Abstract |
In adults, clinical symptoms caused by respiratory syncytial virus (RSV) are confined to the upper respiratory tract, while RSV infection in infants frequently causes bronchiolitis and pneumonia. The preferential localization of RSV infection to the upper airways may be due partially to protective immunity, but may also depend on a difference in susceptibility of epithelial cells from upper and lower airways, or on antiviral activities of bronchoalveolar macrophages (AM). In the study, the authors have compared the susceptibility of primary adult human nasal epithelium (NE), primary human bronchial epithelium (BE), a human bronchial epithelial cell line (BEAS-2B), and adult human AM, to infection with RSV. The cell cultures were infected with multiplicities of infection (moi) of 1 and 0.1. Virus release into the supernatants was assayed at days 1, 2, 4, and 7, and % of virus positive cells determined by immunofluorescence at the same timepoints. Based on study observations, the authors conclude that at least under the conditions of primary culture, both adult human NE and BE are highly susceptible to RSV infection; however, the NE release more infectious virus than BE. Although AM are infected by RSV, virus replication and spread by reinfection are restricted in these cells, suggesting that AM are probably not important in the spread of virus, and may play a protective role in RSV infection of the bronchoalveolar region of the lung. |