Epithelia-damaging virus infections affect vitamin A status in chickens

The effect of infection with infectious bronchitis virus (IBV) and reovirus (RV) on vitamin A status was investigated in chickens with a normal or marginal intake of vitamin A. At the age of 4 wk, chickens were infected with either IBV or RV, primarily affecting the respiratory or intestinal tract, respectively. Both viruses lowered plasma retinol levels significantly. The effect was more pronounced in chickens fed a diet marginally deficient in vitamin A than in those fed a diet adequate in vitamin A. Concentrations of retinol-binding protein, transthyretin and albumin in RV-infected chickens were also significantly lower than in noninfected chickens fed the same diets; in chickens infected with IBV, there was no effect. These results suggest that the reduced vitamin A status of IBV-infected chickens could be attributed to increased rate of utilization by tissues. In RV infection, this mechanism could be involved but impaired absorption of nutrients (including vitamin A) and direct loss of nutrients via the intestinal tract could also be important.