The COVID-19 Vaccines from Johnson & Johnson and AstraZeneca: What's in Them and How Do They Work?

hi my name is jonathan genzen and i'm a clinical pathologist and chief operating officer at arup laboratories we made a video describing the pfizer in modern vaccines back in december many of our employees and their family members found the video to be helpful as a way to better understand how the vaccines worked new classes of coven-19 vaccines based on adenoviruses are now becoming available this video focuses on how these work we'll discuss adenovirus vaccines made by two companies one vaccine is from johnson and johnson this is also called the jansen or yanson vaccine because this is the name of the belgian branch of johnson and johnson that developed it the other vaccine is from astrazeneca this is also called the oxford vaccine because it was developed by an oxford university research team these adenovirus vaccines can be stored at standard refrigerated temperatures making them easier to distribute and administer the type of vaccine you are offered will largely be based on which vaccine is made available to the distribution site that you have access to as background sars cov2 is the name of the virus that causes covid19 spike proteins are present on the surface of the virus and they are used by the virus to help infect cells in your body they are therefore an ideal candidate for vaccine targets if your body makes antibodies to block spike protein or immune cells learn to recognize it you can destroy the virus and prevent it from infecting cells that's what we call immunity the johnson and johnson and astrazeneca vaccines both use adenoviruses to help make the sars-kov2 spike protein we'll focus on three big questions one what is an adenovirus two how can an adenovirus make sars cov2 or covid spike protein and three how do these vaccines actually work what are adenoviruses adenoviruses are a large family of similar viruses there are over a hundred of them they're named after adenoids which is just the medical term for tonsils where the viruses were first discovered more than 50 adenoviruses can infect humans and these are classified into families designated a through g they're also numbered adenoviruses are very common and are typically mild they can be responsible for things like the common cold sore throats or stomach bugs for example here's a picture of an adenovirus inside the virus is double-stranded dna this dna contains the instructions on how to make more adenoviruses we'll talk about the organization of this dna in just a bit imagine it this way an adenovirus is like a tiny truck the cargo of the truck is just instructions on how to build more trucks that's it we talked about dna mrna and protein in our last video and they're important here as well as a quick reminder dna is the complete genetic blueprint dna is transcribed into mrna which is just a temporary message to make something mrna is then translated into protein which is what is actually built i like to think of dna as being a cookbook mrna is more like a recipe you print out right before you go to the kitchen and protein is like the cake that you actually make the pfizer and moderna vaccines contain mrna packaged into small lipid particles their vaccine active ingredient is mrna the johnson johnson and astrazeneca vaccines start one step earlier there is dna for covet spike protein inserted into the adenovirus that is then transcribed by your body into mrna the end goal is the same however to make spike protein here's a basic explanation of how it all works and then we'll go into more detail these companies took the adenovirus dna sequence and inserted dna for the covit spike protein if you're like me you may be wondering how they do this and how they can do this while also preventing typical adenovirus infections this is really cool science so i'll describe it next let's consider the adenovirus genome again it's a double stranded dna virus its dna contains 30 to 40 separate genes that code for different proteins these are grouped into two categories proteins from the early genes are made first these early genes are named e1 e2 e3 and e4 and are shown here in blue it's a bit more complicated than this but these are the common names as you may have guessed there are also late genes these are named l1 to l5 as the name suggests the proteins from these late genes are made a bit later let's focus mostly on e1 at the left because it's really important e1 can be divided into two genes e1a and e1b together we'll just call it e1 e1 is required for the virus to replicate or make more of itself if you delete e1 the adenovirus can't make more of itself the term for that is called replication incompetent that's a key point for these vaccines these adenoviruses can't make more of themselves because the e1 gene has been deleted from the vaccine with this background in mind let's think about how they've turned adenoviruses into vaccines against covid19 here again is the location of the normal adenovirus genes first as we just talked about they delete e1 from the virus dna so that it can't replicate second these companies have also deleted e3 why do they do that turns out you don't need e3 to make the vaccine and deleting it makes room to add something later what do they add back then when they delete e1 they replace it with dna for the sars cov2 or covid spike protein instead finally e4 is modified just a little bit as this helps make the vaccines work a little better so with these changes in mind how do adenovirus vaccines for covet work let's put all the pieces together now you start by administering the vaccine here's an image of the vaccine virus next to a human cell the virus is actually much much smaller than the cell but we've magnified it just so we can see it the vaccine adenovirus binds to the surface of your cells and the virus is internalized into something called an endosome which is a tiny compartment that can break down the virus shell and free the dna this moves toward the nucleus and the endosome disintegrates leaving the viral dna exposed this dna then enters the nucleus where it is transcribed into mrna including the mrna for covet spike protein the mrna then leaves the nucleus for the cytoplasm where it binds to ribosomes which are the cellular machinery that helps make protein the mrna is then translated into kovitz spike protein these spike proteins are expressed on the surface of the cells and released thus enabling your body to generate an immune response against them this entire process is similar to the many adenovirus infections you've already had but in this case the adenovirus can't make more of itself because e1 was deleted your body then eliminates the adenovirus just like other adenovirus infections that you've had in the past what's in these vaccines the main ingredient is the vaccine virus itself there are a few other inactive ingredients that differ between vaccines these are commonly called excipients instead of listing each of these between the johnson and johnson and astrazeneca vaccines i'll just describe the general categories of what these ingredients do some are intended to adjust ph to keep the vaccine stable these vaccines also contain something called non-ionic surfactant typically polysorbate 80. this just keeps the virus from sticking to the glass walls of the tubes that they ship in if polysorbate 80 sounds familiar that's because it's already found in a lot of foods that we eat like some frozen desserts finally the vaccines may contain additional stabilizers as the vaccines become available complete lists of ingredients can be found in patient information sheets these are common and safe ingredients these two vaccines do not contain any mercury or thimerosal these vaccines are also not made in eggs as with other vaccines they should not be given to patients with a history of severe allergies to any of the ingredients the information we've talked about apply to two similar vaccines one from johnson and johnson on the left the other from astrazeneca on the right they are based on different adenoviruses with different names please see the fda website for up-to-date vaccine authorization status in the u.s if you understand how these two vaccines work you can also understand how the other adenovirus vaccines used globally work they're based on similar concepts for example the cancino vaccine from china is based on adenoviruses and the same is true of the sputnik v vaccine developed in russia so in summary after vaccination your body develops an immune response against the covet spike protein that is produced by your cells these adenovirus vaccines can't replicate within your cells and importantly you can't get covet 19 from the vaccine finally your body eliminates the adenovirus and dna just like the other adenovirus infections that you've had in your life that concludes our brief presentation i hope you found it helpful and informative for more information on vaccines please visit the cdc coveted 19 vaccination website thanks for watching and be well you

Channel: ARUP Laboratories

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Length: 11min 20sec (680 seconds)

Published: Mon Mar 08 2021