A significant abundance of stool Actinobacteria, particularly Bifidobacterium, was tied to higher responses to oral and parenteral vaccines and a larger thymus among infants, according to study findings in Pediatrics.
M. Nazmul Huda, MS, of the US Department of Agriculture’s Western Human Nutrition Research Center at the University of California, Davis, and colleagues assessed the stool microbiota of 48 Bangladeshi infants at age 6, 11 and 15 weeks. Responses to oral polio virus, bacilli Calmette-Guérin, tetanus toxoid and hepatitis B vaccines were measured at 15 weeks using T-cell proliferation for all vaccines and the delayed-type hypersensitivity skin test response for bacilli Calmette-Guérin vaccine. Immunoglobulin G responses to oral polio virus, tetanus toxoid and hepatitis B vaccines were evaluated using the antibody in lymphocyte supernatant method. Thymic index was measured by ultrasound.
Thirty-three percent of the study cohort had a birth weight less than 2,500 g and 83% were born by caesarian delivery. All infants were breast-fed and some received supplemental foods.
Actinobacteria, predominantly Bifidobacterium longum subspecies infantis, made up the majority of stool microbiota at 15 weeks.
A high abundance of Actinobacteria, particularly Bifidobacterium, was positively associated with T-cell responses to oral polio virus vaccine, purified protein derivative of Mycobacterium bovis and tetanus toxoid vaccines; delayed-type hypersensitivity skin test response; IgG responses; and thymic index.
B. longum subspecies infantis was positively associated with thymic index and several vaccine responses.
On the genus level, Actinomyces, Corynebacterium, Rothia and Bifidobacterium all had positive associations with at least one response.
Bacterial diversity and abundance of Enterobacteriales, Pseudomonadales and Clostridiales were associated with neutrophilia and lower vaccine responses.
Relative abundance of stool microbiota often differs by mode of delivery, but no such differences were found at 15 weeks. More extensive breast-feeding was associated with a higher abundance of B. longum. Nutritional status correlated positively with B. longum and negatively with Escherichia/Shigella.
“A high abundance of Actinobacteria, particularly Bifidobacterium, in early infancy is associated with a higher [thymic index], greater vaccine-specific and polyclonal T-cell proliferation, and a greater [purified protein derivative-delayed-type hypersensitivity] skin test response. Although this study is observational and not designed to assess causality, the data do suggest that Bifidobacterium colonization enhances both oral and systemic vaccine response by supporting T-cell immunity. … This study raises the possibility that supporting an ‘optimal’ microbial community early in infancy (eg, by supporting breast-feeding) might enhance vaccine responses,” the researchers concluded.
Disclosure: The researchers report no relevant financial disclosures.