Preliminary Step towards COVID-19 Inactivated Vaccine Development in Egypt

Authors

  • Mohamed A Saad A.R.C. Veterinary Serum Vaccine Research Institute (VSVRI), Cairo, Egypt
  • Islam Ryan Egyptian Army Veterinary Corps, Cairo, Egypt
  • Magdy Amin Military Medical Services, Cairo, Egypt
  • Mahmoud S Saleh Main Chemical Laboratories, Egypt Army, Cairo, Egypt
  • Tayseer Abdulaal Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Wael A Hassan Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Mahmoud Samir Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Ahmed A Raouf Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Ayman A Khattab Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Nermeen T Fahmy Egypt Center for Research and Regenerative Medicine, Cairo, Egypt
  • Mohamed I Shindy Egyptian Army Veterinary Corps, Cairo, Egypt
  • Sherein S Abdelgayed Faculty of Veterinary Medicine, Cairo University, Giza, Egypt
  • Mohamed G Seadawy Main Chemical Laboratories, Egypt Army, Cairo, Egypt
  • Abdel-Rahman N Zekri National Cancer Institute, Cairo University, Giza, Egypt
  • Hossam M Fahmy Faculty of Medicine, Ain Shams University, Cairo, Egypt
  • Khaled Amer Faculty of Medicine, Ain Shams University, Cairo, Egypt

Abstract

The current worldwide COVID-19 pandemic is causing severe human health problems, with high
mortality rates and huge economic burdens requiring the urgent development of a safe and effective
vaccine. Here, preclinical evaluation of an inactivated SARS-CoV-2 vaccine candidate (EgySerVac-20)
is reported. Oropharyngeal swabs and nasopharyngeal aspirates obtained from Egyptian patients with
laboratory-confirmed SARS-CoV-2 infection were isolated using Vero cells and were then genetically
characterized. Vaccine inactivation was performed using diluted formaldehyde, followed by safety
testing for the inactivated vaccine. To determine the high humoral immune responses against SARSCOV-
2 infection, the safety and capacity of the vaccine prepared with alum adjuvant were tested. The
immunogenicity and efficacy of the vaccine candidate was tested in vitro by a neutralization assay and
in vivo using mouse models. Our results revealed a cytopathic effect which was observed 48 hours
post infection and the viral particles were identified by rRT-PCR as SARS-CoV-2. Propagation of the
isolated virus in ten serial passages on the Vero cells yielded a virus titer 7.5 log10 TCID50/ml. Complete
inactivation of SARS-CoV-2 was observed at 37°C in 24 hours post treatment by diluted formaldehyde.
Inactivated SARS-CoV-2 infected fluid safety was determined by absence of cytopathic effect by repeated
passage in Vero cell line, indicating loss of virus infectivity. Virus inactivated by diluted formaldehyde
showed no deaths or clinical symptoms in mice groups post intraperitoneal inoculation (0.5ml/mouse).
EgySerVac-20 inactivated vaccine has safely induced high levels of neutralizing antibodies titers in
mice, where 0.1 ml immunization dose showed protective efficacy against SARS-CoV-2 challenge in
mice. This finding will support the future preclinical and clinical trials evaluation for our SARS-CoV-2
vaccine candidate in primates and human, respectively.

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Published

2021-02-28

Issue

Vol. 1 No. 1

Section

Articles