Antibodies elicited by SARS-CoV-2 infection or mRNA vaccines have reduced neutralizing activity against Beta and Omicron pseudoviruses

Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants that possess mutations associated with increased transmission and antibody escape have arisen over the course of the current pandemic. Although the current vaccines have largely been effective against past variants, the number of mutations found on the Omicron (B.1.1.529) spike protein appear to diminish the protection conferred by pre-existing immunity. Using vesicular stomatitis virus (VSV) pseudoparticles expressing the spike protein of several SARS-CoV-2 variants, we evaluated the magnitude and breadth of the neutralizing antibody response over time in individuals after infection and in mRNA-vaccinated individuals. We observed that boosting increases the magnitude of the antibody response to wildtype (D614), Beta, Delta, and Omicron variants; however, the Omicron variant was the most resistant to neutralization. We further observed that vaccinated healthy adults had robust and broad antibody responses whereas responses may have been reduced in vaccinated pregnant women, underscoring the importance of learning how to maximize mRNA vaccine responses in pregnant populations. Findings from this study show substantial heterogeneity in the magnitude and breadth of responses after infection and mRNA vaccination and may support the addition of more conserved viral antigens to existing SARS-CoV-2 vaccines.

Early and Strong Antibody Responses to SARS-CoV-2 Predict Disease Severity in COVID-19 Patients

Background Antibody response to SARS-CoV-2 is a valuable biomarker for the assessment of the spread of the virus in a population and evaluation of the vaccine candidates. Recent data suggest that antibody levels also may have a prognostic significance in COVID-19. Most of the serological studies so far rely on testing antibodies against spike (S) or nucleocapsid (N) protein, however antibodies can be directed against other structural and nonstructural proteins of the virus, whereas their frequency, biological and clinical significance is unknown. Methods A novel antigen array comprising 30 SARS-CoV-2 antigens or their fragments was developed and used to examine IgG, IgA, IgE and IgM responses to SARS-CoV-2 in sera from 103 patients with COVID-19 including 34 patients for whom sequential samples were available, and 20 pre-pandemic healthy controls. Results Antibody responses to various antigens are highly correlated and the frequencies and peak levels of antibodies are higher in patients with severe/moderate disease than in those with mild disease. This finding supports the idea that antibodies against SARS-CoV-2 may exacerbate the severity of the disease via antibody-dependent enhancement. Moreover, early IgG and IgA responses to full length S protein may be used as an additional biomarker for the identification of patients who are at risk of developing severe disease. Importantly, this is the first study reporting that SARS-CoV-2 elicits IgE responses and their serum levels positively correlate with the severity of the disease thus suggesting a link between high levels of antibodies and mast cell activation. Conclusions This is the first study assessing the prevalence and dynamics IgG, IgA, IgE and IgM responses to multiple SARS-CoV-2 antigens simultaneously. Results provide important insights into the pathogenesis of COVID-19 and have implications in planning and interpreting antibody-based epidemiological studies.

SARS-CoV-2 Humoral and Cellular Immune Responses in COVID-19 Convalescent Individuals With HIV

Background SARS-CoV-2-specific immune response features in people with HIV infection (PWH) remain to be fully elucidated. We aimed to evaluate the impact of HIV over humoral and cellular responses in COVID-19 convalescent PWH. Methods Blood samples from 29 PWH with preserved CD4+T-cell counts on ART and 29 HIV-negative (HIVneg) donors were included. SARS-CoV-2-specific IgG levels and IgG titers were determined by ELISA. Antibody neutralization capacity was evaluated against the reference B1 strain SARS-CoV-2. IFN-γ-secreting cells were detected by ELISpot using SARS-CoV-2 Spike, RBD, or Nucleocapsid protein or overlapping peptide pools. Frequency and phenotype of T, B and NK cells and levels of soluble cytokines and chemokines were assessed by flow cytometry. Results SARS-CoV-2-specific antibodies were detected on 65.5% of PWH and 79.3% of HIVneg individuals, with no differences in serum IgG levels and anti-SARS-CoV-2 neutralizing antibodies. All donors exhibited SARS-CoV-2-specific cellular immunity, including those with undetectable antibody responses. PWH showed diminished percentages of antibody-secreting cells compared to HIVneg cohort, with similar B cell proportions between groups. PWH presented an increment in T follicular helper (Tfh, CD4+CXCR5+) percentage, which negatively correlated with IgG titers. Additionally, CD4+PD1+ and CD8+HLA-DR+ cell frequencies were augmented in PWH. Moreover, PWH presented a high proportion of CD95+, CD25+, NKp46+, HLA-DR+, and CD38+/HLA-DR+ NK cells. Both groups displayed similar Tregs frequency, effector/memory, and T-helper profile for CD4TL, exhaustion and memory phenotypes for CD8TL and subtle differences in classical monocytes. Profile of circulating cytokines and chemokines was significantly different between both groups. Magnitude of IFN-γ responses to S or N proteins, and RBD was lower in PWH compared to HIVneg donors. Correlation analysis of immune and clinical parameters showed a distinct immune landscape in the PWH group. Conclusions PWH showed a distinctive immune profile although severity of COVID-19 was not exacerbated. PWH with conserved CD4+T-cell counts exerted both humoral and cellular responses against SARS-CoV-2. Even though cellular response was lower compared to HIVneg individuals, PWH achieved similar antibody responses with a high neutralization capacity. These data reinforce the impact of ART, not only in controlling HIV but also other infections.

