# Field Studies on the Saccharomyces Yeast Strain MIIP as an Immunomodulator to Mitigate PRRSV Infection in Piglets

## TL;DR

A study found that feeding a specific yeast supplement to piglets can reduce infection by a harmful virus and boost their immune system.

## Contribution

The study demonstrates that MIIP yeast supplementation can reduce PRRSV infection and enhance immunity in piglets under field conditions.

## Key findings

- Piglets supplemented with MIIP yeast showed lower PRRSV antibody-positive rates and viremia.
- MIIP supplementation increased IgA levels in serum and milk, indicating enhanced mucosal immunity.
- Infection rates increased again after supplementation stopped, highlighting the need for continuous use.

## Abstract

This field study on pig farms in Taiwan aimed to evaluate whether supplementing pig diets with MIIP yeast (a strain of Saccharomyces cerevisiae) could help prevent or reduce infection with porcine reproductive and respiratory syndrome virus (PRRSV). The results show that pigs receiving the yeast supplement had lower levels of the virus and antibodies in their blood, indicating reduced infection. On farms where piglets are typically infected between 3 and 6 weeks of age, most piglets in the MIIP group remained uninfected, while those in the control group showed 100% infection. The supplement also enhanced immune function by raising IgA levels in the blood and milk of both piglets and sows. However, once supplementation stopped, infection rates rose again, indicating that continuous use is needed. Overall, MIIP yeast is a promising tool to improve pig health and immunity against PRRSV.

Porcine reproductive and respiratory syndrome virus (PRRSV) remains a significant threat to swine health worldwide, primarily due to its extensive genetic diversity and ability to evade host immune responses, which reduces the effectiveness of vaccines. This field study investigated the immunomodulatory effects of the Saccharomyces cerevisiae strain MIIP as a dietary supplement to mitigate PRRSV infection in piglets under commercial farming conditions. Four trials were conducted across PRRSV-affected herds, with variations in PRRS vaccination practices and infection status. MIIP supplementation led to a significant reduction in the PRRSV antibody-positive rate, titers, and viremia in treated piglets compared to both non-concurrent and concurrent control groups. Enhanced mucosal immunity was also observed, as evidenced by higher total IgA concentrations in serum and milk in the MIIP groups. Although not all immune parameters reached statistical significance, trends consistently favored improved antiviral responses in MIIP-treated animals. These results suggest that dietary supplementation with MIIP yeast can enhance both systemic and mucosal immunity, potentially reducing PRRSV infection and transmission. Further research into its mechanisms, particularly its interaction with innate immune pathways and the gut microbiota, is warranted to optimize PRRSV control strategies.