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    Robust induction of B cell and T cell responses by a third dose of inactivated SARS-CoV-2 vaccine
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    Abstract:
    SARS-CoV-2 inactivated vaccines have shown remarkable efficacy in clinical trials, especially in reducing severe illness and casualty. However, the waning of humoral immunity over time has raised concern over the durability of immune memory following vaccination. Thus, we conducted a nonrandomized trial among the healthcare workers (HCWs) to investigate the long-term sustainability of SARS-CoV-2-specific B cells and T cells stimulated by inactivated vaccines and the potential need for a third booster dose. Although neutralizing antibodies elicited by the standard two-dose vaccination schedule dropped from a peak of 29.3 arbitrary units (AU)/mL to 8.8 AU/mL 5 months after the second vaccination, spike-specific memory B and T cells were still detectable, forming the basis for a quick recall response. As expected, the faded humoral immune response was vigorously elevated to 63.6 AU/mL by 7.2 folds 1 week after the third dose along with abundant spike-specific circulating follicular helper T cells in parallel. Meanwhile, spike-specific CD4
    Keywords:
    Vaccination schedule
    Memory B cell
    Humoral immunity
    Background: HIV infection dysregulates the B cell compartment, affecting memory B cell formation and the antibody response to infection and vaccination. Understanding the B cell response to SARS-CoV-2 in people living with HIV (PLWH) may explain the increased morbidity, reduced vaccine efficacy, reduced clearance, and intra-host evolution of SARS-CoV-2 observed in some HIV-1 coinfections. Methods: We compared B cell responses to COVID-19 in PLWH and HIV negative (HIV-ve) patients in a cohort recruited in Durban, South Africa, during the first pandemic wave in July 2020 using detailed flow cytometry phenotyping of longitudinal samples with markers of B cell maturation, homing, and regulatory features. Results: This revealed a coordinated B cell response to COVID-19 that differed significantly between HIV-ve and PLWH. Memory B cells in PLWH displayed evidence of reduced germinal centre (GC) activity, homing capacity, and class-switching responses, with increased PD-L1 expression, and decreased Tfh frequency. This was mirrored by increased extrafollicular (EF) activity, with dynamic changes in activated double negative (DN2) and activated naïve B cells, which correlated with anti-RBD-titres in these individuals. An elevated SARS-CoV-2-specific EF response in PLWH was confirmed using viral spike and RBD bait proteins. Conclusions: Despite similar disease severity, these trends were highest in participants with uncontrolled HIV, implicating HIV in driving these changes. EF B cell responses are rapid but give rise to lower affinity antibodies, less durable long-term memory, and reduced capacity to adapt to new variants. Further work is needed to determine the long-term effects of HIV on SARS-CoV-2 immunity, particularly as new variants emerge. Funding: This work was supported by a grant from the Wellcome Trust to the Africa Health Research Institute (Wellcome Trust Strategic Core Award [grant number 201433/Z/16/Z]). Additional funding was received from the South African Department of Science and Innovation through the National Research Foundation (South African Research Chairs Initiative [grant number 64809]), and the Victor Daitz Foundation.
    Memory B cell
    Citations (12)
    Abstract Background HIV infection dysregulates the B cell compartment, affecting memory B cell formation and the antibody response to infection and vaccination. Understanding the B cell response to SARS-CoV-2 in people living with HIV (PLWH) may explain the increased morbidity, reduced vaccine efficacy, reduced clearance, and intra-host evolution of SARS-CoV-2 observed in some HIV-1 coinfections. Methods We compared B cell responses to COVID-19 in PLWH and HIV negative (HIV-ve) patients in a cohort recruited in Durban, South Africa, during the first pandemic wave in July 2020 using detailed flow cytometry phenotyping of longitudinal samples with markers of B cell maturation, homing and regulatory features. Results This revealed a coordinated B cell response to COVID-19 that differed significantly between HIV-ve and PLWH. Memory B cells in PLWH displayed evidence of reduced germinal center (GC) activity, homing capacity and class-switching responses, with increased PD-L1 expression, and decreased Tfh frequency. This was mirrored by increased extrafollicular (EF) activity, with dynamic changes in activated double negative (DN2) and activated naïve B cells, which correlated with anti-RBD-titres in these individuals. An elevated SARS-CoV-2 specific EF response in PLWH was confirmed using viral spike and RBD bait proteins. Conclusions Despite similar disease severity, these trends were highest in participants with uncontrolled HIV, implicating HIV in driving these changes. EF B cell responses are rapid but give rise to lower affinity antibodies, less durable long-term memory, and reduced capacity to adapt to new variants. Further work is needed to determine the long-term effects of HIV on SARS-CoV-2 immunity, particularly as new variants emerge. Funding This work was supported by a grant from the Wellcome Trust to the Africa Health Research Institute (Wellcome Trust Strategic Core Award [grant number 201433/Z/16/Z]). Additional funding was received from the South African Department of Science and Innovation through the National Research Foundation (South African Research Chairs Initiative, [grant number 64809]), and the Victor Daitz Foundation.
