Bacille Calmette-Guérin Immunization Research Articles

The genomic landscape of infant CD4 T cells and monocytes after BCG vaccination

Abstract The live-attenuated Bacille Calmette-Guérin (BCG) vaccine has been introduced a century ago to prevent tuberculosis and is still administered to >80% of newborns worldwide. Independent of its effect on TB, BCG introduction markedly reduced childhood mortality. Although BCG vaccine is routinely administered to infants, there is a gap in understanding the influence of BCG on the neonatal immune system. In adults, BCG induces trained or heterologous immunity. Here, to better understand the molecular changes in the infant immune system after BCG immunization, we performed RNA sequencing and ATAC sequencing in circulating CD4 T cells and monocytes of 28 infants prior to and 6–12 weeks after administering BCG. Consistent with data from BCG-vaccinated adults, the expression profile of 168 differentially expressed genes (DEG) supports the activation of monocytes after BCG vaccination, and ATAC sequencing data identified epigenetic modification that impact accessibility of genes in Nod1 and Nod 2 signaling pathways. In CD4 T cells, we identified a total of 322 DEG, including 95 upregulated and 226 downregulated genes. The functional enrichment and transcription factor analysis showed the enrichment of ErbB signaling pathways which regulate cell proliferation and differentiation mediated through MAPK signaling pathways. These results combined with peaks identified by ATAC sequencing were indicative of the expansion of Th1 CD4 T cells in BCG vaccinated infants. This study provides an understanding of molecular changes in monocytes and CD4 T cells after BCG vaccination that may explain the improved capacity of the infant immune system to respond to intracellular pathogens.

Visualizing the early immune response to Mycobacterium tuberculosisinfection in macaques immunized with intravenous BCG

Abstract Tuberculosis (TB) causes 1.6 million deaths annually and the standard human vaccine, intradermal (ID) Bacille-Calmette Guérin (BCG), does not prevent pulmonary TB. Previously, we showed that intravenous (IV) BCG immunization elicited robust TB-specific lung-resident T cell responses compared to ID BCG in rhesus macaques (RMs). Following Mycobacterium tuberculosis (Mtb) challenge, 6 out of 10 RMs had no detectable disease as demonstrated by bacterial burden, granuloma formation, and primary Mtb-specific immune responses. Together, these data suggest that Mtb is cleared rapidly from the lungs of IV BCG-vaccinated RMs. To investigate the vaccine-induced lung environment and anamnestic response that might mediate protection against Mtb early after challenge, we developed a high-dose Mtb infection model in RMs that allowed us to locate and live-image areas of Mtb infection in the lungs using confocal microscopy. RMs immunized for 5 months with either IV or ID BCG were challenged with Mtb Erdman mCherry and euthanized 4 or 11 days later to characterize the lung microenvironment. We observed reductions in bacterial burdens in the lungs of RMs that received IV BCG compared to ID BCG-vaccinated and unvaccinated controls by CFU plating, flow cytometry, and confocal microscopy despite using a high challenge dose. Increased T cells were quantified in the lungs of both IV and ID BCG-vaccinated RMs compared to unvaccinated controls by flow cytometry and confocal microscopy. This research provides an opportunity to mine immune correlates of protection in a preclinical model, at the site of infection, and at a post-challenge time point that has been minimally characterized. NIH Intramural Program

100 Years of BCG Immunization: Past, Present, and Future

The 100th anniversary of the introduction of Bacille-Calmette-Guérin (BCG) as a tuberculosis (TB) vaccine is an occasion warranting further investigation of the early attempts which culminated in the introduction of BCG as a TB vaccine, as well as of subsequent recognition of failures, new findings that broaden its applications, outstanding questions, and approaches towards the development of novel vaccine candidates [...].

BCG and SARS-CoV-2-What Have We Learned?

