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Haemophilus parahaemolyticus serotypes. Pathogenicity and cross immunity.
Summary
Pigs vaccinated with Haemophilus parahaemolyticus serotype 2 developed cross-immunity against other serotypes. This study demonstrates significant cross-protection between different Haemophilus parahaemolyticus serotypes.
Area of Science:
- Veterinary Microbiology
- Animal Immunology
- Swine Diseases
Background:
- Haemophilus parahaemolyticus is a significant swine pathogen.
- Different serotypes of H. parahaemolyticus can cause respiratory disease in pigs.
- Understanding immunity between serotypes is crucial for disease control.
Purpose of the Study:
- To investigate the cross-immunity between different serotypes of Haemophilus parahaemolyticus in pigs.
- To evaluate the protective effects of prior exposure to H. parahaemolyticus serotype 2 against subsequent challenges with homologous and heterologous serotypes.
- To characterize the pathological outcomes following challenge with various H. parahaemolyticus serotypes.
Main Methods:
- Intranasal inoculation of pigs with H. parahaemolyticus serotype 2.
- Subsequent challenge with homologous (serotype 2) and heterologous (serotypes 1, 4, 5) serotypes of H. parahaemolyticus.
- Clinical observation for symptoms and post-mortem examination for pathological changes.
- Re-isolation and serotyping of H. parahaemolyticus from affected tissues.
Main Results:
- Pigs inoculated with H. parahaemolyticus serotype 2 resisted challenge with serotypes 2, 4, and 5, showing no clinical signs and only chronic pleuropneumonia with serotype 2 re-isolation.
- Pigs challenged with serotype 1 after prior serotype 2 inoculation showed chronic pleuropneumonia (serotype 2 re-isolated) and acute fibrinous pneumonia (serotype 1 re-isolated).
- Control pigs inoculated solely with serotype 1 developed severe acute fibrinous pleuropneumonia.
Conclusions:
- A considerable degree of cross-immunity exists between different serotypes of Haemophilus parahaemolyticus.
- Prior exposure to serotype 2 confers partial protection against other serotypes, influencing the type and severity of pneumonia.
- These findings have implications for vaccine development and herd immunity strategies against H. parahaemolyticus infections in swine.