Comparative study of a whole-cell pertussis vaccine and a recombinant acellular pertussis vaccine. The Italian Multicenter Group for the Study of Recombinant Acellular Pertussis Vaccine

Long-Term Analysis of Pertussis Vaccine Immunity to Identify Potential Markers of Vaccine-Induced Memory Associated With Whole Cell But Not Acellular Pertussis Immunization in Mice

Over two decades ago acellular pertussis vaccines (aP) replaced whole cell pertussis vaccines (wP) in several countries. Since then, a resurgence in pertussis has been observed, which is hypothesized to be linked, in part, to waning immunity. To better understand why waning immunity occurs, we developed a long-term outbred CD1 mouse model to conduct the longest murine pertussis vaccine studies to date, spanning out to 532 days post primary immunization. Vaccine-induced memory results from follicular responses and germinal center formation; therefore, cell populations and cytokines involved with memory were measured alongside protection from challenge. Both aP and wP immunization elicit protection from intranasal challenge by decreasing bacterial burden in both the upper and lower airways, and by generation of pertussis specific antibody responses in mice. Responses to wP vaccination were characterized by a significant increase in T follicular helper cells in the draining lymph nodes and CXCL13 levels in sera compared to aP mice. In addition, a population of B. pertussis⁺ memory B cells was found to be unique to wP vaccinated mice. This population peaked post-boost, and was measurable out to day 365 post-vaccination. Anti-B. pertussis and anti-pertussis toxoid antibody secreting cells increased one day after boost and remained high at day 532. The data suggest that follicular responses, and in particular CXCL13 levels in sera, could be monitored in pre-clinical and clinical studies for the development of the next-generation pertussis vaccines.

Whole-cell pertussis vaccine in early infancy for the prevention of allergy in children

BACKGROUND

Atopic diseases are the most common chronic conditions of childhood. The apparent rise in food anaphylaxis in young children over the past three decades is of particular concern, owing to the lack of proven prevention strategies other than the timely introduction of peanut and egg. Due to reported in vitro differences in the immune response of young infants primed with whole-cell pertussis (wP) versus acellular pertussis (aP) vaccine, we systematically appraised and synthesised evidence on the safety and the potential allergy preventive benefits of wP, to inform recommendation for future practice and research.

OBJECTIVES

To assess the efficacy and safety of wP vaccinations in comparison to aP vaccinations in early infancy for the prevention of atopic diseases in children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, Ovid MEDLINE, Embase, and grey literature. The date of the search was 7 September 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-randomised studies of interventions (NRSIs) that reported the occurrence of atopic diseases, and RCTs only to assess safety outcomes. To be included studies had to have at least six months follow-up, and involve children under 18 years old, who received a first dose of either wP (experimental intervention) or aP (comparator) before six months of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies for eligibility, extracted the data, and assessed risk of bias using standard Cochrane methods. We assessed the certainty of the evidence using GRADE. Our primary outcomes were diagnosis of IgE-mediated food allergy and all-cause serious adverse events (SAEs). Secondary outcomes included: diagnosis of not vaccine-associated anaphylaxis or urticaria, diagnosis of asthma, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and diagnosis of encephalopathy. Due to paucity of RCTs reporting on the atopic outcomes of interest, we assessed a broader outcome domain (cumulative incidence of atopic disease) as specified in our protocol. We summarised effect estimates as risk ratios (RR) and 95% confidence intervals (CI). Where appropriate, we pooled safety data in meta-analyses using fixed-effect Mantel-Haenszel methods, without zero-cell corrections for dichotomous outcomes.

