scholarly journals Recombinant protein subunit SARS-CoV-2 vaccines formulated with CoVaccine HT adjuvant induce broad, Th1 biased, humoral and cellular immune responses in mice

2021 ◽  
Author(s):  
Chih-Yun Lai ◽  
Albert To ◽  
Teri Ann S. Wong ◽  
Michael M. Lieberman ◽  
David E. Clements ◽  
...  
Keyword(s):  
Vaccine Development ◽  
Herd Immunity ◽  
Neutralizing Antibody ◽  
Protein Subunit ◽  
Cellular Immune Responses ◽  
Oil In Water ◽  
History Of ◽  
Antibody Titers ◽  
Outbred Mice ◽  
Cellular Immune

ABSTRACTThe speed at which several COVID-19 vaccines went from conception to receiving FDA and EMA approval for emergency use is an achievement unrivaled in the history of vaccine development. Mass vaccination efforts using the highly effective vaccines are currently underway to generate sufficient herd immunity and reduce transmission of the SARS-CoV-2 virus. Despite the most advanced vaccine technology, global recipient coverage, especially in resource-poor areas remains a challenge as genetic drift in naïve population pockets threatens overall vaccine efficacy. In this study, we described the production of insect-cell expressed SARS-CoV-2 spike protein ectodomain and examined its immunogenicity in mice. We demonstrated that, when formulated with CoVaccine HT™adjuvant, an oil-in-water nanoemulsion compatible with lyophilization, our vaccine candidates elicit a broad-spectrum IgG response, high neutralizing antibody titers, and a robust, antigen-specific IFN-γ secreting response from immune splenocytes in outbred mice. Our findings lay the foundation for the development of a dry-thermostabilized vaccine that is deployable without refrigeration.

scholarly journals Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

2021 ◽  
Author(s):  
Margherita Rosati ◽  
Mahesh Agarwal ◽  
Xintao Hu ◽  
Santhi Devasundaram ◽  
Dimitris Stellas ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Efficacy ◽  
Rhesus Macaques ◽  
Neutralizing Antibody ◽  
Anatomical Site ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Antibody Titers ◽  
Cellular Immune

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

scholarly journals A Combination Adjuvant for the Induction of Potent Antiviral Immune Responses for a Recombinant SARS-CoV-2 Protein Vaccine

2021 ◽  
Author(s):  
Sonia Jangra ◽  
Jeffrey J. Landers ◽  
Raveen Rathnasinghe ◽  
Jessica J. O’Konek ◽  
Katarzyna W. Janczak ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Cellular Response ◽  
Neutralizing Antibody ◽  
Protein Vaccine ◽  
Cellular Immune Responses ◽  
Antibody Titers ◽  
Potential Vaccine ◽  
Cellular Immune ◽  
Sterilizing Immunity

AbstractSeveral promising vaccines for SARS-CoV-2 have received emergency use authorization in various countries and are being administered to the general population. However, many issues associated with the vaccines and the protection they provide remain unresolved, including the duration of conferred immunity, whether or not sterilizing immunity is imparted, and the degree of cross-variant protection that is achieved with these vaccines. Early evidence has suggested potentially reduced vaccine efficacy towards certain viral variants in circulation. Development of adjuvants compatible with these vaccine platforms that enhance the immune response and guide the adaptive and cellular immune responses towards the types of responses most effective for broad protection against SARS-CoV-2 will likely be pivotal for complete protection. Natural viral infection stimulates strong immune responses through the activation of three main pathways involving Toll-, RIG-I-, and NOD-like receptors (TLRs, RLRs, NLRs). As induction of appropriate innate responses is crucial for long-lasting adaptive immunity and for shaping the correct types of immune responses, we developed a combination, intranasal, adjuvant integrating a nanoemulsion-based adjuvant (NE) that activates TLRs and NLRP3 with an RNA agonist of RIG-I (IVT DI). This rationally designed combination adjuvant yielded a synergistic immune response with highly robust humoral and cellular responses towards SARS-CoV-2 using a recombinant spike protein S1 subunit antigen. Significantly enhanced virus neutralizing antibody titers were achieved towards both a homologous SARS-CoV-2 virus (IC50 titers of 1:104) and a mouse-adapted variant containing the N501Y mutation present in the B1.1.7 UK and B.1.351 South Africa variants. Importantly, NE/IVT DI dramatically enhanced the TH1-biased cellular response, which is expected to provide more durable and tailored cellular immunity while avoiding potential vaccine enhanced pathology previously associated with TH2-biased responses in some SARS-CoV and MERS-CoV vaccines. Our previous work with the NE/IVT DI adjuvant has demonstrated its compatibility with a broad range of antigen types. Thus, this combined adjuvant approach has strong potential for improving the induced immune profile for a variety of SARS-CoV-2 vaccine candidates such that better protection against future drift variants and prevention of transmission can be achieved.

