Immunogenicity and reactogenicity of two diphtheria-tetanus-whole cell pertussis vaccines in Iranian pre-school children, a randomized controlled trial

Genomic epidemiology of Iranian Bordetella pertussis: 50 years after the implementation of whole cell vaccine

Pertussis caused by Bordetella pertussis, remains a public health problem worldwide, despite high vaccine coverage in infants and children in many countries. Iran has been using whole cell vaccine for the last 50 years with more than 95% vaccination rate since 1988 and has experienced pertussis resurgence in recent years. Here, we sequenced 55 B. pertussis isolates mostly collected from three provinces with the highest number of pertussis cases in Iran, including Tehran, Mazandaran, and Eastern-Azarbayjan from the period of 2008-2016. Most isolates carried ptxP3/prn2 alleles (42/55, 76%), the same genotype as isolates circulating in acellular vaccine-administrating countries. The second most frequent genotype was ptxP3/prn9 (8/55, 14%). Only three isolates (5%) were ptxP1. Phylogenetic analysis showed that Iranian ptxP3 isolates can be divided into eight clades (Clades 1-8) with no temporal association. Most of the isolates from Tehran grouped together as one distinctive clade (Clade 8) with six unique single nucleotide polymorphisms (SNPs). In addition, the prn9 isolates were grouped together as Clade 5 with 12 clade-supporting SNPs. No pertactin deficient isolates were found among the 55 Iranian isolates. Our findings suggest that there is an ongoing adaptation and evolution of B. pertussis regardless of the types of vaccine used.

Efficacy of Arsenicum album 30cH in preventing febrile episodes following DPT-HepB-Polio vaccination - a randomized, double-blind, placebo-controlled clinical trial

BACKGROUND

Among the post-immunization adverse events, especially of Diphtheria-Pertusis-Tetanus (DPT), fever is a common systemic reaction. There is anecdotal support for the use of the homeopathic medicine Arsenicum album in preventing post-vaccination fever. The investigators intended to evaluate its efficacy in preventing febrile episodes following vaccination.

METHODS

In the community medicine out-patient of Mahesh Bhattacharyya Homoeopathic Medical College and Hospital, West Bengal, India, between August 2014 and January 2017, a double-blind, randomized, placebo-controlled trial was conducted on 120 children (verum: 60, placebo: 60) who presented for the 2nd and 3rd dose of DPT-HepB-Polio vaccination and reported febrile episodes following the 1st dose. Intervention used was Arsenicum album 30cH 6 doses or placebo (indistinguishable from verum), thrice daily for two subsequent days. Parents were advised to report any event of febrile attacks within 48h of vaccination, either directly or over telephone.

RESULTS

The groups were comparable at baseline. Children reporting fever after the 2nd dose was 29.8% and 30.4% respectively for the homeopathy group and control group respectively [Relative Risk (RR)=1.008] with no significant difference (P=0.951) between groups. Again after the 3rd dose, children reporting fever were 31.5% and 28.3% respectively for the homeopathy group and control group respectively (RR=0.956) with no significant difference (P=0.719) between groups.

CONCLUSION

Empirically selected Arsenicum album 30cH could not produce differentiable effect from placebo in preventing febrile episodes following DPT-HepB-Polio vaccination. [Trial registration: CTRI/2017/02/007939].

mRNA vaccines - a new era in vaccinology

mRNA vaccines represent a promising alternative to conventional vaccine approaches because of their high potency, capacity for rapid development and potential for low-cost manufacture and safe administration. However, their application has until recently been restricted by the instability and inefficient in vivo delivery of mRNA. Recent technological advances have now largely overcome these issues, and multiple mRNA vaccine platforms against infectious diseases and several types of cancer have demonstrated encouraging results in both animal models and humans. This Review provides a detailed overview of mRNA vaccines and considers future directions and challenges in advancing this promising vaccine platform to widespread therapeutic use.

Restricted antibody response to Bordetella pertussis filamentous hemagglutinin induced by whole-cell and acellular pertussis vaccines

BACKGROUND

Filamentous hemagglutinin (FHA) is a principal virulence factor, an important immunogenic antigen of Bordetella pertussis, and a major component of many acellular pertussis vaccines. In the present study, the human antibody response to different regions of FHA was determined in healthy children and adults vaccinated with either whole-cell or acellular pertussis vaccines.

METHODS

To define the immunodominant regions of FHA, four overlapping recombinant fragments were expressed and produced in Escherichia coli and then purified by His-tagged based affinity chromatography. Two groups comprising healthy preschool children (n = 50) and adults (n = 26) were vaccinated with a single dose of commercial whole-cell and acellular DTaP vaccines, respectively. An antigen-based ELISA was applied to measure serum levels of anti-FHA antibody to both native and recombinant proteins in vaccinated volunteers.

RESULTS

In both groups of vaccinated individuals, the anti-FHA antibody response was mainly directed against epitopes located within a fragment of FHA spanning amino acid residues 1877-2250 of the mature FHA molecule (p < 0.001). No or little antibody was detected against the other recombinant segments of FHA.

CONCLUSION

Our results suggest that the human antibody response to FHA is directed to an immunodominant region located within residues 1877-2250 of the FHA molecule. Characterization and epitope mapping of the major components of acellular pertussis vaccine and future modifications in vaccine formulation may improve its efficacy and protectivity.

Genetic Profile Variation in Vaccine Strains and Clinical Isolates of Bordetella pertussis Recovered from Iranian Patients

BACKGROUND

Re-emergence of pertussis has been reported in Iran despite a high rate of vaccination coverage. Low efficacy of the vaccine might be due to the genetic divergence between clinical versus vaccine strains. In the current study, the genetic profiles of clinical isolates and vaccine strains of Bordetella pertussis (B. pertussis) were assessed by using Pulsed Field Gel Electrophoresis (PFGE).

METHODS

Following phenotypic and molecular identification of isolates, XbaI-digested genomic DNA of 5 clinical isolates, 2 vaccine strains and a Tohama I strain were analyzed by PFGE along with B. parapertussis as a control.

RESULTS

Seven distinct PFGE profiles were found among all examined isolates/strains. In 5 clinical isolates, 4 profiles were identified whereas the vaccine strains displayed 2 distinct profiles. The reference strain, Tohama I had a distinct profile. Vaccine and clinical profiles had low similarity, with relatedness of approximately 40%.

CONCLUSION

The genetic profiles of B. pertussis were different between circulating isolates and vaccine strains used in the national vaccination programs. Since new genetic profiles of B. pertussis can be disseminated periodically, the profiles of isolates circulating in the population should be monitored over the course of the re-emergence.