Kinetics of viral replication in experimental rotavirus infection: effects of high dietary fat

Epidemiological studies suggest that dietary fat can affect the frequency and severity of diarrhoeal illnesses in childhood. To study the effects of dietary fat on the kinetics of rotavirus antigen, 3-week-old mice of rotavirus-seronegative mothers were fed isocaloric diets with 40% of the total calories as fat [either butter (high saturated fat), olive oil (high monounsaturated fat), or corn oil (high polyunsaturated fat)] with one group on low fat (10% of calories) standard diet as controls. Seven-day-old mice from the first litter were killed and their stomach contents (milk) analyzed for total fatty acids. Seven-day-old mice from the second litter were inoculated with EDIM rotavirus, and some were killed at 48 h and others at 120 h postinoculation. The stool was removed from the distal colon of each mouse and examined for evidence of diarrhoea. The small intestine was removed, the contents washed, and the intestine divided into equal thirds. All stool and tissue samples were made to 10% (wt/vol), homogenised, and tested for rotavirus antigen by ELISA. We found that (a) dietary fat markedly altered the fatty acid profile of milk, (b) high saturated dietary fat (butter) delayed the onset of diarrhoea, reduced the excretion of rotavirus antigen in stool, and reduced mucosal antigen in the lower third of the small intestine at 120 h compared to 48 h postinoculation, (c) high polyunsaturated dietary fat initially increased the frequency of diarrhoea and viral antigen in the middle and lower segment at 120 h, followed by a reduction in rotavirus excretion in stool.(ABSTRACT TRUNCATED AT 250 WORDS)