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Bivalent COVID-19 vaccines that contain two mRNAs encoding Wuhan-1 and Omicron BA.4/5 spike proteins are successful in preventing infection from the original strain and Omicron variants, but the quality of adaptive immune responses is still not well documented. This study aims at characterizing adaptive immune responses to the bivalent booster vaccination in 46 healthy participants. Plasma and PBMC were collected prior and three weeks after bivalent booster. We measured anti-N, anti-S, and RBD IgM, IgA, IgG plasma titers against original, Omicron BA.1, and BA.5 variants (pending) as well as total anti-S IgG titers and surrogate Virus Neutralization capacity against the Alpha, Delta, and BA.1 variant. With spectral flow-cytometry we identified peripheral blood B-cells specific for the RBD of the S-protein of the original and BA.1 variants. T-cell-specific responses were assessed by cytokine release assay after stimulation with SARS-CoV-2 peptides from the original, BA.1, BA.4, and BA.5 variants (pending). Finally, we performed TRB and IGH repertoire studies on sorted CD4+, CD8+, CD19+ lymphocytes, to study breadth of SARS-CoV-2 specific clonotypes (pending). 27/46 participants were analyzed;9 had SARS-CoV-2 infection (COVID+), while 18 are infection naive (COVID-). In both groups, median time since last dose of SARS-CoV-2 vaccine (3rd or 4th) was 11 months. All subjects were positive for anti-S IgG prior to bivalent booster. The COVID + group displayed anti-S IgG pre-booster levels and neutralization against BA.1 higher than the COVID- group. Significant increase post-boost of total anti-S IgG and BA.1 neutralizing activity was detected in the COVID- but not in the COVID+ group;however, no difference in neutralization activity post-boost was detected between the two groups. Furthermore, the COVIDgroup showed significant increase in the frequency of CD19+ and CD27+ switched memory B-cells specific for BA.1 RBD in post-boost compared to pre-boost samples. However, post-boost frequencies of the same B-cells were higher in the COVID+ compared to the COVID- group. These preliminary findings confirm that among individual immunized with the original COVID-19 mRNAvaccine, prior COVID infection provides increased protection against SARS-CoV-2 variants. They also demonstrate that booster immunization with the bivalent vaccine induces robust adaptive immune responses against Omicron variant.[Formula presented][Formula presented]Copyright © 2023 Elsevier Inc.
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Background: Patients with primary and secondary immunodeficiencies have shown an impaired humoral immune response to COVID-19 vaccination. It is therefore of paramount importance to investigate anti-SARS-CoV-2 antibody levels in plasma pools and in immunoglobulin (IgG) products used to treat these patients. AIM: To assess the evolution of anti-SARS-CoV-2 antibodies (S protein) in plasma pools and IgG products and its neutralizing activity to original-type virus (Wuhan) and the variants of concern (VOC), including Omicron. Method(s): Healthy donors plasma pools collected in the US and Europe, and the subsequent intravenous (Flebogamma DIFand Gamunex-C, Grifols) and subcutaneous (Xembify, Grifols) IgG manufactured batches were followed from March 2020. Anti-SARS-CoV-2 S protein IgG titers were determined in plasma pools and in IgG batches by ELISA. Neutralization assays analyzed the capacity of IgG products to neutralize original-type virus and VOC (Alpha, Beta, Delta, Omicron BA.1 and BA.5), using pseudo viruses expressing S protein. Results were expressed as the dilution producing 50% neutralization (ID50). Result(s): In plasma pools, anti-SARS-CoV-2 S antibodies continuously increased throughout the study period regardless of the geographic origin. In the US, the first positive plasma pools were collected at the end of 2020. Since July 2021, an exponential increase over 30-fold of anti-SARS-CoV-2 S antibodies was reported. This trend continued increasing until the end of study period. Similarly, IgG products showed a similar evolution of anti-SARS-CoV-2 S antibodies. As expected, IgG batches released at the end of 2020 presented low SARS-CoV-2 neutralization activity. However, IgG products manufactured since August 2021 showed high neutralization activity against original-type virus and the rest of VOC. Regarding Omicron BA.5, a 5 to 10-fold increase was observed over time. Conclusion(s): This study reported the onset of elevated anti-SARS-CoV-2 antibody titers in plasma pools and IgG products since mid-2021, reflecting the evolution of the pandemic and vaccine campaigns. Intravenous and subcutaneous IgG products efficiently neutralized the current circulating VOC, Omicron BA.5. Further research is warranted to assess whether a clinical protective titer against SARS-CoV-2 and passive immunization is achieved in patients with immunodeficiencies treated with IgG products.Copyright © 2023 Elsevier Inc.
