Comparative genomics of whole-cell pertussis vaccine strains from India.

BACKGROUND: Despite high vaccination coverage using acellular (ACV) and whole-cell pertussis (WCV) vaccines, the resurgence of pertussis is observed globally. Genetic divergence in circulating strains of Bordetella pertussis has been reported as one of the contributing factors for the resurgence of the disease. Our current knowledge of B. pertussis genetic evolution in circulating strains is mostly based on studies conducted in countries using ACVs targeting only a few antigens used in the production of ACVs. To better understand the adaptation to vaccine-induced selection pressure, it will be essential to study B. pertussis populations in developing countries which are using WCVs. India is a significant user and global supplier of WCVs. We report here comparative genome analyses of vaccine and clinical isolates reported from India. Whole-genome sequences obtained from vaccine strains: WCV (J445, J446, J447 and J448), ACV (BP165) were compared with Tohama-I reference strain and recently reported clinical isolates from India (BPD1, BPD2). Core genome-based phylogenetic analysis was also performed using 166 isolates reported from countries using ACV. RESULTS: Whole-genome analysis of vaccine and clinical isolates reported from India revealed high genetic similarity and conserved genome among strains. Phylogenetic analysis showed that clinical and vaccine strains share genetic closeness with reference strain Tohama-I. The allelic profile of vaccine strains (J445:ptxP1/ptxA2/prn1/fim2-1/fim3-1; J446: ptxP2/ptxA4/prn7/fim2-2/fim3-1; J447 and J448: ptxP1/ptxA1/ prn1/fim2-1/fim3-1), which matched entirely with clinical isolates (BPD1:ptxP1/ptxA1/prn1/fim2-1 and BPD2: ptxP1/ptxA1/prn1/fim2-1) reported from India. Multi-locus sequence typing (MLST) demonstrated the presence of dominant sequence types ST2 and primitive ST1 in vaccine strains which will allow better coverage against circulating strains of B. pertussis. CONCLUSIONS: The study provides a detailed characterization of vaccine and clinical strains reported from India, which will further facilitate epidemiological studies on genetic shifts in countries which are using WCVs in their immunization programs.

Human Immune Responses to Pertussis Vaccines.

Pertussis still represents a major cause of morbidity and mortality worldwide. Although vaccination is the most powerful tool in preventing pertussis and despite nearly 70 years of universal childhood vaccination, incidence of the disease has been rising in the last two decades in countries with high vaccination coverage. Two types of vaccines are commercially available against pertussis: whole-cell pertussis vaccines (wPVs) introduced in the 1940s and still in use especially in low and middle-income countries; less reactogenic acellular pertussis vaccines (aPVs), licensed since the mid-1990s.In the last years, studies on pertussis vaccination have highlighted significant gaps and major differences between the two types of vaccines in the induction of protective anti-pertussis immunity in humans. This chapter will discuss the responses of the immune system to wPVs and aPVs, with the aim to enlighten critical points needing further efforts to reach a good level of protection in vaccinated individuals.

Genetic verification of Bordetella pertussis seed strains used for production of Japanese acellular pertussis vaccines.

In Japan, the Bordetella pertussis strain Tohama provided by the National Institute of Health, Japan has been used for the production of acellular pertussis (aP) vaccines since 1981. In the present study, in order to verify the genetic consistency of B. pertussis vaccine seed strains, we analyzed the genetic properties of the working seeds obtained from five Japanese vaccine manufacturers, and compared them with those of B. pertussis Tohama reference strains (NIID L-7 and ATCC BAA-589). Genetic analyses with pulsed-field gel electrophoresis and allele typing showed 100% genetic identity among the five seed strains and the Tohama reference strains. In addition, Southern blot analyses revealed the absence of four orthologous genes (BB0537, BB0920, BB1149 and BB4885), which are specifically absent in the strain Tohama, and in the genome of all seed strains tested, suggesting that the regions of difference (RD11-RD14) are absent in their genomes. Consequently, no genetic difference was observed among the working seeds and Tohama reference strains. Our observations indicate that B. pertussis seed strains for Japanese aP vaccine production are genetically comparable with B. pertussis Tohama.

Protocol for Pertussis Immunisation and Food Allergy (PIFA): a case-control study of the association between pertussis vaccination in infancy and the risk of IgE-mediated food allergy among Australian children.

