At day one and day five after infection, PUFA-fed mice had higher lung viral load and lower body weight than the control; they also had impaired production of lung IFN-γ, lung IgA-specific antibodies, and serum IgG, although lung IFN-α/β and the relative proportions of bronchial lymph node CD4+ and CD8+ T lymphocytes did not differ from control after infection. This evidence concerns the gene IFNG and infection.