Abstract
The recent viral infection disease pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global public health crisis. Iran, as one of the countries that reported over five million infected cases by September 2021, has been concerned with the urgent development of effective vaccines against SARS-CoV-2. In this paper, we report the results of a study on potency and safety of an inactivated SARS-CoV-2 vaccine candidate (FAKHRAVAC) in a preclinical study so as to confirm its potential for further clinical evaluation. Here, we developed a pilot-scale production of FAKHRAVAC, a purified inactivated SARS-CoV-2 virus vaccine candidate that induces neutralizing antibodies in Balb/c mice, guinea pigs, rabbits, and non-human primates (Rhesus macaques—RM). After obtaining ethical code of IR.IUMS.REC.1399.566, immunizations of animals were conducted by using either of three different vaccine dilutions; High (H): 10 μg/dose, Medium (M): 5 μg/dose, and Low (L): 1 μg/dose, respectively. In the process of screening for viral seeds, viral strains that resulted in the most severe clinical manifestation in patients have been isolated for vaccine development. The viral seed produced the optimal immunity against SARS-CoV-2 virus, which suggests a possible broader neutralizing ability against SARS-CoV-2 strains. The seroconversion rate at the H-, M-, and L-dose groups of all tested animals reached 100% by 28 days after immunization. These data support the eligibility of FAKHRAVAC vaccine candidate for further evaluation in a clinical trial.
Highlights
The strain of the viral seed that used in our study “FAKHRAVAC” is categorized in clade one, along with the most recent strain of SARS-CoV-2 reported from Australia and UK “P
Was injected to Balb/c mice and Rabbit, while, the highest IgG boost in Guinea pig and Rhesus macaques (RMs) obtained by day 21 when H dosage of FAKHRAVAC were administrated
Previous studies conferred Rhesus macaques (RMs) that were infected with SARSCoV-2, developed pulmonary infiltrates and histological lesions
Summary
Three out of ten vaccine candidates that developed to third-phase of clinical trial by end of 2020 were inactivated vaccines including the Sinovac, Bharat Biotech, and Wuhan institute of biological products [2,3,4]. Vaccine-induced disease enhancement has been a concern for vaccine developers in the past 50 years. In alum resulted in enhanced respiratory disease (ERD) as a type of antibody-dependent enhancement (ADE) due to Th1 /Th2 imbalance in cellular immunity upon subsequent RSV infection. During monitoring of inactivated vaccine candidate via two-dose immunization program in this study, no observable antibody-dependent enhancement (ADE) or immunepathological exacerbation was observed in vaccinated Rhesus macaques (RMs). We report on the potency and safety of an inactivated SARS-CoV-2 vaccine candidate (FAKHRAVAC) in a preclinical study to confirm its potential for further clinical evaluation
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