A single dose ChAdOx1 nCoV-19 vaccine elicits high antibody responses in individuals with prior SARS-CoV-2 infection comparable to that of double dose vaccinated SARS-CoV-2 infection naïve individuals

Background A single dose COVID-19 vaccines, mostly mRNA-based vaccines, are shown to induce robust antibody responses in individuals who were previously infected with SARS-CoV-2, suggesting the sufficiency of a single dose to those individuals. However, these important data are limited to developed nations and lacking in resource-limited countries, like Ethiopia. Methods We compared receptor-binding domain (RBD)-specific IgG antibodies in 40 SARS-CoV-2 naïve participants and 25 participants previously infected with SARS-CoV-2, who received two doses of ChAdOx1 nCoV-19 vaccine. We measured the antibody response in post-vaccination blood samples from both groups of participants collected at four different post-vaccination time points: 8- and 12-weeks after each dose of the vaccine administration using an in-house developed ELISA. Results We observed a high level of anti-RBD IgG antibodies titers 8-weeks after a single dose administration (16/27; 59.3%) among naïve participants, albeit dropped significantly (p<0.05) two months later, suggesting the protective immunity elicited by the first dose ChAdOx1 nCoV-19 vaccine will likely last for a minimum of three months. However, as expected, a significant (p<0.001) increase in the level of anti-RBD IgG antibodies titers was observed after the second dose administration in all naïve participants. By contrast, the ChAdOx1 nCoV-19 vaccine-induced anti-RBD IgG antibody titers produced by the P.I participants at 8- to 12-weeks post-single dose vaccination were found to be similar to the antibody titers seen after a two-dose vaccination course among infection- naïve participants and showed no significant (p>0.05) increment following the second dose administration. Conclusion Taken together, our findings show that a single ChAdOx1 nCoV-19 dose in previously SARS-CoV-2 infected individuals elicits similar antibody responses to that of double dose vaccinated naïve individuals. Age and sex were not associated with the level of vaccine-elicited immune responses in both individuals with and without prior SARS-CoV-2 infection. Further studies are required to assess the need for a booster dose to extend the duration and amplitude of the specific protective immune response in Ethiopia settings, especially following the Omicron pandemic.

Obesity and Metabolic Dysregulation in Children Provide Protective Influenza Vaccine Responses

The most effective intervention for influenza prevention is vaccination. However, there are conflicting data on influenza vaccine antibody responses in obese children. Cardio-metabolic parameters such as waist circumference, cholesterol, insulin sensitivity, and blood pressure are used to subdivide individuals with overweight or obese BMI into ‘healthy’ (MHOO) or ‘unhealthy’ (MUOO) metabolic phenotypes. The ever-evolving metabolic phenotypes in children may be elucidated by using vaccine stimulation to characterize cytokine responses. We conducted a prospective cohort study evaluating influenza vaccine responses in children. Participants were identified as either normal-weight children (NWC) or overweight/obese using BMI. Children with obesity were then characterized using metabolic health metrics. These metrics consisted of changes in serum cytokine and chemokine concentrations measured via multiplex assay at baseline and repeated at one month following vaccination. Changes in NWC, MHOO and MUOO were compared using Chi-square/Fisher’s exact test for antibody responses and Kruskal–Wallis test for cytokines. Differences in influenza antibody responses in normal, MHOO and MUOO children were statistically indistinguishable. IL-13 was decreased in MUOO children compared to NWC and MHOO children (p = 0.04). IL-10 approached a statistically significant decrease in MUOO compared to MHOO and NWC (p = 0.07). Influenza vaccination does not provoke different responses in NCW, MHOO, or MUOO children, suggesting that obesity, whether metabolically healthy or unhealthy, does not alter the efficacy of vaccination. IL-13 levels in MUO children were significantly different from levels in normal and MHOO children, indicating that the metabolically unhealthy phenotypes may be associated with an altered inflammatory response. A larger sample size with greater numbers of metabolically unhealthy children may lend more insight into the relationship of chronic inflammation secondary to obesity with vaccine immunity.