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The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from wildlife has raised concerns about spillover from humans to animals, the establishment of novel wildlife reservoirs, and the potential for future outbreaks caused by variants of wildlife origin. Norway rats (Rattus norvegicus) are abundant in urban areas and live in close proximity to humans, providing the opportunity for spillover of SARS-CoV-2. Evidence of SARS-CoV-2 infection and exposure has been reported in Norway rats. We investigated SARS-CoV-2 infection and exposure in Norway rats from Southern Ontario, Canada. From October 2019 to June 2021, 224 rats were submitted by collaborating pest control companies. The majority of samples were collected in Windsor (79.9%;n = 179), Hamilton (13.8%;n = 31), and the Greater Toronto Area (5.8%;n = 13). Overall, 50.0% (n = 112) were female and most rats were sexually mature (55.8%;n = 125). Notably, 202 samples were collected prior to the emergence of variants of concern (VOC) and 22 were collected while the Alpha variant (B.1.1.7) was the predominant circulating VOC in humans. Nasal turbinate (n = 164) and small intestinal (n = 213) tissue samples were analyzed for SARS-CoV-2 RNA by RT-PCR. Thoracic cavity fluid samples (n = 213) were tested for neutralizing antibodies using a surrogate virus neutralization test (sVNT) (GenScript cPass);confirmatory plaque reduction neutralization test (PRNT) was conducted on presumptive positive samples. We did not detect SARS-CoV-2 RNA in any samples tested. Two out of eleven samples positive on sVNT had neutralizing antibodies confirmed positive by PRNT (1 : 40 and 1 : 320 PRNT70);both were collected prior to the emergence of VOC. It is imperative that efforts to control and monitor SARS-CoV-2 include surveillance of rats and other relevant wildlife species as novel variants continue to emerge.
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Background: Intravenous (IV) and subcutaneous (SC) Immunoglobulin G (IG) replacement products are in wide use in patients with primary antibody deficiency syndrome (PAD). There is limited data on the levels of anti-SARS-CoV-2 spike antibodies in IG products or their ability to neutralize emerging SARS-CoV-2 variants. There is lack of data on the impact of IG therapy on serum anti-SARS-CoV-2 spike or neutralizing antibody titers in PAD patients. Method(s): We measured anti-SARS-CoV-2 anti-spike antibody levels and neutralizing titers against historical (WA1/2020) and variant (B.1.617.2 [Delta] and BA.1 [Omicron]) strains in 158 lots of 6 different IG products, collected between August 2021 to April 2022 and manufactured between December 2019 to December 2021. IG products were compared to serum from 20 healthy donors vaccinated with 2 doses of Pfizer-BioNTech mRNA vaccine. Serum anti-spike antibody level and SARS-CoV-2 neutralization activity were measured in 27 PAD patients treated with the tested IG products. Result(s): Anti-spike antibody titers started to increase in products manufactured in March 2021 and reached peak level, comparable to vaccinated healthy donors, in products manufactured in August 2021 (Fig. 1). The neutralization activity against WA1/2020 and Delta strains showed a similar pattern (Fig. 2). However, 95% of the tested products had no neutralization activity against Omicron. Until November 2021, IVIG products infused to patients in the study had anti-spike titers comparable to unvaccinated healthy donors (Fig. 3). Beginning in February 2022, IVIG products had anti-spike titers comparable to vaccinated healthy controls. Concurrent with a rise in anti-spike antibodies in IG products, PAD patients showed an increase in serum levels of anti-spike antibody and neutralizing activity against WA1/202 and Delta but not against Omicron variants. Testing of immunoglobulin replacement products neutralization activity against emerging variants BQ.1 and BQ.1.1 is underway.[Formula presented][Formula presented][Formula presented] Conclusion(s): The anti-SARS spike antibody and neutralization activity of IVIG products lags after the emergence of COVID-19 variants and currently have poor activity against Omicron strain. Because of the protracted manufacturing process, this is expected to be an ongoing challenge. As variants emerge, clinicians should consider additional means of protection for PAD patients such as vaccination, or prophylaxis with monoclonal antibodies.Copyright © 2023 Elsevier Inc.
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The anti-spike (S), anti-nucleocapsid (N), and neutralizing activities of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of pooled plasma derived from donors in Japan from January 2021 to April 2022 were evaluated. Anti-S titers and neutralizing activities showed a wave-like trend affected by daily vaccinations and/or the number of reported cases of SARS-CoV-2 infections, whereas anti-N titers remained at negative levels. These results suggest that anti-S and neutralizing titers would fluctuate in pooled plasma in future. Pooled plasma may be potentially used for mass-immunity evaluation, and titer estimation in intravenous immunoglobulin, a derivative of pooled plasma.