MAIN RESULTS

We identified four eligible studies reporting on atopic outcomes, representing 7333 children. Based on a single trial, there was uncertain evidence on whether wP vaccines affected the risk of overall atopic disease (RR 0.85, 95% CI 0.62 to 1.17) or asthma only (RR 1.04, 95% CI 0.59 to 1.82; 497 children) by 2.5 years old.Three NRSIs were judged to be at serious or critical risk of bias due to confounding, missing data, or both, and were ineligible for inclusion in a narrative synthesis.  We identified 21 eligible studies (137,281 children) that reported the safety outcomes of interest. We judged seven studies to be at high risk of bias and those remaining, at unclear risk.  The pooled RR was 0.94 for all-cause SAEs (95% CI 0.78 to 1.15; I² = 0%; 15 studies, 38,072 children). For every 1000 children primed with a first dose of wP, 11 had an SAE. The corresponding risk with aP was 12 children (95% CI 9 to 13). The 95% CI around the risk difference ranged from three fewer to two more events per 1000 children, and the certainty of the evidence was judged as moderate (downgraded one level for imprecision). No diagnoses of encephalopathy following vaccination were reported (95% CI around the risk difference - 5 to 12 per 100,000 children; seven primary series studies; 115,271 children). The certainty of the evidence was judged as low, since this is a serious condition, and we could not exclude a clinically meaningful difference.

AUTHORS' CONCLUSIONS

There is very low-certainty evidence that a first dose of wP given early in infancy, compared to a first dose of aP, affects the risk of atopic diseases in children. The incidence of all-cause SAEs in wP and aP vaccinees was low, and no cases of encephalopathy were reported. The certainty of the evidence was judged as moderate for all-cause SAEs, and low for encephalopathy. Future studies should use sensitive and specific endpoints of clinical relevance, and should be conducted in settings with high prevalence of IgE-mediated food allergy. Safety endpoints should prioritise common vaccine reactions, parental acceptability, SAEs and their potential relatedness to the dose administered.

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis (wP) vaccines was suspended in some countries in the 1970s and 1980s because of concerns about adverse effects. Following this action, there was a resurgence of whooping cough. Acellular pertussis (aP) vaccines, containing purified or recombinant Bordetella pertussis (B. pertussis) antigens, were developed in the hope that they would be as effective, but less reactogenic than the whole-cell vaccines. This is an update of a Cochrane review first published in 1999, and previously updated in 2012. In this update, we included no new studies.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children and to compare them with the whole-cell vaccines.

SEARCH METHODS

We searched CENTRAL (2013, Issue 12), MEDLINE (1950 to January week 2, 2014), EMBASE (1974 to January 2014), Biosis Previews (2009 to January 2014) and CINAHL (2009 to January 2014).

SELECTION CRITERIA

We selected double-blind randomised efficacy and safety trials of aP vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in the studies. Differences in trial design precluded a meta-analysis of the efficacy data. We pooled the safety data from individual trials using a random-effects meta-analysis model.

MAIN RESULTS

We included six efficacy trials with a total of 46,283 participants and 52 safety trials with a total of 136,541 participants. Most of the safety trials did not report the methods for random sequence generation, allocation concealment and blinding, which made it difficult to assess the risk of bias in the studies. The efficacy of multi-component (≥ three) vaccines varied from 84% to 85% in preventing typical whooping cough (characterised by 21 or more consecutive days of paroxysmal cough with confirmation of B. pertussis infection by culture, appropriate serology or contact with a household member who has culture-confirmed pertussis), and from 71% to 78% in preventing mild pertussis disease (characterised by seven or more consecutive days of cough with confirmation of B. pertussis infection by culture or appropriate serology). In contrast, the efficacy of one- and two-component vaccines varied from 59% to 78% against typical whooping cough and from 41% to 58% against mild pertussis disease. Multi-component acellular vaccines are more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with aP vaccines than with wP vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component (≥ three) aP vaccines are effective in preventing whooping cough in children. Multi-component aP vaccines have higher efficacy than low-efficacy wP vaccines, but they may be less efficacious than the highest-efficacy wP vaccines. Acellular vaccines have fewer adverse effects than whole-cell vaccines for the primary series as well as for booster doses.

