Aims: Human metapneumovirus (HMPV) is a recently discovered respiratory pathogen that presents with similar clinical indications to respiratory syncytial virus (RSV), ranging from mild respiratory symptoms to severe cough, wheezing, bronchiolitis and pneumonia. There is mounting evidence suggesting an association between HMPV infection and asthma exacerbation in both adults and children. Our study examines HMPV infection of primary human bronchial airway cells, comparing responses from normal and asthmatic patients.

Methods: We infected primary human bronchial epithelial cells, fibroblasts and macrophages with HMPV and examined viral replication, production of inflammatory mediators and anti-viral responses.

Results: HMPV can infect human bronchial epithelial cells, fibroblasts and macrophages; however, we have observed several differences between the cell types. Viral replication peaks at 48 hours post infection in epithelial cells, whereas replication is still increasing at 72 hours post infection in fibroblasts. Epithelial cells express MIG, whereas fibroblasts and macrophages release MCP-1. All cell types have a strong anti-viral response, expressing IP-10 and RANTES and the interferon-stimulated gene, ISG56.

Conclusions: Our data demonstrate that HMPV infects and replicates in primary human bronchial epithelial cells, fibroblasts and macrophages, and induce a strong inflammatory and anti-viral response. Future studies are looking at these indices in cells obtained from asthmatic patients to identify a mechanism to explain the link between HMPV infection and asthma etiology and exacerbation.