ABSTRACT
Objective To prepare antiserum against S protein of SARS-CoV-2 and preliminarily develop a method for determination of antigen content in inactivated SARS-CoV-2 vaccine. Methods Goats and rabbits were immunized with recombinant S protein of SARS-CoV-2, and the obtained antisera were determined for titer by indirect ELISA and neutralization assay and for specificity by Western blot, then purified by protein G resin affinity chro-matography. A sandwich ELISA for determination of antigen content of inactivated SARS-CoV-2 vaccine was developed by using purified goat antibody as capture antibody and purified rabbit antibody as detection antibody. Results The titer of antiserum of goats after immunization for 4 times reached 220 000 by ELISA and 1 536 by neutralization assay, while that of rabbits after immunization for 3 times reached 220 000 by ELISA and 4 096 by neutralization assay. Both goat and rabbit antibodies showed specific binding to the S protein of SARS-CoV-2. A double antibody sandwich ELISA method for determination of antigen content was successfully developed by using the purified antibodies, which showed a good linearity with a R2 value of more than 0. 99. Conclusion High titer goat and rabbit antisera against S protein of SARS-CoV-2 were prepared successfully, and double antibody sandwich ELISA method for determination of antigen content of inactivated SARS-CoV-2 vaccine was preliminarily developed. © 2021 Changchun Institute of Biological Products. All rights reserved.
ABSTRACT
Objective To prepare high titer neutralizing antiserum against SARS-CoV-2. Methods SPF rabbits were immunized with RBD protein of SARS-CoV-2, expressed in 293 cells, as an immunogen. The prepared antiserum was determined for titer by ELISA and microneutralization test, and distributed to several manufacturers for development of inactivated SARS-CoV-2 vaccine for determination of titer. Results After 3 times of immunization, the antiserum titer reached more than 1 600 000, while the neutralizing titer was 8 192. The geometric mean titer (GMT) determined by microneutralization test in five manufacturers was 6. 950. Conclusion High titer neutralizing antiserum against SARS-CoV-2 was successfully prepared and distributed to several manufacturers of inactivated SARS-CoV-2 vaccine candidate for virus identification and adventitious virus agent test, which broke through the technical bottleneck restricting the rapid development of SARS-CoV-2 vaccine. © 2020 Changchun Institute of Biological Products. All rights reserved.