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BACKGROUND: We report spike protein-based lineage and AZD7442 (tixagevimab/cilgavimab) neutralizing activity of SARS-CoV-2 variants identified from breakthrough infections in the PROVENT pre-exposure prophylaxis trial (NCT04625725). METHODS: Variants identified from PROVENT participants with reverse-transcription polymerase chain reaction-positive symptomatic illness were phenotypically assessed to determine neutralization susceptibility of variant-specific pseudotyped virus-like particles. RESULTS: At completion of 6 months' follow-up, no AZD7442-resistant variants were observed in breakthrough COVID-19 cases. SARS-CoV-2 neutralizing antibody titers were similar in breakthrough and non-breakthrough cases. CONCLUSION: Symptomatic COVID-19 breakthrough cases in PROVENT were not due to resistance-associated substitutions in AZD7442 binding sites or lack of AZD7442 exposure.
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Background: Increasing the interval between the first and second SARS-CoV-2 vaccine doses enhances vaccine immunogenicity, however the optimal timing of the third vaccine is unknown. In this study, we investigated how the time interval between the first and second (V1-V2), or second and third (V2-V3) doses affects immunogenicity after three doses of the BNT162b2 (Comirnaty, Pfizer-BioNTech) vaccine. Methods: This is an observational cohort consisting of 360 participants enrolled in the COVID-19 Occupational Risks, Seroprevalence, and Immunity among Paramedics in Canada (CORSIP) study. Immune responses to BA.1 and other variants were measured from serum using an ACE2 competitive binding assay for surrogate SARS-CoV-2 neutralization. We fit a multiple linear regression model to estimate the independent association between both the V1-V2 and V2-V3 intervals and serum SARS-CoV-2 neutralization, while adjusting for age, sex, and the V3-to-blood collection interval. We examined vaccine dosing intervals as continuous variables and categorized them into quartiles. Results: The mean age was 40 years, 45% were female sex (at birth), and the median BA.1 surrogate neutralization was 61% (IQR 38-77%). The multivariate analysis indicated that longer V1-V2 (ß = 0.1292, 95% CI: 0.04807-0.2104) and V2-V3 (ß = 0.2653, 95% CI: 0.2291-0.3015) intervals were associated with increased surrogate neutralization of BA.1. These results were consistent when examining responses against Spike from other SARS-CoV-2 strains. When categorized into V2-V3 quartiles, the first (56-231 days), and second (231-266 days) quartiles demonstrated decreased BA.1 surrogate neutralization compared to the longest V2-V3 quartile (282-329 days). There was no significant difference in surrogate neutralization between the long (266-282 days) and longest (282-329 days) V2-V3 intervals. Conclusion: Longer intervals between first, second and third doses are independently associated with increased immunogenicity for all tested SARS-CoV-2 strains. Increasing the intervals between the second and third vaccine doses up to 8.9 months provided additive benefits increasing the immunogenicity of BNT162b2 vaccine schedules.
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Nanobodies bind a target antigen with a kinetic profile similar to a conventional antibody, but exist as a single heavy chain domain that can be readily multimerized to engage antigen via multiple interactions. Presently, most nanobodies are produced by immunizing camelids; however, platforms for animal-free production are growing in popularity. Here, we describe the development of a fully synthetic nanobody library based on an engineered human VH3-23 variable gene and a multispecific antibody-like format designed for biparatopic target engagement. To validate our library, we selected nanobodies against the SARS-CoV-2 receptor-binding domain and employed an on-yeast epitope binning strategy to rapidly map the specificities of the selected nanobodies. We then generated antibody-like molecules by replacing the VH and VL domains of a conventional antibody with two different nanobodies, designed as a molecular clamp to engage the receptor-binding domain biparatopically. The resulting bispecific tetra-nanobody immunoglobulins neutralized diverse SARS-CoV-2 variants with potencies similar to antibodies isolated from convalescent donors. Subsequent biochemical analyses confirmed the accuracy of the on-yeast epitope binning and structures of both individual nanobodies, and a tetra-nanobody immunoglobulin revealed that the intended mode of interaction had been achieved. This overall workflow is applicable to nearly any protein target and provides a blueprint for a modular workflow for the development of multispecific molecules.
