Diphtheria Antibodies and T lymphocyte Counts in Patients Infected With HIV-1.

We assessed the IgG levels anti-diphtheria (D-Ab) and T cell counts (CD4+ and CD8+) in HIV-1 infected subjects undergoing or not highly active antiretroviral therapy (HAART). Approximately 70% of all HIV-1 patients were unprotected against diphtheria. There were no differences in D-Ab according to CD4 counts. Untreated patients had higher D-Ab (geometric mean of 0.62 IU/ml) than HAART-patients (geometric mean of 0.39 IU/ml). The data indicated the necessity of keeping all HIV-1 patients up-to-date with their vaccination.

Vitamin D is directly associated with favorable glycemic, lipid, and inflammatory profiles in individuals with at least one component of metabolic syndrome irrespective of total adiposity: Pró-Saúde Study, Brazil.

Vitamin D insufficiency has been suggested as a risk factor for several metabolic disorders. The objective of the study was to investigate the association between serum 25 hydroxyvitamin D [25(OH)D] and metabolic health markers of Brazilian individuals with normal-weight, overweight or obesity. We hypothesized that serum 25(OH)D would be inversely associated with glycemic, lipid and inflammatory markers indicative of metabolic abnormality. Data of 511 individuals (33-79 years), recruited from a longitudinal investigation (Pró-Saúde Study), were analyzed cross-sectionally. Anthropometric, biochemical, body composition, socio-demographic and lifestyle data were collected. Based on body mass index (BMI; normal weight, overweight, obesity) and metabolic health (metabolically healthy (MH) and metabolically unhealthy (MU)) categories, the participants were classified into 6 phenotypes. Individuals having zero components of the metabolic syndrome were considered as "MH". MH obesity was frequent in 2.0% of the participants and 56.0% exhibited vitamin D insufficiency (<20 ng/mL). In the subgroups of the same BMI category, there were no significant differences in 25(OH)D concentrations between individuals classified as MH and MU. After adjustments (including %body fat and BMI), an inverse association was observed between 25(OH)D and visceral adipose tissue (B = -6.46, 95% confidence interval, CI: -12.87, -0.04), leptin (B = -0.09, 95% confidence interval, CI: -0.14, -0.03), insulin (B = -0.21, 95%CI: -0.34, -0.07), HOMA-IR (B = -0.06, 95%CI: -0.10, -0.02), triglycerides (B = -2.44, 95%CI: -3.66, -1.22), and TNF-α (B = -0.12, 95%CI: -0.24, -0.005) only in MU individuals. Our results indicate that the association of 25(OH)D concentrations with a favorable biochemical profile (glycemic, lipidic and inflammatory) seems to depend on the individual's overall metabolic health, suggesting more benefits from higher serum vitamin D in MU individuals, regardless of their adiposity.

Association between circulating exhausted CD4+ T cells with poor meningococcal C conjugate vaccine antibody response in HIV-infected children and adolescents.

OBJECTIVES: To investigate the expression levels of surface markers of activation (CD38 and HLA-DR), inhibition (PD-1, TIGIT and CD57) and co-stimulation (CD28 and CD127) on CD4+ T cells of children/adolescents with vertical HIV infection (HI patients) and HIV-uninfected (HU) controls vaccinated with the meningococcal C conjugate vaccine (MCC). METHODS: HI patients (n=12), aged 8-17 years, were immunized with two MCC injections, while HU controls (n=9), aged 5.3-10.7 years, received a single MCC dose (as per national recommendation at the time of this study, a single MCC vaccine dose should be given for healthy children and youth aged 1-18 years). The HI patients were categorized according to the combined antiretroviral therapy (cART) treatment. Blood samples were obtained before vaccination, after priming, and after the administration of a booster dose of vaccine to determine the serum bactericidal antibody (SBA) titers and the expression levels of surface markers on CD4+ T cells by flow cytometry. The levels of serum cytokines, IL-4 and CXCL-13 were also measured using Luminex kits. RESULTS: The co-expression of the TIGIT-HLA-DR-CD38 molecules increased in the CD4+ T cells of HI patients/no-cART who also showed a lower frequency of CD127+CD28+ CD4+ T cells than HI patients/cART and HU group subjects. There were significant negative correlations between the frequency of exhausted CD4+ T cells and the SBA response. IL-4 levels were higher in HI patients/cART and positively correlated with SBA titers but negatively associated with the expression of exhaustion markers. Moreover, the CXCL-13 levels were positively correlated with the exhausted CD4+ T cells. CONCLUSION: The results of our study suggest that the co-expression of exhaustion markers and/or loss of co-stimulatory molecules influence the SBA response in HI patients.

