Immunogenicity of adjuvanted psoralen-inactivated sars-cov-2 vaccines and sars-cov-2 spike protein dna vaccines in balb/c mice

Appavu K. Sundaram*, Daniel Ewing, Zhaodong Liang, Vihasi Jani, Ying Cheng, Peifang Sun, Kanakatte Raviprakash, Shuenn Jue Wu, Nikolai Petrovsky, Gabriel Defang, Maya Williams, Kevin R. Porter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


The development of a safe and effective vaccine to protect against COVID-19 is a global priority due to the current high SARS-CoV-2 infection rate. Currently, there are over 160 SARS-CoV-2 vaccine candidates at the clinical or pre-clinical stages of development. Of these, there are only three whole-virus vaccine candidates produced using β-propiolactone or formalin inactivation. Here, we prepared a whole-virus SARS-CoV-2 vaccine (SARS-CoV-2 PsIV) using a novel psoralen inactivation method and evaluated its immunogenicity in mice using two different adjuvants, alum and Advax-2. We compared the immunogenicity of SARS-CoV-2 PsIV against SARS-CoV-2 DNA vaccines expressing either full-length or truncated spike proteins. We also compared the psoralen-inactivated vaccine against a DNA prime, psoralen-inactivated vaccine boost regimen. After two doses, the psoralen-inactivated vaccine, when administered with alum or Advax-2 adjuvants, generated a dose-dependent neutralizing antibody responses in mice. Overall, the pattern of cytokine ELISPOT responses to antigen-stimulation observed in this study indicates that SARS-CoV-2 PsIV with the alum adjuvant promotes a Th2-type response, while SARS-CoV-2 PsIV with the Advax-2 adjuvant promotes a Th1-type response.

Original languageEnglish
Article number626
Issue number5
StatePublished - May 2021
Externally publishedYes


  • 4-aminomethyl-4,5,8-trimethy lpsoralen (AMT)
  • Advax-2
  • Anti-SARS-CoV-2-neutralizing antibodies
  • COVID-19
  • Conformational epitopes of surface antigens
  • DNA vaccine
  • Prime-boost
  • Psoralen-inactivated SARS-CoV-2 vaccine
  • SARS-CoV-2


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