Genetically detoxified pertussis toxin (PT-9K/129G): implications for immunization and vaccines

Pertussis toxin (PT) is one of the major virulence factors of Bordetella pertussis and the primary component of all pertussis vaccines available to date. Because of its various noxious effects the toxin needs to be detoxified. In all currently available vaccines, detoxification is achieved by treatment with high quantity of chemical agents such as formaldehyde, glutaraldehyde or hydrogen peroxide. Although effective in detoxification, this chemical treatment alters dramatically the immunological properties of the toxin. In contrast, PT genetically detoxified through the substitution of two residues necessary for its enzymatic activity maintains all functional and immunological properties. This review describes in detail the characteristics of this PT-9K/129G mutant and shows that it is non-toxic and a superior immunogen compared with chemically detoxified PT. Importantly, data from an efficacy trial show that the PT-9K/129G-based vaccine induces earlier and longer-lasting protection, further supporting the hypothesis that PT-9K/129G represents an ideal candidate for future pertussis vaccine formulations.

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis (wP) vaccines was suspended in some countries in the 1970s and 1980s because of concerns about adverse effects. Following such action, there was a resurgence of whooping cough. Acellular pertussis (aP) vaccines, containing purified or recombinant Bordetella pertussis (B. pertussis) antigens, were developed in the hope that they would be as effective, but less reactogenic than the whole-cell vaccines.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children.

SEARCH METHODS

We searched the Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 4) which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1950 to December week 4, 2011), EMBASE (1974 to January 2012), Biosis Previews (2009 to January 2012), and CINAHL (2009 to January 2012).

SELECTION CRITERIA

We selected double-blind randomised efficacy and safety trials of aP vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in the studies. Differences in trial design precluded a meta-analysis of the efficacy data. We pooled the safety data from individual trials using a random-effects meta-analysis model.

MAIN RESULTS

We included six efficacy trials with a total of 46,283 participants and 52 safety trials with a total of 136,541 participants. Most of the safety trials did not report the methods for random sequence generation, allocation concealment and blinding, which made it difficult to assess the risk of bias in the studies. The efficacy of multi-component (≥ three) vaccines varied from 84% to 85% in preventing typical whooping cough (characterised by 21 or more consecutive days of paroxysmal cough with confirmation of B. pertussis infection by culture, appropriate serology or contact with a household member who has culture-confirmed pertussis), and from 71% to 78% in preventing mild pertussis disease (characterised by seven or more consecutive days of cough with confirmation of B. pertussis infection by culture or appropriate serology). In contrast, the efficacy of one- and two-component vaccines varied from 59% to 75% against typical whooping cough and from 13% to 54% against mild pertussis disease. Multi-component acellular vaccines are more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with aP vaccines than with wP vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component (≥ three) aP vaccines are effective and show less adverse effects than wP vaccines for the primary series as well as for booster doses.

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis vaccines was suspended in some countries in the 1970s/1980s because of concerns about adverse effects. There was a resurgence of whooping cough. Acellular pertussis vaccines (containing purified or recombinant Bordetella pertussis antigens) were developed in the hope that they would be as effective but less reactogenic than the whole-cell vaccines.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children.

SEARCH STRATEGY

We searched the Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which contains the Acute Respiratory Infections Group's Specialised Register; MEDLINE (1950 to April week 2 2009) and EMBASE (1974 to April 2009).

SELECTION CRITERIA

Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed data extraction and study quality assessment. Differences in trial design precluded pooling of the efficacy data. The safety data from individual trials were pooled using the Cochrane statistical package Review Manager 5.

MAIN RESULTS

Six efficacy trials and 52 safety trials were included. The efficacy of multi-component (≥ 3) vaccines varied from 84% to 85% in preventing typical whooping cough, and from 71% to 78% in preventing mild pertussis disease. In contrast, the efficacy of one- and two-component vaccines varied from 59% to 75% against typical whooping cough, and from 13% to 54% against mild pertussis disease. Multi-component acellular vaccines is more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with acellular than with whole-cell pertussis vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole-cell pertussis vaccines for the primary series as well as for booster doses.

WITHDRAWN: Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole cell pertussis vaccines was suspended in some countries in the late 1970s and early 1980s, leading to a resurgence of whooping cough. Acellular pertussis vaccines containing purified or recombinant Bordetella pertussis antigens were developed in the hope that they would be as effective but less toxic than the whole cell vaccines.

OBJECTIVES

The objective of this review was to assess the effects of acellular pertussis vaccines in children.

SEARCH STRATEGY

The Cochrane Controlled Trials Register and Medline were searched up to January 1998.