Subject(s)
COVID-19 , Single-Domain Antibodies , Humans , Single-Domain Antibodies/chemistry , Saccharomyces cerevisiae/metabolism , SARS-CoV-2 , Antibodies , EpitopesABSTRACT
The 50% plaque reduction neutralization assay (PRNT50) has been previously used to assess the neutralization capacity of donor plasma against wild-type and variant of concern (VOC) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Emerging data suggest that plasma with an anti-SARS-CoV-2 level of ≥2 × 104 binding antibody units/mL (BAU/mL) protects against SARS-CoV-2 Omicron BA.1 infection. Specimens were collected using a cross-sectional random sampling approach. For PRNT50 studies, 63 previously analyzed specimens by PRNT50 versus SARS-CoV-2 wild-type, Alpha, Beta, Gamma, and Delta were analyzed by PRNT50 versus Omicron BA.1. The 63 specimens plus 4,390 specimens (randomly sampled regardless of serological evidence of infection) were also tested using the Abbott SARS-CoV-2 IgG II Quant assay (anti-spike [S]; Abbott, Chicago, IL, USA; Abbott Quant assay). In the vaccinated group, the percentages of specimens with any measurable PRNT50 versus wild-type or VOC were wild type (21/25 [84%]), Alpha (19/25 [76%]), Beta (18/25 [72%]), Gamma (13/25 [52%]), Delta (19/25 [76%]), and Omicron BA.1 (9/25 [36%]). In the unvaccinated group, the percentages of specimens with any measurable PRNT50 versus wild type or VOC were wild-type SARS-CoV-2 (16/39 [41%]), Alpha (16/39 [41%]), Beta (10/39 [26%]), Gamma (9/39 [23%]), Delta (16/39 [41%]), and Omicron BA.1 (0/39) (Fisher's exact tests, vaccinated versus unvaccinated for each variant, P < 0.05). None of the 4,453 specimens tested by the Abbott Quant assay had a binding capacity of ≥2 × 104 BAU/mL. Vaccinated donors were more likely than unvaccinated donors to neutralize Omicron when assessed by a PRNT50 assay. IMPORTANCE SARS-CoV-2 Omicron emergence occurred in Canada during the period from November 2021 to January 2022. This study assessed the ability of donor plasma collected earlier (January to March 2021) to generate any neutralizing capacity against Omicron BA.1 SARS-CoV-2. Vaccinated individuals, regardless of infection status, were more likely to neutralize Omicron BA.1 than unvaccinated individuals. This study then used a semiquantitative binding antibody assay to screen a larger number of specimens (4,453) for individual specimens that might have high-titer neutralizing capacity against Omicron BA.1. None of the 4,453 specimens tested by the semiquantitative SARS-CoV-2 assay had a binding capacity suggestive of a high-titer neutralizing capacity against Omicron BA.1. These data do not imply that Canadians lacked immunity to Omicron BA.1 during the study period. Immunity to SARS-CoV-2 is complex, and there is still no wide consensus on correlation of protection to SARS-CoV-2.
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BACKGROUND: The number of exposures to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and to vaccination antigens impact the magnitude and avidity of the polyclonal response. METHODS: We studied binding and avidity of different antibody isotypes to the spike, the receptor binding domain (RBD), and the nucleoprotein (NP) of wild type (WT) and BA.1 SARS-CoV-2 in convalescent, mRNA vaccinated, mRNA boosted, hybrid immune individuals, and in individuals with breakthrough cases during the peak of the BA.1 wave. RESULTS: We found an increase in spike binding antibodies and antibody avidity with increasing number of exposures to infection and/or vaccination. Nucleoprotein antibodies were detectible in convalescent individuals and a proportion of breakthrough cases, but displayed low avidity. Omicron breakthrough infections elicited high levels of cross-reactive antibodies between WT and BA.1 antigens in vaccinated individuals without prior infection directed against the spike and receptor binding domain (RBDs). The magnitude of the antibody response and avidity correlated with neutralizing activity against WT virus. CONCLUSIONS: The magnitude and quality of the antibody response increased with the number of antigen exposures, including breakthrough infections. However, cross-reactivity of the antibody response after BA.1 breakthroughs, was impacted by the number of prior antigenic exposures.
