By Sharon Nirenberg
NEW YORK (Reuters Health) - The composition of intestinal microbes may impact the efficacy of the seasonal influenza vaccine, a study in mice shows.
"Gut bacteria express a protein called flagellin, which triggers a receptor known as TLR5 (toll-like receptor 5) on immune cells, causing increased production of antibodies in response to flu vaccination," said co-author Dr. Bali Pulendran of Emory Vaccine Research Center in Atlanta, Georgia.
"Depletion of gut bacteria by antibiotic treatment may affect immunity to vaccination in humans," Dr. Pulendran told Reuters Health by email. "People in different communities, such as those in rural areas of developing countries versus those in developed countries, have very different types of gut bacteria, and it is conceivable that this difference influences immunity to vaccination."
In a report online September 18 in Immunity, Dr. Pulendran and colleagues describe how they administered the trivalent influenza vaccine to Tlr5-knock-out mice as well as wild-type mice.
The mice without Tlr5 demonstrated reduced antibody titers and decreased plasma cell frequency in response to vaccination, the researchers found.
They also compared vaccine-induced immune response between mice raised in a germ-free environment, mice treated with antibiotics, and germ-exposed mice.
Mice raised in a germ-free environment and those treated with antibiotics showed reduced antibody titers in response to vaccination. However, when the germ-free and antibiotic-treated mice orally received flagellated E. coli to reconstitute the gut microbiota, the antibody response to the vaccine was restored.
"The results of our experiment do raise the possibility that antibiotic treatment may impact immunity to vaccination in humans, but this can only be definitively tested in an experiment in humans," Dr. Pulendran concluded.
Comment: A wonderful concept that further illustrates the pitfalls of antibiotic misuse. There are many things about proliferating & rampant antibiotic use that we are yet to know, and I believe that in half century from now antibiotic use would be far more restricted as compared to what we have today due to various reasons, including the fact that we may come to know that they do end up causing long term problems to people taking them.