Immune response in swine given soluble antigens from group E Streptococcus

Area of Science:

• Veterinary immunology
• Bacteriology
• Swine infectious diseases

Background:

• Streptococcal lymphadenitis in swine is caused by Group E Streptococcus (GES).
• Effective vaccines are crucial for controlling this economically significant disease in swine herds.
• Previous studies explored various antigen preparations for inducing immunity.

Purpose of the Study:

• To evaluate the efficacy of different nonliving Group E Streptococcus (GES) antigen preparations in inducing immunity against streptococcal lymphadenitis in swine.
• To determine if vaccination with GES antigens reduces abscess formation and severity after challenge exposure.

Main Methods:

• Swine were injected with soluble or whole cell antigens of GES, including autoclaved extracts and pepsin-extracted antigens.
• Antibody responses to antiphagocytic factor were measured using bactericidal and long-chain tests.
• Vaccinated and control swine were challenged with live virulent GES via feed or carrier swine exposure.
• Abscess development, number, and size were assessed post-challenge.

Main Results:

• Swine vaccinated with autoclaved GES extracts produced higher antibody titers to antiphagocytic factor compared to other antigen groups and controls.
• Vaccination with autoclaved GES extracts significantly reduced the incidence of abscesses by 71.4% after challenge exposure.
• Abscesses in vaccinated swine were generally smaller, suggesting arrested development, with 58.3% less than 1 cm compared to 38.2% in controls.

Conclusions:

• Nonliving Group E Streptococcus (GES) antigen, particularly autoclaved extracts, can induce a degree of immunity against streptococcal lymphadenitis in swine.
• Vaccination with GES antigen shows potential for controlling lymphadenitis by reducing abscess formation and severity.
• Further research into optimizing GES vaccine formulations is warranted for practical application in swine herds.