CVnCoV protects human ACE2 transgenic mice from ancestral B BavPat1 and emerging B.1.351 SARS-CoV-2

The ongoing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic necessitates the fast development of vaccines as the primary control option. Recently, viral mutants termed "variants of concern" (VOC) have emerged with the potential to escape host immunity. VOC B.1.351 was first discovered in South Africa in late 2020, and causes global concern due to poor neutralization with propensity to evade preexisting immunity from ancestral strains. We tested the efficacy of a spike encoding mRNA vaccine (CVnCoV) against the ancestral strain BavPat1 and the novel VOC B.1.351 in a K18-hACE2 transgenic mouse model. Naive mice and mice immunized with formalin-inactivated SARS-CoV-2 preparation were used as controls. mRNA-immunized mice developed elevated SARS-CoV-2 RBD-specific antibody as well as neutralization titers against the ancestral strain BavPat1. Neutralization titers against VOC B.1.351 were readily detectable but significantly reduced compared to BavPat1. VOC B.1.351-infected control animals experienced a delayed course of disease, yet nearly all SARS-CoV-2 challenged naive mice succumbed with virus dissemination and high viral loads. CVnCoV vaccine completely protected the animals from disease and mortality caused by either viral strain. Moreover, SARS-CoV-2 was not detected in oral swabs, lung, or brain in these groups. Only partial protection was observed in mice receiving the formalin-inactivated virus preparation. Despite lower neutralizing antibody titers compared to the ancestral strain BavPat1, CVnCoV shows complete disease protection against the novel VOC B.1.351 in our studies.

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CVnCoV and CV2CoV protect human ACE2 transgenic mice from ancestral B BavPat1 and emerging B.1.351 SARS-CoV-2

Nature Communications ◽

10.1038/s41467-021-24339-7 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Donata Hoffmann ◽

Björn Corleis ◽

Susanne Rauch ◽

Nicole Roth ◽

Janine Mühe ◽

...

Keyword(s):

Mouse Model ◽

Transgenic Mice ◽

Neutralizing Antibody ◽

Transgenic Mouse Model ◽

Host Immunity ◽

The Novel ◽

Viral Strain ◽

Fast Development ◽

Antibody Titers ◽

Ancestral Strain

AbstractThe ongoing SARS-CoV-2 pandemic necessitates the fast development of vaccines. Recently, viral mutants termed variants of concern (VOC) which may escape host immunity have emerged. The efficacy of spike encoding mRNA vaccines (CVnCoV and CV2CoV) against the ancestral strain and the VOC B.1.351 was tested in a K18-hACE2 transgenic mouse model. Naive mice and mice immunized with a formalin-inactivated SARS-CoV-2 preparation were used as controls. mRNA-immunized mice develop elevated SARS-CoV-2 RBD-specific antibody and neutralization titers which are readily detectable, but significantly reduced against VOC B.1.351. The mRNA vaccines fully protect from disease and mortality caused by either viral strain. SARS-CoV-2 remains undetected in swabs, lung, or brain in these groups. Despite lower neutralizing antibody titers compared to the ancestral strain BavPat1, CVnCoV and CV2CoV show complete disease protection against the novel VOC B.1.351 in our studies.

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Evaluation of high-throughput SARS-CoV-2 serological assays in a longitudinal cohort of mild COVID-19 patients: sensitivity, specificity and association with virus neutralization test

10.1101/2020.09.30.20194290 ◽

2020 ◽

Author(s):

Antonin Bal ◽

Bruno Pozzetto ◽

Mary-Anne Trabaud ◽

Vanessa Escuret ◽

Muriel Rabilloud ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Healthcare Workers ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Virus Neutralization Test ◽

