Browsing by Author "Liu, Zhuyun"

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    A Recombinant Protein XBB.1.5 RBD/Alum/CpG Vaccine Elicits High Neutralizing Antibody Titers against Omicron Subvariants of SARS-CoV-2
    (2023) Thimmiraju, Syamala Rani; Adhikari, Rakesh; Villar, Maria Jose; Lee, Jungsoon; Liu, Zhuyun; Kundu, Rakhi; Chen, Yi-Lin; Sharma, Suman; Ghei, Karm; Keegan, Brian; Versteeg, Leroy; Gillespie, Portia M.; Ciciriello, Allan; Islam, Nelufa Y.; Poveda, Cristina; Uzcategui, Nestor; Chen, Wen-Hsiang; Kimata, Jason T.; Zhan, Bin; Strych, Ulrich; Bottazzi, Maria Elena; Hotez, Peter J.; Pollet, Jeroen
    (1) Background: We previously reported the development of a recombinant protein SARS-CoV-2 vaccine, consisting of the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, adjuvanted with aluminum hydroxide (alum) and CpG oligonucleotides. In mice and non-human primates, our wild-type (WT) RBD vaccine induced high neutralizing antibody titers against the WT isolate of the virus, and, with partners in India and Indonesia, it was later developed into two closely resembling human vaccines, Corbevax and Indovac. Here, we describe the development and characterization of a next-generation vaccine adapted to the recently emerging XBB variants of SARS-CoV-2. (2) Methods: We conducted preclinical studies in mice using a novel yeast-produced SARS-CoV-2 XBB.1.5 RBD subunit vaccine candidate formulated with alum and CpG. We examined the neutralization profile of sera obtained from mice vaccinated twice intramuscularly at a 21-day interval with the XBB.1.5-based RBD vaccine, against WT, Beta, Delta, BA.4, BQ.1.1, BA.2.75.2, XBB.1.16, XBB.1.5, and EG.5.1 SARS-CoV-2 pseudoviruses. (3) Results: The XBB.1.5 RBD/CpG/alum vaccine elicited a robust antibody response in mice. Furthermore, the serum from vaccinated mice demonstrated potent neutralization against the XBB.1.5 pseudovirus as well as several other Omicron pseudoviruses. However, regardless of the high antibody cross-reactivity with ELISA, the anti-XBB.1.5 RBD antigen serum showed low neutralizing titers against the WT and Delta virus variants. (4) Conclusions: Whereas we observed modest cross-neutralization against Omicron subvariants with the sera from mice vaccinated with the WT RBD/CpG/Alum vaccine or with the BA.4/5-based vaccine, the sera raised against the XBB.1.5 RBD showed robust cross-neutralization. These findings underscore the imminent opportunity for an updated vaccine formulation utilizing the XBB.1.5 RBD antigen.
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    A trivalent protein-based pan-Betacoronavirus vaccine elicits cross-neutralizing antibodies against a panel of coronavirus pseudoviruses
    (Springer Nature, 2024) Thimmiraju, Syamala Rani; Adhikari, Rakesh; Redd, JeAnna R.; Villar, Maria Jose; Lee, Jungsoon; Liu, Zhuyun; Chen, Yi-Lin; Sharma, Suman; Kaur, Amandeep; Uzcategui, Nestor L.; Ronca, Shannon E.; Chen, Wen-Hsiang; Kimata, Jason T.; Zhan, Bin; Strych, Ulrich; Bottazzi, Maria Elena; Hotez, Peter J.; Pollet, Jeroen
    The development of broad-spectrum coronavirus vaccines is essential to prepare for future respiratory virus pandemics. We demonstrated broad neutralization by a trivalent subunit vaccine, formulating the receptor-binding domains of SARS-CoV, MERS-CoV, and SARS-CoV-2 XBB.1.5 with Alum and CpG55.2. Vaccinated mice produced cross-neutralizing antibodies against all three human Betacoronaviruses and others currently exclusive to bats, indicating the epitope preservation of the individual antigens during co-formulation and the potential for epitope broadening.
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    Process development and scale-up optimization of the SARS-CoV-2 receptor binding domain–based vaccine candidate, RBD219-N1C1
    (Springer Nature, 2021) Lee, Jungsoon; Liu, Zhuyun; Chen, Wen-Hsiang; Wei, Junfei; Kundu, Rakhi; Adhikari, Rakesh; Rivera, Joanne Altieri; Gillespie, Portia M.; Strych, Ulrich; Zhan, Bin; Hotez, Peter J.; Bottazzi, Maria Elena; James A. Baker III Institute for Public Policy
    A SARS-CoV-2 RBD219-N1C1 (RBD219-N1C1) recombinant protein antigen formulated on Alhydrogel® has recently been shown to elicit a robust neutralizing antibody response against SARS-CoV-2 pseudovirus in mice. The antigen has been produced under current good manufacturing practices (cGMPs) and is now in clinical testing. Here, we report on process development and scale-up optimization for upstream fermentation and downstream purification of the antigen. This includes production at the 1-L and 5-L scales in the yeast, Pichia pastoris, and the comparison of three different chromatographic purification methods. This culminated in the selection of a process to produce RBD219-N1C1 with a yield of >400 mg per liter of fermentation with >92% purity and >39% target product recovery after purification. In addition, we show the results from analytical studies, including SEC-HPLC, DLS, and an ACE2 receptor binding assay that were performed to characterize the purified proteins to select the best purification process. Finally, we propose an optimized upstream fermentation and downstream purification process that generates quality RBD219-N1C1 protein antigen and is fully scalable at a low cost.
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    Receptor-binding domain recombinant protein on alum-CpG induces broad protection against SARS-CoV-2 variants of concern
    (Elsevier, 2022) Pollet, Jeroen; Strych, Ulrich; Chen, Wen-Hsiang; Versteeg, Leroy; Keegan, Brian; Zhan, Bin; Wei, Junfei; Liu, Zhuyun; Lee, Jungsoon; Kundu, Rahki; Adhikari, Rakesh; Poveda, Cristina; Jose Villar, Maria; Rani Thimmiraju, Syamala; Lopez, Brianna; Gillespie, Portia M.; Ronca, Shannon; Kimata, Jason T.; Reers, Martin; Paradkar, Vikram; Hotez, Peter J.; Elena Bottazzi, Maria; James A. Baker III Institute for Public Policy
    We conducted preclinical studies in mice using a yeast-produced SARS-CoV-2 RBD subunit vaccine candidate formulated with aluminum hydroxide (alum) and CpG deoxynucleotides. This formulation is equivalent to the CorbevaxTM vaccine that recently received emergency use authorization by the Drugs Controller General ofIndia. We compared the immune response of mice vaccinated with RBD/alum to mice vaccinated with RBD/alum + CpG. We also evaluated mice immunized with RBD/alum + CpG and boosted with RBD/alum. Mice were immunized twice intramuscularly at a 21-day interval. Compared to two doses of the /alum formulation, the RBD/alum + CpG vaccine induced a stronger and more balanced Th1/Th2 cellular immune response, with high levels of neutralizing antibodies against the original Wuhan isolate of SARS-CoV-2 as well as the B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.2 and (Delta) variants. Neutralizing antibody titers against the B.1.1.529 (BA.1, Omicron) variant exceeded those in human convalescent plasma after Wuhan infection but were lower than against the other variants. Interestingly, the second dose did not benefit from the addition of CpG, possibly allowing dose-sparing of the adjuvant in the future. The data reported here reinforces that the RBD/alum + CpG vaccine formulation is suitable for inducing broadly neutralizing antibodies against SARS-CoV-2, including variants of concern.