SELECTION CRITERIA

Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data.

MAIN RESULTS

Six efficacy trials and 45 safety trials were included. Acellular pertussis vaccines with three or more pertussis vaccines were more effective than those with one or two antigens. They were also more effective than one type of whole cell pertussis vaccine, but less effective than two other types of whole cell vaccines. Differences in trial design precluded pooling of the efficacy data and results should be interpreted with caution. Most systemic and local adverse events were significantly less common with acellular than with whole cell pertussis vaccines.

AUTHORS' CONCLUSIONS

Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole cell pertussis vaccines. However in areas where whooping cough is more likely to be fatal, the higher toxicity of some whole cell vaccines may be offset by their increased effectiveness.

WITHDRAWN: Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole cell pertussis vaccines was suspended in some countries in the late 1970s and early 1980s, leading to a resurgence of whooping cough. Acellular pertussis vaccines containing purified or recombinant Bordetella pertussis antigens were developed in the hope that they would be as effective but less toxic than the whole cell vaccines.

OBJECTIVES

The objective of this review was to assess the effects of acellular pertussis vaccines in children.

SEARCH STRATEGY

The Cochrane Controlled Trials Register and Medline were searched up to January 1998.

SELECTION CRITERIA

Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data.

MAIN RESULTS

Six efficacy trials and 45 safety trials were included. Acellular pertussis vaccines with three or more pertussis vaccines were more effective than those with one or two antigens. They were also more effective than one type of whole cell pertussis vaccine, but less effective than two other types of whole cell vaccines. Differences in trial design precluded pooling of the efficacy data and results should be interpreted with caution. Most systemic and local adverse events were significantly less common with acellular than with whole cell pertussis vaccines.

AUTHORS' CONCLUSIONS

Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole cell pertussis vaccines. However in areas where whooping cough is more likely to be fatal, the higher toxicity of some whole cell vaccines may be offset by their increased effectiveness.

Prevalence of pathogenicity island IICFT073 genes among extraintestinal clinical isolates of Escherichia coli

Uropathogenic Escherichia coli is the most common cause of urinary tract infection (UTI). Cystitis in women is by far the most common UTI; pyelonephritis in both sexes and prostatitis in men are more severe but are less frequent complaints. The ability of E. coli to cause UTI is associated with specific virulence determinants, some of which are encoded on pathogenicity islands (PAI). One such PAI (PAI IICFT073), of the prototypical uropathogenic E. coli strain CFT073, contains 116 open reading frames, including iron-regulated genes, carbohydrate biosynthetic genes, the serine protease autotransporter picU, a two-partner secretion system, a type I secretion system, mobility genes, and a large number of hypothetical genes. To determine the association of PAI IICFT073 with UTI, PCR was used to examine the prevalence of the five virulence-associated loci among the ECOR collection and a collection of E. coli isolated from patients with cystitis, pyelonephritis, prostatitis, or septicemia. All PAI IICFT073 loci were found to be more prevalent among the B2 phylogenetic group than any other group within the ECOR collection and among invasive prostatitis strains than were cystitis or pyelonephritis strains. These data support the theory that clinical isolates causing prostatitis are more virulent than those producing cystitis or pyelonephritis in women.

Diphtheria-tetanus-acellular pertussis vaccine adsorbed (Triacelluvax; DTaP3-CB): a review of its use in the prevention of Bordetella pertussis infection