Despite controversy over the protective effect of the BCG (Bacille Calmette-Guérin) vaccine in preventing pulmonary tuberculosis (TB) in adults, it has been used worldwide since 1921. Although the first reports in the 1930s had noted a remarkable decrease in child mortality after BCG immunization, this could not be explained solely by a decrease in mortality from TB. These observations gave rise to the suggestion of nonspecific beneficial effects of BCG vaccination, beyond the desired protection against M. tuberculosis. The existence of an innate immunity-training mechanism based on epigenetic changes was demonstrated several years ago. The emergence of the pandemic caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2) in 2019 revived the debate about whether the BCG vaccine can affect the immune response against the virus or other unrelated pathogens. Due to the mortality of the coronavirus disease (COVID-19), it is important to verify each factor that may have a potential protective value against the severe course of COVID-19, complications, and death. This paper reviews the results of numerous retrospective studies and prospective trials which shed light on the potential of a century-old vaccine to mitigate the pandemic impact of the new virus. It should be noted, however, that although there are numerous studies intending to verify the hypothesis that the BCG vaccine may have a beneficial effect on COVID-19, there is no definitive evidence on the efficacy of the BCG vaccine against SARS-CoV-2.

Vaccine Development Against Tuberculosis Over the Last 140 Years: Failure as Part of Success.

The year 2020 was shaped by the COVID-19 pandemic which killed more people than any other infectious disease in this particular year. At the same time, the development of highly efficacious COVID-19 vaccines within less than a year raises hope that this threat can be tamed in the near future. For the last 200 years, the agent of tuberculosis (TB) has been the worst killer amongst all pathogens. Although a vaccine has been available for 100 years, TB remains a substantial threat. The TB vaccine, Bacille Calmette-Guérin (BCG), has saved tens of millions of lives since its deployment. It was the best and only choice available amongst many attempts to develop efficacious vaccines and all competitors, be they subunit vaccines, viable vaccines or killed whole cell vaccines have failed. Yet, BCG is insufficient. The last decades have witnessed a reawakening of novel vaccine approaches based on deeper insights into immunity underlying TB and BCG immunization. In addition, technical advances in molecular genetics and the design of viral vectors and adjuvants have facilitated TB vaccine development. This treatise discusses firstly early TB vaccine developments leading to BCG as the sole preventive measure which stood the test of time, but failed to significantly contribute to TB control and secondly more recent attempts to develop novel vaccines are described that focus on the genetically modified BCG-based vaccine VPM1002, which has become the frontrunner amongst viable TB vaccine candidates. It is hoped that highly efficacious vaccines against TB will become available even though it remains unclear whether and when this ambition can be accomplished. None the less it is clear that the goal of reducing TB morbidity and mortality by 90% or 95%, respectively, by 2030 as proposed by the World Health Organization depends significantly on better vaccines.

A 20-year retrospective study of osteoarticular tuberculosis in a pediatric third level referral center

PurposeThe objective of the present study is to describe the clinical, diagnostic, radiological and therapeutic aspects of osteoarticular tuberculosis (OATB) in patients in a tertiary pediatric hospital, to know if the diagnosis of OATB in pediatrics is a challenge due to its insidious clinical presentation.MethodsA retrospective, descriptive study of the cases of Tuberculosis (TB) in children was carried out. A total of 159 cases met the condition for the analysis.ResultsThe most frequent TB modality was extrapulmonary in 85%. Out of this, only 29% was OATB. The mean age was 4.9 years (range 8 months–16 years). Eighty-six per cent of cases received Bacille Calmette-Guérin (BCG) vaccination at birth. Median time of symptoms prior to diagnosis was 8 months. Microbiological confirmation was achieved only in five cases, with a high sensitivity to the antimicrobial treatment. Mycobacterium bovis BCG strain Tokio 172 was confirmed in three cases. Mortality rate was 0% during the time of studyConclusionOur study describes the epidemiological characteristics of OATB cases in Mexican children. This data revealed a high prevalence of bone and joint TB infection. Pediatric OATB should be considered in cases with lytic bone lesions, fever and local pain. In countries with BCG immunization program, M. bovis should not be forgotten as an etiological agent. The low detection rate with one technique approach highlights the urgent need for more sensitive test to diagnose OATB in children.

