Oral Administration of Probiotics Protected Mice from Influenza Virus Infection

Influenza viruses are highly mutable and give rise to annual outbreaks. In this study, the analysis showed that intake of probiotics alleviated symptoms of influenza virus (H1N1) infection in mice. Five days after infection, in the infected-model group the body weight was significantly reduced. Two Bifidobacteria and three Lactobacilli probiotics administer orally were found to delay the body weight loss by three days. Subsequent rate of body weight loss during the following two days was reduced in B. adolescentis and B. breve groups, whereas the rate of body weight loss in the Lactobacillus rhamnosus, L. platarium and L. fermentum groups was comparable to that of the control group. Five days after infection, the viral load of the lungs of 50% of the mice in the B. breve group were reduced but the load of all the other groups were comparable to the control. The relative expression of MxA (an antiviral protein) was comparable in all the experimental groups, while that of Oasia (another antiviral protein) was significantly higher in the L. planetarium and L. fermentum groups. The histopathological sections of the lungs examined on the fifth days after infection in all the probiotic groups showed a marked improvement in inflammatory infiltration, and bronchus integrity. The results indicated that the protective effects of Bifidobacteria and Lactobacilli probiotics on influenza virus infection could be a combination of the various immunological and functional factors for the different probiotics.