Growth of respiratory syncytial virus in primary epithelial cells from the human respiratory tract

Abstract

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract disease in infants and children. To study RSV replication, we have developed an in vitro model of human nasopharyngeal mucosa, human airway epithelium (HAE). RSV grows to moderate titers in HAE, though they are significantly lower than those in a continuous epithelial cell line, HEp-2. In HAE, RSV spreads over time to form focal collections of infected cells causing minimal cytopathic effect. Unlike HEp-2 cells, in which wild-type and live-attenuated vaccine candidate viruses grow equally well, the vaccine candidates exhibit growth in HAE that parallels their level of attenuation in children.

FIG. 1.

Growth of RSV in respiratory epithelial tissue culture systems. Titers of RSV strains were determined by plaque assay on HEp-2 cell monolayer cultures maintained under semisolid overlay at 37°C for wild-type RSV and at 32°C for live-attenuated mutants as previously described (13). Virus recovery was significantly greater from HEp-2 cells than from primary human epithelial cells (HAE) (P < 0.01 at 48 and 72 h).

FIG. 2.

Demonstration of the limited growth and focal nature of the infection of RSV in HAE. Shown are expression of GFP by rgRSV in (A) HEp-2 cells and (B) HAE at 72 h after initiation of infection and results of immunoperoxidase staining with a goat biotin-conjugated antibody to RSV (Biodesign International, Saco, ME) in (C) HAE and (D) an adenoid organ culture.