BCG Vaccine Protection against TB Infection among Children Older than 5 Years in Close Contact with an Infectious Adult TB Case.

The Bacille Calmette–Guérin (BCG) vaccine has been shown to provide considerable protection against miliary or meningeal tuberculosis (TB), but whether it prevents other forms of disease remains controversial. Recent evidence has shown that the BCG vaccine also provides protection against latent TB infection (LTBI). The aim of the current study was to examine whether BCG has a protective role against LTBI among children in close contact with an adult index case in a low TB endemicity setting with the use of the QuantiFERON-TB Gold In-Tube test (QFT-GIT). A cross-sectional study was conducted over a 10-year period among children referred to our outpatient TB clinic with a history of close contact with an adult with pulmonary TB. All subjects had a QFT-GIT performed. In total, 207 children > 5 to 16 years of age with known recent exposure were enrolled. BCG-vaccinated subjects had a 59% lower risk of presenting with LTBI after close contact with an adult index case compared with unvaccinated subjects (OR = 0.41, 95% CI: 0.23–0.73, p = 0.002). After adjustment for possible confounders, the protective effect of prior BCG immunization was estimated at 68% (OR = 0.32, 95% CI: 0.15–0.66, p = 0.002). Other risk factors for LTBI included a history of migration (OR = 2.27, 95% CI: 1.13–4.53, p = 0.021) and transmission of infection to other exposed child contacts (OR = 4.62, 95% CI: 2.27–9.39, p = 0.001). We were able to determine a strong protective role of BCG vaccination among children older than 5 years, immunized at school entry, who had close contact with an adult infectious TB case.

Determinant of BCG vaccine coverage among Indonesian children aged 0–2 months

IntroductionThe success of the Bacille Calmette-Guérin (BCG) vaccine is an indicator of the level of children's health in Indonesia. This study aimed to analyze the determinants of the BCG vaccine coverage among Indonesian children aged 0–2 months. MethodsThe cross-sectional design was obtained from the Indonesian Demographic and Health Survey (IDHS) data from 2017. A total of 718 children aged 0–2 months were involved in this study. The instrument used in this study refers to the DHS Survey Questionnaire Phase 7. Child health information about the BCG immunization coverage is available in the Women's Questionnaire Topics. The variables include the mother’s age, the mother’s level of education, wealth, residence, distance, contraceptive use, visiting the health facilities and BCG vaccine coverage. Binary logistic regression was used to analyze the determinants of BCG vaccine coverage. ResultsThe prevalence of BCG vaccine coverage among Indonesian children aged 0–2 months was 45.96%. The mothers’ age [AOR = 1.76; 95% CI = 1.14–2.73], contraceptive use [AOR = 4.24; 95% CI = 2.93–6.15], and visits to the health facilities in the last 6 months [AOR = 1.72; 95% CI = 1.11–2.67] were associated with BCG vaccine coverage among Indonesian children aged 0–2 months. However, education, wealth quintile, residence, and distance were not significantly related to BCG vaccination. DiscussionThis study indicates that mothers of a sufficient maternal age can meet the needs of their children concerning the BCG vaccine. In addition, regular visits for the mother to the health community center can provide the BCG vaccine in a timely manner. Increasing the awareness among the mothers through health promotion and counseling should be promoted.

Bacille Calmette-Guérin Vaccine Strain Modulates the Ontogeny of Both Mycobacterial-Specific and Heterologous T Cell Immunity to Vaccination in Infants.