INTRODUCTION: Atopic diseases, including food allergy, have become a predominant cause of chronic illness among children in developed countries. In Australia, a rise in hospitalisations among infants coded as anaphylaxis to foods coincided with the replacement of whole-cell pertussis (wP) vaccine with subunit acellular pertussis (aP) vaccine on the national immunisation schedule in the late 1990s. Atopy is characterised by a tendency to mount T helper type 2 (Th2) responses to otherwise innocuous environmental antigens. Compared with infants who receive aP as their first pertussis vaccine, those who receive wP appear less likely to mount Th2 immune responses to either vaccine or extraneous antigens. We therefore speculate that removal of wP from the vaccine schedule contributed to the observed rise in IgE-mediated food allergy among Australian infants. METHODS AND ANALYSIS: This is a retrospective individually matched case-control study among a cohort of Australian children born from 1997 to 1999, the period of transition from wP to aP vaccines; we include in the cohort children listed on Australia's comprehensive population-based immunisation register as having received a first dose of either pertussis vaccine by 16 weeks old. 500 cohort children diagnosed as having IgE-mediated food allergy at specialist allergy clinics will be included as cases. Controls matched to each case by date and jurisdiction of birth and regional socioeconomic index will be sampled from the immunisation register. Conditional logistic regression will be used to estimate OR (±95% CI) of receipt of wP (vs aP) as the first vaccine dose among cases compared with controls. ETHICS AND DISSEMINATION: The study is approved by all relevant human research ethics committees: Western Australia Child and Adolescent Health Services (2015052EP), Women's and Children's Hospital (HREC/15/WCHN/162), Royal Children's Hospital (35230A) and Sydney Children's Hospital Network (HREC/15/SCHN/405). Outcomes will be disseminated through publication and scientific presentation. TRIAL REGISTRATION NUMBER: NCT02490007.

Identification of pertussis-specific effector memory T cells in preschool children.

Whooping cough remains a problem despite vaccination, and worldwide resurgence of pertussis is evident. Since cellular immunity plays a role in long-term protection against pertussis, we studied pertussis-specific T-cell responses. Around the time of the preschool acellular pertussis (aP) booster dose at 4 years of age, T-cell memory responses were compared in children who were primed during infancy with either a whole-cell pertussis (wP) or an aP vaccine. Peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with pertussis vaccine antigens for 5 days. T cells were characterized by flow-based analysis of carboxyfluorescein succinimidyl ester (CFSE) dilution and CD4, CD3, CD45RA, CCR7, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) expression. Before the aP preschool booster vaccination, both the proliferated pertussis toxin (PT)-specific CD4(+) and CD8(+) T-cell fractions (CFSE(dim)) were higher in aP- than in wP-primed children. Post-booster vaccination, more pertussis-specific CD4(+) effector memory cells (CD45RA(-) CCR7(-)) were induced in aP-primed children than in those primed with wP. The booster vaccination did not appear to significantly affect the T-cell memory subsets and functionality in aP-primed or wP-primed children. Although the percentages of Th1 cytokine-producing cells were alike in aP- and wP-primed children pre-booster vaccination, aP-primed children produced more Th1 cytokines due to higher numbers of proliferated pertussis-specific effector memory cells. At present, infant vaccinations with four aP vaccines in the first year of life result in pertussis-specific CD4(+) and CD8(+) effector memory T-cell responses that persist in children until 4 years of age and are higher than those in wP-primed children. The booster at 4 years of age is therefore questionable; this may be postponed to 6 years of age.

Immunogenicity of a five-component acellular pertussis vaccine in infants and young children.

OBJECTIVE: To compare the reactogenicity and immunogenicity of an acellular vaccine containing pertussis toxoid, filamentous hemagglutinin, and fimbriae 2 and 3, with and without the 69-kd membrane protein, alone or combined with diphtheria and tetanus toxoids. PARTICIPANTS AND SETTING: One hundred thirty-seven 17- to 18-month-old and 22 4- to 6-year-old children who had received three or four previous doses of whole-cell vaccine, respectively, were recruited from public health immunization clinics. DESIGN AND INTERVENTIONS: Three groups of children were sequentially enrolled in the study to receive the acellular pertussis vaccine with or without a 69-kd protein (CP4 or CP5, 17- to 18-month-old children), the two vaccines combined with diphtheria and tetanus toxoids (CP4DT or CP5DT, 17- to 18-month-old children), or the CP5DT vaccine (4- to 6-year-old children). Children were assigned to the first two groups in a randomized and double-blind fashion; the last group was formed by open enrollment. Data regarding adverse reactions were recorded by the parents and collected via a structured interview administered seven times, five times during the first 72 hours. Serum samples were obtained before and 1 month after the immunization, and antibodies against each constituent of the vaccine were measured. RESULTS: A systemic adverse reaction was reported in 40% to 65.7% of 17- to 18-month-old and 38.1% of 4- to 6-year-old children; no severe reactions occurred. A local reaction was reported in 8.6% to 29.4% and 71.4% of children, respectively. No differences were detected between respectively. No differences were detected between vaccines; inclusion of the 69-kd membrane protein did not increase reactogenicity. All vaccines elicited an antibody response to all antigens contained in the formulation. CONCLUSIONS: The five-component acellular pertussis vaccine (Connaught Laboratories Ltd, Willowdale, Ontario) is safe and immunogenic in 17- to 18-month-old and 4- to 6-year-old children. The 69-kd protein was immunogenic, and its inclusion neither increased side effects associated with the vaccine nor adversely affected the antibody response to the other components.