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

Science ◽  
2020 ◽  
Vol 369 (6505) ◽  
pp. 806-811 ◽  
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.

scholarly journals Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques

2021 ◽  
Vol 17 (9) ◽  
pp. e1009701
Author(s):  
Margherita Rosati ◽  
Mahesh Agarwal ◽  
Xintao Hu ◽  
Santhi Devasundaram ◽  
Dimitris Stellas ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Efficacy ◽  
Rhesus Macaques ◽  
Neutralizing Antibody ◽  
Anatomical Site ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Antibody Titers ◽  
Cellular Immune

The speed of development, versatility and efficacy of mRNA-based vaccines have been amply demonstrated in the case of SARS-CoV-2. DNA vaccines represent an important alternative since they induce both humoral and cellular immune responses in animal models and in human trials. We tested the immunogenicity and protective efficacy of DNA-based vaccine regimens expressing different prefusion-stabilized Wuhan-Hu-1 SARS-CoV-2 Spike antigens upon intramuscular injection followed by electroporation in rhesus macaques. Different Spike DNA vaccine regimens induced antibodies that potently neutralized SARS-CoV-2 in vitro and elicited robust T cell responses. The antibodies recognized and potently neutralized a panel of different Spike variants including Alpha, Delta, Epsilon, Eta and A.23.1, but to a lesser extent Beta and Gamma. The DNA-only vaccine regimens were compared to a regimen that included co-immunization of Spike DNA and protein in the same anatomical site, the latter of which showed significant higher antibody responses. All vaccine regimens led to control of SARS-CoV-2 intranasal/intratracheal challenge and absence of virus dissemination to the lower respiratory tract. Vaccine-induced binding and neutralizing antibody titers and antibody-dependent cellular phagocytosis inversely correlated with transient virus levels in the nasal mucosa. Importantly, the Spike DNA+Protein co-immunization regimen induced the highest binding and neutralizing antibodies and showed the strongest control against SARS-CoV-2 challenge in rhesus macaques.

scholarly journals Towards Quantitative and Standardized Serological and Neutralization Assays for COVID-19

2021 ◽  
Vol 22 (5) ◽  
pp. 2723
Author(s):  
Linhua Tian ◽  
Elzafir B. Elsheikh ◽  
Paul N. Patrone ◽  
Anthony J. Kearsley ◽  
Adolfas K. Gaigalas ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Epidemiologic Studies ◽  
Cross Reactivity ◽  
Receptor Binding Domain ◽  
Proof Of Concept ◽  
Reference Standard ◽  
Improve Measurement ◽  
Antibody Titers

Quantitative and robust serology assays are critical measurements underpinning global COVID-19 response to diagnostic, surveillance, and vaccine development. Here, we report a proof-of-concept approach for the development of quantitative, multiplexed flow cytometry-based serological and neutralization assays. The serology assays test the IgG and IgM against both the full-length spike antigens and the receptor binding domain (RBD) of the spike antigen. Benchmarking against an RBD-specific SARS-CoV IgG reference standard, the anti-SARS-CoV-2 RBD antibody titer was quantified in the range of 37.6 µg/mL to 31.0 ng/mL. The quantitative assays are highly specific with no correlative cross-reactivity with the spike proteins of MERS, SARS1, OC43 and HKU1 viruses. We further demonstrated good correlation between anti-RBD antibody titers and neutralizing antibody titers. The suite of serology and neutralization assays help to improve measurement confidence and are complementary and foundational for clinical and epidemiologic studies.

scholarly journals A single immunization with a rhabdovirus-based vector expressing severe acute respiratory syndrome coronavirus (SARS-CoV) S protein results in the production of high levels of SARS-CoV-neutralizing antibodies

2005 ◽  
Vol 86 (5) ◽  
pp. 1435-1440 ◽  
Author(s):  
Milosz Faber ◽  
Elaine W. Lamirande ◽  
Anjeanette Roberts ◽  
Amy B. Rice ◽  
Hilary Koprowski ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Neutralizing Antibodies ◽  
Neutralizing Antibody ◽  
Protein S ◽  
S Protein ◽  
Cellular Immune Responses ◽  
Glycoprotein G ◽  
Cellular Immune ◽  
Animal Reservoirs ◽  
S Genes

