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Virulence genes of Pasteurella multocida cap B and its potential cross protection in mice
Adam Bashir Tawor1,2, Osman Erganiş3, Aslı Balevi3
1Department of Microbiology, Faculty of Veterinary Medicine, University of SelçUk, Konya, 42110, Turkey. 193146002003@ogr.selcuk.edu.tr.
Abstract:
Pasteurella multocida is a Gram-negative coccobacillus from the Pasteurellaceae family, commonly residing as a commensal organism in the respiratory tracts of healthy animals. However, it possesses multiple virulence factors and can cause severe respiratory diseases. This study aimed to characterize P. multocida and its virulence genes and evaluate the immunogenicity of an inactivated vaccine of serogroup B using different administration routes. A total of 250 samples were collected from animals showing respiratory symptoms. Using 5% blood agar, 27 P. multocida isolates were obtained, and 21 (8.4%) were confirmed via PCR targeting the kmt1 gene. Nineteen virulence-associated genes were screened, categorized into outer membrane, fimbrial, somatic antigen, and iron-binding genes. The plpB, tadD, gatG, and hgbA genes were detected in both serogroup B and E isolates, whereas ompA, toxA, pcgD, latB, nctB, ppgB, natG, hgbB, and exbB were absent in all isolates. The immunogenicity of an inactivated P. multocida vaccine was evaluated in mice using subcutaneous and intramuscular routes. Subcutaneous vaccination produced a significantly higher antibody titer at 3 and 5 weeks post-vaccination with a 0.5 mL dose; in contrast, intramuscular immunization resulted in a rapid increase after booster doses. Analysis of variance (ANOVA) and Duncan's multiple range test (p < 0.05) revealed statistically significant differences between treatments. The comparison between subcutaneous and intramuscular routes also showed a significant difference (p < 0.001). This study concludes that although P. multocida serogroup B harbors fewer virulence factors, it effectively induces an immune response in mice but fails to provide cross-protection against the local serogroup E strain.
Insights
This study characterized Pasteurella multocida strains and evaluated a serogroup B vaccine in mice. Subcutaneous vaccination showed superior antibody titers, but no cross-protection against serogroup E was observed.
Area of Science:
- Veterinary Microbiology
- Immunology
- Bacteriology
Background:
- Pasteurella multocida, a Gram-negative bacterium, commonly colonizes animal respiratory tracts but can cause severe disease.
- Virulence factors contribute to P. multocida pathogenicity, necessitating characterization for effective disease control.
- Understanding immune responses to P. multocida vaccines is crucial for developing effective animal health strategies.
Purpose of the Study:
- To characterize Pasteurella multocida isolates and their virulence genes.
- To evaluate the immunogenicity of an inactivated P. multocida serogroup B vaccine using subcutaneous and intramuscular administration routes in mice.
- To assess potential cross-protection against local serogroup E strains.
Main Methods:
- Isolation and identification of P. multocida from animal samples using blood agar and PCR targeting the kmt1 gene.
- Screening of 19 virulence-associated genes, including outer membrane, fimbrial, somatic antigen, and iron-binding genes.
- Immunization of mice with an inactivated P. multocida serogroup B vaccine via subcutaneous and intramuscular routes, followed by antibody titer measurement and statistical analysis (ANOVA, Duncan's test).
Main Results:
- 27 P. multocida isolates were obtained, with 21 confirmed by PCR.
- Specific virulence genes (plpB, tadD, gatG, hgbA) were present in serogroup B and E isolates, while others were absent.
- Subcutaneous vaccination induced significantly higher antibody titers at 3 and 5 weeks compared to intramuscular, which showed a rapid response after boosters.
- Statistical analysis confirmed significant differences between vaccination routes (p < 0.001).
Conclusions:
- P. multocida serogroup B, despite having fewer virulence factors, effectively elicits an immune response in mice.
- Subcutaneous administration of the inactivated serogroup B vaccine is more immunogenic than intramuscular administration in the studied model.
- The evaluated vaccine does not provide cross-protection against the local P. multocida serogroup E strain.
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