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[Experimental study of the relationship between Bordetella pertussis and B. parapertussis infections in suckling
1Department of Pediatrics, Keio University, School of Medicine, Tokyo.
Abstract:
Bordetella parapertussis can occasionally be isolated in the late period of epidemic pertussis and even from the same patient infected with B. pertussis, thereby closely related to B. pertussis. Compared with B. pertussis, it is more frequently isolated from vaccinated individuals as well. Based on the findings, we carried out an experimental study to establish their interrelationship in mice infected with B. parapertussis alone or with both bacteria. The total of 4 groups, each of which constituted ten 10-12 day-day-old mice were in this study. Each 10 mice from mothers which were either unimmunized or immunized with filamentous hemagglutinin-predominant pertussis vaccine were infected with either freshly isolated 1.2 x 10(4) CFU strain 422 of B. parapertussis alone or mixed with 6 x 10(3) CFU strain 18-323 of B. pertussis and 6 x 10(3) CFU strain 422 of B. parapertussis transnasally. We then compared bacterial colonization 1, 2 and 3 weeks after challenge, using the numbers of bacteria in the lungs and peripheral white blood cell count. In the B. parapertussis infection group, B. parapertussis could colonize neither the lungs regardless of pertussis antibodies. In the group infected with a mixture of B. pertussis and B. parapertussis, 10(6) CFU of B. pertussis was primarily found in mice not given the pertussis antibodies, however, 10(5) CFU of B. parapertussis was found in mice given the pertussis antibodies. These results suggest that B. pertussis helps B. parapertussis to colonize in the presence of the pertussis antibodies, thus explaining above the clinical findings.
Insights
Bordetella pertussis aids B. parapertussis colonization in mice with pertussis antibodies. This explains why B. parapertussis is found in vaccinated individuals during pertussis outbreaks.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Bordetella parapertussis is closely related to B. pertussis and often isolated during pertussis outbreaks.
- B. parapertussis is more frequently isolated from vaccinated individuals compared to B. pertussis.
Purpose of the Study:
- To investigate the interrelationship between B. pertussis and B. parapertussis in a mouse model.
- To understand the colonization dynamics of B. parapertussis in the presence of B. pertussis and pertussis antibodies.
Main Methods:
- Experimental infection of 10-12 day-old mice (n=40) with B. parapertussis alone or mixed with B. pertussis.
- Mice mothers were either unimmunized or immunized with a filamentous hemagglutinin-predominant pertussis vaccine.
- Bacterial colonization in lungs and peripheral white blood cell counts were assessed 1, 2, and 3 weeks post-infection.
Main Results:
- B. parapertussis did not colonize the lungs in mice infected with B. parapertussis alone, irrespective of pertussis antibodies.
- In mice infected with both B. pertussis and B. parapertussis, B. pertussis primarily colonized mice without antibodies (10^6 CFU).
- B. parapertussis showed colonization (10^5 CFU) in mice that received pertussis antibodies, suggesting a role for antibodies in this interaction.
Conclusions:
- B. pertussis facilitates B. parapertussis colonization in the presence of pertussis antibodies.
- This interaction may explain the clinical observation of B. parapertussis isolation from vaccinated individuals during pertussis outbreaks.