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COVID-19, caused by the novel SARS-CoV-2 virus, poses major challenges for global public health. The detection of antibodies in blood serum is one of the important methods for diagnostics of COVID-19 patients. The main aim was to study the dynamics of the appearance of neutralizing antibodies and antibodies to the SARS-CoV-2 proteins in COVID-19 patients sera. Material and methods. The blood sera of four groups of people were studied: "intact" donors (blood sera were collected in 2016-2019);patients with a laboratory-confirmed diagnosis of acute respiratory viral infection;patients with influenza (antibodies to the influenza virus have been identified) and patients with a PCR confirmed diagnosis of COVID-19. Blood sera were analyzed in ELISA with commercial kits for detection of IgG to SARS-CoV-2 (N, S) proteins and total antibodies to RBD of protein S and in neutralization test (NT). Results and discussion. Antibodies to SARS-CoV-2 were not detected in paired blood sera of people from groups 1-3 by ELISA and NT. At the time of hospitalization of patients with COVID-19 in the sera of 12 (19%) patients antibodies to SARS-CoV-2 were absent when they were determined by NT and ELISA. In blood sera taken 4-9 days after hospitalization, neutralizing antibodies and antibodies to at least one viral protein were detected in ELISA. Conclusion. At the time of hospitalization, the overwhelming majority of patients had a humoral immune response to the SARS-CoV-2. In the dynamics of observation, the levels of antibodies to SARS-CoV-2 proteins increased, to a greater extent to RBD.Copyright © 2022 Geotar Media Publishing Group
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Intro: Different vaccines against COVID-19 have been approved by the World Health Organization (WHO) at different stages, however, limited data is available on long-term kinetics of antibodies induced by vaccines. This study was performed to investigate the persistence and dynamicity of BBV-152 (Covaxin)- and AZD1222 (Covishield)-induced immunoglobulin-G (IgG) antibodies over the year and neutralizing antibodies' status after the one-month post booster dose. Method(s): This 52-week longitudinal cohort study documented antibody persistence and neutralizing antibody status among 278 health-care workers (HCWs) from four different healthcare and research facilities in Odisha, enrolled in January 2021 and continued until March 2022. An automated chemiluminescence immune assay (CLIA) platform from Abbott Diagnostics was used to quantify IgG antibodies against SARS-CoV-2's spike receptor-binding domain (RBD) and a surrogate virus neutralization test (sVNT) was performed by enzyme-linked immunosorbent assay (ELISA). If any participants developed any symptoms of COVID-19, nasopharyngeal swabs were collected and sent to ICMR- RMRC, Bhubaneswar for RT-PCR confirmation. Finding(s): Among the 243 participants, 119 HCWs (48.97%) were Covaxin recipients and the remaining 124 (51.02%) were Covishield recipients. During the seven follow- ups, 104 participants (42.79%) were identified as vaccine breakthrough cases. In 139 non-infected HCWs, the median antibody titer significantly waned after ten months of double dose, both for Covaxin (342.7 AU/mL at DD1 vs 43.9 AU/mL at DD10) and Covishield (2325.8 AU/mL at DD3 vs 595.2 AU/mL at DD10). No statistically significant differences in antibody titers were observed based on age, gender, comorbidities, and blood groups. The median inhibition activity of sVNT was increased significantly for Covaxin and Covishield booster recipients. Among the booster dose recipients, 24 had breakthrough cases by the Omicron variant. Conclusion(s): Results of this longitudinal cohort study can be used to implement vaccination strategies and could also aid in tracking and designing vaccine mandates to minimize vaccine escape.Copyright © 2023
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Intro: GBP510 contains the self-assembling recombinant nanoparticle displaying SARS-CoV-2 Spike protein receptor binding domain and is adjuvanted with AS03. We report interim Phase 3 study (NCT05007951) results up to 4 weeks post-dose 2 (Data-cut: March-18-2022), where immunogenicity to the D614G ancestral strain and safety of 25mug GBP510/AS03 candidate was compared to ChAdOx1-S (Vaxzevria). Method(s): This Phase 3 randomized, active-controlled, observer-blind, parallel- group study in adults was conducted in 6 countries. Cohort1: 1,895 subjects (naive to COVID-19 vaccination and infection) randomized at 2:1 ratio (GBP510/AS03:ChAdOx1-S) to assess immunogenicity and safety;Cohort 2: 2,141 subjects at 5:1 ratio, regardless of their serostatus at screening for safety assessment. Subjects were vaccinated twice at a 4-week interval with 0.5 mL of the test vaccine (GBP510/AS03) or active control (ChAdOx1-S) in deltoid muscle. The primary objective was to demonstrate the superiority of geometric mean titer (GMT) and non-inferiority in seroconversion rate (SCR: >=4-fold rise from baseline) of neutralizing antibodies over ChAdOx1-S by live-virus neutralization assay (FRNT). Finding(s): At 2 weeks post-dose 2, GMT ratio of the two groups (Test vaccine/Active control) was 2.93 [95% CI: 2.63, 3.27], satisfying the hypothesis of superiority (95% CI lower limit> 1). The SCR difference (Test vaccine - Active control) was 10.76% [95% CI: 7.68, 14.32], satisfying the hypothesis of non- inferiority (95% CI lower limit> -5%). Good cell-mediated immune responses for Th1 cytokines were also observed with the test vaccine (FluoroSpot). The AE incidence rate for the test vaccine was higher than the active control for solicited local AEs (56.69% vs 49.20%), and comparable for solicited systemic AEs (51.21% vs 53.51%) and unsolicited AEs (13.34% vs 14.66%) after any vaccination. Conclusion(s): Higher immune responses were observed with GBP510/AS03 compared to ChAdOx1-S against D614G strain after 2 weeks post-dose 2. GBP510/AS03 showed a clinically acceptable safety profile;no safety concerns were identified during the study period.Copyright © 2023