Virus Neutralization ◽

Serological Tests ◽

Course Of Disease ◽

Antibody Titers ◽

Sensitivity Specificity

BackgroundThe association between SARS-CoV-2 commercial serological assays and virus neutralization test (VNT) has been poorly explored in mild COVID-19 patients.MethodsA total of 439 serum specimens were longitudinally collected from 76 healthcare workers with RT-PCR-confirmed COVID-19. The sensitivity (determined weekly) of nine commercial serological assays were evaluated. Specificity was assessed using 69 pre-pandemic sera. Correlation, agreement and concordance with the VNT were also assessed on a subset of 170 samples. Area under the ROC curve (AUC) was estimated at several neutralizing antibody titers.ResultsThe Wantai Total Ab assay targeting the receptor binding domain (RBD) within the S protein presented the best sensitivity at different times during the course of disease. The specificity was greater than 95% for all tests except for the Euroimmun IgA assay. The overall agreement with the presence of neutralizing antibodies ranged from 62.2% (95%CI; 56.0-68.1) for bioMérieux IgM to 91.2% (87.0-94.2) for Siemens. The lowest negative percent agreement (NPA) was found with the Wantai Total Ab assay (NPA 33% (21.1-48.3)). The NPA for other total Ab or IgG assays targeting the S or the RBD was 80.7% (66.7-89.7), 90.3 (78.1-96.1) and 96.8% (86.8-99.3) for Siemens, bioMérieux IgG and DiaSorin, respectively. None of commercial assays have sufficient performance to detect a neutralizing titer of 80 (AUC<0.76).ConclusionsAlthough some assays presented a better agreement with VNT than others, the present findings emphasize that commercialized serological tests including those targeting the RBD cannot substitute a VNT for the assessment of functional antibody response.

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Optimization of Non-Coding Regions Improves Protective Efficacy of an mRNA SARS-CoV-2 Vaccine in Nonhuman Primates

10.1101/2021.08.13.456316 ◽

2021 ◽

Author(s):

Makda Gebre ◽

Susanne Rauch ◽

Nicole Roth ◽

Jingyou Yu ◽

Abishek Chandrashekar ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Nonhuman Primates ◽

Protective Efficacy ◽

Neutralizing Antibody ◽

Antigen Expression ◽

Antibody Responses ◽

Partial Protection ◽

Viral Loads ◽

Coding Regions ◽

Cell Responses

The CVnCoV (CureVac) mRNA vaccine for SARS-CoV-2 has recently been evaluated in a phase 2b/3 efficacy trial in humans. CV2CoV is a second-generation mRNA vaccine with optimized non-coding regions and enhanced antigen expression. Here we report a head-to-head study of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in nonhuman primates. We immunized 18 cynomolgus macaques with two doses of 12 ug of lipid nanoparticle formulated CVnCoV, CV2CoV, or sham (N=6/group). CV2CoV induced substantially higher binding and neutralizing antibodies, memory B cell responses, and T cell responses as compared with CVnCoV. CV2CoV also induced more potent neutralizing antibody responses against SARS-CoV-2 variants, including B.1.351 (beta), B.1.617.2 (delta), and C.37 (lambda). While CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded robust protection with markedly lower viral loads in the upper and lower respiratory tract. Antibody responses correlated with protective efficacy. These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of an mRNA SARS-CoV-2 vaccine in nonhuman primates.

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Long-term SARS-CoV-2 RNA Shedding and its Temporal Association to IgG Seropositivity

10.1101/2020.06.02.20120774 ◽

2020 ◽

Cited By ~ 3

Author(s):

Vineet Agarwal ◽

AJ Venkatakrishnan ◽

Arjun Puranik ◽

Christian Kirkup ◽

Agustin Lopez-Marquez ◽

...

Keyword(s):

Upper Bound ◽

Neutralizing Antibody ◽

Initial Diagnosis ◽

Viral Rna ◽

Temporal Association ◽

Viral Loads ◽

Antibody Titers ◽

The Mean

Analysis of 851 COVID-19 patients with a SARS-CoV-2-positive PCR at follow-up shows 99 patients remained SARS-CoV-2-positive after four weeks from initial diagnosis. Surprisingly, a majority of these long-term viral RNA shedders were not hospitalized (61 of 99), with variable PCR Crossing point values over the month post diagnosis. For the 851-patient cohort, the mean lower bound of viral RNA shedding was 17.3 days (SD: 7.8), and the mean upper bound of viral RNA shedding from 668 patients transitioning to confirmed PCR-negative status was 22.7 days (SD: 11.8). Among 104 patients with an IgG test result, 90 patients were seropositive to date, with mean upper bound of time to seropositivity from initial diagnosis being 37.8 days (95%CI: 34.3-41.3). Juxtaposing IgG/PCR tests revealed that 14 of 90 patients are non-hospitalized and seropositive yet shed viral RNA. This study emphasizes the need for monitoring viral loads and neutralizing antibody titers in long-term shedders.

