Effective Apical Infection of Differentiated Human Bronchial Epithelial Cells and Induction of Proinflammatory Chemokines by the Highly Pneumotropic Human Adenovirus Type 14p1.

Elena Lam,Albert Heim,Mirja Ramke,Thomas Dobner,Gregor Warnecke,Sonja Schrepfer,Verena Kopfnagel,Michael Nevels

doi:10.1371/journal.pone.0131201

Abstract

BackgroundOnly a few pneumotropic types of the human adenoviruses (e.g. type B14p1) cause severe lower respiratory tract infections like pneumonia and acute respiratory distress syndrome (ARDS) even in immunocompetent patients. By contrast, many other human adenovirus (HAdV) types (e.g. HAdV-C5) are associated mainly with upper respiratory tract infections. This is in accordance with a highly physiological cell culture system consisting of differentiated primary human bronchial epithelial cells which are little susceptible for apical HAdV-C5 infections.Objective and MethodsWe hypothesized that a pneumotropic and highly pathogenic HAdV type infects differentiated human bronchial epithelial cells efficiently from the apical surface and also induces proinflammatory cytokines in order to establish ARDS and pneumonia. Therefore, the apical infection of differentiated primary human bronchial epithelial cells with the pneumotropic and virulent type HAdV-B14p1 was investigated in comparison to the less pneumotropic HAdV-C5 as a control.ResultsBinding of HAdV-B14p1 to the apical surface of differentiated human bronchial epithelial cells and subsequent internalization of HAdV DNA was 10 fold higher (p<0.01) compared to the less-pneumotropic HAdV-C5 one hour after infection. Overall, the replication cycle of HAdV-B14p1 following apical infection and including apical release of infectious virus progeny was about 1000-fold more effective compared to the non-pneumotropic HAdV-C5 (p<0.001). HAdV-B14p1 infected cells expressed desmoglein 2 (DSG2), which has been described as potential receptor for HAdV-B14p1. Moreover, HAdV-B14p1 induced proinflammatory chemokines IP-10 and I-Tac as potential virulence factors. Interestingly, IP-10 has already been described as a marker for severe respiratory infections e.g. by influenza virus A H5N1.ConclusionsThe efficient "apical to apical" replication cycle of HAdV-B14p1 can promote endobronchial dissemination of the infection from the upper to the lower respiratory tract. Simultaneous induction of proinflammatory cytokines probably contributes to the high virulence of HAdV-B14p1.

Highlights

Four types of the 71 human adenovirus (HAdV) types frequently cause lower respiratory tract infections, presenting as pneumonia and acute respiratory distress syndrome (ARDS).HAdV-B14 was first described as respiratory pathogen in Dutch military recruits in the late 1950s [1] and found to be associated with pharyngoconjunctival fever in college students but was not associated with severe clinical diseases [2]
HAdV-B14p1 infected cells expressed desmoglein 2 (DSG2), which has been described as potential receptor for HAdV-B14p1
The epithelial cells were cultured for 6 weeks for differentiation until differentiation was observed by expression of cilia (S1 Fig) and high transepithelial electrical resistance (TEER) >400 Ωcm2

Summary

Introduction

Four types (type 4 of species HAdV-E, types 3, 7 and 14p1 of species HAdV-B) of the 71 human adenovirus (HAdV) types frequently cause lower respiratory tract infections, presenting as pneumonia and acute respiratory distress syndrome (ARDS).HAdV-B14 was first described as respiratory pathogen in Dutch military recruits in the late 1950s [1] and found to be associated with pharyngoconjunctival fever in college students but was not associated with severe clinical diseases [2]. HAdV-B14p1 causes lower respiratory tract infections in military recruits (as HAdV-E4 and -B7) and in the civilian population affecting infants, young adults, and elderly individuals with and without preexisting medical conditions [4]. These findings indicated a higher virulence of the re-emergent HAdV-B14p1 even compared to HAdV-E4 and HAdV-B7. A few pneumotropic types of the human adenoviruses (e.g. type B14p1) cause severe lower respiratory tract infections like pneumonia and acute respiratory distress syndrome (ARDS) even in immunocompetent patients. Many other human adenovirus (HAdV) types (e.g. HAdV-C5) are associated mainly with upper respiratory tract infections. This is in accordance with a highly physiological cell culture system consisting of differentiated primary human bronchial epithelial cells which are little susceptible for apical HAdV-C5 infections

Methods

Results

Conclusion