A cross-reacting material CRM197 conjugate vaccine induces diphtheria toxin neutralizing antibody response in children and adolescents infected or not with HIV.

Anti-diphtheria antibody levels decrease with aging, and frequent booster vaccinations are required to maintain herd immunity. We analyzed the diphtheria toxin neutralizing antibody (DT-Nab) response induced by a conjugate vaccine (meningococcal C polysaccharide-CRM197) in HIV-vertically infected (HI) children and adolescents and healthy controls (HC) with matched age. We report the association of DT-Nab with the bactericidal antibodies to serogroup C meningococcus (MenC). Before vaccination, 21 HI patients (50%) had no protection against diphtheria (≤0.01IU/ml of antibody) and only 8 (19%) showed complete protection (≥0.1IU/ml). About half of the HC (56%) had complete protection before immunization and 6 subjects (12%) had no protection against diphtheria. After one and two vaccine injections, 96% of HC and 64% of HI vaccinees, respectively, showed full protection against diphtheria. These data indicate that CRM197 was able to induce primary and/or booster response in both groups of individuals.

Lower Baseline Germinal Center Activity and Preserved Th1 Immunity Are Associated With Hepatitis B Vaccine Response in Treated HIV Infection.

BACKGROUND: Why HIV-infected individuals have poor responses to standard dose and schedule hepatitis B virus immunization is not well understood. METHODS: We compared the serologic and cellular immune profiles of treated HIV-infected individuals with similar durations of infection and preserved CD4 counts (> 350 cells/microliter) by hepatitis B vaccine (HBV) response before and after vaccination. RESULTS: Similar levels of immune activation and plasma cytokine profile were found between non-responders and responders. The baseline plasma levels of CXCL-13, a surrogate of germinal center reactivity, were significantly lower in HBV responders compared to HBV non-responders and were a predictor of both vaccine response and titer. Furthermore, response to HBV vaccination was associated with a significantly higher frequency of circulating IgGhigh memory B cells post vaccination and preserved Th1 antigen-specific T-cell responses. CONCLUSIONS: Taken together, our data suggest that preserved Th1 responses are associated with hepatitis B vaccine response in treated HIV infection.

Antibody persistence following meningococcal C conjugate vaccination in children and adolescents infected with human immunodeficiency virus.

OBJECTIVE: HIV-infected individuals (HIVI) are threatened by meningococcal infection and presented lower response to vaccines. Data are scarce on long-term persistence of human serum bactericidal antibody (hSBA) after a meningococcal C conjugate (MCC) vaccine in HIVI youth; the authors aimed to describe this persistence in HIVI. METHODS: HIVI and HIV uninfected individuals (HIVU), aged 2-18 years, CD4 >15% were recruited. Seroprotection (hSBA ≥1:4) at baseline and at 12-18 months after immunization was evaluated and the association of the different factors with the long-term persistence was calculated using logistic regression. RESULTS: A total of 145 HIVI, 50 HIVU were recruited and immunized, and their median age was 11 years (median age in HIVI group was 12 years, and 10 years in HIVU group, p-value=0.02). 85 HIVI (44%) had undetectable viral load (UVL). Seroprotection rate was 27.2%: 24.1% in HIVI and 36% in HIVU 12-18 months after immunization (p=0.14). Baseline immunity (odds ratio [OR]=70.70, 95% CI: 65.2-766.6); UVL at entry (OR: 2.87, 95% CI: 0.96-8.62) and lower family income (OR: 0.09, 95% CI: 0.01-0.69) were associated with seroprotection among HIVI. CONCLUSION: Seroprotection at 12-18 months after single dose of MCC was low for both groups, and higher among individuals who presented baseline immunity. Among HIVI, vaccine should be administered after UVL is achieved.

