An international team of researchers has identified an East African bat coronavirus capable of entering human cells.

Abstract. Astroviruses are positive-sense single-stranded RNA viruses that cause significant disease across avian and mammalian hosts, yet their replicatio

Author summary Enteroviruses cause over a billion infections annually, leading to serious conditions such as hand, foot, and mouth disease and viral meningitis. While these viruses are known to encode...

Astroviruses are positive-sense single-stranded RNA viruses that cause significant disease across avian and mammalian hosts, yet their replication mechanisms remain poorly understood. The replication of astrovirus RNA occurs via a double-stranded RNA intermediate that is used as a template for the synthesis of new positive-sense RNA, which is covalently linked to the virus-encoded protein VPg. These viruses also produce a capsid-encoding subgenomic (sg) RNA that is 3′-coterminal with the genomic RNA. The mechanisms by which the astrovirus sgRNA is produced and regulated during infection have not yet been characterized. Using high throughput sequencing of RNA from cells infected with each of five different astrovirus strains, we demonstrate that the presence of a (−)sgRNA is a conserved feature of infection, supporting a premature termination model of subgenomic RNA production. A pronounced pile-up in the mapping positions of the 3ʹ ends of negative-sense RNA reads marks the precise 3ʹ terminus of the (−)sgRNA. We investigate the relative abundance and dynamics of positive and negative RNA species during virus replication and virion packaging, and perform a mutational analysis of conserved residues in the genomic and subgenomic 5ʹ termini. Together, this work elucidates the dynamics of genomic and subgenomic RNA synthesis during astrovirus infection. ### Competing Interest Statement The authors have declared no competing interest. Wellcome Trust, https://ror.org/029chgv08, 220620/Z/20/Z, 220814/Z/20/Z

Host body temperature can define a virus’s replicative profile—influenza A viruses (IAVs) adapted to 40° to 42°C in birds are less temperature sensitive in vitro compared with human isolates adapted t...

Positive-sense RNA viruses often encode large polyproteins that are proteolytically processed by viral and host proteases into functional replication proteins. Astroviruses infect intestinal and neuro...

Enteroviruses are a widespread and diverse set of pathogens responsible for over ~1 billion human infections annually. Upon cell entry, translation of the virus genome is mediated by an internal ribos...

Enteroviruses comprise a large group of mammalian pathogens that often utilize two open reading frames (ORFs) to encode their proteins: the upstream protein (UP) and the main polyprotein. In some enteroviruses, in addition to the canonical upstream AUG (uAUG), there is another AUG that may represent an alternative upstream initiation site. An analysis of enterovirus sequences containing additional upstream AUGs identified several clusters, including strains of pathogenic Enterovirus alphacoxsackie and E. coxsackiepol. Using ribosome profiling on coxsackievirus CVA-13 (E. coxsackiepol), we demonstrate that both upstream AUG codons can be used for translation initiation in infected cells. Moreover, we confirm translation from both upstream AUGs using a reporter system. Mutating the additional upstream AUG in the context of CVA-13 did not result in phenotypic changes in immortalized cell lines. However, the wild-type virus outcompeted this mutant in human intestinal organoids and differentiated neuronal systems, representing an advantage in physiologically relevant infection sites. Mutation of the stop codon of the shorter upstream ORF led to dysregulated translation of the other ORFs in the reporter system, suggesting a potential role for the additional uORF in modulating the expression level of the other ORFs. These findings demonstrate the remarkable plasticity of enterovirus IRES-mediated initiation and the competitive advantage of double-upstream-AUG-containing viruses in terminally differentiated intestinal organoids and neuronal systems. ### Competing Interest Statement The authors have declared no competing interest.

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