Serum IgG antibody responses to pertussis toxin and filamentous hemagglutinin in nonvaccinated and vaccinated children and adults with pertussis.
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Levels of IgG antibody to pertussis toxin (PT) and filamentous hemagglutinin (FHA) were measured in paired serum samples from 781 patients fulfilling at least one laboratory criterion for pertussis that was suggested by an ad hoc committee sponsored by the World Health Organization. The patients were participants or family members of participants in a double-blind efficacy trial of a monocomponent pertussis toxoid vaccine. Of 596 nonvaccinated children, 90% had significant (two-fold or more) rises in PT IgG and FHA IgG levels. Only 17 (32%) of 53 children previously vaccinated with three doses of pertussis toxoid had rises in PT IgG levels because they already had elevated PT IgG levels in their acute-phase serum samples. PT IgG and FHA IgG levels were significantly higher in acute-phase serum samples from 29 adults than in acute-phase serum samples from the nonvaccinated children. Nevertheless, significant rises in levels of PT IgG (79% of samples) and FHA IgG (90%) were demonstrated in adults. In conclusion, assay of PT IgG and FHA IgG in paired serum samples is highly sensitive for diagnosing pertussis in nonvaccinated individuals. Assay of PT IgG levels in paired sera is significantly less sensitive for diagnosis of pertussis for children vaccinated with pertussis toxoid. (+info)
Immunogenicity of a Salmonella typhimurium aroA aroD vaccine expressing a nontoxic domain of Clostridium difficile toxin A.
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The C-terminal repeat domain of Clostridium difficile toxin A harbors toxin-neutralizing epitopes and is considered to be a candidate component of a vaccine against C. difficile-associated disease (CDAD). Fourteen of the 38 C-terminal toxin A repeats (14CDTA) were cloned into pTECH-1 in frame with the immunogenic fragment C of tetanus toxin (TETC) to generate plasmid p56TETC. Expression of the TETC-14CDTA fusion protein was driven from the anaerobically inducible nirB promoter within attenuated Salmonella typhimurium BRD509 (aroA aroD). The TETC-14CDTA fusion protein was purified and shown to bind to known toxin A receptors found on the surface of rabbit erythrocytes. Intranasal (i.n.) and intragastric (i.g.) immunization with 10(7) and 10(10) CFU, respectively, of BRD509(p56TETC) generated significant (P < 0.05) anti-toxin A serum responses after a single dose. Antibody titers were elevated following a boosting dose with either live vaccine or a subcutaneous injection of 0.5 microgram of purified 14CDTA protein. Importantly, serum from mice immunized with BRD509(p56TETC) neutralized toxin A cytotoxicity. Both i.n. and i.g. immunizations also generated toxin A-specific immunoglobulin A on the pulmonary and intestinal mucosa, respectively. Intranasal vaccination induced consistently higher serum and mucosal anti-toxin A antibody responses. Significant anti-tetanus toxoid serum and mucosal antibodies were also generated by both immunization routes. The availability of live attenuated Salmonella typhi for human use may allow the development of a multivalent mucosal vaccine against CDAD, tetanus, and typhoid. (+info)
Combination vaccines for childhood immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP)
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An increasing number of new and improved vaccines to prevent childhood diseases are being introduced. Combination vaccines represent one solution to the problem of increased numbers of injections during single clinic visits. This statement provides general guidance on the use of combination vaccines and related issues and questions. To minimize the number of injections children receive, parenteral combination vaccines should be used, if licensed and indicated for the patient's age, instead of their equivalent component vaccines. Hepatitis A, hepatitis B, and Haemophilus influenzae type b vaccines, in either monovalent or combination formulations from the same or different manufacturers, are interchangeable for sequential doses in the vaccination series. However, using acellular pertussis vaccine product(s) from the same manufacturer is preferable for at least the first three doses, until studies demonstrate the interchangeability of these vaccines. Immunization providers should stock sufficient types of combination and monovalent vaccines needed to vaccinate children against all diseases for which vaccines are recommended, but they need not stock all available types or brand-name products. When patients have already received the recommended vaccinations for some of the components in a combination vaccine, administering the extra antigen(s) in the combination is often permissible if doing so will reduce the number of injections required. To overcome recording errors and ambiguities in the names of vaccine combinations, improved systems are needed to enhance the convenience and accuracy of transferring vaccine-identifying information into medical records and immunization registries. Further scientific and programmatic research is needed on specific questions related to the use of combination vaccines. (+info)
Induction of genital immunity by DNA priming and intranasal booster immunization with a replication-defective adenoviral recombinant.
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Mice immunized through different routes such as i.m., intradermally, or intratracheally with a DNA vaccine to rabies virus developed high titers of serum Ab but only borderline levels of mucosal Abs determined from vaginal secretions. DNA vaccines given by either route enhanced vaginal IgA and IgG2a secretion upon a subsequent intranasal booster immunization with an E1-deleted adenoviral recombinant expressing the same Ag of rabies virus. DNA vaccine priming reduced the Ab response to the adenoviral Ags and counterbalanced the impaired B cell response to the rabies virus Ag expressed by the adenoviral recombinant in mice preimmune to adenovirus. The vaginal B cell response could further be enhanced by using the Th2-type cytokines IL-4 or IL-5 as genetic adjuvants concomitantly with the DNA vaccine before intranasal booster immunization with the recombinant vaccine. (+info)
Combination vaccines for childhood immunization.
