How Much Do You Know about Virus-like Particles and VLPs Vaccine?

Posted by Jerry Carter on April 1st, 2021

Virus-like particles (VLPs) are highly structured protein particles composed of single or multiple structural proteins of the virus self-assembled, with a diameter between 20 and 150 nm, maintaining the natural conformation of viral antigenic proteins, and thus have the function of stimulating host innate and adaptive immune responses.

Morphologically, VLPs resemble immature virions, but are incapable of replication and infection due to the lack of regulatory proteins and infectious nucleic acids. Popularly speaking, viroid particles are the reassembly of the remaining material after removing the genetic material of the virus, and still have the characteristics of the original virus in structure, but they have no reproductive capacity, that is, no pathogenicity, but they can still make the animal body produce an immune response against the virus, thereby producing antibodies so that the body has a good defense ability against the erosion of the virus.

In 2019, the global pandemic of novel coronavirus (referred to as coronavirus), experts in the global medical and biological fields are committed to finding and developing solutions for the treatment and prevention of novel coronavirus pneumonia (referred to as coronavirus pneumonia), but the current clinical study results of hydroxychloroquine and repassivir are not optimistic. It has been suggested in the literature that 87% of patients discharged from the hospital for rehabilitation still have symptoms and 44% feel deteriorated quality of life 2 months after the onset of coronavirus pneumonia. The treatment of coronavirus is still based on symptomatic treatment, and there is no effective antiviral therapy. Therefore, we focus more on the research and development of vaccines for the prevention and control of coronavirus. According to the statistics of World Health Organization (WHO), the research and development is currently being carried out from 8 different types of technology platforms worldwide, including inactivated vaccines, non-replicative vector vaccines, replicative vector vaccines, live attenuated vaccines, DNA vaccines, RNA vaccines, protein subunit vaccines and virus-like particle (VLP) vaccines.

VLPs can be divided into two categories according to different structures: encapsulated and non-encapsulated. Non-enveloped VLPs are self-assembled from one or more components of a pathogen or assembled after fusion of one or more target antigens on the surface of a VLP, and usually do not contain host components. The role of VLPs with the immune system is mainly related to two factors: the size and surface geometry of VLPs. Because of its viral structure, VLPs can not only interact with the human innate immune response system, but also effectively elicit specific humoral immune responses and specific cellular immune responses after entering the body. As exogenous antigens, VLPs can be effectively presented by MCH I and II. VLP vaccine research and development technology has been widely studied and applied, and the VLP vaccines that have been marketed or under development include human papillomavirus vaccine, hepatitis B vaccine, hepatitis E vaccine, and norovirus vaccine.

In conclusion, VLPs vaccine, as a new type of genetically engineered vaccine, has strong immune advantages: regular surface structure, appropriate size, no nucleic acid, inability to replicate autonomously, no infectivity, easy to be recognized by the immune system and produce a good immune effect; half-life in serum; stable quality, safety and reliability. This puts forward a good direction for future genetic engineering vaccine research.