[Plans for using vaccination in Aujeszky's disease]

Area of Science:

• Veterinary Virology
• Immunology
• Swine Health

Background:

• Swine fever (AD) remains a significant concern in swine farming.
• Maternal immunity can interfere with piglet vaccination effectiveness.
• Understanding the interaction between passive immunity and vaccination is crucial for disease control.

Purpose of the Study:

• To investigate the impact of maternally derived antibodies on the efficacy of a live swine fever vaccine (MK-25) in piglets.
• To determine the optimal vaccination timing and dosage in the presence of passive immunity.
• To assess the virological and immunological responses following vaccination and challenge.

Main Methods:

• Clinical, serological, virological, and pathomorphological assessments were performed on 140 piglets from vaccinated sows.
• Piglets were vaccinated with varying doses of MK-25 vaccine at different time points and subsequently challenged with a virulent AD virus.
• Virus isolation, antibody titration, and histopathological examination of neural and lymphoid tissues were conducted.

Main Results:

• No clinical signs of encephalitis were observed, but non-suppurative meningoencephalitis was detected in some vaccinated groups.
• Lymphohistiocytic interstitial pneumonia and intranuclear inclusions in tonsillar macrophages were identified.
• Virus was isolated from tonsils and lungs; increased antibody titers were observed in all vaccinated pigs.
• Passively acquired immunity neutralized the vaccine virus, preventing active immunity development until overcome by increased vaccine quantities.

Conclusions:

• Maternally derived antibodies significantly neutralize live swine fever vaccine virus in piglets.
• Vaccination timing and dosage adjustments are necessary to overcome maternal immunity and achieve effective active immunization.
• Histopathological findings indicate subclinical effects of vaccination and challenge, highlighting the importance of comprehensive monitoring.