Differences in Bacille Calmette-Guérin (BCG) immunogenicity and efficacy have been reported, but various strains of BCG are administered worldwide. Since BCG immunization may also provide protection against off-target antigens, we sought to identify the impact of different BCG strains on the ontogeny of vaccine-specific and heterologous vaccine immunogenicity in the first 9 months of life, utilizing two African birth cohorts. A total of 270 infants were studied: 84 from Jos, Nigeria (vaccinated with BCG-Bulgaria) and 187 from Cape Town, South Africa (154 vaccinated with BCG-Denmark and 33 with BCG-Russia). Infant whole blood was taken at birth, 7, 15, and 36 weeks and short-term stimulated (12 h) in vitro with BCG, Tetanus and Pertussis antigens. Using multiparameter flow cytometry, CD4+ T cell memory subset polyfunctionality was measured by analyzing permutations of TNF-α, IL-2, and IFN-γ expression at each time point. Data was analyzed using FlowJo, SPICE, R, and COMPASS. We found that infants vaccinated with BCG-Denmark mounted significantly higher frequencies of BCG-stimulated CD4+ T cell responses, peaking at week 7 after immunization, and possessed durable polyfunctional CD4+ T cells that were in a more early differentiated memory stage when compared with either BCG-Bulgaria and BCG-Russia strains. The latter responses had lower polyfunctional scores and tended to accumulate in a CD4+ T cell naïve-like state (CD45RA+CD27+). Notably, BCG-Denmark immunization resulted in higher magnitudes and polyfunctional cytokine responses to heterologous vaccine antigens (Tetanus and Pertussis). Collectively, our data show that BCG strain was the strongest determinant of both BCG-stimulated and heterologous vaccine stimulated T cell magnitude and polyfunctionality. These findings have implications for vaccine policy makers, manufacturers and programs worldwide and also suggest that BCG-Denmark, the first vaccine received in many African infants, has both specific and off-target effects in the first few months of life, which may provide an immune priming benefit to other EPI vaccines.

CORRELATION BETWEEN COVERAGE OF BCG IMMUNISATION AND HEALTHY HOUSES WITH FINDINGS OF PAEDIATRIC TUBERCULOSIS

Background: Tuberculosis in children is still found in East Java Province at 2017 with 2,749 cases of paediatric tuberculosis. The Bacille Calmette-Guérin (BCG) immunisation coverage and healthy houses in East Java Province increase every year. Purpose: This study aims to analyse the correlation between BCG immunisation and healthy houses with paediatric tuberculosis discovery in East Java Province during 2015–17. Methods: This study is observational with a correlation study design. The population in this study were children aged 0–14 years who suffered from tuberculosis in a district or city in East Java Province in 2015–17. Sampling of this study uses aggregate data on paediatric tuberculosis discovered in children aged 0–14 years, coverage of BCG immunisation and coverage of healthy houses in districts/cities in East Java in 2015–17 found in Health Profile of East Java Province 2015–17. The variables studied were paediatric tuberculosis in children aged 0–14 years, BCG immunisation coverage and healthy house; the analysis techniques were the Kolmogorov-Smirnov normality test and Pearson correlation. Results: This study shows that there is correlation between BCG immunisation and paediatric tuberculosis (p = 0.01, p <0.05) with a correlation value of 0.67, indicating a strong and positive correlation. The results also show that there is a correlation between healthy houses and children with tuberculosis (p = 0.01, p <0.05) with a correlation value of 0.63, indicating a strong and positive correlation. Conclusion: BCG immunisation coverage and healthy houses are positively correlated with paediatric tuberculosis discovered in East Java district/city.

Inactivated Lactobacillus plantarum Carrying a Surface-Displayed Ag85B-ESAT-6 Fusion Antigen as a Booster Vaccine Against Mycobacterium tuberculosis Infection.

