One question frequently asked is "How does a vaccine given to the sow result in benefits in the growing pig that last until slaughter when the antibody immunity passed from the sow via the colostrum has been depleted?"

Leaders in PCV2 vaccinology and research Merial, reveal that while maternally derived antibodies protect the piglet from PCV2 virus during the pig’s first contact with the virus in the first days and weeks of life, allowing the pig’s immune system to mature properly, it has now been demonstrated piglets also receive important cell-mediated immunity cells via the colostrum.

These maternal T-cells producing PCV2 specific IFNγ, part of the sow’s active immunity against PCV2, have been shown to be transferred through the colostrum in addition to the all-important PCV2 antibodies. The passive transfer of immunity early in life is thought to be critical in the development of the pig’s immune system and helps enable it to fight any viral challenge encountered later in life.

In two separate experiments T-cells have been detected in pigs, increasing during the first week of life and remaining present until at least thirty days of age.

Merial vet Ricardo Neto said: “The discovery of the transfer of maternal PCV2 specific T-cells is very exciting. We know CIRCOVAC gives pigs protection from the day of birth through maternal antibodies via colostrum but the discovery of PCV2 specific T-cell transfer can help explain why the benefits of the passive immunity afforded by Circovac are observed in pigs right up to the day of slaughter.”

While this type of cell can be present in the sow for years, further research is needed to understand more fully how these cells transferred through the colostrum in the pig impact on the development of immunity to PCV2.