Fha Deficient Bordetella pertussis Isolates in Iran with 50 Years Whole Cell Pertussis Vaccination

Abstract

Background: Bordetella pertussis, a highly contagious respiratory. Notably, the resurgence of pertussis has recently been associated with the lacking production of vaccine virulence factors. This study aimed to screen pertactin (Prn) and filamentous hemagglutinin (Fha) production in Iran with 50 years' whole cell vaccine (WCV) immunization program.
 Methods: Overall, 130 B. pertussis isolates collected from Pertussis Reference Laboratory of Iran during 2005-2018. Real-time PCR was performed by targeting IS481, ptxP, IS1001 and IS1002 for species confirmation of B. pertussis. Western-blot was used to evaluate the expression of virulence factors (pertactin and filamentous hemagglutinin).
 Results: All tested B. pertussis isolates expressed Prn and all except two isolates expressed Fha. We have sequenced genomes of these strains and identified differences compared with genome reference B. pertussis Tohama I.
 Conclusion: Many countries reporting Prn and Fha-deficiency due to acellular vaccine (ACV) pressure. Our results demonstrate in a country with WCV history, Fha-deficient isolates may rise independently. However, Prn-deficient isolates are more under the ACV pressure in B. pertussis isolates. Continues surveillance will provide a better understanding of the effect of WCV on the evolution of the pathogen deficiency.

Genome Characteristic of Bordetella parapertussis Isolated from Iran

“…Tehran as a capital and Eastern Azarbayjan, a north-western province, each had three isolates. These two provinces had the most B. pertussis isolates in recent years as reported previously [ 6 , 15 ]. During 2012–2015 around 112 B. pertussis isolates collected from different provinces in Iran [ 6 ] showing low isolation rate of B. parapertussis in the country with 50 years whole cell pertussis vaccination history.…”

“…The emergence of Prn negative B. parapertussis isolates could be a global concern especially in countries with ACV immunisation program since this phenotype can easily escape vaccine pressure by not expressing Ptx and Prn as two main components of ACVs. We previously showed that no mutation or disruption was found in the prn gene in current circulating predominant B. pertussis isolates in Iran and no Prn negative isolate was reported from Iran with WCV immunisation program [ 6 , 15 , 16 ]. Here, western blot was carried out to investigate the expression of Prn in our B. parapertussis isolates and it showed all seven isolates express Prn and confirmed the WCV immunisation did not affect phenotype evolution of this species in Iran.…”

“…Nasal swabs of pertussis suspected patients were sent to pertussis reference laboratory of Pasture Institute of Iran for bacterial isolation and infection confirmation during the 2012–2015 pertussis epidemic in Iran [ 6 ]. As previously described [ 15 ], samples were cultured on Regan-Lowe medium containing charcoal agar and 10% defibrinated sheep blood and incubated at 37 °C for 72 h. B . para pertussis isolates were confirmed by a combination of colony morphology, Gram stain and conventional biochemical tests such as oxidase and real-time PCR.…”