Biology subjects

Flinchbaugh, Z.

Publications and source records attributed to Flinchbaugh, Z..

5 recordsLinked to original sources

bioRxiv2021

Protein Vaccine Induces a Durable, More Broadly Neutralizing Antibody Response in Macaques than Natural Infection with SARS-CoV-2 P.1

FDA-approved and Emergency Use Authorized (EUA) vaccines using new mRNA and viral-vector technology are highly effective in preventing moderate to severe disease, however, information on their long-term efficacy and protective breadth against SARS-CoV-2 Variants of Concern (VOCs) is currently scarce. Here we describe the durability and broad-spectrum VOC immunity of a prefusion-stabilized spike (S) protein adjuvanted with liquid or lyophilized CoVaccine HT in cynomolgus macaques. This recombinant subunit vaccine is highly immunogenic and induces robust spike-specific and broadly neutralizing antibody responses effective against circulating VOCs (B.1.351 [Beta], P.1 [Gamma], B.1.617 [Delta]) for at least 3 months after the final boost. Protective efficacy and post-exposure immunity were evaluated using a heterologous P.1 challenge nearly 3 months after the last immunization. Our results indicate that while immunization with both high and low S doses shorten and reduce viral loads in the upper and lower respiratory tract, a higher antigen dose is required to provide durable protection against disease as vaccine immunity wanes. Histologically, P.1 infection causes similar COVID-19-like lung pathology as seen with early pandemic isolates. Post-challenge IgG concentrations were restored to peak immunity levels and vaccine-matched and cross-variant neutralizing antibodies were significantly elevated in immunized macaques indicating an efficient anamnestic response. Only low levels of P.1-specific neutralizing antibodies with limited breadth were observed in control (non-vaccinated but challenged) macaques suggesting that natural infection may not prevent reinfection by other VOCs. Overall, these results demonstrate that a properly dosed and adjuvanted recombinant subunit vaccine can provide long-lasting and protective immunity against circulating VOCs. One Sentence SummaryA recombinant subunit protein formulated with CoVaccine HT adjuvant induces superior immunity than natural infection and reduces viral load while protecting cynomolgus macaques from COVID-19-like disease caused by late SARS-CoV-2 P.1 (Gamma) challenge.

immunology↗

bioRxiv2021

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

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.

immunology↗

bioRxiv2021

Protection against SARS-CoV-2 Beta Variant in mRNA-1273 Boosted Nonhuman Primates

Neutralizing antibody responses gradually wane after vaccination with mRNA-1273 against several variants of concern (VOC), and additional boost vaccinations may be required to sustain immunity and protection. Here, we evaluated the immune responses in nonhuman primates that received 100 {micro}g of mRNA-1273 vaccine at 0 and 4 weeks and were boosted at week 29 with mRNA-1273 (homologous) or mRNA-1273.{beta} (heterologous), which encompasses the spike sequence of the B.1.351 (beta or {beta}) variant. Reciprocal ID50 pseudovirus neutralizing antibody geometric mean titers (GMT) against live SARS-CoV-2 D614G and the {beta} variant, were 4700 and 765, respectively, at week 6, the peak of primary response, and 644 and 553, respectively, at a 5-month post-vaccination memory time point. Two weeks following homologous or heterologous boost {beta}-specific reciprocal ID50 GMT were 5000 and 3000, respectively. At week 38, animals were challenged in the upper and lower airway with the {beta} variant. Two days post-challenge, viral replication was low to undetectable in both BAL and nasal swabs in most of the boosted animals. These data show that boosting with the homologous mRNA-1273 vaccine six months after primary immunization provides up to a 20-fold increase in neutralizing antibody responses across all VOC, which may be required to sustain high-level protection against severe disease, especially for at-risk populations. One-sentence summarymRNA-1273 boosted nonhuman primates have increased immune responses and are protected against SARS-CoV-2 beta infection.

immunology↗

bioRxiv2021

A modular protein subunit vaccine candidate produced in yeast confers protection against SARS-CoV-2 in non-human primates

Vaccines against SARS-CoV-2 have been distributed at massive scale in developed countries, and have been effective at preventing COVID-19. Access to vaccines is limited, however, in low- and middle-income countries (LMICs) due to insufficient supply, high costs, and cold storage requirements. New vaccines that can be produced in existing manufacturing facilities in LMICs, can be manufactured at low cost, and use widely available, proven, safe adjuvants like alum, would improve global immunity against SARS-CoV-2. One such protein subunit vaccine is produced by the Serum Institute of India Pvt. Ltd. and is currently in clinical testing. Two protein components, the SARS-CoV-2 receptor binding domain (RBD) and hepatitis B surface antigen virus-like particles (VLPs), are each produced in yeast, which would enable a low-cost, high-volume manufacturing process. Here, we describe the design and preclinical testing of the RBD-VLP vaccine in cynomolgus macaques. We observed titers of neutralizing antibodies (>104) above the range of protection for other licensed vaccines in non-human primates. Interestingly, addition of a second adjuvant (CpG1018) appeared to improve the cellular response while reducing the humoral response. We challenged animals with SARS-CoV-2, and observed a ~3.4 and ~2.9 log10 reduction in median viral loads in bronchoalveolar lavage and nasal mucosa, respectively, compared to sham controls. These results inform the design and formulation of current clinical COVID-19 vaccine candidates like the one described here, and future designs of RBD-based vaccines against variants of SARS-CoV-2 or other betacoronaviruses.

immunology↗

bioRxiv2021

Evaluation of mRNA-1273 against SARS-CoV-2 B.1.351 Infection in Nonhuman Primates

BackgroundVaccine efficacy against the B.1.351 variant following mRNA-1273 vaccination in humans has not been determined. Nonhuman primates (NHP) are a useful model for demonstrating whether mRNA-1273 mediates protection against B.1.351. MethodsNonhuman primates received 30 or 100 {micro}g of mRNA-1273 as a prime-boost vaccine at 0 and 4 weeks, a single immunization of 30 {micro}g at week 0, or no vaccine. Antibody and T cell responses were assessed in blood, bronchioalveolar lavages (BAL), and nasal washes. Viral replication in BAL and nasal swabs were determined by qRT-PCR for sgRNA, and histopathology and viral antigen quantification were performed on lung tissue post-challenge. ResultsEight weeks post-boost, 100 {micro}g x2 of mRNA-1273 induced reciprocal ID50 neutralizing geometric mean titers against live SARS-CoV-2 D614G and B.1.351 of 3300 and 240, respectively, and 430 and 84 for the 30 {micro}g x2 group. There were no detectable neutralizing antibodies against B.1351 after the single immunization of 30 {micro}g. On day 2 following B.1.351 challenge, sgRNA in BAL was undetectable in 6 of 8 NHP that received 100 {micro}g x2 of mRNA-1273, and there was a [~]2-log reduction in sgRNA in NHP that received two doses of 30 {micro}g compared to controls. In nasal swabs, there was a 1-log10 reduction observed in the 100 {micro}g x2 group. There was limited inflammation or viral antigen in lungs of vaccinated NHP post-challenge. ConclusionsImmunization with two doses of mRNA-1273 achieves effective immunity that rapidly controls lower and upper airway viral replication against the B.1.351 variant in NHP.

immunology↗