Biomedical subjects

H Käyhty

Publications and source records attributed to H Käyhty.

At least 19 recordsLinked to original sources

PubMed2007

A randomized study on donor immunization with tetanus-diphtheria, Haemophilus influenzae type b and inactivated poliovirus vaccines to improve the recipient responses to the same vaccines after allogeneic bone marrow transplantation.

The HLA-identical sibling donors of 111 bone marrow transplantation (BMT) recipients were randomised to receive or not to receive tetanus-diphtheria (T-d), Haemophilus influenzae type b (Hib), and inactivated poliovirus (IPV) vaccines 2-10 weeks before BM harvest. Fifty-three (DV+ group) recipients received the graft from a vaccinated donor and 58 (DV- group) from an unvaccinated donor. All recipients were vaccinated with the T-d, Hib and IPV vaccines at 3, 6 and 12 months after BMT. Diphtheria and Hib antibody concentrations were consistently higher in the DV+ than in the DV- group from 6 months post transplantation onwards. The differences were significant at 6 and 13 months for diphtheria and at 12 months for Hib antibody concentrations. Tetanus, PV1, PV2 and PV3 antibody levels were similar in both groups. Patients transplanted from donors with high tetanus, diphtheria and Hib antibody concentrations had higher respective antibody concentrations after BMT than those transplanted from donors with low antibody concentrations. Especially patients whose donors have low-specific antibody concentrations may benefit from donor vaccination with protein and conjugate vaccines.

Adult↗

PubMed2006

Subclass distribution of natural salivary IgA antibodies against pneumococcal capsular polysaccharide of type 14 and pneumococcal surface adhesin A (PsaA) in children.

A number of studies have shown that the ratio of IgA1 and IgA2 subclasses in secretions can depend upon the nature of the antigen inducing their production. In order to evaluate the effect of the nature of the antigen on the subclass distribution of the naturally occurring salivary IgA antibodies against Streptococcus pneumoniae, we used enzyme immunoassay to measure the levels of natural IgA, IgA1 and IgA2 antibodies to pneumococcal capsular polysaccharide type 14 (PS14) and pneumococcal surface adhesin A (PsaA) in saliva of children during their first 2 years of life. The sum of anti-PS14 and anti-PsaA IgA1 and IgA2 correlated significantly with the antigen-specific total IgA, which showed that IgA1 and IgA2 add up to IgA. IgA1 was the predominant subclass for both antigens. The median of anti-PS14 and anti-PsaA IgA1 was higher than that of IgA2, and the antigen-specific IgA1 was found in a larger proportion of samples than IgA2. The ratio of IgA1 to IgA2 (IgA1/IgA2 ratio) was lower for anti-PS14 than for anti-PsaA, suggesting that the PS antigen induced more IgA2 than the protein antigen. The possible impact of the IgA subclass distribution on protection of mucosal surfaces by natural or vaccine-induced antibodies needs to be determined.

Adhesins, Bacterial↗

PubMed2003

Maternal immunization with pneumococcal polysaccharide vaccine in the Philippines.

A randomized, controlled study was conducted to evaluate the immunogenicity and reactogenicity of the 23-valent pneumococcal (Pnc) polysaccharide (PS) vaccine among pregnant women and to ascertain the transfer of anti-Pnc antibody (Ab) from mother to infant. One hundred and sixty women received either one dose of Pnc PS vaccine, Haemophilus influenzae type b conjugate vaccine and tetanus toxoid (TT) (Pnc vaccine group, N=106) or TT only (control group, N=54). Sera were obtained from all mothers prior to vaccination and 4 weeks after from the vaccinated group. Cord blood was obtained in 75% of deliveries. Anti-Pnc Ab for serotypes 1, 5, 6B, 14, 18C and 19F was determined using enzyme immunoassay. The Pnc vaccine and control groups were comparable in terms of age, parity, gravidity, prior doses of TT, and pre-vaccination geometric mean concentration (GMC in microg/ml) of anti-Pnc Ab. Between 66 and 87% of the mothers had type-specific Ab prior to vaccination. There was a significant rise in anti-Pnc Ab (varying from 3.3- to 9.1-fold for the individual serotypes) between the pre and post-vaccination samples. Adverse reactions were mild and required no treatment. The level of anti-Pnc Ab in cord blood was significantly lower in the control group compared to the Pnc vaccine group. Vaccination of pregnant women with Pnc Ps vaccine induces good immune response and Ab can be transferred to their infants via cord blood thus providing enhanced protection.

