Engineering of a PTX inactivated Bordetella pertussis strain isolated from clinical specimens in Iran

Background and Aim : One of the important reason of the resurgence of whooping cough (pertussis) caused by Bordetella pertussis is difference between genomic profile of circulating and vaccine strains. Genetically inactivated B. pertussis is one of the new strategies to generate live attenuated vaccine against pertussis. The aim of this study was to construct a PTX inactivated B. pertussis strain based on predominant profile of circulating Iranian isolates.Methods : According to the results of genomic and virulence profile of ۱۰۰ clinical B. pertussis strains from Pasteur Institute of Iran, a B. pertussis strain with predominant pattern was selected. R۹K and E۱۲۹G mutations in ptxS۱ were conducted by the site directed mutagenesis and substitution of mutant ptxS۱ gene were done by homologous recombination. Genetic stability and antigen expression of S۱ mutant strain (S۱mBPIP۹۱) was tested by serially in vitro passages and western blot assay, respectively. Toxicity reduction was also analyzed by Chinese Hamster Ovary (CHO) cells clustering test.Results : In this study all constructs were well confirmed via restriction enzyme analysis and sequencing. Our results showed stability of the mutations of S۱mBPIP۹۱ after in vitro serially passages. The virulence factors expression was also shown in S۱mBPIP۹۱ strain. CHO cell clustering test was demonstrated reduction of PTX toxicity in S۱mBPIP۹۱ mutant strain.Conclusion : A PTX inactivated B. pertussis strain with predominant genomic and virulence profile in Iran was successfully created and characterized in this study. This attenuated B. pertussis strain should be tested in animal model to use in further studies of both whole cell and acellular pertussis vaccines strategies.

کلیدواژه ها:

Bordetella pertussis ، attenuated vaccine ، pertussis toxin ، homologous recombination