Foreign viral proteins expressed by rabies virus (RV) have been shown to induce potent humoral and cellular immune responses in immunized animals. In addition, highly attenuated and, therefore, very safe RV-based vectors have been constructed. Here, an RV-based vaccine vehicle was utilized as a novel vaccine against severe acute respiratory syndrome coronavirus (SARS-CoV). For this approach, the SARS-CoV nucleocapsid protein (N) or envelope spike protein (S) genes were cloned between the RV glycoprotein G and polymerase L genes. Recombinant vectors expressing SARS-CoV N or S protein were recovered and their immunogenicity was studied in mice. A single inoculation with the RV-based vaccine expressing SARS-CoV S protein induced a strong SARS-CoV-neutralizing antibody response. The ability of the RV-SARS-CoV S vector to confer immunity after a single inoculation makes this live vaccine a promising candidate for eradication of SARS-CoV in animal reservoirs, thereby reducing the risk of transmitting the infection to humans.

scholarly journals A Combined Adjuvant TF–Al Consisting of TFPR1 and Aluminum Hydroxide Augments Strong Humoral and Cellular Immune Responses in Both C57BL/6 and BALB/c Mice

Vaccines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1408
Author(s):  
Qiao Li ◽  
Zhihua Liu ◽  
Yi Liu ◽  
Chen Liang ◽  
Jiayi Shu ◽  
...  
Keyword(s):  
Immune Responses ◽  
Vaccine Development ◽  
Inbred Mouse ◽  
Effective Vaccine ◽  
Mouse Strains ◽  
Cellular Immune Responses ◽  
Recombinant Hbsag ◽  
Cellular Immune

TFPR1 is a novel adjuvant for protein and peptide antigens, which has been demonstrated in BALB/c mice in our previous studies; however, its adjuvanticity in mice with different genetic backgrounds remains unknown, and its adjuvanticity needs to be improved to fit the requirements for various vaccines. In this study, we first compared the adjuvanticity of TFPR1 in two commonly used inbred mouse strains, BALB/c and C57BL/6 mice, in vitro and in vivo, and demonstrated that TFPR1 activated TLR2 to exert its immune activity in vivo. Next, to prove the feasibility of TFPR1 acting as a major component of combined adjuvants, we prepared a combined adjuvant, TF–Al, by formulating TFPR1 and alum at a certain ratio and compared its adjuvanticity with that of TFPR1 and alum alone using OVA and recombinant HBsAg as model antigens in both BALB/c and C57BL/6 mice. Results showed that TFPR1 acts as an effective vaccine adjuvant in both BALB/c mice and C57BL/6 mice, and further demonstrated the role of TLR2 in the adjuvanticity of TFPR1 in vivo. In addition, we obtained a novel combined adjuvant, TF–Al, based on TFPR1, which can augment antibody and cellular immune responses in mice with different genetic backgrounds, suggesting its promise for vaccine development in the future.

scholarly journals Antibody titers measured by commercial assays are correlated with neutralizing antibody titers calibrated by international standards

2021 ◽  
Author(s):  
Yu-An Kung ◽  
Chung-Guei Huang ◽  
Sheng-Yu Huang ◽  
Kuan-Ting Liu ◽  
Peng-Nien Huang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Geometric Mean ◽  
Neutralizing Antibody ◽  
Diagnostic Techniques ◽  
International Standards ◽  
World Health ◽  
Serum Samples ◽  
Antibody Titers ◽  
Health Organization

The World Health Organization (WHO) has highlighted the importance of an international standard (IS) for SARS-CoV-2 neutralizing antibody titer detection, with the aim of calibrating different diagnostic techniques. In this study, IS was applied to calibrate neutralizing antibody titers (IU/mL) and binding antibody titers (BAU/mL) in response to SARS-CoV-2 vaccines. Serum samples were collected from participants receiving the Moderna (n = 20) and Pfizer (n = 20) vaccines at three time points: pre-vaccination, after one dose, and after two doses. We obtained geometric mean titers of 1404.16 and 928.75 IU/mL for neutralizing antibodies after two doses of the Moderna and Pfizer vaccines, respectively. These values provide an important baseline for vaccine development and the implementation of non-inferiority trials. We also compared three commercially available kits from Roche, Abbott, and MeDiPro for the detection of COVID-19 antibodies based on binding affinity to S1 and/or RBD. Our results demonstrated that antibody titers measured by commercial assays are highly correlated with neutralizing antibody titers calibrated by IS.