Adult↗

PubMed2003

Effects of sample collection and storage methods on antipneumococcal immunoglobulin A in saliva.

Saliva contains components of both the mucosal and systemic immune systems. Variable flow rates, immunoglobulin proteases, and variation in collection and storage methods all introduce differences in the estimated concentrations of antibodies. We evaluated the effect of four collection methods and three storage protocols on the concentrations of immunoglobulin A (IgA) antibodies to pneumococcal capsular antigens 1, 5, 6B, and 14 and to pneumococcal surface adhesin A (PsaA) in saliva. Specimens were collected from 30 healthy Kenyan adults by collecting drool, by pipette suction, and with two commercial kits, OraSure and Oracol. Aliquots from each specimen were snap-frozen with glycerol in liquid nitrogen or stored for 4 to 8 h at +4 degrees C either with or without the addition of protease enzyme inhibitors prior to storage at -70 degrees C. Anticapsular IgA concentrations were not significantly different with different collection methods, but snap-freezing the specimens in liquid nitrogen led to concentrations 41 to 47% higher than those of specimens stored by the other methods (P < 0.0005).

Adult↗

PubMed2002

Haemophilus influenzae type b and cross-reactive antigens in natural Hib infection dynamics; modelling in two populations.

Natural immunity to Haemophilus influenzae type b (Hib) invasive disease is based on antibodies arising in response to encounters with Hib or cross-reactive (CR) bacteria. The relative importance of Hib and CR contacts is unknown. We applied a statistical model to estimate the total rate of immunizing infections of Hib and CR prior to wide-scale vaccinations in Finland and the UK. The average rates of these contacts were 0.7 and 1.2 per year per child in Finland and the UK, respectively. Using a rough estimate of 0.1 Hib acquisitions per year per child in the UK based on carriage rates, the proportion of Hib among all immunizing contacts was in the order of 10%, suggesting that CR bacteria have a major role. In general, varying frequency of CR contacts may explain some differences in the pre-vaccination incidence and age-distribution of invasive disease in different countries.

Age Factors↗

PubMed2002

Current state of pneumococcal vaccines.

Streptococcus pneumoniae is a leading cause of bacterial pneumonia, meningitis, and acute otitis media in children and adults worldwide. According to World Health Organization estimates, at least 1 million children under 5 years of age die each year from pneumococcal pneumonia. The emergence of resistant strains necessitates the development of an effective vaccine with a large serotype coverage. The 11 most common serotypes cause 72-83% of all serious pneumococcal diseases worldwide. Currently marketed 23-valent pneumococcal polysaccharide vaccine provides large serotype coverage and offers a less expensive option. However, it is efficacious only in adults but not in infants. Conjugate vaccines offer a solution by generating immunological memory already at early age. A recently licensed 7-valent conjugate vaccine is immunogenic and efficacious in infants. Its serotype coverage might be sufficient in Europe and North America, but not in Africa, Asia and Oceania. A need exists to develop pneumococcal vaccines with lower cost and larger serotype coverage. Several 11-valent pneumococcal conjugate vaccines are being evaluated in phase I-III trials. This study reviews the current state of pneumococcal problem and pneumococcal vaccines in clinical use.

Adult↗

PubMed2001

Bridging phase 2 and phase 3 pneumococcal immunologic data for future combination vaccines.

Pneumococcal conjugate vaccines (PncCs) will be introduced into childhood vaccination programs now that the first PncC has been licensed for use. The next generation of PncCs and possible combination vaccines containing PncC will most probably be approved on the basis of phase 2 immunogenicity and safety data. PncCs are combination vaccines that include, at present, 7-11 components. Immune response to different components may vary. Furthermore, there seem to be population-based differences in immune response. Whether these differences are due to the other vaccines that are given simultaneously or due to the genetic background remains to be seen. Immune response can be evaluated by determining both the quantity and the quality of antibodies after vaccination. However, data are still missing on the minimal protective immune response and serologic correlates or surrogates of protection.

Antibodies, Bacterial↗

PubMed2001

Booster response to the tetanus and diphtheria toxoid carriers of 11-valent pneumococcal conjugate vaccine in adults and toddlers.

We measured the tetanus and diphtheria antitoxin responses after administration of one dose of a mixed carrier (tetanus and diphtheria toxoids) 11-valent pneumococcal conjugate vaccine (PncDT) in 20 Finnish adults (mean age 26.1 years) and 20 Finnish (mean age 23.2 months) and 23 Israeli (mean age 18.5 months) toddlers. The vaccinees had previously been immunised with multiple doses of vaccines containing diphtheria and tetanus toxoids. A double-antigen ELISA was used to measure the antitoxin concentrations. PncDT induced significant booster responses in both adults and toddlers to the tetanus and the diphtheria carrier proteins. Thus, the effect on the tetanus and diphtheria immunity of multivalent conjugate vaccines containing tetanus and diphtheria toxoids as carriers needs to be evaluated before such vaccines are routinely implemented.

