Talk:Carriers

Leave it to the Professionals
I think someone should make the Quotes be "We've been Immune so far, but if I start to turn, promise you'll shoot me!" (Bill) and "Rescue 7, are you equipped for Carriers?" (Papa Gator). If you want, you can have Rescue 7's response (A-ffirmative, Papa Gator) added to the List. A Reasonable Pic should be some of the graffiti regarding Carriers, as it is hard to get a useable Picture of a Carrier. Anyone wants to add any references, do so. Stub-ifying the Article for now... 94.195.236.134 11:48, May 9, 2010 (UTC)
 * Found a better quote to use. :3 Sera404 13:48, May 9, 2010 (UTC)
 * Aces! You're pretty good at this! 94.195.236.134 19:32, May 10, 2010 (UTC)
 * I wanted to make a new heading, but this editing page didn't allow me to do it for some reason, so this will seem off topic. Are we certain that the immune even exist? So far, from what the comic states, anybody who doesn't show signs of infection is a carrier. So I was thinking that we might want to get rid of the entire carrier vs immune secttion, since both things seem to be the same.Whachamacallit 21:59, September 21, 2010 (UTC)
 * Leave it in for now; the Survivors in both Left 4 Dead and Left 4 Dead 2 obviously believed they are immune (even if they're not). Sera404 22:11, September 21, 2010 (UTC)
 * Leave it in for now; the Survivors in both Left 4 Dead and Left 4 Dead 2 obviously believed they are immune (even if they're not). Sera404 22:11, September 21, 2010 (UTC)

Louis & Francis as Carriers
I understand that the doctor was never shown explicitly stating in-comic that Louis and Francis are carriers, but can't we use some more hidden evidence to support this?

-When Francis first wakes up with his headache, he asks if he was hit with the butt of the gun AGAIN. Maybe he was uncooperative with the testing?

-On page 75, Louis is seen clutching his head in horror exclaiming "So we've been Infecting people this whole time?" and goes on to mention the pilot and the Slaters. How would he know this without being told by the guards who presumably heard it from the doctor? He obviously was not in contact with Zoey and Bill.

I understand there are some holes in this evidence because we haven't seen the full story, but I feel like we should include them under "Confirmed Carriers". What do you guys think? Nightmirage 19:39, September 22, 2010 (UTC)

I 100% agree with you. As you stated, there's enough evidence to be mostly certain that Louis and Francis are carriers. Or at least, there's a lot more direct evidence supporting the fact that Francis and Louis are carriers then most subject matters. I mean if we put up all those hypotheses about how the special infected come to in the Green Flu article (not that there bad, but they are nothing but hypotheses) why can't we say that Louis and Francis are carriers?Whachamacallit 19:48, September 22, 2010 (UTC)

I was the one who added the "Confirmed Carriers" section earler today. I originally had all 4 survivors as confirmed but then remembered only reading that the Doctor had really only revealed this to zoey and bill. That's why I changed it. I mean, I'm 99.9% sure they're also carriers but at the time I wrote it, it seemed that there was a lack of proof. Up until the recent comic, the carrier article itself was majorily conjecture so since it's in the process of becoming canon, I figured I should be as accurate as possible. But honestly, it would be easier to just confirm all Francis and Louis as well. I'd say do it. Shawty71 20:58, September 22, 2010 (UTC)

I guess. I mean before the Alarm is raised, Louis reacts as though he's just been told he's a Carrier as he says Francis may be the only one he can be with without killing him. What I wanna ask is that Jeff and Annie (The Soldiers) are travelling with whom we believe to be Carriers. Should we class those two as well? Chris Thorpe 21:02, September 22, 2010 (UTC)


 * PS, I would like to refer to this page's bottom-left panel where Jeff and Annie converse with each other. Chris Thorpe 21:08, September 22, 2010 (UTC)

From what I read, I was pretty certain they were carriers too. I think we should edit that in. Imperialscouts 21:12, September 22, 2010 (UTC)

Hypothesis Regarding Carrier Genes
This is my hypothesis regarding the genes for carriers, though I don't claim to be an expert. My hypothesis is that the "Carrier Gene", described by the Doc as passed down the male line, is a Y-linked gene. Such genes are rare, and only expressed in males. This explains the relative rarity of Carriers, and the fact that 75% of playable characters are male. As for Zoey and Rochelle, I suspect that a rare recessive gene exists which also causes immunity. Zoey's mother, for example, carried one recessive gene for immunity, but this was not enough. It may turn out that this immunity is different from the immunity of Carriers - a fact which may be discovered in part 3, when the Doc gets around to testing Zoey's saliva. As well as genetics, part of this theory is based on narrative convenience - it would be quite dramatic if it turned out that Zoey has a previously unknown form of immunity