Safety and immune response after two-dose meningococcal C conjugate immunization in HIV-infected children and adolescents in Rio de Janeiro, Brazil.

We aimed to evaluate immunogenicity and adverse events (AEs) after a booster dose of Meningococcal C conjugated (MCC) vaccine in HIV-infected children and adolescents, who had a previous low seroconversion rate after priming with MCC, at a reference HIV-care center in Rio de Janeiro. METHODS: 2-18 years old HIV-infected subjects with CD4+ T-lymphocyte cell (CD4) ≥15%, without active infection or antibiotic use, were enrolled to receive 2 doses of conjugated meningococcal C oligosaccharide-CRM197 12-18 months apart. All patients were evaluated before and 1-2 months after immunization for seroprotection [defined as human serum bactericidal activity (hSBA) titer ≥1:4]. AEs were assessed at 20 min, 3 and 7 days after each dose. Factors independently associated with seroprotection were studied. RESULTS: 156 subjects were enrolled and 137 received a booster MCC dose. 55% were female, and median age was 12 years. Eight-nine percent were receiving combined antiretroviral therapy (cART) at the booster visit (median duration of 7.7 years), 59.9% had undetectable viral load (VL) at baseline, and 56.2% at the booster visit. Seroprotection was achieved in 78.8% (108/137) subjects, with a significantly higher GMT than after the priming dose (p < 0.01). Mild AEs were experienced after a second MCC dose (38%). In logistic regression, undetectable viral load at entry [odds ratio (OR) = 7.1, 95% confidence interval (95%CI): 2.14-23.37], and probably higher CD4 percent at the booster immunization visit (OR): 1.1, 95%CI: 1.01-1.17 were associated with seroprotection after a booster dose of MCC. CONCLUSION: A booster dose of MCC was safe and induced high seroprotection rate even 12-18 months after priming. MCC should be administered after maximum virologic suppression has been achieved. These results support the recommendation of 2-dose of MCC for primary immunization in HIV-infected children and adolescents with restored immune function.

Association of serum bactericidal antibody and opsonic antibody levels after Neisseria meningitidis serogroup C conjugate vaccine in Brazilian children and adolescents infected or not infected with HIV.

Neisseria meningitidis serogroup C (MenC) is the main causative agent of meningitis in Brazil. HIV infection affects the quality of the immune system. HIV+ children have an increased risk of infection to encapsulated bacteria such as N. meningitidis. We evaluated the opsonic antibody (OPA) levels and its correlation with serum bactericidal antibody (SBA) levels induced by one and two doses of a MenC conjugate vaccine in children and adolescents HIV+ and HIV-exposed but uninfected children (HEU) group. Overall the data show the importance of two doses of vaccine for HIV+ individuals. About 79% and 58% of HIV+ patients showed SBA and OPA positive response after two doses of vaccine, respectively. For HEU group, 62% and 41% of patients showed SBA and OPA positive response after one dose of vaccine, respectively. A positive and significant association between SBA and OPA levels was seen after two doses of vaccine in HIV+ patients.

Association between circulating exhausted CD4+ T cells with poor meningococcal C conjugate vaccine antibody response in HIV-infected children and adolescents

OBJECTIVES: To investigate the expression levels of surface markers of activation (CD38 and HLA-DR), inhibition (PD-1, TIGIT and CD57) and co-stimulation (CD28 and CD127) on CD4+ T cells of children/adolescents with vertical HIV infection (HI patients) and HIV-uninfected (HU) controls vaccinated with the meningococcal C conjugate vaccine (MCC). METHODS: HI patients (n=12), aged 8-17 years, were immunized with two MCC injections, while HU controls (n=9), aged 5.3-10.7 years, received a single MCC dose (as per national recommendation at the time of this study, a single MCC vaccine dose should be given for healthy children and youth aged 1-18 years). The HI patients were categorized according to the combined antiretroviral therapy (cART) treatment. Blood samples were obtained before vaccination, after priming, and after the administration of a booster dose of vaccine to determine the serum bactericidal antibody (SBA) titers and the expression levels of surface markers on CD4+ T cells by flow cytometry. The levels of serum cytokines, IL-4 and CXCL-13 were also measured using Luminex kits. RESULTS: The co-expression of the TIGIT-HLA-DR-CD38 molecules increased in the CD4+ T cells of HI patients/no-cART who also showed a lower frequency of CD127+CD28+ CD4+ T cells than HI patients/cART and HU group subjects. There were significant negative correlations between the frequency of exhausted CD4+ T cells and the SBA response. IL-4 levels were higher in HI patients/cART and positively correlated with SBA titers but negatively associated with the expression of exhaustion markers. Moreover, the CXCL-13 levels were positively correlated with the exhausted CD4+ T cells. CONCLUSION: The results of our study suggest that the co-expression of exhaustion markers and/or loss of co-stimulatory molecules influence the SBA response in HI patients.