Vaccination is considered the most effective strategy for controlling tuberculosis (TB). The existing vaccine, the Bacille Calmette-Guérin (BCG), although partially protective, has a number of limitations. Therefore, there is a need for developing new TB vaccines and several strategies are currently exploited including the use of viral and bacterial delivery vectors. We have previously shown that Lactobacillus plantarum (Lp) producing Ag85B and ESAT-6 antigens fused to a dendritic cell-targeting peptide (referred to as Lp_DC) induced specific immune responses in mice. Here, we analyzed the ability of two Lp-based vaccines, Lp_DC and Lp_HBD (in which the DC-binding peptide was replaced by an HBD-domain directing the antigen to non-phagocytic cells) to activate antigen-presenting cells, induce specific immunity and protect mice from Mycobacterium tuberculosis infection. We tested two strategies: (i) Lp as BCG boosting vaccine (a heterologous regimen comprising parenteral BCG immunization followed by intranasal Lp boost), and (ii) Lp as primary vaccine (a homologous regimen including subcutaneous priming followed by intranasal boost). The results showed that both Lp constructs applied as a BCG boost induced specific cellular immunity, manifested in T cell proliferation, antigen-specific IFN-γ responses and multifunctional T cells phenotypes. More importantly, intranasal boost with Lp_DC or Lp_HBD enhanced protection offered by BCG, as shown by reduced M. tuberculosis counts in lungs. These findings suggest that Lp constructs could be developed as a potential mucosal vaccine platform against mycobacterial infections.

Microphysiologic Human Tissue Constructs Reproduce Autologous Age-Specific BCG and HBV Primary Immunization in vitro.

Current vaccine development disregards human immune ontogeny, relying on animal models to select vaccine candidates targeting human infants, who are at greatest risk of infection worldwide, and receive the largest number of vaccines. To help accelerate and de-risk development of early-life effective immunization, we engineered a human age-specific microphysiologic vascular-interstitial interphase, suitable for pre-clinical modeling of distinct age-targeted immunity in vitro. Our Tissue Constructs (TCs) enable autonomous extravasation of monocytes that undergo rapid self-directed differentiation into migratory Dendritic Cells (DCs) in response to adjuvants and licensed vaccines such as Bacille Calmette-Guérin (BCG) or Hepatitis B virus Vaccine (HBV). TCs contain a confluent human endothelium grown atop a tri-dimensional human extracellular matrix substrate, employ human age-specific monocytes and autologous non heat-treated plasma, and avoid the use of xenogenic materials and exogenous cytokines. Vaccine-pulsed TCs autonomously generated DCs that induced single-antigen recall responses from autologous naïve and memory CD4+ T lymphocytes, matching study participant immune-status, including BCG responses paralleling donor PPD status, BCG-induced adenosine deaminase (ADA) activity paralleling infant cohorts in vivo, and multi-dose HBV antigen-specific responses as demonstrated by lymphoproliferation and TCR sequencing. Overall, our microphysiologic culture method reproduced age- and antigen-specific recall responses to BCG and HBV immunization, closely resembling those observed after a birth immunization of human cohorts in vivo, offering for the first time a new approach to early pre-clinical selection of effective age-targeted vaccine candidates.

Induction and maintenance of a phenotypically heterogeneous lung tissue-resident CD4+ T cell population following BCG immunisation

Tuberculosis (TB) is the biggest cause of human mortality from an infectious disease. The only vaccine currently available, bacille Calmette-Guérin (BCG), demonstrates some protection against disseminated disease in childhood but very variable efficacy against pulmonary disease in adults. A greater understanding of protective host immune responses is required in order to aid the development of improved vaccines. Tissue-resident memory T cells (TRM) are a recently-identified subset of T cells which may represent an important component of protective immunity to TB. Here, we demonstrate that intradermal BCG vaccination induces a population of antigen-specific CD4+ T cells within the lung parenchyma which persist for >12 months post-vaccination. Comprehensive flow cytometric analysis reveals this population is phenotypically and functionally heterogeneous, and shares characteristics with lung vascular and splenic CD4+ T cells. This underlines the importance of utilising the intravascular staining technique for definitive identification of tissue-resident T cells, and also suggests that these anatomically distinct cellular subsets are not necessarily permanently resident within a particular tissue compartment but can migrate between compartments. This lung parenchymal population merits further investigation as a critical component of a protective immune response against Mycobacterium tuberculosis (M. tb).

