Persistent SARS-CoV-2-specific immune defects in kidney transplant recipients following third mRNA vaccine dose.

Kidney transplant recipients (KTRs) show poorer response to SARS-CoV-2 mRNA vaccination, yet response patterns and mechanistic drivers following third doses are ill-defined. We administered third monovalent mRNA vaccines to n = 81 KTRs with negative or low-titer anti-receptor binding domain (RBD) antibody (n = 39 anti-RBDNEG; n = 42 anti-RBDLO), compared with healthy controls (HCs, n = 19), measuring anti-RBD, Omicron neutralization, spike-specific CD8+%, and SARS-CoV-2-reactive T cell receptor (TCR) repertoires. By day 30, 44% anti-RBDNEG remained seronegative; 5% KTRs developed BA.5 neutralization (vs 68% HCs, P < .001). Day 30 spike-specific CD8+% was negative in 91% KTRs (vs 20% HCs; P = .07), without correlation to anti-RBD (rs = 0.17). Day 30 SARS-CoV-2-reactive TCR repertoires were detected in 52% KTRs vs 74% HCs (P = .11). Spike-specific CD4+ TCR expansion was similar between KTRs and HCs, yet KTR CD8+ TCR depth was 7.6-fold lower (P = .001). Global negative response was seen in 7% KTRs, associated with high-dose MMF (P = .037); 44% showed global positive response. Of the KTRs, 16% experienced breakthrough infections, with 2 hospitalizations; prebreakthrough variant neutralization was poor. Absent neutralizing and CD8+ responses in KTRs indicate vulnerability to COVID-19 despite 3-dose mRNA vaccination. Lack of neutralization despite CD4+ expansion suggests B cell dysfunction and/or ineffective T cell help. Development of more effective KTR vaccine strategies is critical. (NCT04969263).

Blockade Antibody Responses in Human Subjects Challenged with a New Snow Mountain Virus Inoculum.

Background: Noroviruses (NoVs) are a leading cause of non-bacterial gastroenteritis in young children and adults worldwide. Snow Mountain Virus (SMV) is the prototype of NoV GII genotype 2 (GII.2) that has been developed as a viral model for human challenge models, an important tool for studying pathogenesis and immune response of NoV infections and for evaluating NoV vaccine candidates. Previous studies have identified blockade antibodies that block the binding of NoV virus-like particles (VLPs) to histo-blood group antigens (HBGAs) as a surrogate for neutralization in human Norwalk virus and GII.4 infections but little is known about SMV blockade antibodies. Methods: In this secondary data analysis study, blockade antibodies were characterized in pre-challenge and post-challenge serum samples from human subjects challenged with a new SMV inoculum. The correlation between blockade antibody geometric mean antibody titers (GMTs) and SMV-specific serum IgG/IgA GMTs were examined after stratifying the subjects by infection status. A linear mixed model was applied to test the association between HBGA blockade antibody concentrations and post-challenge days accounting for covariates and random effects. Results: Laboratory results from 33 SMV inoculated individuals were analyzed and 75.7% (25/33) participants became infected. Serum SMV-specific blockade antibodies, IgA, and IgG were all significantly different between infected and uninfected individuals beginning day 15 post-challenge. Within infected individuals, a significant correlation was observed between both IgG and IgA and blockade antibody concentration as early as day 6 post-challenge. Analysis of blockade antibody using the linear mixed model showed that infected individuals, when compared to uninfected individuals, had a statistically significant increase in blockade antibody concentrations across the post-challenge days. Among the post-challenge days, blockade antibody concentrations on days 15, 30, and 45 were significantly higher than those observed pre-challenge. The intraclass correlation coefficient (ICC) analysis indicated that the variability of blockade antibody titers is more observed between individuals rather than observations within subjects. Conclusions: These results indicate that HBGA-blockade antibody GMTs are generated after SMV challenge and the blockade antibodies were still detectable at day 45 post-challenge. These data indicate that the second generation of SMV inoculum is highly effective.

Blockade Antibody Responses in Human Subjects Challenged with a New Snow Mountain Virus Inoculum.