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Background: Established SARS-CoV-2 NAb tests are labor-intensive. We prospectively measured NAbs vs Wuhan-1 and Omicron BA.2 using the novel GenScript cPass assay and examined correlations with responses measured by gold-standard plaque reduction neutralisation test (PRNT) (Cotugno, Ruggiero et al. Cell Rep 2021) and with anti-Spike IgG quantified by Roche Elecsys. Given the paucity of data, we selected BNT162b2 vaccine recipients with a history of advanced HIV infection (prior AIDS-defining conditions and/or nadir CD4 <200 cells). Method(s): In Mar 2021-Apr 2022, 55 PWH received 2 vaccine doses median 3 weeks apart [IQR 3-3] and a 3rd dose 27 weeks later [23-31]. Plasma samples (n=147) were stored immediately before dose-1 (T0), median 4 weeks [3-5] after dose-2 (T1) and median 13 weeks [9-19] after dose-3 (T2) for batch testing. Result(s): Participants' characteristics: 74% male, 85% white, all on ART, 82% HIV-RNA <50 cps/ml;median age 55 years, ART duration 7 years, nadir CD4 83 cells [36-211], current CD4 440 cells [270-710], CD4:CD8 ratio 0.6 [0.4-1.0];73% had a history of advanced HIV infection;15% received a COVID-19 diagnosis during the study. At T0, T1 and T2, proportions with quantifiable anti-S IgG (>0.8 U/ml) were 11/49 (22%), 50/54 (93%) and 43/43 (100%), respectively;their median anti-S IgG titres were 30 [15-124], 15949 [596-3389] and 8527 [3146-17190] U/ml. Proportions showing Wuhan-1 neutralisation by cPass were 6/50 (12%), 45/53 (85%) and 40/43 (93%), with median neutralisations of 67% [47-70], 97% [91-98] and 98% [98-98] and corresponding NAb titres of 1332 [792-1436], 5354 [3529-6187] and 6242 [5765-6766] U/ml. At T2, 25/28 (89%) showed BA.2 neutralisation by cPass (median 83% [68-93];NAb titre 7836 [3172-12173] U/ml) (Fig 1A). Two participants lacking NAbs at T2 had a history of advanced HIV infection. cPass data were highly correlated with anti-S IgG titres (rho 0.82;p<0.0001) and with PRNT data for both Wuhan-1 (n=27, Fig 1B) and Omicron BA.2 (n=28, Fig 1C). Conclusion(s): cPAss offers a simple methodology for measuring SARS-CoV-2 NAbs. Despite prior advanced HIV infection, neutralising activity improved with successive vaccinations and most participants showed NAbs against both Wuhan-1 and Omicron BA.2 after 3 vaccine doses. (Figure Presented).
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Vaccines against SARS-CoV-2 have alleviated infection rates, hospitalization and deaths associated with COVID-19. In order to monitor humoral immunity, several serology tests have been developed, but the recent emergence of variants of concern has revealed the need for assays that predict the neutralizing capacity of antibodies in a fast and adaptable manner. Sensitive and fast neutralization assays would allow a timely evaluation of immunity against emerging variants and support drug and vaccine discovery efforts. Here we describe a simple, fast, and cell-free multiplexed flow cytometry assay to interrogate the ability of antibodies to prevent the interaction of Angiotensin-converting enzyme 2 (ACE2) and the receptor binding domain (RBD) of the original Wuhan-1 SARS-CoV-2 strain and emerging variants simultaneously, as a surrogate neutralization assay. Using this method, we demonstrate that serum antibodies collected from representative individuals at different time-points during the pandemic present variable neutralizing activity against emerging variants, such as Omicron BA.1 and South African B.1.351. Importantly, antibodies present in samples collected during 2021, before the third dose of the vaccine was administered, do not confer complete neutralization against Omicron BA.1, as opposed to samples collected in 2022 which show significant neutralizing activity. The proposed approach has a comparable performance to other established surrogate methods such as cell-based assays using pseudotyped lentiviral particles expressing the spike of SARS-CoV-2, as demonstrated by the assessment of the blocking activity of therapeutic antibodies (i.e. Imdevimab) and serum samples. This method offers a scalable, cost effective and adaptable platform for the dynamic evaluation of antibody protection in affected populations against variants of SARS-CoV-2.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Antibodies, Blocking , Flow Cytometry , COVID-19 VaccinesABSTRACT
Although immune response enhancement has been reported after primary and booster vaccines of CoronaVac, neutralization breadth of SARS-CoV-2 variants is still unclear. In the present study, we examined the neutralization magnitude and breadth of SARS-CoV-2 variants including Beta (B.1.351), Delta (B.1.617.2) and Omicron (B.1.1.529) in 33 convalescent COVID-19 patients and a cohort of 55 medical staff receiving primary CoronaVac vaccines and an additional homologous booster dose. Results showed that, as compared with the two-dose primary vaccination, the homologous booster dose achieved 2.24-, 3.98-, 4.58- and 2.90-fold increase in neutralization titer against wild-type, Beta, Delta, and Omicron, respectively. After booster dose, neutralization titer reduction for variants was less than that after the primary vaccine or that for convalescents. The proportion of recipients able to neutralize 2 or more variants increased from 36.36% post the primary vaccination to 87.27% after the booster. Significant increase in neutralization breadth of 1.24 (95% confidence interval (CI), 0.89-1.59) variants was associated with a log10 increase in neutralization titer against the wild-type. In addition, anti-RBD IgG level was identified as an excellent surrogate for positive neutralization of SARS-CoV-2 and neutralization breadth of variants. These findings highlight the value of an additional homologous CoronaVac dose in broadening the cross-neutralization against SARS-CoV-2 variants, and are critical for informing the booster dose vaccination efforts.
