Passive transfer of maternal immunoglobulin isotype antibodies against tetanus and influenza and their effect on the response of foals to vaccination.

The research studies how maternal antibodies against influenza and tetanus affect the immune response of young horses (foals) when they are vaccinated against these diseases. It suggests that the timing of initial vaccinations should be delayed until the foal is at least six months old to account for the presence of these maternal antibodies.

Maternal Antibody Transfer and Its Implications

• The study observes that influenza and tetanus-specific antibodies of the IgG sub-isotypes are passed from the mother to foal through the consumption of colostrum, the first milk produced after birth. These antibodies can inhibit the foal’s own immune response to inactive influenza vaccines and tetanus toxin.
• High levels of specific sub-types of these antibodies were found in the foals after consuming colostrum, specifically foals from mares that received booster doses of multi-component vaccines in the last two months of their pregnancy.
• These antibodies declined exponentially over time but were still detectable when the foals reached 26 weeks (approximately six months) of age. This was true regardless of whether the foal was vaccinated before reaching this age.
• The study found that different types of these maternal antibodies declined at different rates.

The Impact of Maternal Antibodies on the Foal’s Response to Vaccination

• Yearlings (one-year-old horses) showed an increase in certain antibody levels after receiving two doses of a multi-component vaccine containing tetanus poison and inactivated influenza antigens. This did not include an increase in influenza IgA antibodies.
• However, yearlings did show a significant immune response to the tetanus vaccine in the form of increased tetanus IgGa, IgGb, and IgG(T) antibodies. A second dose boosted these levels even more, but did not result in an increase in tetanus IgA antibodies.

Recommendations from the Study

• The response of foals to vaccination followed a similar pattern to that observed in yearlings, but the antibody levels were generally lower.
• Interestingly, three-month-old foals showed no increase in certain antibodies in response to the first two vaccine doses and usually required one to three additional booster doses to achieve similar levels to yearlings after two doses.
• Considering the influence of maternal antibodies on the foal’s immune response, the study suggests deferring the primary Immunisation of foals born to vaccinated mares until they are at least six months old.

Concluding, the study provides critical insights into the interaction between maternal antibodies and the immune response of foals to vaccination. The suggested delay in initial immunization could be influential for veterinary practitioners in maximizing the effectiveness of the foal’s immune response to influenza and tetanus vaccinations.