Covax-19/Spikogen: A Novel Insect-Cell Expressed Recombinant Protein Vaccine Provides Broad Based Protection Against Covid-19 Infection
The development of safe and effective vaccines is a key requirement to conquering the COVID-19 pandemic. Recombinant proteins represent the best understood and reliable approach to pandemic vaccine delivery with well-established safety, but nevertheless face challenges in design, structural characterization, manufacture, potency testing, and ensuring adequate immunogenicity. Nikolai Petrovsky's team used in silico structural modeling to design a vaccine based on a stabilized spike protein extracellular domain (ECD). The insect cell-expressed recombinant spike ECD was formulated with Vaxine’s proprietary Advax-CpG55.2 adjuvant. The vaccine known as Covax-19® or SpikoGen® induced high titers of antibody and memory T-cells which translated to protection against SARS-CoV-2 infection in hamsters, ferrets, and aged monkeys. Clinical trials conducted in the Middle East during a major wave of delta variant confirmed SpikoGen® vaccine was highly effective in reducing severe Covid-19 disease due to the delta variant. It was shown to be safe and free from the myocarditis or thrombosis seen with other vaccines. It received its first emergency use authorization from the Iranian FDA on 6 October 2021 making it the first recombinant spike-protein vaccine to be approved worldwide, and the first Australian-developed human vaccine to receive approval in four decades. Since its approval, millions of doses have been safely administered and its approvals have been extended to children 5 years and above. Ongoing work is exploring modifications to tackle the increasing number of vaccine-resistant variants.