A comparative analysis of parechovirus protein structures with other picornaviruses

Leucoverdazyls as Novel Potent Inhibitors of Enterovirus Replication

Enteroviruses (EV) are important pathogens causing human disease with various clinical manifestations. To date, treatment of enteroviral infections is mainly supportive since no vaccination or antiviral drugs are approved for their prevention or treatment. Here, we describe the antiviral properties and mechanisms of action of leucoverdazyls-novel heterocyclic compounds with antioxidant potential. The lead compound, 1a, demonstrated low cytotoxicity along with high antioxidant and virus-inhibiting activity. A viral strain resistant to 1a was selected, and the development of resistance was shown to be accompanied by mutation of virus-specific non-structural protein 2C. This resistant virus had lower fitness when grown in cell culture. Taken together, our results demonstrate high antiviral potential of leucoverdazyls as novel inhibitors of enterovirus replication and support previous evidence of an important role of 2C proteins in EV replication.

Update on nonpolio enterovirus and parechovirus infections in neonates and young infants

PURPOSE OF REVIEW

To review the epidemiology, clinical manifestations, and treatment strategies of nonpolio enterovirus and parechovirus (PeV) infections, and identify research gaps.

RECENT FINDINGS

There is currently no approved antiviral agent for enterovirus or PeV infections, although pocapavir may be provided on a compassionate basis. Elucidation of the structure and functional features of enterovirus and PeV may lead to novel therapeutic strategies, including vaccine development.

SUMMARY

Nonpolio human enterovirus and PeV are common childhood infections that are most severe among neonates and young infants. Although most infections are asymptomatic, severe disease resulting in substantial morbidity and mortality occurs worldwide and has been associated with local outbreaks. Long-term sequelae are not well understood but have been reported following neonatal infection of the central nervous system. The lack of antiviral treatment and effective vaccines highlight important knowledge gaps. Active surveillance ultimately may inform preventive strategies.

Compositional complementarity between genomic RNA and coat proteins in positive-sense single-stranded RNA viruses

During packaging in positive-sense single-stranded RNA (+ssRNA) viruses, coat proteins (CPs) interact directly with multiple regions in genomic RNA (gRNA), but the underlying physicochemical principles remain unclear. Here we analyze the high-resolution cryo-EM structure of bacteriophage MS2 and show that the gRNA/CP binding sites, including the known packaging signal, overlap significantly with regions where gRNA nucleobase-density profiles match the corresponding CP nucleobase-affinity profiles. Moreover, we show that the MS2 packaging signal corresponds to the global minimum in gRNA/CP interaction energy in the unstructured state as derived using a linearly additive model and knowledge-based nucleobase/amino-acid affinities. Motivated by this, we predict gRNA/CP interaction sites for a comprehensive set of 1082 +ssRNA viruses. We validate our predictions by comparing them with site-resolved information on gRNA/CP interactions derived in SELEX and CLIP experiments for 10 different viruses. Finally, we show that in experimentally studied systems CPs frequently interact with autologous coding regions in gRNA, in agreement with both predicted interaction energies and a recent proposal that proteins in general tend to interact with own mRNAs, if unstructured. Our results define a self-consistent framework for understanding packaging in +ssRNA viruses and implicate interactions between unstructured gRNA and CPs in the process.