Adult↗

PubMed2001

Serum and salivary anti-capsular antibodies in infants and children vaccinated with octavalent pneumococcal conjugate vaccines, PncD and PncT.

We studied the immunogenicity of two octavalent pneumococcal (Pnc) conjugate vaccines; Pnc polysaccharides (PS) of serotypes 3, 4, 6B, 9V, 14, 18C, 19F, and 23F were conjugated to diphtheria or tetanus toxoid (PncD and PncT, respectively). Fifty healthy Finnish infants were vaccinated at the ages of 2, 4, 6, and 15 months with either PncD or PncT. Serum IgG antibodies to the vaccine serotypes were analysed by enzyme-linked immunosorbent assay (EIA). All eight PSs induced a significant antibody response both after the primary series and after the booster. Response to PncD was higher for PSs 3, 9V, 14 and 18C and to PncT for serotype 4. Salivary IgA and IgG anti-Pnc antibodies were measured for serotypes 4, 6B, 9V, 14, 18C, and 19F. Mucosal antibodies were found rarely after the primary series but in a greater proportion after the booster. In conclusion, both vaccines were immunogenic.

Antibodies, Bacterial↗

PubMed2001

Avidity and subclasses of IgG after immunization of infants with an 11-valent pneumococcal conjugate vaccine with or without aluminum adjuvant.

Finnish and Israeli infants received an 11-valent mixed-carrier pneumococcal conjugate vaccine with or without aluminum adjuvant at 2, 4, 6, and 12 months of age. The relative avidity of serotype 1-, 5-, 6B-, 14-, 19F-, and 23F-specific IgG antibodies in serum obtained at 7, 12, and 13 months of age was measured by EIA, using thiocyanate as a chaotropic agent. For all serotypes, except 14, avidity increased between the ages of 7 and 12 months. After boosting at 12 months, avidity further increased for all serotypes. The adjuvant improved antibody avidity against serotype 5. The IgG antibodies produced were mainly IgG1 subclass, although some infants also produced IgG2 after boosting. In conclusion, the immunization of infants with this 11-valent pneumococcal conjugate vaccine increased avidity of IgG, suggesting successful immunologic priming.

Adjuvants, Immunologic↗

PubMed2001

Immunogenicity and reactogenicity of diphtheria, tetanus and pertussis toxoids combined with inactivated polio vaccine, when administered concomitantly with or as a diluent for a Hib conjugate vaccine.

In an open trial, 400 infants were randomized to vaccination with a combined diphtheria-tetanus-pertussis-inactivated polio vaccine (DTaP-IPV) either mixed with a Haemophilus influenzae type b (Hib) tetanus toxoid conjugate immediately before injection (DTaP-IPV/Hib (mix)) or given concurrently with the Hib conjugate at separate injection sites (DTaP-IPV+Hib (sep)). The pertussis component consisted of pertussis toxoid alone. The vaccines were given intramuscularly at 3, 5 and 12 months of age. No vaccine-related serious adverse events occurred. Local reactions were evaluated from diary cards completed by the parents. Infants who received DTaP-IPV/Hib (mix) experienced fewer local reactions. Sera were obtained 28-45 days after the second and third vaccinations. Total Hib capsular antibodies were similar in the two groups after the second injection but lower in the group receiving DTaP-IPV/Hib (mix) than in the group receiving DTaP-IPV+Hib (sep) after the third injection (geometric mean 6.1 vs 10.4 microg/ml). Mixing of the vaccines also led to somewhat lower diphtheria toxin antibodies (5.9 vs. 7.7 IU/ml after the third injection) while tetanus antibodies were higher (3.9 vs. 2.5 IU/ml after the third injection). Antibodies against pertussis toxin and the three polio virus types were similar in the two groups. The moderate impairment of the Hib antibody response caused by mixing of the Hib conjugate with aluminium adsorbed DTaP may be due to physicochemical interference but is probably of little clinical importance because of the ability of the Hib conjugates to induce an immunologic memory.

Antibodies, Bacterial↗

PubMed2001

Cross-reactivity of antibodies to type 6B and 6A polysaccharides of Streptococcus pneumoniae, evoked by pneumococcal conjugate vaccines, in infants.

