|MadSci Network: Virology|
Hi Alexis, What makes herpes incurable is that it hides itself very well from the immune system and that once someone has caught it, it remains inside that person's body forever. Herpes simplex virus (HSV) infects epithelial cells (skin cells) and replicate in them quite rapidly but the immune system fights off the infection in about two weeks because the replication is high and that HSV does not "hide" in skin cells. During the first infection, however, some viruses also infect sensitive nerves near the site of infection and are transported along the axons to the neuron itself where it enters a latent stage. During this time, the virus' DNA is circular and the virus does not express any of its proteins, which makes it "invisible" to the immune system. Following reactivation of the latent virus after, for example, exposure to cold, UV light, stress, or if the patient becomes immunocompromised, the virus migrate again towards the epithelium along the axons to infect epithelial cells and cause lesions. Once a neuron is infected, it remains infected for the rest of the person's life and, depending on each individuals, reactivation can occur once, twice or up to 20 times a year... or only once every 5, 10, 20 years! The only thing doctors can do to help patients with herpes is to limit the replication of the virus using antivirals that targets HSV specifically. Some drugs already exist on the market for that (in Canada at least...). The topic application of these drugs reduce the length of the reactivation events by 5 to 7 days (so that people suffer 1 week instead of 2...). Infected people can also help themselves by limiting their exposure to the reactivating agents and to keep their immune system strong. Scientists try to come up with new ways to fight off HSV by developing agents that boost the immune system during a reactivation event, or even maybe a vaccine. A vaccine against HSV is very hard to develop since it is a very sneaky virus so that it may be quite a while before one comes available. It seems possible though! So there is still hope to find a way to prevent HSV infection, if not to cure it altogether. I hope this answered your question. Sincerely, Mike
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