Comparison of a three-component acellular pertussis vaccine with a whole-cell pertussis vaccine in 4- through 6-year-old children. Elmwood Pediatric Associates, Pennridge Pediatric Associates.

OBJECTIVE: To compare the safety and immunogenicity of a three-component acellular pertussis (DTaP) vaccine containing pertussis toxin (PT), filamentous hemagglutinin (FHA), and pertactin with whole-cell pertussis (DTwP) vaccine in 4- through 6-year-old children. PARTICIPANTS: One hundred seventy-two healthy 4- through 6-year-old children previously immunized with the DTwP vaccine at or near 2, 4, 6, and 18 months of age. INTERVENTIONS: Prevaccination serum samples were obtained on all study participants. One hundred twelve children received 0.5 mL of the DTaP vaccine intramuscularly. Fifty-three children received 0.5 mL of a commercially available DTwP vaccine intramuscularly. Approximately 30 days following vaccination, additional serum samples were obtained. MEASUREMENTS: Parents monitored adverse reactions for 7 days following immunization. Significantly fewer children in the DTaP group reported temperatures of greater than 38.1 degrees C and an area of redness of more than 10 mm and moderate-to-severe pain at the injection site. RESULTS: Antibody responses to PT, FHA, pertactin, and diphtheria and tetanus toxoids were measured by enzyme-linked immunosorbent assay. Among subjects who were seronegative prior to vaccination, response was defined as the detection of antibody levels following vaccination; among children with detectable antibody levels prior to vaccination, in terms of the rise in antibody titers. Data using a twofold and a fourfold rise in antibody titers as criteria to define response were evaluated. Children in the DTaP group had significantly greater increases in geometric mean titers of antibodies against PT, FHA, and pertactin. Over 90% of the DTaP group responded to PT, FHA, and pertactin according to the criteria of both the twofold and the fourfold rise in antibody titers. Significantly fewer of the DTwP group responded to PT, FHA, and pertactin with at least a fourfold rise in antibody titers. When analyzing subjects with at least a twofold increase in antibody titers, a statistically significant difference remained in regard to anti-FHA antibodies. All study subjects had protective antibody titers against diphtheria and tetanus toxoids following vaccination. The geometric mean titer of antibodies against tetanus was significantly greater in the DTwP group than in the DTaP group. CONCLUSION: The three-component DTaP vaccine administered as a booster immunization in 4-through 6-year-old children produced less fever and less redness and pain at the injection site than the DTwP vaccine and was as immunogenic as the DTaP vaccine.

Pertussis (whooping cough) toxin and Bordetella pertussis whole-cell antibody levels in a healthy New Zealand population.

Enzyme linked immunosorbent assay (ELISA) tests were used to measure IgG antibody levels to Bordetella pertussis whole-cell and to pertussis toxin in a healthy New Zealand population. The percentage of individuals with measurable antibody to B pertussis whole-cell increased from 47.3% in the 5 year olds to 93.0% in the 40-49 age group, from which the percentage with antibody dropped to 88.7% in the 50-65 age group. The percentage of persons with antibody to the toxin increased with age from 17.5% in the 5 year olds to 67.0% in the 40-49 age group, from which the percentage of individuals with antibody dropped to 45.4% in the 50-65 age group. Similarly, the percentage of persons with antibody to both B pertussis whole-cell and pertussis toxin increased with age from 15.5% in the 5 year olds to 63.0% in the 40-49 age group, and then the percentage with antibody to whole-cell and toxin dropped to 45.4% in the 50-65 age group. The percentage of individuals with antibody to pertussis toxin is generally markedly lower than the percentage of persons with antibody to B pertussis whole-cell across the age range. Suggestions are made as to how to improve herd immunity for pertussis.

