Editing 2406: Viral Vector Immunity

{{comic
| number    = 2406
| date      = January 1, 2021
| title     = Viral Vector Immunity
| image     = viral_vector_immunity.png
| titletext = We've secretly replaced this customer's instant coffee with our patented substitute. Let's see what she ... uh oh, I think she spotted us through the window. Now she's getting something from the closet ... oh jeez, she has a sword! Run!!
}}

==Explanation==
This comic is the third in five releases after [[2402: Into My Veins]] and [[2404: First Thing]], that references the new {{w|COVID-19 vaccine}} 

The comic attempts to explain a virus vector vaccine, and one way it can fail, using the story of the {{w|Trojan Horse}} as an analogy.

A vaccine is a way to familiarize a host's immune system with a pathogen without actually causing the host to fall ill.  There are many types of vaccines that have been developed, all of which are ways to present a significant segment of a pathogen's molecular structure to the host body, so that the immune system recognizes the pathogen and mounts an immune response faster when a real infection happens.

A {{w|viral vector}} is a tool used by molecular biologists to deliver genetic materials into cells.

A viral vector vaccine, also known as a live vector vaccine, uses a modified virus, different from the pathogen being immunized against, as a carrier to deliver a molecular payload into the host body. This modified virus is called the vector because it is the method of delivery of a piece of the pathogen's genetic code.  If the recipient has a strong immune response to the vector itself (i.e., the proteins making up the surface of the vector virus), the immunization may be less effective because the vector virus, and hence its payload of viral genetic material, will be destroyed before they can enter the host's cells.  It is to some degree a dice roll, with regard to whether some recipients will already be immune to a vector.

For example, a modified (to be harmless) cold virus can be used to deliver genetic material (RNA or DNA) of another virus into the patient's cells. The cells are induced to manufacture protein found in the pathogenic protein, which the patient's immune system detects and reacts to. That way the immune system recognizes the pathogenic virus without actually being infected with it, which decreases the time needed to react to a real infection.  Any patients whose immune systems recognize the modified cold virus (the vector), and destroy it rapidly, won't get the full intended benefit of creating a strong immune response to the second virus (the payload inside).

The comic represents this idea with the Trojan horse being the vector, carrying a payload of Greek soldiers into the cell, as represented by the City of Troy.  In the original Trojan Horse story, Greek soldiers hid inside a statue of a horse which the Trojans are told was a gift to Athena; the Trojans brought it within their walls (which the Greek army had failed to penetrate in an extended siege), which allowed the soldiers to undermine the city's defenses and let in the rest of their army to take the city.

In the comic the warriors, rather than finding the wooden horse a benign object, recognize the shape of the delivery vehicle (the Trojan horse) as being similar to an animal that trampled one of their own earlier and therefore refuse it entry. An amusing point here is that they are not as such surprised at the arrival of a wooden vehicle at their doorstep, rather that its shape resembling an animal they have found threatening before, which is similar to how simple in its judgements the immune system can be. In addition, although the warriors suggest pushing the wooden horse into a gorge, there are no gorges very close to Troy, which is situated near the sea on the [https://www.livius.org/articles/place/troy/troy-5/ Plain of Troy].

The title text is a further riff on this theme, playing on an advertising campaign for freeze dried coffee.  In the advertisements a narrator would claim to have secretly replaced fresh brewed coffee with that made from freeze dried to see if subjects could tell the difference, the contents of the coffee cup being the payload and the narrator the virus vector.  The test subject's use of a sword relates the situation back to the Trojan scenario of the panel.

==Transcript==
:[A large wooden horse statue on wheels stands before a city wall, upon which are standing several warriors who are shouting and brandishing spears.]
:Warrior 1: Look! It's a statue of that horrible animal that trampled Steve!
:Warrior 2: Burn it!
:Warrior 3: Smash it!
:Warrior 4: Push it into the gorge!

:[Caption below the panel:]
:How vaccine failure due to viral vector immunity works
{{comic discussion}}
[[Category:COVID-19]]
[[Category:Biology]]