Immunogenicity and Protective Efficacy of a Highly Thermotolerant, Trimeric SARS-CoV-2 Receptor Binding Domain Derivative

Malladi, SK and Patel, UR and Rajmani, RS and Singh, R and Pandey, S and Kumar, S and Khaleeq, S and Van Vuren, PJ and Riddell, S and Goldie, S and Gayathri, S and Chakraborty, D and Kalita, P and Pramanick, I and Agarwal, N and Reddy, P and Girish, N and Upadhyaya, A and Khan, MS and Kanjo, K and Bhat, M and Mani, S and Bhattacharyya, S and Siddiqui, S and Tyagi, A and Jha, S and Pandey, R and Tripathi, S and Dutta, S and McAuley, AJ and Singanallur, NB and Vasan, SS and Ringe, RP and Varadarajan, R (2021) Immunogenicity and Protective Efficacy of a Highly Thermotolerant, Trimeric SARS-CoV-2 Receptor Binding Domain Derivative. In: ACS Infectious Diseases .

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Abstract

The receptor binding domain (RBD) of SARS-CoV-2 is the primary target of neutralizing antibodies. We designed a trimeric, highly thermotolerant glycan engineered RBD by fusion to a heterologous, poorly immunogenic disulfide linked trimerization domain derived from cartilage matrix protein. The protein expressed at a yield of �80-100 mg/L in transiently transfected Expi293 cells, as well as CHO and HEK293 stable cell lines and formed homogeneous disulfide-linked trimers. When lyophilized, these possessed remarkable functional stability to transient thermal stress of up to 100 °C and were stable to long-term storage of over 4 weeks at 37 °C unlike an alternative RBD-trimer with a different trimerization domain. Two intramuscular immunizations with a human-compatible SWE adjuvanted formulation elicited antibodies with pseudoviral neutralizing titers in guinea pigs and mice that were 25-250 fold higher than corresponding values in human convalescent sera. Against the beta (B.1.351) variant of concern (VOC), pseudoviral neutralization titers for RBD trimer were �3-fold lower than against wildtype B.1 virus. RBD was also displayed on a designed ferritin-like Msdps2 nanoparticle. This showed decreased yield and immunogenicity relative to trimeric RBD. Replicative virus neutralization assays using mouse sera demonstrated that antibodies induced by the trimers neutralized all four VOC to date, namely B.1.1.7, B.1.351, P.1, and B.1.617.2 without significant differences. Trimeric RBD immunized hamsters were protected from viral challenge. The excellent immunogenicity, thermotolerance, and high yield of these immunogens suggest that they are a promising modality to combat COVID-19, including all SARS-CoV-2 VOC to date. ©

Item Type:	Journal Article
Publication:	ACS Infectious Diseases
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Biological Sciences > Microbiology & Cell Biology Division of Biological Sciences > Centre for Infectious Disease Research
Date Deposited:	28 Nov 2021 09:56
Last Modified:	28 Nov 2021 09:56
URI:	http://eprints.iisc.ac.in/id/eprint/69994

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