Effect of dietary intake of fat-soluble vitamins on intensity of experimental swine influenza virus infection in mice

Abstract

Mice were fed defined diets low in in vitamins A, D, and E, or containing added fat-soluble vitamins, for four weeks and were then inoculated intranasally with swine influenza virus. Intensity of influenzal infection was determined quantitatively by use of a combined death and lung consolidation end point. Vitamin A was shown to have a definite and significant ability to decrease the intensity of experimental swine influenza virus infection in mice, resulting in fewer mice infected from a standard inoculum, as well as less severe disease and fewer deaths among those mice that did become infected. The difference in morbidity was not due to lowering of the ability to produce antibody. Mice fed diets with vitamin E in combination with vitamin A had more severe infections than mice fed vitamin A alone or vitamin A in combination with vitamin D. Vitamin E, when added in combination with vitamin D, did not alter the severity of infection in mice fed such diets as compared to mice which received vitamin D as the sole supplemental fat-soluble vitamin. Intensity of infection in mice fed diets containing (1) no fat-soluble vitamins, (2) vitamin D alone, (3) vitamin E alone, or (4) vitamins D and E in combination was essentially the same.