DTaP3-CB (Triacelluvax) is an acellular pertussis (aP) vaccine containing 3 antigens from purified Bordetella pertussis bacteria combined with diphtheria and tetanus toxoids (DT). In addition to purified filamentous haemagglutinin and pertactin, DTaP3-CB contains pertussis toxin which has been genetically rather than chemically detoxified. As shown in randomised, double-blind clinical trials in infants, DTaP3-CB elicits an immune response similar to or greater than that of whole cell (DTwP) vaccines. Results of a large multicentre study comparing DTaP3-CB with 12 acellular and 1 DTwP vaccine indicate that DTaP3-CB, like all acellular vaccines, induces variable immune responses to different pertussis antigens; however, antibody titres to pertussis toxin are normally higher after immunisation with the genetically detoxified vaccine than with other 3- or 4-component vaccines. When given as a fourth or fifth booster dose, DTaP3-CB produced a significant immune response in infants primed with 3 doses of either a DTaP or DTwP vaccine. Virtually all infants immunised with DTaP3-CB had a serological response to diphtheria and tetanus toxoids. Data from 2 very large efficacy studies indicate that DTaP3-CB has high and long lasting protective efficacy against culture-confirmed pertussis which is greater than that of a 2-component vaccine (DTaP2-SB) and the whole cell DTwP-CON vaccine after a 3-, 5- and 12-month immunisation schedule and after a 2-, 4- and 6-month schedule with the DTwP-CON vaccine. However, the DTwP-CON whole cell vaccine has been noted for its low immunogenicity in 1 study and low efficacy and immunogenicity in another study. On the other hand, DTaP3-CB vaccine has similar efficacy to DTaP3-SB (after immunisation at 2, 4 and 6 months), DTaP5-CON and DTwP-EVANS against culture-confirmed pertussis with > or =21 days cough in infants immunised according to a 3-, 5- and 12-month schedule. Infants immunised with DTaP3-CB experienced significantly fewer adverse events such as pain, redness, swelling and irritability than infants given DTwP. DTaP3-CB has a similar tolerability profile to other acellular vaccines and is associated with similar rates of local tenderness, irritability, fever (> or =40 degrees C) and persistent crying. Comparative trials have shown that infants immunised with DTaP3-CB had a lower incidence of pain at the site of injection and fever (> or =38 degrees C) compared with other acellular vaccines, although this may have little clinical significance. Concomitant administration of DTaP3-CB with hepatitis B, oral polio or Haemophilus influenzae type B vaccines did not affect the immunogenicity of these other paediatric vaccines.

CONCLUSION

Data from clinical trials with DTaP3-CB vaccine indicate that this vaccine induces high and long lasting efficacy. It is at least as efficacious as most whole cell vaccines and generally similar in efficacy to the most efficacious acellular pertussis vaccines containing 3 or more pertussis antigens. DTaP3-CB is better tolerated than whole cell vaccines and has a similar tolerability profile to other acellular vaccines; the possible lower risk of severe adverse events remains to be confirmed. The low reactogenicity of DTaP3-CB is likely to make it well tolerated and therefore well accepted for the immunisation of infants, thereby enabling wider implementation of vaccination programmes.

Genetically derived toxoids for use as vaccines and adjuvants

Until very recently, development of vaccines has been based on an empirical approach. For example, bacterial toxins have been detoxified using empirical chemical treatment. Progress in biotechnology and molecular biology has allowed the fine knowledge of the structure-function relationship of several bacterial toxins. Thanks to this, the genetic attenuation of bacterial toxins has been made possible. Following this approach, a genetically detoxified pertussis toxin has been produced. This molecule is now the component of an acellular pertussis vaccine, which has been shown to be highly immunogenic and efficacious in infants. The same strategy of molecular detoxification of bacterial toxins has been applied to cholera toxin and to the Escherichia coli heat-labile enterotoxin. Toxin mutants devoid of any toxic activity have been produced and shown in animals to be highly immunogenic and to exhibit strong adjuvanticity when administered at mucosal sites in conjunction with several antigens. These successful results show that rational design of stronger and safer vaccines is feasible.

Non-pertussis components of combination vaccines: problems with potency testing

Vaccines comprising combinations of diphtheria, tetanus and pertussis (DTP) with Haemophilus influenzae type b polysaccharide-protein conjugate (Hib), inactivated poliomyelitis virus (IPV) and hepatitis B virus (HBV) are already available, and new combinations using acellular pertussis components in a triple vaccine (DTaP) are under development. Evidence to date has shown that control of the efficacy, safety and stability of combination vaccines cannot be based on information already available on the individual components or existing licensed formulations. Several examples of immunological interference between components of a combination vaccine have been observed both in clinical trials and in laboratory tests. Examples of these for D, T and Hib components in DTP and DTaP combinations have been investigated.