Effect of a booster dose of serogroup B meningococcal vaccine on antibody response to Neisseria meningitidis in mice vaccinated with different immunization schedules.

The generation and maintenance of memory antibody response by different primary immunization schedules with the Cuban-produced outer membrane protein based vaccine was investigated in a murine model. We analyzed the duration of the antibody response (IgG-ELISA and bactericidal titer) and the effect of a booster dose on the antibody response. The IgG avidity index was determined in an attempt to find a marker for memory development. This study also included an analysis of IgG subclasses induced by primary and booster immunization. The specificity of bactericidal antibodies was investigated using local strains of the same serotype/serosubtype (4,7:P1.19,15) as the vaccine strain and mutant strains lacking major outer membrane proteins. A significant recall response was induced by a booster dose given 7 months after a primary series of 2, 3 or 4 doses of vaccine. The primary antibody response showed a positive dose-effect. In contrast, a negative dose-effect was found on the booster bactericidal antibody response. There was a significant increase in IgG1 levels after the fourth and booster doses. Three doses of vaccine were required to induce a significant increase in IgG avidity. Two injections of vaccine induced a significant antibody response to PorA protein, while 4 injections induced a larger range of specificities.

Immunogenicity and safety of meningococcal C conjugate vaccine in children and adolescents infected and uninfected with HIV in Rio de Janeiro, Brazil.

BACKGROUND: We aimed to evaluate the Meningococcal (Neisseria meningitidis) C conjugated (MCC) vaccine seroconversion and adverse events (AEs) in HIV-infected and HIV-uninfected children and adolescents in Rio de Janeiro, Brazil. METHODS: HIV-infected or HIV-uninfected subjects, 2-18 years old, with CD4+ T-lymphocyte cell (CD4) percentage >15%, without active infection or antibiotic use, were enrolled. All patients were evaluated before and 1-2 months after immunization for seroconversion (defined as ≥4-fold titer increase in human serum bactericidal activity) and at 20 minutes, 3 and 7 days after immunization for AEs. Factors associated with seroconversion among HIV-infected group were studied. RESULTS: Two hundred four subjects were enrolled: 154 HIV-infected and 50 HIV-uninfected. Median age was 12 years, and 53% were female. Among the HIV-infected group, 82 (53%) had a history of at least 1 C clinical category of Centers for Diseases Control and Prevention event, and 134 (87%) were using combination antiretroviral therapy. The median nadir CD4 percentage was 13% (0-47%). Seventy-six (37.3%) experienced mild AEs. Seroconversion occurred in 46 of 154 (30%) in the HIV-infected group and in 38 of 50 (76%) in the uninfected group (P < 0.01). Factors associated with seroconversion in the HIV-infected group were as follows: never had a C clinical category event [odds ratio (OR) = 2.1, 95% confidence interval (CI): 1.0-4.4]; undetectable viral load at immunization (OR: 2.4, 95% CI: 1.1-5.2) and higher CD4 nadir/100 cells (OR: 1.1, 95% CI: 1.0-1.2). CONCLUSION: MCC vaccine should be administered to HIV-infected children and adolescents after maximum immunologic and virologic benefits have been achieved with combination antiretroviral therapy. Our data suggest that a single dose of MCC vaccine is insufficient for HIV-infected individuals 2-18 years of age.

Antibody and memory CD4(+) T-cell responses after meningococcal disease.

