(?)Herpes Simplex - Reinfection

[Ian A. York]

In article <3e82pt$o3c at ixnews2.ix.netcom.com> jrbrady at ix.netcom.com (James Brady) writes:
>
>What are the consequences of reinfection of the herpes simplex virus by 
>someone already infected.  That is, if an infected person who does not 

	You've asked a good question.  In the great majority of cases, 
the already-infected individual will be immune to reinfection.  People 
infected with HSV generally have a very high level of antibody to HSV, 
and this antibody is capable of neutralizing extracellular HSV.  
Infections are initiated with extracellular HSV, so pre-infected people 
are rarely re-infected.  (Antibody is not efficient at neutralizing 
reactivating HSV, because in that case the virus can complete its life 
cycle and spread to adjacent cells without ever coming in contact with 
the extracellular medium and antibody.  Antibody probably limits the 
reactivation, and cellular immunity also limits the infection to a 
considerable extent.)  However, there are cases of people who have been 
infected with more than one virus, based on genotyping the viruses 
present.  In this case, I would expect the new infection to be mild, 
because pre-existing immunity should limit it as well.  (There is enough 
cross-reactivity that I would expect HSV-2 superinfection of HSV-1 to 
also be limited, and vice-versa.)  There could well be more than one 
virus hanging out in sensory ganglia.  Based on in vitro experiments, 
infection of a neuron which is already latently infected might induce 
reactivation of the latent virus, so it's possible that there would be a 
reactivation as well as a re-infection, if you follow me here.  However, 
I don't know that this has actually been shown in vivo.  If it was me in 
that situation, I would consider myself fully susceptible, just from a 
standpoint of caution (even though several years of research on HSV have 
left me with a screaming-hot anti-HSV immune response).  
	I'm not an MD, so there may be some clinical information I'm not 
familar with.  Hope this helps, anyway.

Ian
-- 
Ian York   (york at mbcrr.harvard.edu)
Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
Phone (617)-632-4328     Fax  (617)-632-2627