Novel molecular biology approaches to acellular vaccines

Bacterial toxins are commonly detoxified by chemical treatment in order to use them in human vaccines. We have used site-directed mutagenesis of toxin genes to obtain bacteria that produce naturally nontoxic mutants of bacterial toxins, such as pertussis toxin (PT), cholera toxin (CT) and Escherichia coli heat-labile enterotoxin (LT). Genetically detoxified PT showed a superior safety and immunogenicity in animal models, phase I and phase II clinical trials, and a superior protective efficacy in the early and late stage of a phase III efficacy trial, proving in a definitive and extensive way that genetic detoxification of bacterial toxins can, and should, replace chemical treatment. The results obtained with genetically inactivated LT and CT indicate that genetic detoxification of bacterial toxins can be used not only to produce vaccines for systemic immunization that are superior to the ones produced by conventional technologies, but suggest that these type of molecules may be the prototype molecules for the design and construction of innovative vaccines with a totally new design, such as mucosally delivered preventive and therapeutic vaccines.

The effect of pertussis toxin and whole-cell pertussis vaccine on haemodynamics and autonomic responsiveness in the rat depends on route of administration and age

Vaccination of children with Diphtheria, Tetanus, Poliomyelitis and pertussis vaccine (DTPoP-vaccine) containing the whole-cell pertussis component is known to be associated with manifestation of side-effects such as acute encephalopathy, convulsions and hypotensive-hyporesponsive episodes. In young and adult rats the effects of pertussis toxin and DTPoP-vaccine on haemodynamics and autonomic responsiveness are evaluated following treatment with high dose via different routes of administration (s.c., i.p. and i.v.). The effect of pertussis toxin is dose-dependent (between 1 and 20 micrograms kg-1) and largest responses are observed after i.v. administration. At 20 micrograms kg-1, i.v. pertussis toxin decreases baseline diastolic blood pressure and increases baseline heart rate by 31% and inhibits autonomic responsiveness (salbutamol-induced increase in diastolic blood pressure and arecoline-induced decrease in heart rate). In adult rats DTPoP-vaccine induces generally more prominent effects than in young rats. In adult rats DTPoP-vaccine reduces baseline diastolic blood pressure by 25% while no response is observed in young rats. In adult rats DTPoP inhibits the adrenergic response though less compared to treatment of pertussis toxin. After treatment with DTPoP-vaccine (single or twice) only minor differences are observed between young and adult rats. Present results show that adult rats are more sensitive to pertussis toxin and pertussis vaccine than young rats and that the responses depend on the route of administration.

Molecular basis of vaccination

Vaccines represent the most cost-effective means to prevent infectious diseases. Most of the vaccines which are currently available were developed long before the era of molecular biology and biotechnology. They were obtained following empirical approaches leading to the inactivation or to the attenuation of microorganisms, without any knowledge neither of the mechanisms of pathogenesis of the disease they were expected to protect from, nor of the immune responses elicited by the infectious agents or by the vaccine itself. The past two decades have seen an impressive progress in the field of immunology and molecular biology, which have allowed a better understanding of the interactions occurring between microbes and their hosts. This basic knowledge has represented an impetus towards the generation of better vaccines and the development of new vaccines. In this monograph we briefly summarize some of the most important biotechnological approaches that are currently followed in the development of new vaccines, and provide details on an approach to vaccine development: the genetic detoxification of bacterial toxins. Such an approach has been particularly successful in the rational design of a new vaccine against pertussis, which has been shown to be extremely efficacious and safe. It has been applied to the construction of powerful mucosal adjuvants, for administration of vaccines at mucosal surfaces.

Response to diphtheria and tetanus booster vaccination in pediatric renal transplant recipients

BACKGROUND

Although inactivated vaccines are recommended for immunocompromized patients, efficacy and safety of diphtheria and tetanus immunization in renal transplant recipients have received little attention so far. The aim of the study was to investigate the response to a standard diphtheria and tetanus booster vaccination in pediatric renal transplant recipients.