Background: Noroviruses (NoVs) are a leading cause of non-bacterial gastroenteritis in young children and adults worldwide. Snow Mountain Virus (SMV) is the prototype of NoV GII genotype 2 (GII.2) that has been developed as a viral model for human challenge studies, an important tool for studying pathogenesis and immune response of NoV infections and for evaluating NoV vaccine candidates. Previous studies have identified blockade antibodies that block the binding of NoV virus-like particles (VLPs) to histo-blood group antigens (HBGAs) as a surrogate for neutralization in human Norwalk virus and GII.4 infections but little is known about SMV blockade antibodies. Methods: In this secondary data analysis study, blockade antibodies were characterized in pre-challenge and post-challenge serum samples from human subjects challenged with a new SMV inoculum. The correlation between blockade antibody geometric mean antibody titers (GMTs) and SMV-specific serum IgG/IgA GMTs were examined after stratifying the subjects by infection status. A linear mixed model was applied to test the association between HBGA blockade antibody concentrations and post-challenge days accounting for covariates and random effects. Results: Laboratory results from 33 SMV inoculated individuals were analyzed and 75.7% (25/33) participants became infected. Serum SMV-specific blockade antibodies, IgA, and IgG were all significantly different between infected and uninfected individuals beginning day 15 post-challenge. Within infected individuals, a significant correlation was observed between both IgG and IgA and blockade antibody concentration as early as day 6 post-challenge. Analysis of blockade antibody using the linear mixed model showed that infected individuals, when compared to uninfected individuals, had a statistically significant increase in blockade antibody concentrations across the post-challenge days. Among the post-challenge days, blockade antibody concentrations on days 15, 30, and 45 were significantly higher than those observed pre-challenge. The intraclass correlation coefficient (ICC) analysis indicated that the variability of blockade antibody titers is more observed between individuals rather than within subjects. Conclusions: These results indicate that HBGA-blockade antibody GMTs are generated after SMV challenge and the blockade antibodies were still detectable at day 45 post-challenge. These data indicate that the second-generation of SMV inoculum is highly effective.

Durability of immune responses to mRNA booster vaccination against COVID-19.

BackgroundMaintaining durable immunity following vaccination represents a major challenge, but whether mRNA booster vaccination improves durability is unknown.MethodsWe measured antibody responses in 55 healthy adults, who received a booster dose of the Pfizer-BioNTech or Moderna vaccine against SARS-CoV-2 and calculated the half-life of the antibody titers. We also measured memory B and T cell responses in a subset of 28 participants. In 13 volunteers who received a second booster vaccine, we measured serum antibody titers and memory B and T cell responses.ResultsThe booster (third immunization) dose at 6 to 10 months increased the half-life of the serum-neutralizing antibody (nAb) titers to 76 days from 56 to 66 days after the primary 2-dose vaccination. A second booster dose (fourth immunization) a year after the primary vaccination further increased the half-life to 88 days. However, despite this modestly improved durability in nAb responses against the ancestral (WA.1) strain, there was a loss of neutralization capacity against the Omicron subvariants BA.2.75.2, BQ.1.1, and XBB.1.5 (48-, 71-, and 66-fold drop in titers, respectively, relative to the WA.1 strain). Although only 45% to 65% of participants demonstrated a detectable nAb titer against the newer variants after the booster (third dose), the response declined to below the detection limit in almost all individuals by 6 months. In contrast, booster vaccination induced antigen-specific memory B and T cells that persisted for at least 6 months.ConclusionThe durability of serum antibody responses improves only marginally following booster immunizations with the Pfizer-BioNTech or Moderna mRNA vaccines.

Durability of immune responses to the booster mRNA vaccination against COVID-19.

Waning immunity to vaccination represents a major challenge in vaccinology. Whether booster vaccination improves the durability of immune responses is unknown. Here we show, using a cohort of 55 adult vaccinees who received the BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine against SARS-CoV-2, that a booster (i.e., 3 rd immunization) dose at 6 - 10 months increased the half-life of serum neutralizing antibody (nAb) titers to 76 days from 56 - 66 days estimated after the primary two-dose vaccination series. A second booster dose (i.e., 4 th immunization) more than a year after the primary vaccination increased the half-life further to 88 days. However, despite this modestly improved durability in nAb responses against the Wuhan strain, there was a loss in neutralization capacity against Omicron subvariants, especially the recently emerged variants, BA.2.75.2 and BQ.1.1 (35 and 50-fold drop in titers respectively, relative to the ancestral (WA.1) strain. While only 55 â€" 65% of participants demonstrated a detectable nAb titer against the newer variants after the booster (3 rd dose), the response declined to below the detection limit in almost all individuals by 6 months. Notably, even against BA.1 and BA.5, the titers declined rapidly in a third of the vaccinees and were below the detection limit at 6 months. In contrast, booster vaccination induced antigen-specific memory B and T cells that persisted for at least 6 months. Collectively, our data show that the durability of immune responses improves following subsequent booster immunizations; however, the emergence of immune evasive variants reduces the effectiveness of booster doses in preventing infection.