scholarly journals Distinct cellular immune signatures in acute Zika virus infection are associated with high or low persisting neutralizing antibody titers

2021 ◽  
Author(s):  
Elizabeth E. McCarthy ◽  
Pamela M. Odorizzi ◽  
Emma Lutz ◽  
Carolyn P. Smullin ◽  
Iliana Tenvooren ◽  
...  
Keyword(s):  
Zika Virus ◽  
Neutralizing Antibodies ◽  
Viral Infections ◽  
Immune Cell ◽  
Acute Infection ◽  
Neutralizing Antibody ◽  
Natural Immunity ◽  
Zikv Infection ◽  
Antibody Titers ◽  
Cellular Immune

Although the formation of a durable neutralizing antibody response after an acute viral infection is a key component of protective immunity, little is known about why some individuals generate high versus low neutralizing antibody titers to infection or vaccination. Infection with Zika virus (ZIKV) during pregnancy can cause devastating fetal outcomes, and efforts to understand natural immunity to this infection are essential for optimizing vaccine design. In this study, we leveraged the high-dimensional single-cell profiling capacity of mass cytometry (CyTOF) to deeply characterize the cellular immune response to acute and convalescent ZIKV infection in a cohort of blood donors in Puerto Rico incidentally found to be viremic during the 2015-2016 epidemic in the Americas. During acute ZIKV infection, we identified widely coordinated responses across innate and adaptive immune cell lineages. High frequencies of multiple activated innate immune subsets, as well as activated follicular helper CD4+ T cells and proliferating CD27-IgD- B cells, during acute infection were associated with high titers of ZIKV neutralizing antibodies at 6 months post-infection. On the other hand, low titers of ZIKV neutralizing antibodies were associated with immune features that suggested a cytotoxic-skewed immune "set-point." Our study offers insight into the cellular coordination of immune responses and identifies candidate cellular biomarkers that may offer predictive value in vaccine efficacy trials for ZIKV and other acute viral infections aimed at inducing high titers of neutralizing antibodies.

scholarly journals Safety and Immunogenicity Evaluation of Inactivated whole-virus-SARS-COV-2 As Emerging Vaccine Development In Egypt

2021 ◽  
Author(s):  
Amani A. Saleh ◽  
Mohamed A. Saad ◽  
Islam Ryan ◽  
Magdy Amin ◽  
Mohamed I. Shindy ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Clinical Symptoms ◽  
Neutralizing Antibody ◽  
Positive Development ◽  
Virus Challenge ◽  
Cell Monolayers ◽  
Transmission Electron ◽  
Dose Concentration ◽  
Antibody Titers

AbstractThe current worldwide pandemic COVID-19 is causing severe human health problems, with high numbers of mortality rates and huge economic burdens that require an urgent demand for safe, and effective and vaccine development. Our study was the first trail to development and evaluation of safety and immune response to inactivated whole SARS-COV-2 virus vaccine adjuvanted with aluminium hydroxide. We used characterized SARS-COV-2 strain, severe acute respiratory syndrome coronavirus 2 isolates (SARS-CoV-2/human/EGY/Egy-SERVAC/2020) with accession numbers; MT981440; MT981439; MT981441; MT974071; MT974069 and MW250352 at GenBank that isolated from Egyptian patients SARS-CoV-2-positive. Development of the vaccine was carried out in a BSL - 3 facilities and the immunogenicity was determined in mice at two doses (55µg and 100µg per dose). All vaccinated mice were received a booster dose 14 days post first immunization. Our results demonstrated distinct cytopathic effect on the vero cell monolayers induced through SARS-COV-2 propagation and the viral particles were identified as Coronaviridae by transmission electron microscopy. SARS-CoV-2 was identified by RT-PCR performed on the cell culture. Immunogenicity of the developed vaccine indicated the high antigen-binding and neutralizing antibody titers, regardless the dose concentration, with excellent safety profiles.However, no deaths or clinical symptoms in mice groups. The efficacy of the inactivated vaccine formulation was tested by wild virus challenge the vaccinated mice and detection of viral replication in lung tissues. Vaccinated mice recorded complete protection from challenge infection three weeks post second dose. SARS-COV-2 replication was not observed in the lungs of mice following SARS-CoV-2 challenge, regardless of the level of serum neutralizing antibodies. This finding will support the future trials for evaluation an applicable SARS-CoV-2 vaccine candidate.

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