METHODS

Forty-two children, median age 13.2 years (range, 7.8-18.9 years) with complete primary immunization 9.2 years (0.9-15.4 years) before transplantation were enrolled. Immunosuppression consisted of cyclosporine plus prednisolone in 15 (36%), cyclosporine, azathioprine, and prednisolone in 24 (57%), and tacrolimus plus prednisolone in 3 (7%). Antibodies were measured by enzyme-linked immunosorbent assay before and 1, 6, and 12 months after vaccination.

RESULTS

Before vaccination, protective antibody concentrations exceeding 0.1 IU/ml against diphtheria were found in 16 children (38%). Thirty-eight (90%) had protective antibody concentrations against tetanus. After booster immunization, the protection rate against diphtheria rose to 95% at 1 month with a decline to 93% at 6 and 76% at 12 months. Protection against tetanus was complete after vaccination and persisted over the observation. Antibody concentrations were comparable to those reported for healthy children. Statistical analysis showed no influence of allograft function, immunosuppressive regimen, previous cytotoxic therapy, or time between primary immunization and end-stage renal failure on antibody response. Immunization was well tolerated and kidney function remained unaffected in patients with stable allograft function.

CONCLUSIONS

Diphtheria and tetanus vaccination can be performed effectively and safely in renal transplant recipients as generally recommended.

Adverse reactions and antibody response to four doses of acellular or whole cell pertussis vaccine combined with diphtheria and tetanus toxoids in the first 19 months of life

To assess the safety, immunogenicity, and lot consistency of a five-component acellular pertussis vaccine combined with diphtheria and tetanus toxoid (Connaught Laboratories Limited), we randomly allocated 432 infants to receive one of three lots of an acellular pertussis vaccine or a single lot of whole cell pertussis vaccine. Infants were immunized at 2, 4 and 6 months of age and between 17 and 19 months of age. Local and systemic adverse reactions were reported significantly more frequently by recipients of the whole cell than acellular vaccine after each dose. The antibody response against pertussis toxin, filamentous hemagglutinin, and 69 kDa protein was of greater magnitude in acellular pertussis vaccine recipients than whole cell pertussis vaccine recipients. Small differences were detected amongst the vaccine lots tested. We conclude that the acellular pertussis vaccine is safe and immunogenic for the first four doses in children under 2 years of age.

The effect of formaldehyde, hydrogen peroxide and genetic detoxification of pertussis toxin on epitope recognition by murine monoclonal antibodies

The effect of detoxification of pertussis toxin (PT) for vaccine usage by either genetic manipulation, hydrogen peroxide or formaldehyde treatment on epitope recognition by a large collection of murine monoclonal pertussis toxin antibodies (PT MAbs) was assessed in a solid-phase and a soluble phase enzyme-linked immunosorbent assay (ELISA). The MAb binding patterns were found to be different in the two assays as the immobilization step appeared to cause conformational alterations in the native as well as the toxoided forms of PT. According to the solid-phase ELISA, genetic, hydrogen peroxide and 0.35% formaldehyde detoxification of PT resulted in reduced epitope binding in 2.9, 31.4 and 78.1% of the MAbs, respectively. In the soluble-phase ELISA, in which the MAbs were allowed to react with the toxoids or native toxin in solution, the percentages of MAbs showing decreased binding activity were 9.1, 50.0 and 71.4%, respectively. Stabilization of native PT and the genetically inactivated PT by 0.035% formaldehyde reduced the epitope binding activity in 50.0 and 8.7% of the MAbs, respectively. Increased antibody binding in the soluble-phase ELISA was observed in some of the toxoids: this ranged from 0% in the 0.35% formaldehyde-treated PT to 13.6% in the hydrogen peroxide-treated and 27.3% in the genetically detoxified PT. Regarding the effects of detoxification on epitopes recognized by PT-neutralizing MAbs in the soluble-phase ELISA, we found that treatment of PT with either 0.035%, 0.35% formaldehyde or hydrogen peroxide induced impairment of epitope binding in 72.7, 81.8 and 45.5% of the MAbs, respectively. In the genetically inactivated PT, the epitopes recognized by the neutralizing MAbs either appeared to remain intact or to show increased MAb binding activity. The epitope-binding patterns of several PT MAbs with mouse-protective properties varied considerably and were shown to be dependent on the detoxification procedure employed. The relevance of epitope alterations on PT as a vaccine component is discussed. The results of the present study may have important implications for future quality assessment of PT for use in acellular pertussis vaccines.

