It has been shown that infectious agents such as viruses often exert a dramatic effect on their host cell's genome architecture. In many cases, viruses induce methylation of host DNA sequences in order to enhance their infectivity. What specific host gene functions would you consider as strong candidates for such methylation by infecting viruses?

Video transcript

Hi everyone. Welcome back. Let's look at our next problem. It says blank prevents viral gene transcription replication acting as an antiviral defensive mechanism. So let's recall that of course viruses get into host cells and then their own D. N. A. Is incorporated. Um Or if they're retroviruses there are N. A. Is reverse transcribed into DNA. Which is then incorporated into the host DNA. And for the virus to keep on in its life cycle and keep on infecting the host. The viral genes need to be expressed along with the host DNA. But research has shown that that organisms have a defense against this. Um And when we look at our answer choices choice B. DNA methylation has been shown to prevent viral gene transcription and replication. So we recall from our content video that DNA methylation is when a methyl group is added to either a C. Or an A base in the DNA strand. And it has been found that in fact D. N. A. Hyper methylation um prevents the majority of viral uh retro jeans and retro transposon uh makes them silenced in the human genome. So DNA methylation is therefore an antiviral defensive mechanism since its silences that viral gene transcription, shutting down that infection process. So let's just look at our other answer choices to see why this isn't correct why they aren't correct choice A. Is reverse transcription and that's that process by which our N. A. Gets converted. It's converted into D. N. A. This takes place when retroviruses in fact an organism. Retro viruses use RNA to store their genetic material and when they infect a host cell um reverse transcriptase um generates a DNA molecule from the RNA of the virus that then gets incorporated into the host DNA. So reverse transcription is that process but it's not an antiviral defense mechanism. It's part of the process by which retroviruses infect something. So that's why Choice A. Isn't correct choice C. DNA replication. Um That's a pretty easy one to eliminate. That's just you know, DNA is process of copying itself and is not used as an antiviral defense. Choice D. Is based substitution. Um This is a form of DNA mutation. Not a way of defending against viruses. Just a mutation where one base is switched out for a different base. Um So this is not a method of defense against viruses. So again it's Choice B. DNA methylation which prevents viral gene transcription and replication acting as an antiviral defensive mechanism. So you in the next video