Explained: What are VLP-based Covid-19 vaccines, and why is the platform attracting vaccine cos?

Serum Institute of India (SII) has announced it has partnered with UK biotech company, Spybiotech, a spin-off of the University of Oxford, to develop a COVID-19 virus-like-particle (VLP)-based vaccine. The vaccine has entered a Phase 1/2 trial in Australia. In October, another Indian drug maker, Aurobindo Pharma, said it entered into collaboration with Hyderabad-based Centre for Cellular and Molecular Biology (CCMB), a Council of Scientific and Industrial Research (CSIR) lab, to manufacture a COVID-19 vaccine based on VLP.

It isn't SII and Aurobindo Pharma alone, there more than a dozen COVID-19 vaccine candidates currently under development that are based on VLP.

What is VLP?

VLP resembles the SARS-CoV-2 virus. The VLP is constructed incorporating all key structural proteins, mirroring the molecular structure of coronavirus. However, it doesn't cause infection as it doesn't have the genetic material that helps it replicate like a natural virus. VLPs can be produced using mammalian cells, insect cells, bacteria, yeast and plant cells. Animal studies have found out that vaccines based on VLP induce immune response, providing protection against any future COVID-19 infection. To be sure, there are several VLP-based vaccines commercially available including vaccines against Human Papilloma Virus (HPV) and Hepatitis B Virus (HBV). Most licensed VLP vaccines use the aluminum adjuvant to boost their efficacy.

Why do companies consider VLP vaccines?

When compared to vaccines that deal with live viruses that require biosafety level-3 containment manufacturing facilities, limiting their ability to scale up rapidly, VLP on other hand require current good manufacturing practices (CGMP)-compliant manufacturing sites. This enables faster scale-up, which is critical during a pandemic. In addition, VLP vaccines can be developed and produced at much shorter timelines of 3–12 weeks, compared to viral vector or whole virion vaccines that need at least six months.

How long will it take to see VLP COVID vaccines?

Two VLP vaccines have reached the clinical trial stage. Canadian biotech firm Medicago, backed by tobacco behemoth Phillip Morris, vaccine candidate based on VLP has reached phase 2/3 trial. The vaccine uses plant leaves from the tobacco family to produce VLP. The other Covid-19 vaccine is SII-Spybiotech, which has entered phase 1/2 trial. The VLP vaccines may not be hitting the market any time soon, but they will also be a useful option.