    Memory B cell
    Citations (0)
    Abstract SIV/HIV infection is associated with B cell dysfunction, the significance of which is not known. We compared the B cell dynamics in blood, lymph nodes (LNs) and gut during SIVsab pathogenic infection of pigtailed macaques (PTMs) and nonprogressive SIVsab infection of African green monkeys (AGMs) by monitoring the B cell subsets, B regulatory cells (Bregs), CD4+ T follicular helper (Tfh) cells, B cell immune activation, apoptosis, exhaustion and homing to the intestine. Binding anti-gp41 and neutralizing antibodies (Nabs) were also measured. Acute SIV infection induced a transient but significant loss of total circulating B cells in PTMs only. In AGMs, total B cell from LNs increased during chronic infection. B cells transiently increased in the gut and naïve subset decreased in all three compartments in both species. Memory B cell subsets showed a different dynamic for both species. Bregs increased in PTM, correlated with IL-10 expression. B cell proliferation occurred in both species. PTMs expressed high baseline levels of α4β7, high degree of B cell activation and apoptosis and high frequency of Tfh. The dynamics of Ab response was similar in both species, but rapid progressor PTMs lacked the ability to mount anti-gp41. Our data show that B cell dysfunction only occurs in pathogenic SIV infection. While B cell changes were not correlated with production of Nabs, rapid disease progression associated a severe incapacity to mount an anti-SIV Ab response.
    Memory B cell
    Regulatory B cells
    Simian immunodeficiency virus
    Naive B cell
    Homing (biology)
    Abstract Background: Both normal aging and HIV infection impact B cell functionality and lead to activation of resting B cells, memory cell depletion and altered gene expression. As a result, HIV+ individuals and the elderly fail to demonstrate robust and durable immune responses against pneumococcal polysaccharides. Herein, we assessed altered B cell function in high risk groups by utilizing single cell technology. Methods: HIV-positive individuals with CD4+T cell counts >200 on Antiretroviral Therapy (ART) and HIV-negative individuals age groups 21-40 and 50-65 received pneumococcal vaccination. Serum IgG and IgM PPS-specific antibodies were measured pre- and post-immunization using ELISA method. Evaluation of B cells was performed using flow cytometry and single cell RT-PCR. Results: IgM memory B cells are important players in responding to pneumococcal antigens and are present in reduced quantities in HIV+ and aging HIV- individuals. Single cell analysis of IgM memory B cells demonstrated heterogeneity and identified two unique subpopulations. One of the subpopulations represents B cells with higher expression of TACI and BAFF-R and is more likely to dominate in T-cell independent immune responses. IgD+IgM+memory B cells were present in equal proportions in both subpopulations. Conclusion: Pneumococcal vaccine responses in HIV+ and aging HIV- individuals are multifactorial and largely depend on the abundance and phenotypic characteristics of IgM memory B cells.
