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This study shows that early treatment with baloxavir marboxil is effective against the bovine H5N1 influenza virus, but delayed treatment significantly reduces its effectiveness and increases the risk of emergence of resistant viruses.

In this study, the authors report a single cycle-replicating SARS-CoV-2 vaccine candidate virus (ΔEM) and show that it induces spike-specific IgA and CD8+ T cells targeting spike and nucleocapsid proteins and provides broad and efficient protection in vaccinated animals.

Omicron subvariants may differ in their replicative fitness and their potential to cause more severe disease. In this study, the authors characterized Omicron BA.2.75 in a hamster model and found that it replicates more efficiently in the lungs than BA.2 and BA.5.

Results indicate that the sublineages BA.4 and BA.5 of SARS-CoV-2 Omicron variants have similar pathogenicity to that of the BA.2 sublineage in rodents, highlighting the importance of evaluating viral replication and pathogenesis using clinical isolates.

Isolates of authentic SARS-CoV-2 variants BA.1 and BA.2 exhibit similar infectivity and pathogenicity and show susceptibility to neutralizing therapeutic antibodies and antiviral compounds in mouse and hamster models.

Therapeutic monoclonal antibodies (COV2-2196/COV2-2130) inhibited the replication of SARS-CoV-2 Omicron BA.1 but not BA.1.1 variants in the lungs of Syrian hamsters. Antivirals (molnupiravir and S-217622) were effective against BA.1 in hamsters.

This Review explores the evolution of SARS-CoV-2 since its emergence in late 2019 and discusses how the changes in the various variants and subvariants have affected the viral life cycle and ongoing transmission. In addition, prevention and treatment strategies are outlined, as well as the effects of antigenically distinct variants and immune imprinting on immunity after natural infection or vaccination.

A/Texas/37/2024 (huTX37-H5N1), a virus isolated from the eyes of an infected farm worker who developed conjunctivitis, proved lethal in mice and ferrets, spreading systemically with high titres in both respiratory and non-respiratory organs, and transmitted by respiratory droplets in ferrets.

Ensitrelvir is an oral antiviral agent that targets SARS-CoV-2 and is clinically useful against infection with omicron variants. The authors characterized mutant viruses with reduced sensitivity to ensitrelvir in vitro and in vivo.

Resistance to nirmatrelvir, an oral antiviral agent that targets SARS-CoV-2 and is clinically useful against infection with Omicron variants, is currently not well understood. In this study, the authors characterize mutant viruses with reduced sensitivity to nirmatrelvir in vitro and in vivo.

A collaborative study demonstrates that, compared with previous SARS-CoV-2 variants, B.1.1.529 isolates cause less infection and disease in mice and hamsters, in agreement with preliminary data from studies in humans.

A new study demonstrates that the receptor-binding domain of the SARS-CoV-2 spike protein binds to sialylated glycans, especially glycolipids, to facilitate viral entry, an insight that identifies new potential targets for SARS-CoV-2 interventions.

A yeast surface display screen identifies five Aedes aegypti salivary proteins that are antigenic in mice repeatedly bitten by these mosquitoes. Antiserum against one of these proteins, Anopheles gambiae bacteria-responsive 1, partially protected mice against lethal mosquito-borne Zika virus infection.

Here, biological attributes of two early human isolates of the newly emerged H7N9 influenza viruses are characterized: the potential of these viruses to infect and/or transmit within various animal models is discussed, as is their relative sensitivity to neuraminidase inhibitors and experimental polymerase inhibitors compared to an H1N1 pandemic strain.

Omicron variants BQ.1.1 and XBB increased pathogenicity in wild-type hamsters, with BQ.1.1 showing higher mortality in human ACE2 transgenic hamsters compared to earlier Omicron variants..