A new vaccine has been rapidly thrown through clinical trials and is showing very promising progress. Professor Sarah Gilbert at the University of oxford has taken lead in the project using a Viral Vector called ChAdOx1.
ChAdOx1 is a Non-replicating Simian Adenoviral Vectored Vaccine. i will split that up for you:
-Non-replicating is pretty straight forward, simply that it cannot replicate to make more of the virus which then goes on to infect other cells and so on, which is exactly how normal viral pathogens work.
-Simian meaning that it was originally taken from a monkey. we take the virus that normally infects monkeys and similar animals which humans don't come in contact with. Humans have most likely been in contact with a similar Adenovirus which means we will have the antibodies for it and the pathogen will be destroyed too quickly to be used as a vaccine.
-Adenoviral describes a type of virus that causes mild human colds so are not very harmful. but this also means that this virus can invade and infect the human cell
Viruses have spike proteins on their cell surface which have a specific 3D shape complementary to the receptor on our T-helper cells (immune cell) which allow them to enter cells through a process called endocytosis*. When these viruses infect our body we produce antibodies that have a specific shape complementary to the pathogen which bind and destroy the virus.
so we can manipulate this process to create antibodies for COVID-19. we can take the genes that code for the spike proteins on the COVID virus and introduce it into the ChAdOx1 vector. we then inject this vector as a vaccine into the body, the cells in the body will then produce antibodies specific to the spike proteins, so when our bodies next meet the dorona virus it will be able to produce antibodies at a faster rate and more readily combat the virus.
ChAdOx1 viral vector is a safe vaccine we can use as it is non-replicating as we said before. this can mean we can vaccinate those that are very immuno-comprimised* as the virus will not replicate and cause a harmful effect on those people.
to figure out if this vaccine was effective in producing a T-cell stimulation. they used the same biological technology on MERS-CoV which is in the same family of the corona virus. these are their results.
this graph may look very confusing but by just looking at the shape of it we can simplify it.
on day 0 the injection of the vaccine was given and we can see that we have a low level of responses of t cells, because the body has not encountered this pathogen before and so needs to make loads of antibodies to fight it and so the time it takes to do this is slow initially.
Between then and day 28 we can see that the t cell responses to the virus has exponentially increased, as the body is going through processes to activate t-cells and make antibodies. After this peak the t cell responses lowers as the pathogen has been removed but we can see the t cell response levels out at a good level as we still have the antibodies specific to the virus in the bloodstream ready for when it is next encountered. Now the pathogen should not have any harmful effects.
Endocytosis*- the process of actively transporting molecules into the cell by engulfing it with its membrane.
immuno-comprimised* - having a weakened immune system.
Covid conversations - Sarah Gilbert on Vaccines - University of Oxford - Youtube