Streptococcus pneumoniae serotypes 6B and 6A are important causes of infections, yet only 6B is included in current vaccines. It is, therefore, crucial to evaluate whether functional antibodies are produced against both types after vaccination. Concentration and opsonophagocytic activity (OPA) of antibodies to 6B and 6A polysaccharides were determined in serum samples from infants immunized with 3 different pneumococcal conjugate vaccines containing serotype 6B. In all vaccine groups, a significant correlation was found between the anti-6B and -6A antibody concentration and OPA. However, OPA to the vaccine serotype was detectable more commonly than OPA to the cross-reactive type. Furthermore, 5%-15% of the serum samples showed high OPA against the 6B but not the 6A strain. On average, 2-6 times more anti-6B antibodies were needed for 50% opsonophagocytic killing of the type 6A than the type 6B strain. Although pneumococcal type 6B conjugate vaccines elicit antibodies that cross-react with type 6A, not all anti-6B antibodies are functionally cross-reactive.

Antibodies, Bacterial↗

PubMed2001

Natural development of antibodies to pneumococcal capsular polysaccharides depends on the serotype: association with pneumococcal carriage and acute otitis media in young children.

To study the natural development of antibodies to pneumococcal capsular polysaccharides of types 1, 6B, 11A, 14, 19F, and 23F and its association with pneumococcal carriage and acute otitis media (AOM), 329 children were followed-up prospectively during their first 2 years of life. Nasopharyngeal carriage was determined by cultures of nasopharyngeal swab samples, and etiology of AOM was determined by cultures of middle ear fluid. Antibodies were measured in serum samples collected at 6, 12, 18, and 24 months by EIA. Antibodies increased modestly but significantly with age. Contact with serotypes 11A and 14 was associated with increased antibody concentration as early as age 6 months. Children with contact with serotypes 6B, 19F, and 23F had antibody levels similar to those in children without contact. Antibodies increased modestly, even in children without known contact with Streptococcus pneumoniae and in children with contact with heterologous serotypes. Antibody concentrations were equal after carriage or AOM.

Antibodies, Bacterial↗

PubMed2001

Do antibodies to pneumococcal surface adhesin a prevent pneumococcal involvement in acute otitis media?

Antibodies to the pneumococcal (Pnc) surface protein PsaA are immunogenic and protective in experimental animal models, but their role in protection from Pnc disease in humans is not known. In the present study, the ability of antibodies to PsaA to prevent the progression of Pnc carriage to Pnc acute otitis media (Pnc AOM) was evaluated. Antibodies to PsaA were measured in acute-phase serum samples of children with AOM and with Streptococcus pneumoniae cultured from the nasopharynx. The risk of Pnc AOM was evaluated by a logistic regression model with anti-PsaA concentration as the predictive variable. Higher concentrations of antibodies to PsaA were associated with lower risk of the Pnc nasopharyngeal carriage progression to Pnc AOM. This was true in children 9-24 months old (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.31-0.78) but not in children <9 months old (OR, 0.81; 95% CI, 0.48-1.35).

Adhesins, Bacterial↗

PubMed2001

Tolerability and immunogenicity of an 11-valent pneumococcal conjugate vaccine in adults.

We studied the safety and immunogenicity in healthy adults of an 11-valent pneumococcal conjugate vaccine. Capsular polysaccharides (PS) of serotypes 1, 4, 5, 7F, 9V, 19F and 23F were conjugated to tetanus toxoid, and of serotypes 3, 6B, 14 and 18C to diphtheria toxoid. Ten subjects received the conjugate vaccine with and the other ten subjects without aluminium hydroxide adjuvant. The reference vaccine was a marketed 23-valent PS vaccine. Safety data were recorded over 5 days after the immunisation. IgG antibody concentrations, avidity and subclass distribution were measured by EIA. The conjugate without aluminium induced more local adverse effects than the conjugate with aluminium or PS vaccine. All vaccines evoked significant antibody increases to all vaccine specific antigens. Both conjugate vaccines induced antibodies mainly of IgG(2) subclass, and adjuvanted conjugate vaccine induced IgG antibodies with increased avidity. This first administration, to man, of a mixed protein carrier 11-valent pneumococcal conjugate vaccine demonstrated its ability to induce an immune response without significant adverse effects, enabling further study on its use in paediatric populations.

Adjuvants, Immunologic↗

PubMed2001

Pneumococcal carriage and otitis media induce salivary antibodies to pneumococcal surface adhesin a, pneumolysin, and pneumococcal surface protein a in children.