Another possibility is that there is a single Immune/Carrier gene. If this gene were X-recessive, it would mean that Zoey's father was immune, while her mother only had one copy of the gene. The chance of a woman having this immunity would be 1/X^2, where 1/X is the probability that a man carries the immunity. If fewer than 10% of males are Carriers, less than 1% of females would be. As 25% of known and probable Carriers are female, I disagree with this hypothesis, but thought it worthwhile to bring up for comparison. Chamale 04:32, September 23, 2010 (UTC)

I understand that you're not an expert, but I am so please don't be offended when I tell you why that wouldn't work (although you were on the right track). Y-linked genes are not rare since they are the definitive sex-linked genes for a male. Zoey apparently has the carrier gene (since the Dr. says it to her) so if it is a hereditary father-daughter transfer, than it sounds like an X-linked recessive gene. It can't be a Y-linked (unless Zoey is a XXY which I find hard to believe) BUT, it technically couldn’t also be just an X-linked recessive either. Otherwise, it would be hereditary from the mother as well. So now we have to find a genetic trace that links father-daughter, AND father-son. This is problematic because typically a hereditary abnormality linked to the father affects the daughter, or son, but not both. Remember, the daughter ONLY gets an X from the father, and the son ONLY gets the Y from the father (outside of polyploidal examples). Therefore, any hypothesis that claims the carrier gene is solely a sex-linked gene is incorrect

But that doesn’t explain how it could work which I know was the point of your post. My hypothesis is that there is a third recessive gene involved that is not sex-linked but works in concert with the sex-linked genes. But that’s not enough, this gene also has to have a genetic factor that prevents a female from passing it on (maybe a problem during meiosis?) otherwise the gene contradicts my explanation above. Let’s put this hypothesis to work then. In this example, we’ll say that this third part of the "carrier gene complex" will be known as igf where “i” indicates carrier inhibition of infection (we’ll also assume it is recessive). A carrier is someone with a single allele (two alleles would require heredity from mother) of the igf recessive gene which link to both sex genes. A father is a “carrier” so his genes are gf-X (from father's mother) and igf-Y (from father's father). 2nd generation goes as follows: without regards to the mother’s genetic contributions, his children could be one of the following (where “gf” indicates non-carrier):

Daughter A: gf-X (Non-carrier)

Daughter B: igf-X (Carrier)

Son A: gf-Y (Non-carrier)

Son B: igf-Y (Carrier)

So, in the case of Zoey, her genetic punnet square would be gf-X from mother, and igf-X from father. Since it only takes one igf allele, Zoey is a carrier. As for Francis, Louis, and Bill, they would be gf-X from mother and igf-Y from father and would also be carriers. Realistically, this is a more plausible explanation unless someone points out something I overlooked (which of course is always possible) but I think you get the point. Shawty71 21:43, September 23, 2010 (UTC)

Shawty71, thank you for the input. It's nice to have an expert weigh in on any topic. You have figured out the genetics for immunity, if there is only one type of immunity. However, I think you haven't addressed the other hypothesis I raised, which is that two types of immunity exist - Carrier and fully immune. I'll call it the two-immunity hypothesis. It's based on my simple understanding of genetics, where I assume that 1 gene can completely determine whether someone is Immune or just a Carrier. The hypothesis is also based on dramatic license - as the Doctor never got a chance to test Zoey's saliva, it may turn out much later on that she is fully immune. I'm guessing that the Doctor hasn't tested any other females for immunity.

According to my two-immunity hypothesis, Carriers are those with a dominant Y gene which makes them remain sane when infected, but contagious to others. Obviously, only males could be this kind of carrier. Females who are immune get their immunity from a pair of recessive genes on their X-chromosomes. Zoey's mother Carolyn was not immune, but carried the recessive gene for immunity. Zoey's father also had this gene on his X-chromosome, but may not have been immune.

It's possible that Zoey and Rochelle are fully immune, rather than Carriers. If Zoey's test results reveal this, it would provide good evidence for the two-immunity hypothesis. If Rochelle's father had turned into a zombie, it would contradict the Doctor's statement that immunity is inherited from the father. Another possibility, still part of the two-immunity hypothesis, is that immune females are still Carriers despite having different genes for immunity.

You've firmly established the one-immunity hypothesis, so please let me know if there are any flagrant errors in my two-immunity hypothesis. Both hypotheses are highly speculative at the moment, but it would be good to establish some testable predictions before Part 3. Chamale 03:42, September 24, 2010 (UTC)