Antigen-specific immunoglobulin variable region sequencing measures humoral immune response to vaccination in the equine neonate.
Authors: Tallmadge Rebecca L, Miller Steven C, Parry Stephen A, Felippe Maria Julia B
Journal: PloS one
Summary
# Editorial Summary Maternal antibodies present at birth can suppress a foal's own immune response to vaccination, yet this study reveals that neonatal vaccination still stimulates a genetically diverse antibody-producing response independent of passive immunity. Using molecular sequencing of antibody genes from foals vaccinated with either keyhole limpet hemocyanin or equine influenza vaccine, researchers found that vaccinated foals mounted measurable immunoglobulin responses regardless of their dam's vaccination status—with KLH-specific IgG rising significantly (p<0.0001) between days 21 and 42 in foals from non-vaccinated mares, and detectable B cell responses occurring even in foals from vaccinated mares despite suppressed serum antibody levels. The repertoire of antibody genes expressed showed genuine isotype switching and diversity comparable to vaccinated adult horses, suggesting neonatal B cells are responding with functional maturation rather than merely passively receiving protection. However, the limited expansion of memory B cells and cytokine response during the study period indicates that whilst early vaccination establishes the foundation for adaptive immunity, the protective window remains narrow and may require strategic timing or booster protocols to optimise long-term immunity. These findings support neonatal vaccination as immunologically sound practice, though they highlight the importance of careful vaccination scheduling that accounts for the gradual rather than immediate development of foal immunity.
Read the full abstract on PubMed
Practical Takeaways
- •Vaccinating pregnant mares may compromise subsequent humoral immune responses to vaccination in their foals, particularly for influenza, suggesting vaccination timing strategies warrant consideration
- •Neonatal foals can mount independent B cell responses to vaccines despite maternal antibodies, but practical response amplification may be limited in the first 6 weeks of life
- •Early neonatal vaccination generates appropriate immunological diversity and isotype switching, providing a foundation for later booster responses, even when maternal immunity is present
Key Findings
- •KLH-specific IgG significantly increased between days 21-42 in vaccinated foals from non-vaccinated mares (p<0.0001), but only trended toward increase in foals from vaccinated mares (p=0.07)
- •Influenza-specific IgG rapidly decreased in vaccinated foals from vaccinated mares despite vaccination, indicating maternal antibody suppression of humoral response
- •Both IGHM and IGHG sequences were detected in antigen-specific B cells of vaccinated foals regardless of maternal vaccination status, demonstrating independent neonatal immune repertoire generation
- •Vaccinated neonates generated diverse immunoglobulin repertoires with isotype switching comparable to vaccinated mares, but showed limited lymphocyte population expansion during the study period