Currently, Neisseria meningitidis serogroup C (MenC) is the major cause of bacterial meningitis in Brazil, affecting mainly teenagers and adults due to the lack of routine public vaccination of these age groups. The goal of this study was to investigate the bactericidal antibody response and the development of CD4(+) T cell memory during the convalescent phase of patients infected with N. menigitidis. Most (85.7%) of the patients developed a protective antibody response against MenC and 57% also responded to N. meningitidis serogroup B. We detected a significant CD4(+) T central memory (TCM) response to meningococcal outer membrane proteins.

Subsets of memory CD4+ T cell and bactericidal antibody response to Neisseria meningitidis serogroup C after immunization of HIV-infected children and adolescents.

Meningococcal disease is endemic in Brazil, with periodic outbreaks and case fatality rates reach as high as 18 to 20% of cases. Conjugate vaccines against meningococci are immunogenic in healthy children. However, we have previously shown a poor bactericidal antibody response to a Men C conjugate vaccine in Brazilian HIV-infected children and adolescents after a single vaccine administration. The goal of the present work was to investigate associations between bactericidal antibody response induced by MenC vaccine and the frequency and activation profile (expression of CD38, HLA-DR and CCR5 molecules) of total CD4+ memory T cell sub-populations in HIV-1-infected children and adolescents. Responders to vaccination against MenC had a predominance (about 44%) of CD4+ TINTERMEDIATE subset followed by TTRANSITIONAL memory subset (23 to 26%). Importantly, CD4+ TINT frequency was positively associated with bactericidal antibody response induced by vaccination. The positive correlation persisted despite the observation that the frequency TINT CD38+HLA-DR+ was higher in responders. In contrast, CD4+ TCENTRAL MEMORY (TCM) subset negatively correlated with bactericidal antibodies. In conclusion, these data indicate that less differentiated CD+ T cells, like TCM may be constantly differentiating into intermediate and later differentiated CD4+ T cell subsets. These include CD4 TINT subset which showed a positive association with bactericidal antibodies.

CD4+ T-cell activation impairs serogroup C Neisseria meningitis vaccine response in HIV-infected children.

OBJECTIVE: To investigate the influence of CD4 T-cell activation and regulatory populations in HIV-infected children antibody response to vaccination with a conjugate C polysaccharide vaccine. DESIGN: CD4 T-cell activation was evaluated by expression of CD38, HLA-DR and CCR5 molecules. Regulatory CD4 T cells (TReg) were characterized as FoxP3CD127CD25 and inducer T cells (TInd) as CD4FoxP3CD25CD39. METHODS: All patients (n = 36) were HIV-vertically infected, aged 2-17 years-old and were vaccinated with one vaccine injection. Blood samples were obtained before and after immunization to determine bactericidal antibody titers (SBA), CD4 T-cell activation and frequency of TReg and TInd subsets (multiparametric flow cytometry). RESULTS: Children not-responding (n = 18) to MenC vaccine expressed higher frequency of activated CD4 T cells (HLA-DRCD38CCR5) than responders (n = 18), both before and after vaccination (P < 0.05). A significant higher frequency of TReg was detected in responders compared with nonresponders (P = 0.0001). We also detected an inverse correlation between CD4DRCD38CCR5 (P = 0.01) or CD4DRCD38 (P = 0.02) T cells and TReg cell frequency after vaccination. CD4 T-cell activation negatively correlated (P = 0.006) with postvaccination SBA titers but a positive correlation (P = 0.0001) was detected between TReg cells and SBA. TReg and TInd subsets were inversely correlated (P = 0.04). CONCLUSION: Our findings suggest that higher CD4 T-cell activation leads to poor vaccine response in children living with HIV, which may be associated with a TReg/TInd disequilibrium.

Type III apparatus of Pseudomonas aeruginosa as a tool to diagnose pulmonary infection in cystic fibrosis patients.

Pseudomonas aeruginosa is associated with increased mortality in cystic fibrosis (CF) patients, and expresses type III secretion system proteins (TTSP), which is a common mechanism used by gram-negative pathogens for delivery of anti-host factors. Our aim was to investigate whether or not these antigens (TTSP) would be recognized by CF sera, by Western blot reaction. We have showed herein that all patients (n = 11) not chronically infected by P. aeruginosa had their first serum positive for TTSP (ExoS, ExoT, PopB, and/or PopD). All chronic patients had a strong positive serology to TTSP, although relatively weak reactions to TTSP were observed for some individuals in the negative control group. Therefore, TTSP that were early produced in P. aeruginosa infected CF patients, induced a detectable antibody response in those patients and were easily detected by Western-blot reaction.