    Memory B cell
    Immunoglobulin D
    Immunosenescence
    Pneumococcal vaccine
    Memory T cell
    B-1 cell
    Naive B cell
    Citations (0)
    In individuals who have once developed humoral immunity to an infectious/foreign antigen, the antibodies present in their body can mediate instant protection when the antigen re-enters. Such antigen-specific antibodies can be readily detected in the serum. Long term humoral immunity is, however, also critically dependent on the ability of memory B cells to engage in a secondary antibody response upon re-exposure to the antigen. Antibody molecules in the body are short lived, having a half-life of weeks, while memory B cells have a life span of decades. Therefore, the presence of serum antibodies is not always a reliable indicator of B cell memory and comprehensive monitoring of humoral immunity requires that both serum antibodies and memory B cells be assessed. The prevailing view is that resting memory B cells and B cell blasts in peripheral blood mononuclear cells (PBMC) cannot be cryopreserved without losing their antibody secreting function, and regulated high throughput immune monitoring of B cell immunity is therefore confined to—and largely limited by—the need to test freshly isolated PBMC. Using optimized protocols for freezing and thawing of PBMC, and four color ImmunoSpot® analysis for the simultaneous detection of all immunoglobulin classes/subclasses we show here that both resting memory B cells and B cell blasts retain their ability to secrete antibody after thawing, and thus demonstrate the feasibility of B cell immune monitoring using cryopreserved PBMC.
    Citations (26)
    Multiple B cell abnormalities have been described in humans infected with HIV. These abnormalities include hypergammaglobulinaemia, diminished B cell response to mitogenic stimuli, lymphoma and a depletion of the memory B cell population. There is also evidence to suggest that B cells in HIV infected patients are functionally impaired. The initial antibody response to HIV infection is slow to appear and antibody responses to B cell mediated vaccines in HIV infected individuals are less robust and less durable than in uninfected individuals. Although B cell abnormalities have been characterized in humans, efforts to link these abnormalities to a specific defect within the B cell compartment have not been entirely successful. The SIV/macaque model of HIV infection of humans provides a means for addressing questions about the naive and memory B cell populations, whose activity may be differentially compromised by HIV infection, but lacking is the ability to resolve these functionally relevant B cell populations in the rhesus macaque. In this study, we established CD27 as a definitive memory B cell marker in the rhesus macaque. Further, we demonstrated that the naive and memory B cell populations are depleted from the periphery within 14 days of SIV infection and that the memory B cell population recovered more quickly. We also showed that chronic SIV infection resulted in a loss of CD40 mediated naive B cell survival, indicating a potential mechanism through which SIV infection may lead to the production of non-reactive or self reactive antibody producing cells. Together, these findings demonstrated that B cell dysfunctions associated with SIV infection are not limited to the memory B cell population as previously thought, but rather that naive B cell deficits may be more severe than what has been observed in the memory compartment. Increased focus on abrogating alterations that occur within the naive compartment have the potential to improve viral control in infected individuals. This study of phenotypic and functional B cell changes over the course of infection will aid in the development of strategies that have the potential to improve prophylactic and therapeutic B cell mediated vaccine efficacy.
    Memory B cell
    Rhesus macaque
    Simian immunodeficiency virus
    Naive B cell
    Memory cell
    Citations (1)
    The isolation and characterization of neutralizing antibodies from infection and vaccine settings informs future vaccine design, and methodologies that streamline the isolation of antibodies and the generation of B cell clones are of great interest. Retroviral transduction to express Bcl-6 and Bcl-xL and transform primary B cells has been shown to promote long-term B cell survival and antibody secretion
    Memory B cell
    Naive B cell
    Memory T cell
    ABSTRACT Background Hepatitis B is a major global health problem. More than 90% of hepatitis B-vaccinated immunocompetent adults become fully immune. The main purpose of vaccination is immunization. Whether non-responders have a lower percentage of total or antigen-specific memory B cells in comparison with responders is still controversial. We aimed to assess and compare the frequency of various B cell subpopulations in non-responders and responders. Methods Fourteen responders and 14 non-responders of hospital healthcare workers were enrolled in this study. We used flow cytometry to evaluate various CD19+ B cell subpopulations using fluorescent-labeled antibodies against CD19, CD10, CD21, CD27 and IgM and ELISA to evaluate total anti-HBs antibodies. Results We found no significant differences in the frequency of various B cell subpopulations between the non-responder and responder groups. Furthermore, the frequency of the isotype-switched memory B cell population was significantly higher in the atypical memory B cell subset compared with the classical memory B cell subset in the responder and total groups (p=0.010 and 0.003, respectively). Conclusions Responders and non-responders to HBsAg vaccine had comparable memory B cell populations. Whether anti-HBs Ab production has a correlation with the level of class switching in B lymphocytes in healthy vaccinated individuals needs further investigation.
    Memory B cell
    Hepatitis B
    Isotype
    Hepatitis B vaccine
    Citations (1)