Part II - The Gift That Keeps on Giving
It's the middle of the semester and you are very stressed about the upcoming exam and paper you have due. You
begin to feel that pesky cold sore developing on your lower lip. It has been happening for years, mainly when you get
run down. You realize you are not alone in your dilemma and that over 50% of adults have cold sores (oral herpes).
Though you have spent many waking hours wondering where you got the virus from, you have never figured it out.
What bothers you most about the situation is how your body allows for the virus to keep causing the symptoms. You
know the virus remains latent in nerves, but why would your immune system allow the virus to reactivate and cause
you so much discomfort, over and over and over again?
Herpes viruses have the somewhat unique ability to remain latent (dormant) and stay with an individual for the
rest of his or her life (Le., no one is ever cured of a herpes virus). Herpes Simplex Virus-1 (HSV-1) is the virus that
causes cold sores and remains latent in the nerve ganglia. While in the latent phase, the virus is not producing active
viral particles. Therefore, the only time the host sees HSV-1 antigens is after reactivation and active seplication of the
virus in epithelial cells. Since the immune system has already seen HSV-1 during previous cold sores, HSV-1 has a
very small window of opportunity to replicate and specad prior to memory immune response recognition. To expand
this window of opportunity, herpes viruses have developed a set of evasion genes that "down modulate the immune
Questions
1. As described above, HSV-1 has two infectious stages within the body: active replication and latent infection.
Immune evasion genes are critical during active replication. What is the procem by which HSV-1 replicates in
epithelial cells?
2. Reactivation of the virus often occun during times of stress. Why might this be the case?
3. How does HSV-1 evade the immune system to allow itself time to replicate? Critique your ICP67 diagram from
the homework asignment, and explain the function of your other assigned gene to your assigned peer group