Subject(s)
COVID-19 , SARS-CoV-2 , Antibody Formation , COVID-19 Vaccines , Humans , Immunoglobulin G , Neutralization Tests , Spike Glycoprotein, CoronavirusABSTRACT
BACKGROUND: Since sensitivity and specificity vary widely between tests, SARS-CoV-2 serology results should be interpreted with caution. METHODS: The study included serum samples from patients who had recovered from COVID-19 (n = 71), individuals vaccinated against SARS-CoV-2 (n = 84), and asymptomatic individuals (n = 33). All samples were tested for the presence of binding antibodies (enzyme immunoassay; EIA), neutralizing (NT) antibodies (virus neutralization test; VNT), and surrogate NT (sNT) antibodies (surrogate virus neutralization test; sVNT) of SARS-CoV-2. RESULTS: SARS-CoV-2-binding antibodies were detected in 71 (100%) COVID-19 patients, 77 (91.6%) vaccinated individuals, and 4 (12.1%) control subjects. Among EIA-positive samples, VNT was positive (titer ≥ 8) in 100% of COVID-19 patients and 63 (75.0%) of the vaccinated individuals, while sVNT was positive (>30% inhibition) in 62 (87.3%) patients and 59 (70.2%) vaccinated individuals. The analysis of antibody levels showed a significant moderate positive correlation between EIA and VNT, a moderate positive correlation between EIA and sVNT, and a strong positive correlation between VNT and sVNT. The proportion of positive sVNT detection rate was associated with VNT titer. The lowest positivity (72.4%/70.8%) was detected in samples with low NT titers (8/16) and increased progressively from 88.2% in samples with titer 32 to 100% in samples with titer 256. CONCLUSIONS: sVNT appeared to be a reliable method for the assessment COVID-19 serology in patients with high antibody levels, while false-negative results were frequently observed in patients with low NT titers.
ABSTRACT
Introduction. The rapid spread of a new coronavirus infection among populations in many countries worldwide has contributed to the genetic evolution of the virus, resulting in the emergence of multiple genetic variants of the SARSCoV-2 coronavirus. Mutations in the viral genome can affect the ability of the virus to bypass the immune system and complicate development of diagnostic and prophylactic drugs. Data on the neutralizing activity of the sera obtained against previously circulating genetic variants of the virus in relation to current SARS-CoV-2 strains may serve as a scientific basis for the selection of the antigens in vaccine development. The aim of this work was to study cross-reactivity of SARSCoV-2 coronavirus strains belonging to different genetic variants, which were isolated in the territory of the Russian Federation during 2020-2022 in the neutralization reaction using mouse hyperimmune sera. Materials and methods. Ten strains of SARS-CoV-2 coronavirus belonging to different genetic variants were used (three non-VOC strains, alpha, beta, gamma, delta, delta+AY, omicron 1 and omicron 2). The hCoV-19/Australia/VIC01/2020 strain (Wuhan) was included in the study as a prototypical variant. BALBc mice were immunized with inactivated concentrated antigen mixed with a 1:1 adjuvant, which was a virus-like immunostimulatory complex based on Quillaja saponaria (Quillaja saponaria). The antibody titer was determined in the neutralization reaction. Results. Essential decrease of neutralizing ability of antibodies specific to non-vOC genetic variants of SARS-CoV-2 coronavirus was revealed against beta VOC and to a lesser degree against alpha and gamma VOC variants. The differences in the neutralizing activity level of antibodies for alpha and beta VOC variants are not significant among themselves, and with gamma VOC variants - there are no significant differences. Neutralizing ability of antibodies specific to delta VOC against alpha and beta VOC variants decreased 4-fold. Neutralizing activity of sera obtained to omicron 1 and 2 variants in relation to the prototype coronavirus variant was reduced 18-fold, to the gamma variant - 12-fold, to delta variants - more than 30-fold;for other variants it was even lower. Conclusions. The results obtained testify to the presence of cross-reactivity between strains of coronavirus belonging to genetic lines Wuhan, alpha, beta, gamma;it is weaker for delta variants. Mutations in the genome of VOC omicron variants led to a significant decrease in antigenic cross-links with earlier genetic variants of the coronavirus. These findings explain the low efficacy of vaccines based on the Wuhan strain, synthetic immunogens, and recombinant proteins based on it against omicron VOC variants, which have caused a rise in morbidity since early 2022, as well as cases of re-infection of humans with new genetic variants of the coronavirus.Copyright © 2023 Saint Petersburg Pasteur Institute. All rights reserved.
