[PERSISTENCE OF BORDETELLA PERTUSSIS BACTERIA AND A POSSIBLE MECHANISM OF ITS FORMATION]

Area of Science:

• Microbiology
• Immunology
• Epidemiology

Background:

• Pertussis morbidity is rising globally despite mass vaccination efforts.
• Disease presentation is shifting towards atypical forms in adolescents and adults, with asymptomatic carriage prevalent.
• Infant infections predominantly originate from household contacts, highlighting the role of adult reservoirs.

Purpose of the Study:

• To investigate the changing epidemiology of pertussis.
• To explore the mechanisms behind Bordetella pertussis persistence and asymptomatic carriage.
• To understand the role of bacterial genetic changes in pertussis resurgence.

Main Methods:

• Analysis of Bordetella pertussis strains from human patients with typical and atypical pertussis.
• Experimental infection models in mice and monkeys to study bacterial invasion, survival, and population dynamics.
• Investigation of genetic factors, including IS-element integration into virulence genes like bvgAS operon.

Main Results:

• Atypical pertussis forms and asymptomatic carriage of Bordetella pertussis are widespread.
• Prolonged persistence of the causative agent has been identified.
• Accumulation of avirulent insertion Bvg mutants of B. pertussis was observed in experimental models and in healthy carriers (over 50%).
• Changes in circulating bacterial genotypes and the formation of persistent bacterial forms are linked to IS-element integration.

Conclusions:

• Reduced virulence in B. pertussis, potentially due to gene inactivation, facilitates long-term host persistence and the formation of healthy carriers.
• The rise in pertussis in developed nations using acellular vaccines may be linked to vaccines reducing disease severity but not preventing infection or carriage.
• Further research into bacterial persistence mechanisms is crucial for developing novel preventive strategies and vaccines.