Acellular pertussis vaccines: maybe slightly less effective, but better tolerated.

(1) With the exception of an American vaccine, whole-cell pertussis vaccines, including the preparation marketed in France, have an efficacy of 90 to 95%. Systemic and local reactions are frequent and can be severe. Cellular vaccines do not seem to cause permanent brain lesions or sudden infant death. (2) Four acellular pertussis vaccines are marketed in France: two have two antigenic components and two have three components. (3) The efficacy of the best acellular pertussis vaccines does not exceed 85% after primary vaccination. Clinical protection may be shorter-lived with acellular than with cellular vaccines. (4) Systemic and local adverse effects, both mild and severe, are significantly less frequent with acellular vaccines.

[Can we control pertussis better? II. Old and new vaccines against pertussis]. / Czy mozemy lepiej zapobiegac krztuscowi? II. Stare i nowe szczepionki przeciw krztuscowi.

Although in many countries pertussis had been successfully controlled by the routine mass immunization in infants and children, the disease continues to cause extensive morbidity and mortality throughout the world. Whole-cell pertussis vaccine plays an important role in the control of pertussis in the world and the vaccine proved to be very successful during nearly 50 years of its use. However, the whole-cell pertussis vaccine causes an increased rate of local and general adverse events although many of these events described as caused by vaccination are occurring co-incidentally, not being related to vaccination. Results of recent clinical and field trials in the USA, Sweden, Italy, Germany and Senegal showed that acellular pertussis vaccines are effective in preventing pertussis in children and safe in infants. However, a crucial issue in more general use of acellular pertussis vaccine is its availability and its price. It may be prove too expensive for many countries, including Poland. The cost can be expected to decrease in the future, when the production capacity and the number of doses used increase. The introduction of acellular pertussis vaccine in the immunization programme in Poland will need several organizational, technological and scientific actions.

[An observation on immunization reaction and serological effect of adsorbed purified pertussis vaccine].

An observation on immunization reaction and serological effect of adsorbed purified pertussis vaccine for the first time in China had been carried out in Zhengzhou. Phase I field trial had been conducted in 8 adults and 20 children in whom there was no local reaction and temperature reaction in adults and only mild temperature reaction (37.6 degrees C-38 degrees C) in 4 children. Phase II field trial showed that the adsorbed purified pertussis vaccine manifested trivial reaction, none developed severe temperature reaction (39.1 degrees C), and 8 person-times of moderate temperature reaction (38.1 degrees C-39.1 degrees C) occurred in 100 children after 3 doses. Whereas 2 person-times of severe reaction and 39 person-times of mild reaction occurred in 101 children after receiving the whole cell pertussis vaccine. None showed local severe reaction (5.1 cm) and 1 person-time of mild local reaction appeared at 48 hours after each of 3 doses of adsorbed purified pertussis vaccine (102, 102, 98 children, respectively); Whereas, 3 person-times of severe local reaction and 17 person-times of mild local reaction occurred after each of 3 doses of whole cell pertussis vaccine (97, 100, 97 children, respectively). Satisfactory immunogenicity of the adsorbed purified pertussis vaccine was confirmed. The high serum hemagglutinin titer was achieved in 90 children, the GMT reached 817 (9.16 for preimmunization), and titers reaching 1:320 and over (a level protecting human from being infected) accounted for 84.4 percent. The average levels of anti-LPF and anti-FHA antibodies in 60 and 53 persons attained to 24.17 +/- 3.9421 EU/ml and 38.85 +/- 7.2466 EU/ml, respectively.

The agglutinin response to whole-cell and acellular pertussis vaccines is Bordetella pertussis--strain dependent.

