Stability of Neutralizing Antibody of PastoCoAd Vaccine Candidates against a Variant of Concern of SARS-CoV-2 in Animal Models

Authors
Mohammad Panahi 1
Ali Teimoori 2
Saber Esmaeili 3
Hossein Aminianfar 4
Alireza Milani 1
Seyed Younes Hosseini 5
Parisa Esmaeili 3
Alireza Biglari 6
Kazem Baesi 1
1 Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran
2 Department of Virology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
3 National Reference Laboratory for Plague, Tularemia and Q Fever, Research Center for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Akanlu, Kabudar Ahang, Hamadan, Iran
4 Institute of Biomedical Research, University of Tehran, Tehran, Iran
5 Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
6 Pasteur Institute of Iran, Tehran, Iran
10.61186/ibj.3980
Abstract
Background: Since the beginning of the SARS-CoV-2 pandemic, there have been mutations caused by new SARS-CoV-2 variants, such as Alpha, Beta, Gamma, Delta, and Omicron, recognized as the variants of concern (VOC) worldwide. These variants can affect vaccine efficacy, disease control, and treatment effectiveness. The present study aimed to evaluate the levels of total and neutralizing antibodies produced by PastoCoAd vaccine candidates against the VOC strains at different time points.

Methods: Two vaccine candidates were employed against SARS-CoV-2 using adenoviral vectors: prime only (a mixture of rAd5-S and rAd5 RBD-N) and heterologous prime-boost (rAd5-S/SOBERANA vaccine). The immunogenicity of these vaccine candidates was assessed in mouse, rabbit, and hamster models using ELISA assay and virus neutralization antibody test.

Results: The immunogenicity results indicated a significant increase in both total and neutralizing antibodies titers in the groups receiving the vaccine candidates at various time points compared to the control group (p < 0.05). The results also showed that the PastoCoAd vaccine candidates Ad5 S & RBD-N and Ad5 S/SOBERANA could neutralize the VOC strains in the animal models.

Conclusion: The ability of vaccine candidate to neutralize the VOC strains in animal models by generating neutralizing antibodies at different time points may be attributed to the use of the platform based on the Adenoviral vector, the N proteins in the Ad5 S & RBD-N vaccine candidate, and the SOBERANA Plus booster in the Ad5 S/SOBERANA vaccine candidate.
Keywords
COVID-19 Vaccines
Mutation
Nucleocapsid
Spike protein