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Immunological Correlates for Protection against Intranasal Challenge of Bacillus anthracis Spores Conferred by a Protective Antigen-Based Vaccine in Rabbits

Infection and Immunity ◽

10.1128/iai.74.1.394-398.2006 ◽

2006 ◽

Vol 74 (1) ◽

pp. 394-398 ◽

Cited By ~ 59

Author(s):

Shay Weiss ◽

David Kobiler ◽

Haim Levy ◽

Hadar Marcus ◽

Avi Pass ◽

...

Keyword(s):

Bacillus Anthracis ◽

Protective Antigen ◽

Passive Immunization ◽

Neutralizing Antibody ◽

Protective Efficiency ◽

Immunological Parameters ◽

Partial Protection ◽

Bacillus Anthracis Spores ◽

Antibody Titers ◽

Antibody Levels

ABSTRACT Correlates between immunological parameters and protection against Bacillus anthracis infection in animals vaccinated with protective antigen (PA)-based vaccines could provide surrogate markers to evaluate the putative protective efficiency of immunization in humans. In previous studies we demonstrated that neutralizing antibody levels serve as correlates for protection in guinea pigs (S. Reuveny et al., Infect. Immun. 69:2888-2893, 2001; H. Marcus et al., Infect. Immun. 72:3471-3477, 2004). In this study we evaluated similar correlates for protection by active and passive immunization of New Zealand White rabbits. Full immunization and partial immunization were achieved by single and multiple injections of standard and diluted doses of a PA-based vaccine. Passive immunization was carried out by injection of immune sera from rabbits vaccinated with PA-based vaccine prior to challenge with B. anthracis spores. Immunized rabbits were challenged by intranasal spore instillation with one of two virulent strains (strains Vollum and ATCC 6605). The immune competence was estimated by measuring the level of total anti-PA antibodies, the neutralizing antibody titers, and the conferred protective immunity. The results indicate that total anti-PA antibody titers greater than 1 × 105 conferred protection, whereas lower titers (between 104 and 105) provided partial protection but failed to predict protection. Neutralizing antibody titers between 500 and 800 provided partial protection, while titers higher than 1,000 conferred protection. In conclusion, this study emphasizes that regardless of the immunization regimen or the time of challenge, neutralizing antibody titers are better predictors of protection than total anti-PA titers.

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Course of Specific T Lymphocyte Cytotoxicity, Plasma and Cellular Viral Loads, and Neutralizing Antibody Titers in 17 Recently Seroconverted HIV Type 1-Infected Patients

AIDS Research and Human Retroviruses ◽

10.1089/aid.1997.13.1383 ◽

1997 ◽

Vol 13 (16) ◽

pp. 1383-1394 ◽

Cited By ~ 19

Author(s):

ELISABETH LEGRAND ◽

ISABELLE PELLEGRIN ◽

DIDIER NEAU ◽

JEAN-LUC PELLEGRIN ◽

JEAN-MARIE RAGNAUD ◽

...

Keyword(s):

T Lymphocyte ◽

Neutralizing Antibody ◽

Viral Loads ◽

Antibody Titers ◽

Lymphocyte Cytotoxicity ◽

Hiv Type 1

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Evaluation of high-throughput SARS-CoV-2 serological assays in a longitudinal cohort of patients with mild COVID-19: clinical sensitivity, specificity and association with virus neutralization test

Clinical Chemistry ◽

10.1093/clinchem/hvaa336 ◽

2021 ◽

Author(s):

Antonin Bal ◽

Bruno Pozzetto ◽

Mary-Anne Trabaud ◽

Vanessa Escuret ◽

Muriel Rabilloud ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Neutralization Test ◽