VDJ Gene Usage in IgM Repertoires of Rhesus and Cynomolgus Macaques

Macaques are frequently used to evaluate candidate vaccines and to study infection-induced antibody responses, requiring an improved understanding of their naïve immunoglobulin (IG) repertoires. Baseline gene usage frequencies contextualize studies of antigen-specific immune responses, providing information about how easily one may stimulate a response with a particular VDJ recombination. Studies of human IgM repertoires have shown that IG VDJ gene frequencies vary several orders of magnitude between the most and least utilized genes in a manner that is consistent across many individuals but to date similar analyses are lacking for macaque IgM repertoires. Here, we quantified VDJ gene usage levels in unmutated IgM repertoires of 45 macaques, belonging to two species and four commonly used subgroups: Indian and Chinese origin rhesus macaques and Indonesian and Mauritian origin cynomolgus macaques. We show that VDJ gene frequencies differed greatly between the most and least used genes, with similar overall patterns observed in macaque subgroups and individuals. However, there were also clear differences affecting the use of specific V, D and J genes. Furthermore, in contrast to humans, macaques of both species utilized IGHV4 family genes to a much higher extent and showed evidence of evolutionary expansion of genes of this family. Finally, we used the results to inform the analysis of a broadly neutralizing HIV-1 antibody elicited in SHIV-infected rhesus macaques, RHA1.V2.01, which binds the apex of the Env trimer in a manner that mimics the binding mode of PGT145. We discuss the likelihood that similar antibodies could be elicited in different macaque subgroups.

Durability and cross-reactivity of SARS-CoV-2 mRNA vaccine in adolescent children

Importance: Emergent SARS-CoV-2 variants and waning humoral immunity in vaccinated individuals are causing increased infections and hospitalizations. Children are not spared from infection nor complications of COVID-19, and the recent recommendation for boosters in individuals ages 12 years or older calls for broader understanding of the adolescent immune profile after mRNA vaccination. Objective: We sought to test the durability and cross-reactivity of anti-SARS-CoV-2 serologic responses over a six-month time course in vaccinated adolescents against the wildtype and Omicron antigens. Design, Setting and Participants: Adolescents who received a full (two-dose) series of the Pfizer-BioNTech mRNA vaccination participated in this longitudinal cohort study from May 2021 to January 2022. Blood samples were collected in clinical settings from thirty-one adolescents, nineteen of whom provided samples at four timepoints (prior to vaccination, two to three weeks after first dose, two to four weeks after second dose and six months after complete series). Sera were analyzed for antibody responses against wildtype and Omicron variant SARS-CoV-2-specific proteins. Main Outcomes and Measures: The main outcome was to analyze vaccine-induced immune responses over time by ELISA, as well as their cross-reactivity between antibody responses against wildtype SARS-CoV-2 and the Omicron variant of concern. Results: Thirty-one adolescents provided a blood sample for at least one timepoint. The median age of the cohort was 13.9 years. Half of the cohort was male, and one quarter of the population was Hispanic. Anti-Spike and anti-RBD antibodies waned after six months, nearing pre-vaccination levels. After the second dose of the vaccine, adolescent children displayed equal sensitivity for the Omicron-RBD and wildtype SARS-CoV-2-RBD, as well as an upward trend of Omicron-reactive antibodies six months after vaccination. Waning mRNA vaccine-induced immunity in adolescents highlights a vulnerability in pediatric protection against SARS-CoV-2 infection. Conclusions and Relevance: Vaccine-induced immunity wanes in adolescents over time to near pre-vaccinated levels. Cross-reactivity of antibodies generated by adolescents display efficacy against Omicron. These findings highlight the need for SARS-CoV-2 boosters to protect adolescents from highly infectious variants, illness and post-COVID-19 complications.

Cellular and humoral immunity to SARS-CoV-2 infection in multiple sclerosis patients on ocrelizumab and other disease-modifying therapies: a multi-ethnic observational study

Objective: To determine the impact of MS disease-modifying therapies (DMTs) on the development of cellular and humoral immunity to SARS-CoV-2 infection. Methods: MS patients aged 18-60 were evaluated for anti-nucleocapsid and anti-Spike RBD antibody with electro-chemiluminescence immunoassay; antibody responses to Spike protein, RBD, N-terminal domain with multiepitope bead-based immunoassays (MBI); live virus immunofluorescence-based microneutralization assay; T-cell responses to SARS-CoV-2 Spike using TruCulture ELISA; and IL-2 and IFNγ ; ELISpot assays. Assay results were compared by DMT class. Spearman correlation and multivariate analyses were performed to examine associations between immunologic responses and infection severity. Results: Between 1/6/2021 and 7/21/2021, 389 MS patients were recruited (mean age 40.3 years; 74% female; 62% non-White). Most common DMTs were ocrelizumab (OCR) - 40%; natalizumab - 17%, Sphingosine 1-phosphate receptor (S1P) modulators -12%; and 15% untreated. 177 patients (46%) had laboratory evidence of SARS-CoV-2 infection; 130 had symptomatic infection, 47 - asymptomatic. Antibody responses were markedly attenuated in OCR compared to other groups (p≤0.0001). T-cell responses (IFNγ) were decreased in S1P (p=0.03), increased in natalizumab (p<0.001), and similar in other DMTs, including OCR. Cellular and humoral responses were moderately correlated in both OCR (r=0.45, p=0.0002) and non-OCR (r=0.64, p<0.0001). Immune responses did not differ by race/ethnicity. COVID-19 clinical course was mostly non-severe and similar across DMTs; 7% (9/130) were hospitalized. Interpretation: DMTs had differential effects on humoral and cellular immune responses to SARS-CoV-2 infection. Immune responses did not correlate with COVID-19 clinical severity in this relatively young and non-disabled group of MS patients.