UNLABELLED

A panzootic of highly pathogenic avian influenza (HPAI) H5N1 viruses from clade 2.3.4.4b has triggered a multistate outbreak in US dairy cattle and an unknown number of human infections. HPAI viruses are handled in specialized biocontainment facilities. Ethical considerations limit certain evolution experiments aimed at assessing viral resistance to potential therapeutics. We have developed a replicating recombinant vesicular stomatitis virus (rVSV) where we replaced its glycoprotein with the hemagglutinin (HA) and neuraminidase (NA) genes of a 2.3.4.4b H5N1 virus (rVSV-H5N1dc2024), which enables these experiments to be performed under standard biosafety considerations. This virus grows to high titers and encodes a fluorescent reporter to track infection. We demonstrate the utility of rVSV-H5N1dc2024 in neutralization experiments, the evaluation of antibody escape, and the characterization of resistance mutations to NA inhibitors. rVSV-H5N1dc2024 or similar viruses may accelerate efforts to develop and evaluate interventions against this emerging threat to human and animal health.

IMPORTANCE

Highly pathogenic avian influenza H5 viruses have spread globally, established sustained transmission in mammals, and caused human infections. Research on these viruses is restricted to high biocontainment laboratories. We report the characterization and utility of a surrogate, replicating virus that displays the two key influenza virus glycoproteins, hemagglutinin and neuraminidase, and can be safely handled in most research laboratories. This virus is amenable to the evaluation of antiviral antibodies and small-molecule inhibitors and the evolution of viral resistance to these agents. This virus can enable a wider range of researchers to study H5 viruses of pandemic concern.