Local antibodies probably contribute to defense against Streptococcus pneumoniae. This study examined whether pneumococcal carriage and acute otitis media (AOM) induce mucosal antibodies to potential vaccine candidates pneumococcal surface adhesin A (PsaA), pneumolysin (Ply), and pneumococcal surface protein A (PspA). IgA to all 3 proteins was detected by EIA in saliva of 329 children at ages 6, 12, 18, and 24 months and of 17 adults. A higher proportion of IgA-positive samples and higher antibody concentrations were seen in children with pneumococci-positive cultures of nasopharyngeal samples or middle ear fluid than in children with all cultures negative for pneumococci. The strong correlation between IgA and the presence of the secretory component suggests that the IgA was secretory. The findings indicate that pneumococcal carriage and AOM induce local production of anti-PsaA, anti-Ply, and anti-PspA antibodies early in life.

Acute Disease↗

PubMed2001

Efficacy of a pneumococcal conjugate vaccine against acute otitis media.

BACKGROUND: Ear infections are a common cause of illness during the first two years of life. New conjugate vaccines may be able to prevent a substantial portion of cases of acute otitis media caused by Streptococcus pneumoniae. METHODS: We enrolled 1662 infants in a randomized, double-blind efficacy trial of a heptavalent pneumococcal polysaccharide conjugate vaccine in which the carrier protein is the nontoxic diphtheria-toxin analogue CRM197. The children received either the study vaccine or a hepatitis B vaccine as a control at 2, 4, 6, and 12 months of age. The clinical diagnosis of acute otitis media was based on predefined criteria, and the bacteriologic diagnosis was based on a culture of middle-ear fluid obtained by myringotomy. RESULTS: Of the children who were enrolled, 95.1 percent completed the trial. With the pneumococcal vaccine, there were more local reactions than with the hepatitis B vaccine but fewer than with the combined whole-cell diphtheria-tetanus-pertussis and Haemophilus influenzae type b vaccine that was administered simultaneously. There were 2596 episodes of acute otitis media during the follow-up period between 6.5 and 24 months of age. The vaccine reduced the number of episodes of acute otitis media from any cause by 6 percent (95 percent confidence interval, -4 to 16 percent [the negative number indicates a possible increase in the number of episodes]), culture-confirmed pneumococcal episodes by 34 percent (95 percent confidence interval, 21 to 45 percent), and the number of episodes due to the serotypes contained in the vaccine by 57 percent (95 percent confidence interval, 44 to 67 percent). The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51 percent, whereas the number of episodes due to all other serotypes increased by 33 percent. CONCLUSIONS: The heptavalent pneumococcal polysaccharide-CRM197 conjugate vaccine is safe and efficacious in the prevention of acute otitis media caused by the serotypes included in the vaccine.

Acute Disease↗

PubMed2001

Murine monoclonal antibodies to PorA of Neisseria meningitidis show reduced protective activity in vivo against B:15:P1.7,16 subtype variants in an infant rat infection model.

The major outer membrane protein PorA of Neisseria meningitidis is the target for bactericidal serosubtyping antibodies and is currently considered as a potential vaccine candidate against group B meningococcal disease. Although the minor antigenic variability of the PorA has been increasingly recognized and described, its implication for vaccine design remains unclear. In this study, the protective activity of murine monoclonal PorA specific antibodies against four isogenic meningococcal P1.7,16 target strains, the prototype P1.7,16a and three loop 4 point mutation variants (designated P1.7,16b to d) constructed from reference strain H44/76 (B:15:P1.7,16a), was evaluated in the infant rat infection model. All monoclonal antibodies had been obtained by immunization of mice with outer membrane protein preparations from meningococcal serosubtype P1.7,16 reference strain H44/76. A challenge dose of 10(5)cfu/pup was given i.p. 1-2 h after the i.p. injection of 1:100 diluted antibodies, and the development of bacteremia was assessed by culturing blood samples taken 6 h after challenge. MN14C11.6, a reference monoclonal antibody for serosubtype P1.7 epitope located in predicted loop 1 (VR1) identical in all the variants, was equally protective against all loop 4 variants. The three P1.16 specific monoclonal antibodies tested (MN5C11G, MN12H2 and 62D12-8) all completely protected animals against the prototype P1.7,16a, variably against the P1.7,16b and P1.7,16c, but not against the P1.7,16d variant. Our findings therefore suggest that certain subtype variants may escape protection in vivo conferred by PorA specific antibodies.

Animals↗