Prophylactic immunomodulation with α-mannan attenuates PRRSV-induced disease in piglets.

Area of Science:

• Veterinary Virology
• Immunology
• Animal Science

Background:

• Porcine Reproductive and Respiratory Syndrome virus (PRRSV) significantly impacts the global swine industry.
• Effective control measures for PRRSV are currently limited, necessitating novel approaches.

Purpose of the Study:

• To evaluate the anti-PRRSV effects of alpha-mannan (α-mannan) in vitro and in vivo.
• To assess the immunomodulatory potential of α-mannan against PRRSV infection.

Main Methods:

• In vitro cytotoxicity assays and PRRSV replication inhibition tests.
• In vivo studies involving prophylactic oral administration of α-mannan to piglets challenged with PRRSV.
• Monitoring of PRRSV RNA loads, cytokine expression (IFN-γ, TNF-α, IL-6), clinical signs, and pulmonary pathology.

Main Results:

• α-mannan demonstrated no cytotoxicity and did not directly inhibit PRRSV replication in vitro.
• In vitro, α-mannan modulated the immune response by inducing IFN-γ and suppressing PRRSV-induced TNF-α and IL-6.
• In vivo, prophylactic α-mannan administration was associated with trends of reduced PRRSV RNA loads, attenuated pulmonary pathology, shorter viral shedding duration, delayed fever onset, and 100% survival rate.

Conclusions:

• Prophylactic administration of α-mannan shows potential for reducing PRRSV RNA load and mitigating disease severity in piglets.
• α-mannan exhibits immunomodulatory effects beneficial for PRRSV control.
• α-mannan represents a promising candidate for developing novel strategies against PRRSV.