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An increasing number of new and improved vaccines to prevent childhood diseases are being introduced. Combination vaccines represent one solution to the problem of increased numbers of injections during single clinic visits. This statement provides general guidance on the use of combination vaccines and related issues and questions. To minimize the number of injections children receive, parenteral combination vaccines should be used, if licensed and indicated for the patient's age, instead of their equivalent component vaccines. Hepatitis A, hepatitis B, and Haemophilus influenzae type b vaccines, in either monovalent or combination formulations from the same or different manufacturers, are interchangeable for sequential doses in the vaccination series. However, using acellular pertussis vaccine product(s) from the same manufacturer is preferable for at least the first three doses, until studies demonstrate the interchangeability of these vaccines. Immunization providers should stock sufficient types of combination and monovalent vaccines needed to vaccinate children against all diseases for which vaccines are recommended, but they need not stock all available types or brandname products. When patients have already received the recommended vaccinations for some of the components in a combination vaccine, administering the extra antigen(s) in the combination is often permissible if doing so will reduce the number of injections required. To overcome recording errors and ambiguities in the names of vaccine combinations, improved systems are needed to enhance the convenience and accuracy of transferring vaccine-identifying information into medical records and immunization registries. Further scientific and programmatic research is needed on specific questions related to the use of combination vaccines. (+info)
The induction of immunologic memory after vaccination with Haemophilus influenzae type b conjugate and acellular pertussis-containing diphtheria, tetanus, and pertussis vaccine combination.
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The significance of reduced antibody responses to the Haemophilus influenzae type b (Hib) component of acellular pertussis-containing combination vaccines (DTaP-Hib) is unclear. A DTaP-Hib vaccine evaluated in infants vaccinated at ages 2, 3, and 4 months showed reduced anti-Hib polysaccharide IgG (geometric mean concentration [GMC], 1.23 microgram/mL; 57%, >1.0 microgram/mL). Polyribitolribosyl phosphate (PRP) and Hib conjugate (PRP-T) vaccine given as a booster during the second year of life was evaluated for the presence of immunological memory. After boosting, most children achieved anti-PRP IgG >1.0 microgram/mL, although the GMC was higher with PRP-T (88.5 microgram/mL) than with PRP vaccine (7.86 microgram/mL, P<.001). The GMC of the PRP group was higher than anticipated for naive PRP recipients of the same age. PRP-specific IgG avidity was significantly higher after boosting than after priming, providing further evidence for the generation of memory. Despite reduced immunogenicity, DTaP-Hib combination vaccines appear to prime for immunologic memory. (+info)
Th1 T cell responses to HIV-1 Gag protein delivered by a Listeria monocytogenes vaccine are similar to those induced by endogenous listerial antigens.
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Listeria monocytogenes is a facultative intracellular bacterium that lives and grows in the cytoplasm of the host cell. The hallmark of a listerial infection is a cell-mediated immune response to its own secreted virulence factors. Thus, L. monocytogenes vaccines engineered to secrete HIV proteins may be ideal vectors for boosting cellular immune responses against HIV. Using strains of L. monocytogenes that stably express and secrete HIV Gag (Lm-Gag) to deliver this Ag to the immune system, we have previously shown strong MHC class I-restricted cytotoxic T cell responses to this protein. In this study, we examine MHC class II-restricted T cell responses to HIV-Gag delivered by Lm-Gag. We demonstrate the induction of CD4+ T cells that are HIV-Gag specific and identify three epitopes in two strains of mice, BALB/c (H-2d) and C57BL/6 (H-2b), two of which are both H-2d and H-2b restricted, but are not immunodominant for both haplotypes. In addition, we show that the CD4+ T cells induced are of the Th1 phenotype that produce IFN-gamma at levels similar to CD4+ T cells induced to endogenous listerial Ags. These studies suggest that chromosomally modified strains of L. monocytogenes may be useful as vaccine vectors for the induction of Th1 T cell responses against HIV. (+info)
Safety and immunogenicity of Haemophilus influenzae-tetanus toxoid conjugate vaccine given separately or in combination with a three-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine for the first four doses.
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The purpose of this randomized, controlled trial was to assess the safety and immunogenicity of a three-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids and inactivated poliovirus vaccine given either separately or combined as a single injection with a Haemophilus influenzae type b-tetanus toxoid conjugate vaccine. A total of 180 infants were immunized at 2, 4, and 6 months of age; 129 were given a booster dose at 16-19 months of age. Vaccine-associated adverse events were similar whether the vaccines were combined as a single injection or given separately. There were no differences in levels of antibodies to Bordetella pertussis antigens (pertussis toxoid, filamentous hemagglutinin, and pertactin), diphtheria toxoid, or the three poliovirus types. The tetanus antitoxin level after the primary three-dose series was higher in recipients of the combined vaccine (2.37 IU/mL) than in recipients of the separate injections (1.32 IU/mL; two-sided P = .0001). In contrast, combined vaccine recipients had lower levels of antibody to H. influenzae type b polysaccharide after the third dose (1.57 microg/mL) than did those given separate injections (3.22 microg/mL; two-sided P = .0026). The antibody levels were not significantly different before or 1 month after the booster dose (32.9 microg/mL vs. 47.8 microg/mL, respectively; two-sided P = .07). We conclude that the vaccines were immunogenic and well tolerated. Despite lower levels of antibody to the H. influenzae type b polysaccharide after the primary three-dose series, mixing of the vaccines in a single syringe likely induced immunologic priming, as suggested by the high antibody levels after the booster dose. (+info)