Studies of polymicrobial interactions have revealed that cellular receptors such as CD14, CD15, CD18, carcinoembryonic antigen-related cell adhesion molecule (CEACAM), macrophage receptor (MARCO), platelet-activating factor (PAFR), fibronectin (FN) and fimbriae-associated receptors are likely to be involved in increased bacterial adherence after viral infection [9,11,14,18-21]. This evidence concerns the gene FN1 and viral infectious disease.