Neutralizing Antibody ◽

Virus Neutralization Test ◽

Virus Neutralization ◽

Serological Tests ◽

Course Of Disease ◽

Clinical Sensitivity ◽

Antibody Titers ◽

Sensitivity Specificity

Abstract Background The association between SARS-CoV-2 commercial serological assays and virus neutralization test (VNT) has been poorly explored in mild patients with COVID-19. Methods 439 serum specimens were longitudinally collected from 76 healthcare workers with RT-PCR-confirmed COVID-19. The clinical sensitivity (determined weekly) of nine commercial serological assays were evaluated. Clinical specificity was assessed using 69 pre-pandemic sera. Correlation, agreement and concordance with the VNT were also assessed on a subset of 170 samples. Area under the ROC curve (AUC) was estimated at 2 neutralizing antibody titers. Results The Wantai Total Ab assay targeting the receptor binding domain (RBD) within the S protein presented the best sensitivity at different times during the course of disease. The clinical specificity was greater than 95% for all tests except for the Euroimmun IgA assay. The overall agreement with the presence of neutralizing antibodies ranged from 62.2% (95%CI; 56.0-68.1) for bioMérieux IgM to 91.2% (87.0-94.2) for Siemens. The lowest negative percent agreement (NPA) was found with the Wantai Total Ab assay (NPA 33% (21.1-48.3)). The NPA for other total Ab or IgG assays targeting the S or the RBD was 80.7% (66.7-89.7), 90.3 (78.1-96.1) and 96.8% (86.8-99.3) for Siemens, bioMérieux IgG and DiaSorin, respectively. None of commercial assays have sufficient performance to detect a neutralizing titer of 80 (AUC<0.76). Conclusions Although some assays show a better agreement with VNT than others, the present findings emphasize that commercialized serological tests including those targeting the RBD cannot substitute a VNT for the assessment of functional antibody response.

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Sequential infection with H1N1 and SARS-CoV-2 aggravated COVID-19 pathogenesis in a mammalian model, and co-vaccination as an effective method of prevention of COVID-19 and influenza

Signal Transduction and Targeted Therapy ◽

10.1038/s41392-021-00618-z ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Linlin Bao ◽

Wei Deng ◽

Feifei Qi ◽

Qi Lv ◽

Zhiqi Song ◽

...

Keyword(s):

Influenza A ◽

Neutralizing Antibody ◽

Single Infection ◽

Effective Prevention ◽

Viral Loads ◽

Viral Shedding ◽

Pulmonary Damage ◽

Antibody Titers ◽

Flu Vaccine ◽

Sequential Infection

AbstractInfluenza A virus may circulate simultaneously with the SARS-CoV-2 virus, leading to more serious respiratory diseases during this winter. However, the influence of these viruses on disease outcome when both influenza A and SARS-CoV-2 are present in the host remains unclear. Using a mammalian model, sequential infection was performed in ferrets and in K18-hACE2 mice, with SARS-CoV-2 infection following H1N1. We found that co-infection with H1N1 and SARS-CoV-2 extended the duration of clinical manifestation of COVID-19, and enhanced pulmonary damage, but reduced viral shedding of throat swabs and viral loads in the lungs of ferrets. Moreover, mortality was increased in sequentially infected mice compared with single-infection mice. Compared with single-vaccine inoculation, co-inoculation of PiCoVacc (a SARS-CoV-2 vaccine) and the flu vaccine showed no significant differences in neutralizing antibody titers or virus-specific immune responses. Combined immunization effectively protected K18-hACE2 mice against both H1N1 and SARS-CoV-2 infection. Our findings indicated the development of systematic models of co-infection of H1N1 and SARS-CoV-2, which together notably enhanced pneumonia in ferrets and mice, as well as demonstrated that simultaneous vaccination against H1N1 and SARS-CoV-2 may be an effective prevention strategy for the coming winter.

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SARS-CoV-2 seropositivity and subsequent infection risk in healthy young adults: a prospective cohort study

10.1101/2021.01.26.21250535 ◽

2021 ◽

Author(s):

Andrew G. Letizia ◽

Yongchao Ge ◽

Sindhu Vangeti ◽

Carl Goforth ◽

Dawn L Weir ◽

...

