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Streptococcus suis serotype 9 bacterin immunogenicity and protective efficacy
Nadine Büttner1, Andreas Beineke, Nicole de Buhr
1Institut für Mikrobiologie, Zentrum für Infektionsmedizin, Stiftung Tierärztliche Hochschule Hannover, D-30173 Hannover, Germany.
Veterinary Immunology and Immunopathology
|April 21, 2012
Summary
A new Streptococcus suis serotype 9 bacterin protected piglets against death but not illness. This vaccine showed lower efficacy than serotype 2 vaccines, likely due to reduced opsonizing antibody induction against Streptococcus suis.
Area of Science:
- Veterinary Immunology
- Bacteriology
- Swine Infectious Diseases
Background:
- Streptococcus suis causes significant economic losses in the pig industry, particularly meningitis.
- Serotype 9 strains account for a quarter of invasive Streptococcus suis diseases in Europe, yet remain understudied compared to serotype 2.
Purpose of the Study:
- To evaluate the immunogenicity and protective capacity of a novel serotype 9 bacterin in piglets.
- To compare the efficacy of the serotype 9 bacterin against a homologous challenge strain from the same clonal complex.
Main Methods:
- Piglets were vaccinated with a serotype 9 bacterin or placebo and subsequently challenged with a reference serotype 9 strain.
- Clinical signs, mortality, bacterial shedding, gross pathology, and serological responses (IgG, opsonizing antibodies) were assessed.
Main Results:
- The serotype 9 bacterin reduced mortality but did not prevent morbidity or complete bacterial clearance from organs.
- Vaccinated piglets showed reduced incidence of fibrinous-suppurative lesions compared to controls.
- Seroconversion against specific antigens and induction of opsonizing antibodies were observed, but at lower titers than previously seen with serotype 2 vaccines.
Conclusions:
- The serotype 9 bacterin demonstrated partial protection, primarily against mortality, but was less effective than serotype 2 bacterins.
- Lower induction of opsonizing antibodies may explain the reduced efficacy of the serotype 9 bacterin.
- These findings suggest a potential link between reduced vaccine efficacy and the emergence of serotype 9 strains in Europe.