Antibody persistence following meningococcal C conjugate vaccination in children and adolescents infected with human immunodeficiency virus / Persistência de anticorpos seguida de vacina conjugada meningocócica C em crianças e adolescentes infectados por vírus da imunodeficiência humana

Abstract Objective: HIV-infected individuals (HIVI) are threatened by meningococcal infection and presented lower response to vaccines. Data are scarce on long-term persistence of human serum bactericidal antibody (hSBA) after a meningococcal C conjugate (MCC) vaccine in HIVI youth; the authors aimed to describe this persistence in HIVI. Methods: HIVI and HIV uninfected individuals (HIVU), aged 2-18 years, CD4 >15% were recruited. Seroprotection (hSBA ≥1:4) at baseline and at 12-18 months after immunization was evaluated and the association of the different factors with the long-term persistence was calculated using logistic regression. Results: A total of 145 HIVI, 50 HIVU were recruited and immunized, and their median age was 11 years (median age in HIVI group was 12 years, and 10 years in HIVU group, p-value = 0.02). 85 HIVI (44%) had undetectable viral load (UVL). Seroprotection rate was 27.2%: 24.1% in HIVI and 36% in HIVU 12-18 months after immunization (p = 0.14). Baseline immunity (odds ratio [OR] = 70.70, 95% CI: 65.2-766.6); UVL at entry (OR: 2.87, 95% CI: 0.96-8.62) and lower family income (OR: 0.09, 95% CI: 0.01-0.69) were associated with seroprotection among HIVI. Conclusion: Seroprotection at 12-18 months after single dose of MCC was low for both groups, and higher among individuals who presented baseline immunity. Among HIVI, vaccine should be administered after UVL is achieved.

Resumo Objetivo: As pessoas infectadas pelo HIV (HIVI) estão sujeitas a infecção meningocócica e apresentam menor resposta a vacinas. São escassos os dados a respeito da persistência de longo prazo do anticorpo bactericida no soro humano (hSBA) após vacina conjugada meningocócica C (MCC) em HIVI jovens e visamos a descrever essa persistência em HIVI. Métodos: Foram recrutadas pessoas HIVI e pessoas não infectadas por HIV (HIVU), entre 2 e 18 anos, CD4 > 15%. A seroproteção (hSBA ≥ 1:4) basal aos 12-18 meses após a imunização foi avaliada e a associação dos diferentes fatores com a persistência de longo prazo foi calculada com a regressão logística. Resultados: Foram recrutados 145 HIVI e 50 HIVU e imunizados e sua idade média foi determinada em 11 anos (12 no grupo HIVI e 10 no grupo HIVU, valor de p = 0,02); 85 HIVI (44%) apresentaram carga viral indetectável (CVI). A taxa de seroproteção foi 27,2%: 24,1% no grupo HIVI e 36% no grupo HIVU 12-18 meses após imunização (p = 0,14). A imunidade basal [razão de chance (RC) = 7070, IC: 65,2-7666]; CVI no momento da participação (RC: 2,87, IC de 95%: 0,96-8,62) e renda familiar mais baixa (RC: 0,09, IC de 95%: 0,01-0,69) foram associadas a seroproteção entre as pessoas HIVI. Conclusão: A seroproteção aos 12-18 meses após única dose de MCC mostrou-se baixa em ambos os grupos e mais elevada entre as pessoas que apresentaram imunidade basal. Entre as pessoas HIVI, as vacinas devem ser administradas após a CVI ser atingida.

Human antibody and memory B and T-cell responses after primary and booster immunisation against Neisseria meningitidis B.