Keyword(s):

Young Adults ◽

Health Agency ◽

Neutralizing Antibody ◽

Full Length ◽

Spike Protein ◽

Subsequent Infection ◽

Viral Loads ◽

Lower Baseline ◽

Antibody Titers ◽

Study Population

SummaryBackgroundThe risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subsequent infection among seropositive young adults was studied prospectively.MethodsThe study population comprised 3,249 predominantly male, 18-20-year-old Marine recruits. Upon arrival at a Marine-supervised two-week quarantine, participants were assessed for baseline SARS-CoV-2 IgG seropositivity, defined as a 1:150 dilution or greater on receptor binding domain and full-length spike protein enzyme-linked immunosorbent (ELISA) assays. SARS-CoV-2 infection was assessed by PCR at initiation, middle and end of the quarantine. After appropriate exclusions, including participants with a positive PCR during quarantine, we performed three biweekly PCR tests in both seropositive and in seronegative groups once recruits left quarantine and entered basic training and baseline neutralizing antibody titers on all subsequently infected seropositive and selected seropositive uninfected participants.FindingsAmong 189 seropositive participants, 19 (10.1%) had at least one positive PCR test for SARS-CoV-2 during the six-week follow-up (1.1 cases per person-year). In contrast, 1,079 (48.0%) of the 2,247 seronegative participants tested positive (6.2 cases per person-year). The incidence rate ratio was 0.18 (95% CI 0.11-0.28, p<0.00001). Among seropositive recruits, infection was associated with lower baseline full-length spike protein IgG titers (p<0.0001). Compared with seronegative recruits, seropositive recruits had about 10-fold lower viral loads (ORF1ab gene, p<0.005), and trended towards shorter duration of PCR positivity (p=0.18) and more frequent asymptomatic infections (p=0.13). Among seropositive participants, baseline neutralizing titers were detected in 45 of 54 (83.3%) uninfected and in 6 of 19 (31.6%) infected participants during the 6 weeks of observation (ID50 difference p<.0001).InterpretationSeropositive young adults had about one-fifth the risk of subsequent infection compared with seronegative individuals. Although antibodies induced by initial infection are largely protective, they do not guarantee effective SARS-CoV-2 neutralization activity or immunity against subsequent infection. These findings may be relevant for optimization of mass vaccination strategies.FundingDefense Health Agency and Defense Advanced Research Projects Agency

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DNA vaccine protection against SARS-CoV-2 in rhesus macaques

Science ◽

10.1126/science.abc6284 ◽

2020 ◽

Vol 369 (6505) ◽

pp. 806-811 ◽

Cited By ~ 230

Author(s):

Jingyou Yu ◽

Lisa H. Tostanoski ◽

Lauren Peter ◽

Noe B. Mercado ◽

Katherine McMahan ◽

...

Keyword(s):

Dna Vaccine ◽

Protective Efficacy ◽

Rhesus Macaques ◽

Neutralizing Antibody ◽

Vaccine Protection ◽

S Protein ◽

Viral Loads ◽

Cellular Immune Responses ◽

Antibody Titers ◽

Cellular Immune

The global coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made the development of a vaccine a top biomedical priority. In this study, we developed a series of DNA vaccine candidates expressing different forms of the SARS-CoV-2 spike (S) protein and evaluated them in 35 rhesus macaques. Vaccinated animals developed humoral and cellular immune responses, including neutralizing antibody titers at levels comparable to those found in convalescent humans and macaques infected with SARS-CoV-2. After vaccination, all animals were challenged with SARS-CoV-2, and the vaccine encoding the full-length S protein resulted in >3.1 and >3.7 log10 reductions in median viral loads in bronchoalveolar lavage and nasal mucosa, respectively, as compared with viral loads in sham controls. Vaccine-elicited neutralizing antibody titers correlated with protective efficacy, suggesting an immune correlate of protection. These data demonstrate vaccine protection against SARS-CoV-2 in nonhuman primates.

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