title: Replication-Competent Influenza A and B Viruses Expressing a Fluorescent Dynamic Timer Protein for In Vitro and In Vivo Studies.
abstract: Influenza A and B viruses (IAV and IBV, respectively) cause annual seasonal human respiratory disease epidemics. In addition, IAVs have been implicated in occasional pandemics with inordinate health and economic consequences. Studying influenza viruses in vitro or in vivo requires the use of laborious secondary methodologies to identify infected cells. To circumvent this requirement, replication-competent infectious influenza viruses expressing an easily traceable fluorescent reporter protein can be used. Timer is a fluorescent protein that undergoes a time-dependent color emission conversion from green to red. The rate of spectral change is independent of Timer protein concentration and can be used to chronologically measure the duration of its expression. Here, we describe the generation of replication-competent IAV and IBV where the viral non-structural protein 1 (NS1) was fused to the fluorescent dynamic Timer protein. Timer-expressing IAV and IBV displayed similar plaque phenotypes and growth kinetics to wild-type viruses in tissue culture. Within infected cells, Timer's spectral shift can be used to measure the rate and cell-to-cell spread of infection using fluorescent microscopy, plate readers, or flow cytometry. The progression of Timer-expressing IAV infection was also evaluated in a mouse model, demonstrating the feasibility to characterize IAV cell-to-cell infections in vivo. By providing the ability to chronologically track viral spread, Timer-expressing influenza viruses are an excellent option to evaluate the in vitro and in vivo dynamics of viral infection.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, 14642, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Breen
authors.affiliation: Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, 14642, United States of America.
authors.forename: Aitor
authors.initials: A
authors.lastname: Nogales
authors.affiliation: Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, 14642, United States of America.
authors.forename: Steven F
authors.initials: SF
authors.lastname: Baker
authors.affiliation: Department of Population Health, University of Georgia, 953 College Station Road, Athens, Georgia, 30602, United States of America.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Perez
authors.affiliation: Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, New York, 14642, United States of America.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Sobrido
mesh_terms: D000818:Animals; D004285:Dogs; D057809:HEK293 Cells; D006801:Humans; D009980:Influenza A virus / Q000235:genetics / Q000502:physiology*; D009981:Influenza B virus / Q000235:genetics / Q000502:physiology*; D007251:Influenza, Human / Q000235:genetics / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics / Q000502:physiology
chemical_list: D008164:Luminescent Proteins
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