title: Exhaled aerosol transmission of pandemic and seasonal H1N1 influenza viruses in the ferret.
abstract: Person-to-person transmission of influenza viruses occurs by contact (direct and fomites) and non-contact (droplet and small particle aerosol) routes, but the quantitative dynamics and relative contributions of these routes are incompletely understood. The transmissibility of influenza strains estimated from secondary attack rates in closed human populations is confounded by large variations in population susceptibilities. An experimental method to phenotype strains for transmissibility in an animal model could provide relative efficiencies of transmission. We developed an experimental method to detect exhaled viral aerosol transmission between unanesthetized infected and susceptible ferrets, measured aerosol particle size and number, and quantified the viral genomic RNA in the exhaled aerosol. During brief 3-hour exposures to exhaled viral aerosols in airflow-controlled chambers, three strains of pandemic 2009 H1N1 strains were frequently transmitted to susceptible ferrets. In contrast one seasonal H1N1 strain was not transmitted in spite of higher levels of viral RNA in the exhaled aerosol. Among three pandemic strains, the two strains causing weight loss and illness in the intranasally infected 'donor' ferrets were transmitted less efficiently from the donor than the strain causing no detectable illness, suggesting that the mucosal inflammatory response may attenuate viable exhaled virus. Although exhaled viral RNA remained constant, transmission efficiency diminished from day 1 to day 5 after donor infection. Thus, aerosol transmission between ferrets may be dependent on at least four characteristics of virus-host relationships including the level of exhaled virus, infectious particle size, mucosal inflammation, and viral replication efficiency in susceptible mucosa.
authors.affiliation: Program in Applied Science, Lovelace Respiratory Research Institute, Albuquerque, New Mexico, United States of America. fkoster@lrri.org
authors.forename: Frederick
authors.initials: F
authors.lastname: Koster
authors.forename: Kristine
authors.initials: K
authors.lastname: Gouveia
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhou
authors.forename: Kristin
authors.initials: K
authors.lastname: Lowery
authors.forename: Robert
authors.initials: R
authors.lastname: Russell
authors.forename: Heather
authors.initials: H
authors.lastname: MacInnes
authors.forename: Zemmie
authors.initials: Z
authors.lastname: Pollock
authors.forename: R Colby
authors.initials: RC
authors.lastname: Layton
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cromwell
authors.forename: Denise
authors.initials: D
authors.lastname: Toleno
authors.forename: John
authors.initials: J
authors.lastname: Pyle
authors.forename: Michael
authors.initials: M
authors.lastname: Zubelewicz
authors.forename: Kevin
authors.initials: K
authors.lastname: Harrod
authors.forename: Rangarajan
authors.initials: R
authors.lastname: Sampath
authors.forename: Steven
authors.initials: S
authors.lastname: Hofstadler
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Yushi
authors.initials: Y
authors.lastname: Liu
authors.forename: Yung-Sung
authors.initials: YS
authors.lastname: Cheng
mesh_terms: D000336:Aerosols; D000818:Animals; D045853:Exhalation; D005289:Ferrets / Q000821:virology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology; D008168:Lung / Q000821:virology; D008297:Male; D009330:Nebulizers and Vaporizers; D009976:Orthomyxoviridae Infections / Q000635:transmission*; D058873:Pandemics / Q000517:prevention & control; D012367:RNA, Viral / Q000378:metabolism; D012621:Seasons; D013045:Species Specificity; D013997:Time Factors; D019562:Viral Load
chemical_list: D000336:Aerosols; D012367:RNA, Viral