Oral Tolerance to Environmental Mycobacteria Interferes with Intradermal, but Not Pulmonary, Immunization against Tuberculosis.

Bacille Calmette–Guérin (BCG) is currently the only approved vaccine against tuberculosis (TB) and is administered in over 150 countries worldwide. Despite its widespread use, the vaccine has a variable protective efficacy of 0–80%, with the lowest efficacy rates in tropical regions where TB is most prevalent. This variability is partially due to ubiquitous environmental mycobacteria (EM) found in soil and water sources, with high EM prevalence coinciding with areas of poor vaccine efficacy. In an effort to elucidate the mechanisms underlying EM interference with BCG vaccine efficacy, we exposed mice chronically to Mycobacterium avium (M. avium), a specific EM, by two different routes, the oral and intradermal route, to mimic human exposure. After intradermal BCG immunization in mice exposed to oral M. avium, we saw a significant decrease in the pro-inflammatory cytokine IFN-γ, and an increase in T regulatory cells and the immunosuppressive cytokine IL-10 compared to naïve BCG-vaccinated animals. To circumvent the immunosuppressive effect of oral M. avium exposure, we vaccinated mice by the pulmonary route with BCG. Inhaled BCG immunization rescued IFN-γ levels and increased CD4 and CD8 T cell recruitment into airways in M. avium-presensitized mice. In contrast, intradermal BCG vaccination was ineffective at T cell recruitment into the airway. Pulmonary BCG vaccination proved protective against Mtb infection regardless of previous oral M. avium exposure, compared to intradermal BCG immunization. In conclusion, our data indicate that vaccination against TB by the pulmonary route increases BCG vaccine efficacy by avoiding the immunosuppressive interference generated by chronic oral exposure to EM. This has implications in TB-burdened countries where drug resistance is on the rise and health care options are limited due to economic considerations. A successful vaccine against TB is necessary in these areas as it is both effective and economical.

Current status of Bacille Calmette Guérin (BCG) immunisation in Europe – A ptbnet survey and review of current guidelines

BackgroundThe incidence of tuberculosis (TB) and the use of Bacille Calmette-Guérin (BCG) vaccines differ significantly worldwide. Information regarding recent changes in BCG use and immunisation policies is difficult to access. Therefore, this study aimed to systematically collect up-to-date data on the use of BCG in Europe. MethodsA web-based survey of members of the Paediatric Tuberculosis Network European Trials group (ptbnet) and Tuberculosis Network European Trials group (TBnet) was conducted between October 2012 and May 2013. ResultsA total of 89 individuals from 31 European countries participated. Participants from 27/31 (87%) countries reported to have a national BCG immunisation policy/guideline. Reported indications for BCG immunisation were: universally at birth (14/31; 45%), universally at older age (2/31; 6%), at birth for high-risk groups (12/31; 39%), at older age for high-risk groups (6/31; 19%), at older age for Mantoux-negative individuals (6/31;19%), for immigrants (4/31; 13%) and as a travel vaccine (10/31; 32%). Members from 11 (35%) countries reported changes in BCG policies in the previous 5 years: discontinuation of universal immunisation of infants/children (6/11), reintroduction of immunisation of high-risk children (3/11), and change in BCG vaccine strain (2/11). Members from 24/31 (77%) countries reported using BCG Denmark. ConclusionsImmunisation policies regarding BCG vaccine exist in the majority of European countries. Indications for BCG immunisation varied considerably, likely reflecting national TB incidence rates, immigration and other factors influencing TB control strategies. Importantly, the considerable number of recent policy changes highlights the need for regular collection of up-to-date information to inform public health planning.

The impact of maternal infection with Mycobacterium tuberculosis on the infant response to bacille Calmette-Guérin immunization.

