Bifidobacteria support optimal infant vaccine responses.

Area of Science:

• Immunology
• Microbiology
• Neonatal Health

Background:

• Antibiotic exposure in early life is linked to reduced vaccine effectiveness.
• The underlying mechanisms for this impaired immune response are not well understood.

Purpose of the Study:

• To investigate the impact of early-life antibiotic exposure on infant immune responses to vaccination.
• To explore the role of the gut microbiota in mediating these effects.

Main Methods:

• Prospective follow-up of 191 infants from birth to 15 months.
• Systems vaccinology approach, including antibody titrations and transcriptional profiling.
• Faecal metagenomics to analyze gut microbiota composition.

Main Results:

• Neonatal antibiotic exposure, but not intrapartum exposure, was associated with lower antibody titres to pneumococcal and Hib/diphtheria antigens at 7 months.
• Infants exposed to neonatal antibiotics showed an inflammatory transcriptional profile before vaccination and reduced Bifidobacterium abundance.
• Reduced Bifidobacterium abundance correlated with lower vaccine antibody titres six months later.
• Preclinical models showed microbiota-dependent vaccine responses, restorable with Bifidobacterium species.

Conclusions:

• Early-life antibiotic exposure negatively impacts vaccine immunogenicity through microbiota alterations.
• Targeting the microbiota, for example with Bifidobacterium species, may restore vaccine responses.
• Microbiota-targeted interventions show promise for mitigating antibiotic-induced impairment of vaccine responses.