(1/838) A case-control study of risk factors for Haemophilus influenzae type B disease in Navajo children.
To understand the potential risk factors and protective factors for invasive Haemophilus influenzae type b (Hib) disease, we conducted a case-control study among Navajo children less than two years of age resident on the Navajo Nation. We analyzed household interview data for 60 cases that occurred between August 1988 and February 1991, and for 116 controls matched by age, gender, and geographic location. The Hib vaccine recipients were excluded from the analyses. Conditional logistic regression models were fit to examine many variables relating to social and environmental conditions. Risk factors determined to be important were never breast fed (odds ratio [OR] = 3.55, 95% confidence interval [CI] = 1.52, 8.26), shared care with more than one child less than two years of age (OR = 2.32, 95% CI = 0.91, 5.96); wood heating (OR = 2.14, 95% CI = 0.91, 5.05); rodents in the home (OR = 8.18, 95% CI = 0.83, 80.7); and any livestock near the home (OR = 2.18, 95% CI = 0.94, 5.04). (+info)
(2/838) Pneumococcal conjugate vaccine primes for polysaccharide-inducible IgG2 antibody response in children with recurrent otitis media acuta.
Children with frequent recurrent episodes of otitis media may have a deficient IgG2 antibody response to polysaccharide antigens. Five otitis-prone children were vaccinated with heptavalent pneumococcal conjugate vaccine. While all had an IgG1 antibody response to all pneumococcal serotypes included in the conjugate vaccine, the IgG2 response, especially to serotypes 6B, 9V, 19F, and 23F, was poor. However, vaccination with a 23-valent polysaccharide vaccine 6 months after conjugate vaccination induced an 11.5- to 163-fold increase in IgG2 anti-polysaccharide antibody titers. Thus, an IgG2 polysaccharide antibody deficiency can be overcome by priming with a pneumococcal conjugate vaccine followed by a booster with a polyvalent polysaccharide vaccine. (+info)
(3/838) Protein conjugates of synthetic saccharides elicit higher levels of serum IgG lipopolysaccharide antibodies in mice than do those of the O-specific polysaccharide from Shigella dysenteriae type 1.
Our development of vaccines to prevent shigellosis is based on the hypothesis that a critical (protective) level of serum IgG to the O-specific polysaccharide (O-SP) domain of Shigella lipopolysaccharide (LPS) confers immunity. The O-SP is a hapten and must be conjugated to a protein to induce serum antibodies. The O-SP of Shigella dysenteriae type 1 (approximately 27 tetrasaccharide repeat units), prepared by acid hydrolysis of the LPS, was bound to human serum albumin (HSA) by multiple point attachment (O-SP-HSA): The molar ratio of HSA to O-SP was 1.0. Synthetic saccharides, composed of one or multiples of the O-SP tetrasaccharide, equipped with a spacer at their reducing end, were bound to HSA by a single point attachment: The average molar ratios of the saccharides to HSA ranged from 4 to 24. Serum IgG anti-LPS, elicited in mice by O-SP-HSA or synthetic tetra-, octa-, dodeca-, and hexadecasaccharide fragments, was measured by ELISA. Outbred 6-week-old female mice were injected s.c. three times at biweekly intervals with 2.5 micrograms of saccharide as a conjugate and were bled 7 days after the second and third injections. Excepting the tetramer, conjugates of the octamer, dodecamer and hexadecamer elicited IgG LPS antibodies after the second injection, a statistically significant rise (booster) after the third injection, and higher levels than those vaccinated with O-SP-HSA (P = 0.0001). The highest geometric mean levels of IgG anti-LPS were elicited by the hexadecamer with 9 chains or 9 moles of saccharide/HSA (15.5 ELISA units) followed by the octamer with 20 chains (11.1 ELISA units) and the dodecamer with 10 chains (9.52 ELISA units). Clinical evaluation of these synthetic saccharides bound to a medically useful carrier is planned. (+info)
(4/838) Intranasal immunization against dental caries with a Streptococcus mutans-enriched fimbrial preparation.
Streptococcus mutans has been identified as the major etiological agent of human dental caries. The first step in the initiation of infection by this pathogenic bacterium is its attachment (i.e., through bacterial surface proteins such as glucosyltransferases, P1, glucan-binding proteins, and fimbriae) to a suitable receptor. It is hypothesized that a mucosal vaccine against a combination of S. mutans surface proteins would protect against dental caries by inducing specific salivary immunoglobulin A (IgA) antibodies which may reduce bacterial pathogenesis and adhesion to the tooth surface by affecting several adhesins simultaneously. Conventional Sprague-Dawley rats, infected with S. mutans at 18 to 20 days of age, were intranasally immunized with a mixture of S. mutans surface proteins, enriched for fimbriae and conjugated with cholera toxin B subunit (CTB) plus free cholera toxin (CT) at 13, 15, 22, 29, and 36 days of age (group A). Control rats were either not immunized (group B) or immunized with adjuvant alone (CTB and CT [group C]). At the termination of the study (when rats were 46 days of age), immunized animals (group A) had significantly (P < 0.05) higher salivary IgA and serum IgG antibody responses to the mixture of surface proteins and to whole bacterial cells than did the other two groups (B and C). No significant differences were found in the average numbers of recovered S. mutans cells among groups. However, statistically fewer smooth-surface enamel lesions (buccal and lingual) were detected in the immunized group than in the two other groups. Therefore, a mixture of S. mutans surface proteins, enriched with fimbria components, appears to be a promising immunogen candidate for a mucosal vaccine against dental caries. (+info)
(5/838) Alpha C protein as a carrier for type III capsular polysaccharide and as a protective protein in group B streptococcal vaccines.
The alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-alpha9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-alpha2r conjugate vaccine) by reductive amination. Initial experiments with the III-alpha9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-alpha2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 microgram of the III-alpha2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-alpha2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-alpha vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection. (+info)
(6/838) Carbohydrate vaccines in cancer: immunogenicity of a fully synthetic globo H hexasaccharide conjugate in man.
The complex carbohydrate molecule globo H hexasaccharide has been synthesized, conjugated to keyhole limpet hemocyanin, and administered with the immunologic adjuvant QS-21 as a vaccine for patients with prostate cancer who have relapsed after primary therapies such as radiation or surgery. Globo H is one of several candidate antigens present on prostate cancer cells that can serve as targets for immune recognition and treatment strategies. The vaccine, given as five subcutaneous vaccinations over 26 weeks, has been shown to be safe and capable of inducing specific high-titer IgM antibodies against globo H. Its immunogenicity was confirmed in prostate cancer patients with a broad range of stages and tumor burdens. Observations of several patients who had evidence of disease relapse restricted to a rising biochemical marker, prostate-specific antigen (PSA), indicated that a treatment effect could occur within 3 months after completion of the vaccine therapy. This effect was manifested as a decline of the slope of the log of PSA concentration vs. time plot after treatment compared with values before treatment. Five patients continue to have stable PSA slope profiles in the absence of any radiographic evidence of disease for more than 2 years. The concept of using PSA slope profiles in assessing early treatment effects in biological therapies such as vaccines awaits further validation in phase II and III trials. The use of a variety of lesser known candidate glycoprotein and carbohydrate antigens in prostate cancer serves as a focus for the development of a multivalent vaccine of the treatment of relapsed prostate cancer in patients with minimal tumor burden. (+info)
(7/838) Bacterial vaccines and serotype replacement: lessons from Haemophilus influenzae and prospects for Streptococcus pneumoniae.
Conjugate vaccines have reduced the incidence of invasive disease caused by Haemophilus influenzae, type b (Hib), in industrialized countries and may be highly effective against Streptococcus pneumoniae. However, the serotype specificity of these vaccines has led to concern that their use may increase carriage of and disease from serotypes not included in the vaccine. Replacement has not occurred with the use of Hib vaccines but has occurred in trials of pneumococcal vaccines. Mathematical models can be used to elucidate these contrasting outcomes, predict the conditions under which serotype replacement is likely, interpret the results of conjugate vaccine trials, design trials that will better detect serotype replacement (if it occurs), and suggest factors to consider in choosing the serotype composition of vaccines. (+info)
(8/838) Intranasal administration of a Schistosoma mansoni glutathione S-transferase-cholera toxoid conjugate vaccine evokes antiparasitic and antipathological immunity in mice.
Mucosal administration of Ags linked to cholera toxin B subunit (CTB) can induce both strong mucosal secretory IgA immune responses and peripheral T cell hyporeactivity. In this study, intranasal (i.n. ) administration of CTB-conjugated Schistosoma mansoni 28-kDa GST (CTB-Sm28GST) was found to protect infected animals from schistosomiasis, especially from immunopathological complications associated with chronic inflammation. Worm burden and liver egg counts were reduced in infected animals treated with the CTB-Sm28GST conjugate as compared with mice infected only, or with mice treated with a control (CTB-OVA) conjugate. However, a more striking and consistent effect was that granuloma formations in liver and lungs of mice treated with CTB-Sm28GST were markedly suppressed. Such treatment was associated with reduced systemic delayed-type hypersensitivity and lymphocyte proliferative responses to Sm28GST. Production of IFN-gamma, IL-3, and IL-5 by liver cells was also markedly reduced after i.n. treatment of CTB-Sm28GST, whereas IL-4 production was not impaired. Intranasal treatment of infected mice with CTB-Sm28GST increased IgG1-, IgG2a-, IgA-, and IgE-Ab-forming cell responses in liver in comparison with treatment with CTB-OVA, or free Sm28GST. Most importantly, mucosal treatment with CTB-Sm28GST significantly reduced animal mortality when administered to chronically infected mice. Our results suggest that it may be possible to design a therapeutic vaccine against schistosomiasis that both limits infection and suppresses parasite-induced pathology. (+info)