Recombinant proteins for medical use: the attractions and challenges

Recombinant proteins that have survived the challenges of process development and clinical trials are becoming blockbuster medical products. Growth factors, enzymes and antibodies are being improved by mutational approaches, fused with other proteins, and even chemically modified in vitro. Drug development and testing approaches have advanced, and proteins produced in transgenic animals are new becoming available. Future protein products might include cancer vaccines and therapies for a variety of genetic diseases, but alternative treatments involving gene therapy or small synthetic compounds will provide competition.

Full protection in mink against mink enteritis virus with new generation canine parvovirus vaccines based on synthetic peptide or recombinant protein

Two recently developed vaccine--one based on synthetic peptide and one based on recombinant capsid protein--fully protected dogs against heavy experimental canine parvovirus (CPV) infection. The high sequence homology ( > 98%) and antigenic similarity between CPV and mink enteritis virus (MEV), feline panleukopenia virus, and raccoon parvovirus, suggest that both vaccines could protect mink, cats and raccoons against these respective host range variants. This was tested in mink and turned out to be the case. The two vaccines were fully protective and as effective as a conventional commercial vaccine based on inactivated virus. Surprisingly, this protection was obtained after only a single injection. Furthermore, the vaccinal dose of 150 micrograms of conjugated peptide or 3 micrograms of recombinant VP2 particles per animal, are sufficiently low to be cost-effective and applicable on a large scale.

Effect of priming with diphtheria and tetanus toxoids combined with whole-cell pertussis vaccine or with acellular pertussis vaccine on the safety and immunogenicity of a booster dose of an acellular pertussis vaccine containing a genetically inactivated pertussis toxin in fifteen- to twenty-one-month-old children. Italian Multicenter Group for the Study of Recombinant Acellular Pertussis Vaccine

OBJECTIVE

To evaluate the safety and the immunogenicity of a booster dose of recombinant acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP, Biocine SpA) in 15- to 21-month-old children primed in infancy with either whole-cell diphtheria-tetanus-pertussis (DTwP) vaccine or DTaP vaccine.

DESIGN

Open-label second phase of a double-masked, controlled trail, with masked analysis of serum samples.

PARTICIPANTS AND SETTING

Three hundred fifty children, 15 to 21 months of age, who had been primed at 2, 4, and 6 months of age with either three doses of DTaP vaccine (n = 173) or DTwP vaccine (n = 177). The children were enrolled in eight vaccination centers in Italy.

INTERVENTIONS

All children received a booster dose of the DTaP vaccine and were examined for safety at 48 hours and at 7 days after vaccination. Serum samples for evaluation of immunogenicity were obtained from 196 (55%) of the 350 children.

MAIN OUTCOME MEASURES

IgG antibodies to pertussis toxin (Ptox), filamentous hemagglutinin, 69-kilodalton protein, and tetanus toxoid were measured by enzyme-linked immunosorbent assay. Pertussis toxin-neutralizing antibodies were measured by the Chinese hamster ovary cell toxin neutralization assay.

MAIN RESULTS

Adverse reactions to DTaP were infrequent, and there was no difference in the incidence of local or systemic reactions in children given DTaP as a fourth dose in comparison with a first dose. One month after the DTaP booster vaccination, both groups had 6- to 40-fold increases in serum antibody concentrations to all antigens tested; the concentrations against the three pertussis antigens were higher in the DTaP-primed children (p < 0.05). The antibody titers to diphtheria and tetanus toxoids were higher in the DTwP-primed group (p < 0.05), but both groups had protective titers. The geometric mean ratio of anti-Ptox neutralizing antibody per unit of IgG anti-Ptox antibody was higher in the DTaP-primed group (p < 0.001).

CONCLUSIONS

There are quantitative and qualitative differences in booster responses to DTaP vaccine in young children, depending on whether they were given DTaP or DTwP as primary immunization. This DTaP vaccine is safe and highly immunogenic as a booster.