Oral administration of lactobacilli from human intestinal tract protects mice against influenza virus infection
Aims: Our study was conducted to evaluate the potent protective effects of oral administration of probiotic Lactobacillus strains against influenza virus (Flu) infection in a mouse model.
Method and Results: Lyophilized Lactobacillus rhamnosus GG (LGG) and Lactobacillus gasseri TMC0356 (TMC0356) were orally administered to BALB/c mice for 19 days. The test mice were intranasally infected with Flu A/PR/8/34 (H1N1) on day 14, and any changes in clinical symptoms were monitored.
After 6 days of infection, the mice were killed and pulmonary virus titres were determined.
The clinical symptom scores of mice administered oral LGG and TMC0356 were significantly ameliorated, compared to those of the control mice (P < 0·01). The pulmonary virus titres of the mice fed LGG and TMC0356 were also significantly decreased compared to those of control mice (P < 0·05).
Conclusions: These results indicate that oral administration of lactobacilli, such as LGG and TMC0356, might protect a host animal against Flu infection.
Significance and Impact of the Study: These results demonstrate that oral administration of selected lactobacilli might protect host animals from Flu infection by interactions with gut immunity.
Further Readings of Interest
Probiotic curbs autism features in mouse model
Treatment with a single bacterial species curbs anxiety and repetitive behaviors and boosts vocalizations in a mouse model of autism, according to a poster presented Monday at the 2012 Society for Neuroscience annual meeting in New Orleans.
These mice were born to mothers exposed to an infection during their pregnancy. This in utero exposure alters the offspring’s immune system and leads to behaviors reminiscent of autism.
The so-called probiotic treatment does not improve the animals’ social behaviors. Still, the study fuels the long-standing hypothesis that the immune system affects the brain and contributes to some aspects of autism, the researchers say.
The study provides proof of principle that changes to even one of the slew of bacterial species in the gut can affect behavior, says Paul Patterson, professor of biological sciences at the California Institute of Technology. “Now, how does that work? Where it is acting? We don’t know.”
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Narcissus tazetta lectin shows strong inhibitory effects against respiratory syncytial virus, influenza A (H1N1, H3N2, H5N1) and B viruses
A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose–agarose and fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent molecular mass of 26 kDa by gel filtration and 13 kDa by SDS–PAGE, indicating that it is probably a dimer with two identical subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation by the human respiratory syncytial virus (RSV) with an IC50 of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with IC50 values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner.
It is worth noting that the modes of antiviral action of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of influenza A (H1N1) virus.
NTL with a high selective index (SI=CC50/IC50 >141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development as an antiviral agent.