Bacille Calmette–Guérin (BCG) immunization provides variable protection against tuberculosis. Prenatal antigen exposure may have lifelong effects on responses to related antigens and pathogens. We therefore hypothesized that maternal latent Mycobacterium tuberculosis infection (LTBI) influences infant responses to BCG immunization at birth. We measured antibody (n = 53) and cellular (n = 31) responses to M. tuberculosis purified protein derivative (PPD) in infants of mothers with and without LTBI, in cord blood and at one and six weeks after BCG. The concentrations of PPD-specific antibodies declined between birth (median [interquartile range (IQR)]) 5600 ng ml−1 [3300–11 050] in cord blood) and six weeks (0.00 ng ml−1 [0–288]). Frequencies of PPD-specific IFN-γ-expressing CD4+T cells increased at one week and declined between one and six weeks (p = 0.031). Frequencies of IL-2- and TNF-α-expressing PPD-specific CD4+T cells increased between one and six weeks (p = 0.019, p = 0.009, respectively). At one week, the frequency of PPD-specific CD4+T cells expressing any of the three cytokines, combined, was lower among infants of mothers with LTBI, in crude analyses (p = 0.002) and after adjusting for confounders (mean difference, 95% CI −0.041% (−0.082, −0.001)). In conclusion, maternal LTBI was associated with lower infant anti-mycobacterial T-cell responses immediately following BCG immunization. These findings are being explored further in a larger study.

The effect of bacille Calmette-Guérin vaccination at birth on immune response in China

Bacille Calmette-Guérin (BCG) vaccine is still the most effective approach to prevent tuberculosis in childhood. In order to provide protection against severe forms of childhood tuberculosis, it is customary to give BCG vaccination at birth in China. Tuberculin skin testing after vaccination is usually used to evaluate the immunogenic activity and protective efficacy of the BCG. We report the results of a multi-site prospective cohort study to evaluate the immunological reactivity against BCG in four prefectural cities in China. A total of 59,022 newborn infants were vaccinated between January 2011 and March 2012, and follow-up data on 27,517 vaccinated infants were available for this study. Of these, 679 (2.5%) had PPD readings of 0–5mm, 17,072 (62.0%) had PPD readings of 5–10mm of induration, 8864 (32.2%) had readings of 10–15mm, 815 (3.0%) had readings of 15–20mm, and 87 (0.3%) had readings of >20mm of induration. The size of PPD reaction varied significantly with the geographic location, gender, season of vaccination, and grade of hospital administering the BCG vaccine (P<0.001). 97.8% of the infants with a BCG scar of >1mm had a positive TST reaction. However, only 56.9% of infants without a BCG scar had a positive PPD reaction. Our results demonstrate that the BCG immunization among newborn infants in China induces satisfactory immune response. In addition, BCG scars provide a useful indicator of vaccination response in Chinese infants.

The Contribution of Non-Conventional T Cells and NK Cells in the Mycobacterial-Specific IFNγ Response in Bacille Calmette-Guérin (BCG)-Immunized Infants

BackgroundThe Mycobacterium bovis Bacille Calmette-Guérin (BCG) vaccine is given to >120 million infants each year worldwide. Most studies investigating the immune response to BCG have focused on adaptive immunity. However the importance of TCR-gamma/delta (γδ) T cells and NK cells in the mycobacterial-specific immune response is of increasing interest.MethodsParticipants in four age-groups were BCG-immunized. Ten weeks later, in vitro BCG-stimulated blood was analyzed for NK and T cell markers, and intracellular IFNgamma (IFNγ) by flow cytometry. Total functional IFNγ response was calculated using integrated median fluorescence intensity (iMFI).ResultsIn infants and children, CD4 and CD4-CD8- (double-negative (DN)) T cells were the main IFNγ-expressing cells representing 43-56% and 27-37% of total CD3+ IFNγ+ T cells respectively. The iMFI was higher in DN T cells compared to CD4 T cells in all age groups, with the greatest differences seen in infants immunized at birth (p=0.002) or 2 months of age (p<0.0001). When NK cells were included in the analysis, they accounted for the majority of total IFNγ-expressing cells and, together with DN Vδ2 γδ T cells, had the highest iMFI in infants immunized at birth or 2 months of age.ConclusionIn addition to CD4 T cells, NK cells and DN T cells, including Vδ2 γδ T cells, are the key populations producing IFNγ in response to BCG immunization in infants and children. This suggests that innate immunity and unconventional T cells play a greater role in the mycobacterial immune response than previously recognized and should be considered in the design and assessment of novel tuberculosis vaccines.