Vaccination against disease aims at the induction of long-lasting cellular and humoral immune responses. Few studies have addressed the mechanisms by which meningococcal vaccines generate and sustain immunological memory. The goal of this study was to investigate the development of long-term humoral and cellular memory to Neisseria meningitidis serogroup B (MenB) in health subjects after immunisation with the Cuban outer membrane protein (OMP) vaccine (VA-MENGOC-BC). The results showed that three doses of vaccine were necessary to induce a detectable memory B-cell response (mean of 0.46%) which became undetectable 6 months later. After boosting, only 2 of 5 individuals responded with an increase in memory B-cell frequencies (values of 0.15% and 0.34%). Bactericidal and opsonic antibody levels were higher after primary immunisation (log(2) mean and median of 4.7 and 1212, respectively) when compared with post-booster response (log(2) mean of 2.6 and median of 285, respectively). Together, these data suggest a failure of vaccine to induce long-term memory B-cell and serological memory in adults. However, we observed a significant and functional memory T-cell response specially after boosting, with a predominance of activated (CD69(+)) central memory T-cell (CD4(+)CD45(-)CCR7(+)) response. Therefore, this study suggests that vaccination with the MenB vaccine induced the generation and activation of memory T-cells but failed to maintain the memory B-cell population at a stable size and/or function.

Comparison of long-term humoral memory development after immunisation against Neisseria meningitidis B or diphtheria toxoid.

Since genome sequence data became available there has been a marked increase in number of protein antigens that have been suggested as prospective vaccine components against Neisseria meningitidis B (MenB). Few studies have addressed the mechanisms by which meningococcal vaccines generate and sustain immunological memory. The goal of this study was to compare the B-cell response (antibody-secreting cells [ASC], memory B cell and IgG) evoked by a MenB vaccine (VA-MENGOC-BC(®)) with the B-cell response to diphtheria toxoid (DT) induced by a successful vaccine (Diphtheria-Tetanus-Pertussis [DTP]). The results showed different kinetics of specific ASC response after the primary and booster immunisations. Concerning the specific ASC kinetics, MenB vaccine induced a strong primary response, but the recall response showed a limited power over time. In contrast, DTP primary ASC response was weaker than the booster responses. We observed an increase in the relative percent of memory B cells after 1, 2 and 3 doses of MenB vaccine (mean of 0.8%, 1.3% and 1.6%, respectively) but without statistical significance. Similar frequencies were detected after boosting given at 4 months (mean of 1.3%) or 6 months (mean of 0.9%) following the third dose. DT specific memory B cell response showed a slight lower magnitude after the primary immunisation schedule (mean of 1.2% after the third dose) compared with the MenB response. However, a stronger memory B cell response was induced by booster doses of DTP vaccine at 4 months (mean of 1.9%) or 6 months (mean of 1.9%). The kinetics of specific IgG induced by both vaccines was similar, suggesting that memory B cells were responsible for the strong antibody response seen after the booster vaccination.

Antibody response to Pseudomonas aeruginosa in children with cystic fibrosis.

Cystic fibrosis (CF) is the most frequent life threatening autosomal recessive disease in white subjects. The primary cause of morbidity and mortality in children with CF is chronic pulmonary infection, mainly caused by Pseudomonas aeruginosa. The purpose of this study was to assess the value of the measurement of antibodies to P. aeruginosa in diagnosing lung infection by the bacteria in CF patients. We assessed P. aeruginosa antibody titers in CF patients from Rio de Janeiro, Brazil, using cell lysate antigens as well as recombinant PcrV, a Type III Secretion System protein. Sputum (more than 70% of the specimens) or oropharyngeal swabs were obtained whenever patients were regularly followed for their pulmonary disease. Blood samples were obtained with an average interval of 6 months for a period of 2 years. The ELISA cut-offs were assigned as the positive 95% confidence interval of the mean antibody levels from non-fibrocystic controls. Our data showed that most CF patients (81%) of whom were not chronically infected by P. aeruginosa (Groups I and II), had their first serology positive for rPcrV. Cell-lysate ELISA was able to detect P. aeruginosa antibodies before positive culture in the first serum sample of 44% of the patients from Groups I and II. When serum reactivity to rPcrV and cell lysate were combined, 94% of CF patients from Groups I and II (n = 16) had the first serology positive for P. aeruginosa over a mean time of 20 months before the first isolation of P. aeruginosa. In conclusion, longitudinal P. aeruginosa serology should become part of respiratory care follow-up, in conjunction with other lung parameter functions.