CRISPR-Cas9 Ribonucleoprotein-Mediated Genomic Editing in Mature Primary Innate Immune Cells.

CRISPR genome engineering has become a powerful tool to functionally investigate the complex mechanisms of immune system regulation. While decades of work have aimed to genetically reprogram innate immunity, the utility of current approaches is restricted by poor knockout efficiencies or limited specificity for mature cell lineages in vivo. Here, we describe an optimized strategy for non-viral CRISPR-Cas9 ribonucleoprotein (cRNP) genomic editing of mature primary mouse innate lymphocyte cells (ILCs) and myeloid lineage cells that results in an almost complete loss of single or double target gene expression from a single electroporation. Furthermore, we describe in vivo adoptive transfer mouse models that can be utilized to screen for gene function during viral infection using cRNP-edited naive natural killer (NK) cells and bone-marrow-derived conventional dendritic cell precursors (cDCPs). This resource will enhance target gene discovery and offer a specific and simplified approach to gene editing in the mouse innate immune system.

The Effects of Imprinting and Repeated Seasonal Influenza Vaccination on Adaptive Immunity after Influenza Vaccination.

(1) Background: The influenza virus continues to cause significant annual morbidity and mortality. The overall efficacy of seasonal influenza vaccination is suboptimal, which is partly due to host immune factors. The effects of imprinting and repeated seasonal influenza vaccination were investigated to assess for immune factors and mechanisms that impact influenza vaccine responses. (2) Methods: Twenty participants were enrolled into a prospective pilot study based on birth cohort and seasonal influenza immunization history. Immunologic parameters were assessed over a six-month period after the seasonal influenza vaccine was administered. (3) Results: There was no significant imprinting effect, as measured by hemagglutination inhibition (HAI) fold change, HAI geometric mean titer (GMT) for Day 29 or Day 180 post-vaccination and antigen- specific antibody-secreting cells (ASC) for Day 8 post-vaccination. Individuals who had minimal prior seasonal influenza vaccination had a higher magnitude ASC response and a higher HAI fold change post-vaccination than individuals who were repeatedly vaccinated. (4) Conclusions: Repeated seasonal influenza vaccination resulted in a decreased fold change of the immune response, although individuals in this cohort tended to have high HAI titers at baseline that persisted after vaccination. Imprinting effects were not observed in this cohort. These host immune factors should be considered in the development of universal influenza vaccines. ClinicalTrials.gov Identifier: NCT03686514.

Systems biological assessment of immunity to mild versus severe COVID-19 infection in humans.

Coronavirus disease 2019 (COVID-19) represents a global crisis, yet major knowledge gaps remain about human immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We analyzed immune responses in 76 COVID-19 patients and 69 healthy individuals from Hong Kong and Atlanta, Georgia, United States. In the peripheral blood mononuclear cells (PBMCs) of COVID-19 patients, we observed reduced expression of human leukocyte antigen class DR (HLA-DR) and proinflammatory cytokines by myeloid cells as well as impaired mammalian target of rapamycin (mTOR) signaling and interferon-α (IFN-α) production by plasmacytoid dendritic cells. By contrast, we detected enhanced plasma levels of inflammatory mediators-including EN-RAGE, TNFSF14, and oncostatin M-which correlated with disease severity and increased bacterial products in plasma. Single-cell transcriptomics revealed a lack of type I IFNs, reduced HLA-DR in the myeloid cells of patients with severe COVID-19, and transient expression of IFN-stimulated genes. This was consistent with bulk PBMC transcriptomics and transient, low IFN-α levels in plasma during infection. These results reveal mechanisms and potential therapeutic targets for COVID-19.