OBJECTIVE: To determine the significance of the Bordetella pertussis strain used as the antigen in the agglutinin assay for the evaluation of pertussis vaccines. DESIGN: Randomized, double-blind study. SETTING: Health maintenance organization clinics, primary care clinic at a referral hospital, and private practices in Los Angeles County, California. PARTICIPANTS: Forty healthy infants. SELECTION PROCEDURES: Convenience sample. INTERVENTIONS: Twenty infants received whole-cell pertussis-component diphtheria-tetanus-pertussis vaccine (DTP), and 70 infants received acellular pertussis-component diphtheria-tetanus-pertussis vaccine (APDT) at ages 2, 4, and 6 months. MEASUREMENTS: The agglutinin assay was performed using three separate B pertussis strain preparations: (1) strains 130 and 138 in equal quantities, the constituents of the DTP vaccine, (2) strain 460, and (3) strain Tohama, the constituent of the APDT vaccine. RESULTS: The agglutinin titers were highly strain dependent; in both groups of vaccinees at both ages the Tohama values were highest, followed by strain 460 and then strains 130/138. The vaccine groups had comparable titers at age 2 months regardless of the assay antigen used. However, at age 7 months, after three immunizations, the DTP group geometric mean titer was more than 10 times greater than that of the ADPT group using strains 130/138, but only 2.6 times higher using strain 460 and almost equivalent using Tohama strain. CONCLUSION: Vaccine group agglutinin value comparisons strongly depend on assay antigens used.

Acellular pertussis vaccines: what lies ahead?

A safe acellular pertussis vaccine may be in your patients' future. Here's the latest on how this vaccine's effectiveness and side effects compare with those of its whole cell counterpart.

Responses to primary and a booster dose of acellular, component, and whole-cell pertussis vaccines initiated at 2 months of age.

A second generation acellular pertussis vaccine (component pertussis vaccine) containing purified pertussis toxin (PT) and filamentous hemagglutinin (FHA) was tested for its immunogenicity and safety in 2-month-old infants in comparison with first-generation acellular and whole-cell pertussis vaccines. At the ages of 2, 4, 6, and 18 months, respectively, 350 subjects were inoculated one dose of pertussis vaccine, which was combined with diphtheria and tetanus toxoids. Both acellular and component vaccines elicited significantly much fewer local and systemic reactions than whole-cell vaccine did. Besides, although not reaching statistical significance, the component vaccine was less reactogenic than the acellular vaccine. After each dose of the primary immunization, antibodies against PT and FHA were much higher in acellular and component pertussis vaccinees than in whole-cell vaccinees. However, at 18 months of age, just before the booster dose, both anti-PT and anti-FHA declined very close to, or even lower than, the prevaccination levels in all three groups and then responded rapidly to a booster dose to attain high levels. The booster responses were also significantly higher (P < 0.01) in acellular and component groups than in whole-cell group. Component and acellular vaccines induced similar levels of anti-FHA but the former induced higher anti-PT than the latter (P < 0.01). Our results indicate that both in primary immunization and as a booster, acellular and component pertussis vaccines are much more immunogenic for PT and FHA and much less reactogenic than whole-cell vaccine. However, the persistence of anti-PT and anti-FHA was not as good as one can expect from other protein antigens without giving a booster dose. A long-term follow-up of the vaccinees has been underway to understand the persistence of these antibodies after the first booster.

Primary immunization series for infants: comparison of two-component acellular and standard whole-cell pertussis vaccines combined with diphtheria-tetanus toxoids.

At 2 months of age, 145 infants were randomized to receive either a two-component acellular pertussis vaccine [lymphocytosis-promoting factor (LPF)/filamentous hemagglutinin (FHA)] or standard whole-cell pertussis vaccine, each combined with diphtheria-tetanus toxoids, as their primary immunization series. Of the 132 subjects (91%) who completed the study, those receiving the acellular vaccine had significantly fewer adverse reactions: 5% vs 30% (local) and 17% vs 30% (systemic, including fever). During the first 24 hours acetaminophen usage, a general measure of adverse reactions, was lower in the test group. Overall, 35% of the acellular vaccine doses were reaction free vs 12% of the whole-cell doses. No serious reactions occurred in either group. Antibody responses to LPF and to FHA were significantly increased after the second and third immunizations with the test vaccine and were consistently higher than levels achieved with the standard vaccine. Thus the two-component acellular pertussis vaccine was associated with fewer adverse reactions and improved serologic responses to LPF and FHA as compared with the currently recommended whole-cell vaccine.

Developments in pertussis immunisation in Japan.

In Japan acellular pertussis vaccine has totally replaced whole-cell vaccine since 1981. The vaccine is given in combination with diphtheria and tetanus toxoids to children aged 24-48 months; three doses are given with intervals of 3-8 weeks and the fourth dose (booster) is given 12-18 months after the third. There has been a steady decline in cases of pertussis and deaths from the disease since 1979. Comparison of the rates of adverse reactions to whole-cell vaccine in 1973-74 and to acellular vaccine in 1979-80 showed lower rates of fever and of local reactions with the acellular vaccine.