Genotype-specific features reduce the susceptibility of South American yellow fever virus strains to vaccine-induced antibodiesby DeniseHaslwanter et al.
The resurgence of yellow fever in South America has prompted vaccination against the etiologic agent, yellow fever virus (YFV). Current vaccines are based on a live-attenuated YF-17D virus derived from a virulent African isolate. The capacity of these vaccines to induce neutralizing antibodies against the vaccine strain is used as a surrogate for protection. However, the sensitivity of genetically distinct South American strains to vaccine-induced antibodies is unknown. We show that antiviral potency of the polyclonal antibody response in vaccinees is attenuated against an emergent Brazilian strain. This reduction was attributable to amino acid changes at two sites in central domain II of the glycoprotein E, including multiple changes at the domain I–domain II hinge, which are unique to and shared among most South American YFV strains. Our findings call for a reevaluation of current approaches to YFV immunological surveillance in South America and suggest approaches for updating vaccines.
Immune Evasion of SARS-CoV-2 Variants of Concern is Driven by Low Affinity to Neutralizing Antibodiesby Matheus Ferraz et al.
Abstract SARS-CoV-2 VOCs immune evasion is mainly due to lower cross-reactivity from previously elicited class I/II neutralizing antibodies, while increased affinity to hACE2 plays a minor role. The affinity between antibodies and VOC is impacted by remodeling of the electrostatic surface potential of the Spike RBDs. P.3 variant is a putative VOC.
In vitro antiviral activity of the anti-HCV drugs daclatasvir and sofosbuvir against SARS-CoV-2, the aetiological agent of COVID-19by Carolina Q Sacramento et al.
Current approaches of drug repurposing against COVID-19 have not proven overwhelmingly successful and the SARS-CoV-2 pandemic continues to cause major global mortality. SARS-CoV-2 nsp12, its RNA polymerase, shares homology in the nucleotide uptake channel with the HCV orthologue enzyme NS5B. Besides, HCV enzyme NS5A has pleiotropic activities, such as RNA binding, that are shared with various SARS-CoV-2 proteins.