ABSTRACT
Introduction: SARS-CoV-2 affected millions of lives globally and led to devastating impact on public health. India had also witnessed the dreadful effect of SARS-CoV-2 pandemic. Within a short span of time, various SARS-CoV-2 vaccines were developed using different platforms across the world. India has also developed one such indigenous whole-virion inactivated SARSCoV-2 vaccine named as BBV152 (Covaxin). The Covaxin has been found to be immunogenic and second most widely used vaccine in India. Recent studies have also shown significant increase in the humoral and neutralizing antibody response post the administration of booster dose against Omicron variant. Apparently, there is limited data on the long-term persistence of the immune response against the Covaxin in Indian context. Method(s): We evaluated an effectiveness of the Covaxin and comparing its specific immune responses in two categories through prospective cohorts recruited at the vaccination centre, Pune during June 2021 to March 2022. We defined the study population in two groups who were COVID-19 naive individuals (group-1) and COVID-19 recovered individuals (group-2) prior to the immunization with Covaxin. The two cohorts and the study participants were decided considering the baseline antibody titres against SARS-CoV-2, the COVID-19 positivity rate, sample power and loss to follow up. The study population was assessed during three follow-ups at second dose, one and six months post second dose to determine the immune response and effectiveness using S1-RBD IgG ELISA and neutralizing antibody response (NAbs) by plaque reduction neutralization test (PRNT). Result(s): We enrolled participants between age group of 18-80 year (median 32 years). In group-1 and group-2, we recruited 118 and 128 participants respectively. The cohort retention was found to be> 85%,>70% and>40% in 1st, 2nd and 3rd follow up respectively. Loss to the 3rd follow up was coincided with third wave with omicron variant. A rise in geometrical mean titre (GMT) of S1-RBD IgG were observed amongst the participants of both the groups at one-month post immunization (Group 1: S1-RBD: 154.4 to 446.3, Group 2 S1- RBD: 918 to 1127). However, the GMTs at six months post vaccination found to be slightly raised in Group 1 compared to one-month follow-up. Considering the hybrid immunity in group 2 participants, the GMTs of NAbs were higher than group 1 participants at each follow-up against B.1, Delta, Omicron BA.1 and BA.2. Both the groups had shown significant reduction in the levels of NAbs against Delta, Omicron BA.1 and BA.2 compared to B.1. The lowest GMTs of NAbs was observed against BA.1 variant. The IgG and NAbs persisted till six months in 90% participants in both categories except BA.1 variant. Breakthrough cases were reported at one-month (n = 1) and six-months (n = 2) post vaccination respectively from group 1. While reinfection cases (n = 3) were detected at six months post vaccination from group 2 due to Omicron BA.1 variant. Conclusion(s): A two-dose regimen of the Covaxin vaccine enhanced humoral immune response in adults with/without past COVID-19 infection and protected more than 90% adults against SARSCoV-2 infection. Additionally, IgG and NAb responses persisted for six months postvaccination.
ABSTRACT
Porcine epidemic diarrhea virus (PEDV) has been affecting the swine industry, especially in suckling pigs in with a high mortality rate. Among all the strategies to overcome PEDV, boosting mucosal immunity in pig intestine via oral administration appears to be more efficient than other routes. However, there are biological obstacles such as acidic environment that could damage biologics, a product from organisms often used for PEDV treatment. The plant-derived 2C10 monoclonal antibody (mAb) from Nicotiana benthamiana produced by transient expression was revealed as one of the potential candidates against PEDV through oral delivery. Herein, we demonstrated the calcium-alginate microencapsulation system to protect the 2C10 mAb from the harsh condition in the stomach and to be released the 2C10 mAb when arriving in the intestine. The pH-responsive encapsulated 2C10 mAb microbeads were constructed from the calcium-alginate system. The microbeads were well-tolerated under the acidic environment of simulated gastric fluid (SGF) and were digested under the alkaline condition of simulated intestinal fluid (SIF). The encapsulated 2C10 mAb in the SPF-treated microbeads exhibited high virus neutralization efficiency in Vero cells when compared to the unencapsulated 2C10 mAb treated by SPF that cannot neutralize the virus. For these reasons, calcium-alginate microencapsulation system is an attractive platform to be considered as a candidate for the next generation of oral vaccine development.