Vaccine development is a multi-stage process that has been at the forefront of people’s minds since the beginning of the COVID-19 pandemic. The various companies that took it upon themselves to produce the vaccines faced not only many theoretical, but also numerous practical obstacles. They were trying to cram a decade of research, development, and clinical trials in just under two years.
Facing the possibility of similar worldwide pandemics in the future either from coronavirus variants or another kind of pathogen – and aiming at making healthcare providers’ jobs easier – big pharmaceutical companies are employing new technologies for more efficient vaccine development. Some of those technologies involve the use of messenger RNA (mRNA), DNA, lipid nanoparticles (LNP), or a viral vector.
This type of smart vaccine development avoids the use of debilitated viruses and relies on their genetic code instead. This multipurpose and trustworthy new avenue of approach toward preventable disease or preventable disease complications has spawned several vaccines in various stages of development. To help shed some light on these developments, let’s take a closer look at these novel biotechnology tools.
Development
When it comes to lipid nanoparticles and the difficulty of developing a satisfactory delivery method, many materials and formulations (such as polymers and proteins) have been proposed as carriers. The lipid nanoparticles that are now used in mRNA vaccines can be used with other molecules, like antibodies and anti-cancerous drugs.
The investigation continues with ongoing clinical trials to find alternatives and perfect this method. In the case of viral vector vaccines, adenoviruses are the most common carrier of immunogenic information. Other vector options include influenza virus, measles virus, and vesicular stomatitis virus or VSV. Cell line development has to be carefully monitored, as it is the ultimate factory in the process.
Unlike LNP, however, every different virus used as a vector has different characteristics. This is why they aren’t employed to carry the same DNA content or module, or for the same delivery target. Aggregation and stability are still a problem, as well as performance loss due to the sterilization needed to render the vector harmless.
Lipid Nanoparticles
The first method uses messenger RNA, which is a type of RNA (or ribonucleic acid) that acts as an expression regulator for a cell’s genes. Many viruses’ entire genetic code consists of RNA. The most common way of using this molecule with this delivery method is by inserting stands or “modules” of mRNA inside lipid nanoparticles. The nanoparticles envelop the mRNA molecules with their lipid membrane before taking the spherical shape needed to deliver the content to the cells.
They enter a cell through an endosome, which is an invagination of the cellular membrane, and once the charge of the acidic interior of the endosome turns positive, the nanoparticle is released inside the cell. This method of delivery can be used to create vaccines that target different diseases, and what varies is the molecule that is carried inside the lipid nanoparticle.
Viral Vector
Similar to lipid nanoparticles, using a viral vector has similar operative characteristics. Vaccines that use a virus as a platform to deliver immunological information employ a modified version of it, like an adenovirus. Unlike the previous method, this one doesn’t use strands of mRNA, but rather it’s used to transport segments of DNA.
By changing the DNA content of the virus, a different vaccine can be produced. It is important to notice that all the types of viruses that are used to deliver DNA molecules are harmless versions of the original. While vaccines that use viral vectors can cause a slight fever, people vaccinated using this method are at no risk of developing an infectious disease related to the vector or the gene that is transported.
Advantages of LNP and Viral Vector Vaccines
Disease outbreaks can come from previously unknown pathogens or new variants of known microorganisms, as is the case with COVID-19 and its new variations since the start of the 2020 pandemic. Therefore, the clearer and most important advantage of these new biotechnological tools resides in their dynamic customization.
In simple terms, all that’s needed to create a new vaccine is to insert the pathogen’s newly found genetic content in the lipid nanoparticle or in the viral vector that is acting as a carrier. Building on this aspect, as soon as the genome of a new virus is sequenced, it can be spread across different vaccine manufacturers, improving the response time of vaccine production.
