mRNA or viral vector? However, anti Covid-19 vaccine

Covid-19 pandemic has highlighted the importance of scientific research, its quality and, in this specific case, how much it can be quick solving such a big problem thanks to new technologies and knowledges.

In a few months, two types of vaccines have been developed. They will be the solution to the Covid-19 problem worldwide. Let’s see how they work.

source: Fondazione Veronesi

mRNA vaccines

RNA, ribonucleic acid, and DNA, deoxyribonucleic acid (see the tutorial, try to do ex.14 and 25), are the biological association that allows proteins production and genetic transmission. DNA contains the genes which include the instructions for making proteins, RNA (try exercise 28) has different tasks. In fact, the molecule takes on different forms depending on the precise function that has to perform. RNA types are:

• mRNA or messenger RNA, consists of a single strand; it is formed in the nucleus from a DNA template, according to the transcription process. The transcribed mRNA includes the information of one or more genes and is transferred from the nucleus to the cytoplasm through the pores of the nuclear membrane;

• tRNA or RNA transfer, is located in the cytoplasm and its function is to translate information from mRNA to proteins;

• rRNA or ribosomal RNA, constitutes the ribosomes being one of the main components (90%) together with proteins. Finally, protein synthesis takes place in ribosomes.

Here we focus in particular on mRNA. The vaccine works because mRNA contains information and instructions for vaccinated individual’s cells to synthesize the Spike protein.

The Spike protein is the molecule that SARS-CoV-2 viruses, of which Covid-19 virus is part, use as a key to enter human cells, where they can reproduce. The vaccine mRNA, through the Spike protein, induces and stimulates the immune system to produce specific antibodies. A vaccinated person who had contact with someone who has the active infection, has antibodies that block Spike proteins not allowing them to enter the cells and to reproduce.

Once has done its function, mRNA degrades in a very short time and predisposes the individual to fight any further contact with the viruses of the SARS-CoV-2 family.

Viral vector vaccines

Viral vector vaccines use a virus, usually an adenovirus unable to replicate, to deliver the sequence of the genetic code that encodes the Spike protein into the cell. In this way, the immune system is activated against the Spike protein and produces antibodies that can protect the individual who comes into contact with the virus.

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