Composition of Populations and Durations of Persistence of Bordetella pertussis Bacteria in Patients with Whooping Cough and Contact Persons

• Published in: Molecular genetics, microbiology and virology Vol. 38; no. 2; pp. 61 - 69
• Main Authors: Medkova, A. Yu, Semin, E. G., Kulikov, S. V., Nesterova, Yu. V., Babachenko, I. V., Sinyashina, L. N., Karataev, G. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-06-2023; Springer Nature B.V
• Subjects: Bacteria; Biomedical and Life Sciences; Bordetella pertussis; Children; Convalescence; Experimental Papers; Families & family life; Genomes; Immunization; Infectious diseases; Infectivity; Life Sciences; Microbiology; Molecular Medicine; Mutants; Pertussis; Polymerase chain reaction; Respiratory tract; Virulence; Whooping cough; whooping cough; real-time PCR method (PCR-RT); children; adults; contact persons; insertional mutants of; family foci; populations
• ISSN: 0891-4168; 1934-841X
• DOI: 10.3103/S0891416823020064

Whooping cough still occupies a leading position in the group of controlled infectious diseases, despite worldwide mass vaccination. In recent decades, there has been a significant increase in the incidence of whooping cough and the spread of atypical forms among adolescents and adults. It has been proposed that the formation of an anthropogenic source of infection evolves due to
Bordetella pertussis
bacteria with reduced or completely lost virulence that are capable of long-term persistence in the human body and restoration of infectivity under certain conditions. The persistence mechanisms of the causative agent of whooping cough have not yet been studied completely. We hypothesize that one of the mechanisms may be a change of the
bvgAS
operon, which regulates the expression of all virulence genes of
B. pertussis
bacteria because of the integration of IS-elements. Mobile IS-elements are known to have the ability to both embed into the host genome sites and be cut out of them with the restoration of impaired functions. The purpose of this study was to evaluate the duration of persistence and to analyze the population composition of
B. pertussis
bacteria in children with whooping cough and contact persons in family foci. In this study, 80 children with confirmed diagnosis of pertussis and 116 people from 59 family foci of pertussis in contact with those children were examined. Patients were included in the study after they signed an informed consent. To detect
B. pertussis
DNA in nasopharyngeal swabs and to register IS-element integrations, the PCR-RT-IS test-system developed at the Gamaleya Research Institute was used along with nested PCR and sequencing. It has been shown to be possible to detect the causative agent of whooping cough in patients at different stages of the disease and in family members who have been in contact with patients for a long period. It has been found that, in the period of convalescence from whooping cough, the formation of insertional avirulent mutants of
B. pertussis
in the upper respiratory tract, which are capable of long-term persistence in the human body, is observed in 25% of patients. The appearance of avirulent mutants has been registered at a lower frequency (15%) in contact persons from family foci. The long-term detection of the causative agent of whooping cough and the registration of
B. pertussis
bvg
-mutants containing the integration of IS-elements in bacterial carriers confirm the hypothesis that bacterial transition to persistence because of the insertional inactivation of
bvg
AS operon is possible. Identifying persistent
B. pertussis
bacteria and studying the mechanisms of their formation is important for creating new vaccination strategies and improvement of pertussis vaccines.