Non-specific effect of Bacille Calmette-Guérin vaccine on the immune response to routine immunisations

Bacille Calmette-Guérin (BCG) is one of the most commonly administered vaccines worldwide. In addition to protection against tuberculosis (TB), evidence suggests that BCG immunisation has a number of additional beneficial non-specific immunological effects. These include a reduction in overall infant and child mortality attributable to causes other than TB in high-mortality regions. The antibody response to immunisations provides an opportunity to investigate the influence of BCG on the immune response to unrelated antigens. This study compared the antibody response to routine immunisations in BCG-immunised and non-BCG-immunised infants.BCG-immunised infants were recruited from a related study in which BCG was given at birth and non-BCG-immunised infants were recruited from immunisation clinics. All infants received their routine immunisations according to the Australian National Immunisation Program. Concentrations of antibodies against pneumococcal (anti-Pn Ps), Haemophilus influenzae type B (anti-Hib), tetanus toxoid (anti-TT) and hepatitis B surface (anti-HBs) antigen were measured four weeks after the last (six month) set of infant immunisations.A total of 127 parents agreed for their infants to take part in the study of which 108 were included in the final analysis (56 BCG-immunised and 52 non-BCG-immunised). The geometric mean concentration (GMC) of anti-Pn Ps IgG for all serotypes, anti-Hib IgG and anti-TT IgG were higher in the BCG-immunised group than the non-BCG-immunised group. This difference reached statistical significance for serotype 9V (p<0.01) and 18C (p=0.04). The GMC of anti-HBs IgG was lower in the BCG-immunised group than the non-BCG-immunised group (p=0.03). The majority of participants in both groups had antibody levels above the protective threshold.BCG immunisation at birth influences the antibody response to routine immunisations administered later in infancy. This has important implications for the introduction of both pneumococcal conjugate and novel TB vaccines in resource-limited countries.

Novel Recombinant BCG Coexpressing Ag85B, ESAT‐6 and Rv2608 Elicits Significantly Enhanced Cellular Immune and Antibody Responses in C57BL/6 Mice

Tuberculosis (TB) remains an enormous global health problem, and a new vaccine against TB more potent than the current inadequate vaccine, the Bacille Calmette-Guérin (BCG), is urgently needed. BCG has proven to be an effective recombinant delivery vehicle for foreign antigens because of its ability to induce long-lived specific humoral and cellular immunity. Experimental evidences have revealed that Ag85B, ESAT-6 and Rv2608 are important immunodominant antigens of Mycobacterium tuberculosis and are all promising vaccine candidate molecules. In this study, we have constructed a novel recombinant BCG (rBCG) expressing fusion protein Ag85B-ESAT6-Rv2608 and evaluated the immunogenicity of rBCG in C57BL/6 mice. Results show there is strong TB-specific CD4⁺ and CD8⁺ T lymphocytes proliferative response in mice immunized with rBCG vaccine, especially the cytotoxic CD8⁺ T cells playing an important role in protection against TB. And rBCG immunization has induced a significantly strong Th1 immune response, characterized by the increased ratio of IgG2b/IgG1. Results also show that rBCG immunization could increase the secretion of Th1 cytokines such as TNF-α and IL-2 and could decrease the secretion of Th2 cytokine IL-10. Moreover, it was shown that rBCG immunization induced a strong humoral response in mice, characterized by the elevated IgG titre. Therefore, we conclude that this rBCG immunization could increase both cellular immune response and antigen-specific humoral response significantly as compared to BCG immunization in mice. The above results illustrated that rBCG::Ag85B-ESAT6-Rv2608 is a potential candidate against M. tuberculosis for further study.