlights

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  Selective incorporation of the coronavirus genome into virions is mediated by a cis-acting RNA packaging signal.

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  Packaging signals vary across different coronavirus genera and lineages.

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  Different lines of evidence attribute packaging signal recognition to either the nucleocapsid or the membrane protein.

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  Selective coronavirus genome packaging plays a role in evasion of host innate immunity.