In vitro culture of porcine respiratory nasal mucosa explants for studying the interaction of porcine viruses with the respiratory tract.

The mucosal surface of the respiratory tract is a common site of entry of many viruses. Molecular and cellular aspects of the interactions of respiratory viruses with the respiratory nasal mucosa are largely unknown. In order to be able to study those interactions in depth, an in vitro model was set up. This model consists of porcine respiratory nasal mucosa explants, cultured at an air-liquid interface. Light microscopy, scanning electron microscopy and transmission electron microscopy, combined with morphometric analysis and a fluorescent Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labelling (TUNEL) staining were used to evaluate the effects of in vitro culture on the integrity and viability of the explants. The explants were maintained in culture for up to 60 h post-sampling without significant morphometric (epithelial thickness, epithelial morphology, thickness of the lamina reticularis, continuity of the lamina densa, relative amounts of collagen and nuclei) changes and changes in viability. The potential to infect the explants was demonstrated for two porcine respiratory viruses of major importance: suid herpesvirus 1 and swine influenza virus H1N1. In conclusion, this in vitro model represents an ideal tool to study interactions between infectious agents and porcine respiratory nasal mucosa.