title: Establishment and clinical applications of a portable system for capturing influenza viruses released through coughing.
abstract: Coughing plays an important role in influenza transmission; however, there is insufficient information regarding the viral load in cough because of the lack of convenient and reliable collection methods. We developed a portable airborne particle-collection system to measure the viral load; it is equipped with an air sampler to draw air and pass it through a gelatin membrane filter connected to a cone-shaped, megaphone-like device to guide the cough airflow to the membrane. The membrane was dissolved in a medium, and the viral load was measured using quantitative real-time reverse transcriptase-polymerase chain reaction and a plaque assay. The approximate viral recovery rate of this system was 10% in simulation experiments to collect and quantify the viral particles aerosolized by a nebulizer. Using this system, cough samples were collected from 56 influenza A patients. The total viral detection rate was 41% (23/56), and the viral loads varied significantly (from <10, less than the detection limit, to 2240 viral gene copies/cough). Viable viruses were detected from 3 samples with ≤18 plaque forming units per cough sample. The virus detection rates were similar among different groups of patients infected with different viral subtypes and during different influenza seasons. Among patients who did not receive antiviral treatment, viruses were detected in one of six cases in the vaccinated group and four of six cases in the unvaccinated group. We found cases with high viral titers in throat swabs or oral secretions but very low or undetectable in coughs and vice versa suggesting other possible anatomical sites where the viruses might be mixed into the cough. Our system is easy to operate, appropriate for bedside use, and is useful for comparing the viral load in cough samples from influenza patients under various conditions and settings. However, further large-scale studies are warranted to validate our results.
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan; Department of International Health, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Hatagishi
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Ohmiya
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan.
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yano
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Hori
authors.affiliation: Department of Respiratory Medicine, Sendai Medical Center, Sendai, Japan.
authors.forename: Wakana
authors.initials: W
authors.lastname: Saito
authors.affiliation: Department of Respiratory Medicine, Sendai Medical Center, Sendai, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miki
authors.affiliation: Division of Public Health, Department of Infectious Disease Control and International Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Division of Public Health, Department of Infectious Disease Control and International Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Saito
authors.affiliation: Department of International Health, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan; Department of International Health, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Shoji Clinic, Sendai, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Shoji
authors.affiliation: Japan Self-Defense Force Sendai Hospital, Sendai, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Morisaki
authors.affiliation: Takasago Thermal Engineering Co., Ltd., Tokyo, Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Sakata
authors.affiliation: Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Nishimura
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D002460:Cell Line; D003371:Cough / Q000821:virology*; D004285:Dogs; D005260:Female; D006801:Humans; D007251:Influenza, Human / Q000635:transmission*; D008297:Male; D008875:Middle Aged; D009975:Orthomyxoviridae / Q000235:genetics* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019562:Viral Load; D055815:Young Adult
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