Human Coronavirus 229E Infects Polarized Airway Epithelia from the Apical Surface

Abstract

Gene transfer to differentiated airway epithelia with existing viral vectors is very inefficient when they are applied to the apical surface. This largely reflects the polarized distribution of receptors on the basolateral surface. To identify new receptor-ligand interactions that might be used to redirect vectors to the apical surface, we investigated the process of infection of airway epithelial cells by human coronavirus 229E (HCoV-229E), a common cause of respiratory tract infections. Using immunohistochemistry, we found the receptor for HCoV-229E (CD13 or aminopeptidase N) localized mainly to the apical surface of airway epithelia. When HCoV-229E was applied to the apical or basolateral surface of well-differentiated primary cultures of human airway epithelia, infection primarily occurred from the apical side. Similar results were noted when the virus was applied to cultured human tracheal explants. Newly synthesized virions were released mainly to the apical side. Thus, HCoV-229E preferentially infects human airway epithelia from the apical surface. The spike glycoprotein that mediates HCoV-229E binding and fusion to CD13 is a candidate for pseudotyping retroviral envelopes or modifying other viral vectors.While gene transfer is considered the most direct means to treat or prevent the lung disease associated with cystic fibrosis, several barriers prevent the practical application of this approach (36). A problem that currently limits efficient gene transfer to airway epithelia is that the receptor in most cases is localized to the basolateral surface. This has been demonstrated for several retroviral envelopes (32, 33), adenovirus (19,31,34), and adeno-associated virus (7). Thus, the mere fact that a viral vector is derived from a respiratory pathogen does not imply that it will efficiently transduce airway epithelia via the apical surface.As a first step in identifying novel ligand-receptor interactions that might be exploited to direct vectors to the apical surface of airway epithelia, we studied the infection process of human coronavirus 229E (HCoV-229E) in well-differentiated airway epithelia. Human coronaviruses are enveloped, plusstranded RNA viruses represented by the two serologically unrelated strains, HCoV-229E and HCoV-OC43, that cause mainly upper respiratory tract infections (3, 16). Epidemiological data demonstrate that the HCoV infections are responsible for approximately one-third of common colds (17, 35). HCoV-229E contains a genomic RNA of 27,277 nucleotides, a nucleocapsid (N) protein and a lipid envelope with three major membrane proteins. The three membrane proteins are the membrane (M) glycoprotein, the envelope (E) protein, and the surface spike (S) glycoprotein (11).We selected HCoV-229E for our studies for several reasons. First, it is a common cause of respiratory infections in humans (16). Second, the viral proteins involved in cell binding and the host cell glycoprotein that serves as the receptor have been identified (20,38). Third, infection by HCoV-229E involves both binding ...

Measles Virus Preferentially Transduces the Basolateral Surface of Well-Differentiated Human Airway Epithelia

“…For example, we previously reported that human coronavirus (serotype 229E) efficiently transduces the apical surface of well-differentiated airway epithelia (28). In addition, respiratory syncytial virus and parainfluenza virus also have the capacity to enter polarized human airway epithelial cells through the apical surface (P. L. Sinn and P. B. McCray, unpublished observations).…”

The RNA Binding Domain of Influenza A Virus NS1 Protein Affects Secretion of Tumor Necrosis Factor Alpha, Interleukin-6, and Interferon in Primary Murine Tracheal Epithelial Cells

“…Primary lung and airway epithelial cell cultures have been used to investigate cellular responses to infection with many respiratory viruses, including influenza A virus (3,7,11,20,39,42,49,64,65,78,106,117,120,129), respiratory syncytial virus (RSV) (69,135), hantavirus (95), human coronaviruses (104,105,121), human parainfluenza virus type 3 (134), and adenovirus (85,86,110,131,132). Unlike conventional transformed cell lines, primary airway cultures, when differentiated fully, can mirror the in vivo tissue by being organized into a multilayered, polarized culture consisting of multiple cell types (7,42,85,110,117,134,135).…”

Glycocalyx Restricts Adenoviral Vector Access to Apical Receptors Expressed on Respiratory Epithelium In Vitro and In Vivo: Role for Tethered Mucins as Barriers to Lumenal Infection

“…Other viruses are known to efficiently infect the respiratory epithelium and have presumably evolved strategies to circumvent the glycocalyx barrier. Human coronaviruses, filoviruses, respiratory syncytial virus, and Sendai virus have improved gene transfer capacities for the airway epithelium after lumenal delivery compared to AdV (29,38,45,48). Further studies of the interactions of these enveloped viruses with the airway epithelium and a definition of how they circumvent the glycocalyx barrier may reveal mechanisms that will aid the development of improved vectors for the delivery of therapeutic transgenes to the lung epithelium.…”