title: NB protein does not affect influenza B virus replication in vitro and is not required for replication in or transmission between ferrets.
abstract: The influenza B virus encodes a unique protein, NB, a membrane protein whose function in the replication cycle is not, as yet, understood. We engineered a recombinant influenza B virus lacking NB expression, with no concomitant difference in expression or activity of viral neuraminidase (NA) protein, an important caveat since NA is encoded on the same segment and initiated from a start codon just 4 nt downstream of NB. Replication of the virus lacking NB was not different to wild-type virus with full-length NB in clonal immortalized or complex primary cell cultures. In the mouse model, virus lacking NB induced slightly lower IFN-α levels in infected lungs, but this did not affect virus titres or weight loss. In ferrets infected with a mixture of viruses that did or did not express NB, there was no fitness advantage for the virus that retained NB. Moreover, virus lacking NB protein was transmitted following respiratory droplet exposure of sentinel animals. These data suggest no role for NB in supporting replication or transmission in vivo in this animal model. The role of NB and the nature of selection to retain it in all natural influenza B viruses remain unclear.
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Elderfield
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Marios
authors.initials: M
authors.lastname: Koutsakos
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Frise
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Konrad
authors.initials: K
authors.lastname: Bradley
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ashcroft
authors.affiliation: Public Health England, Centre for Infections, Colindale, London, UK.
authors.forename: Shanhjahan
authors.initials: S
authors.lastname: Miah
authors.affiliation: Public Health England, Centre for Infections, Colindale, London, UK.
authors.forename: Angie
authors.initials: A
authors.lastname: Lackenby
authors.affiliation: Section of Virology, Faculty of Medicine, Wright Fleming Institute, Imperial College London, Norfolk Place, London W2 1PG, UK.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Barclay
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005289:Ferrets; D006801:Humans; D009981:Influenza B virus / Q000235:genetics / Q000502:physiology*; D007251:Influenza, Human / Q000635:transmission* / Q000821:virology*; D051379:Mice; D008810:Mice, Inbred C57BL; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D014764:Viral Proteins