Latency in DNA viruses is absolutely FASCINATING !
[ABers can get up and walk away when they get bored]
There is this stuff called chicken pox which most children get - and it gets absorbed somehow into a few cells when the children recover ( = becomes latent ). The child-patients can infect other children ( = CP is a contagious [catching] disease )
and when it (the CP virus) is reactivated - you/one gets an attack of shingles.
So ya dont 'catch' shingles - you reactivate your own shingles virus.
And so you dont 'give' other people shingles - but since it is a cp virus you can give them if they are uninfected, chickenpox - and that has been done a lot.
hence shingles aint catching but it is contagious (for chickenpox and is a transmissible agent)
How do I know ? I was a techie on this:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2072792/
Herpes simplex is 'easier' - the first cold sore may be sudduv more serious (= herpangina) and then the virus becomes latent in the the nerve supplying the skin with the rash. It is reactivated not by contact with other herpes sufferers but with temperatures, sunlight. Lots and lots of herpes when Popey celebrated Mass in Heaton Park in bright sunlight. If you are susceptible to herpes cold sores then the chance of reactivation with classical (pneumococcal) pneumonia is 98% but only 67% in malaria. Amazing what colonial doctors did with their time in the late nineteenth century. We found antibody levels for herpes simplex was 20% at age 20, 40% of the population at 40 years and 60% at 60y, which for the last fifty years I have always thought was low. Completely uncommected with chance of reactivation and re-expression.
and and and quite by chance given my interest for an early age about latency of DNA viruses, I found out a a few years the fella who did the Chicken-pox / shingles bit was none other than my father's senior partner Edgar Hope Simpson - well he kept that quiet in the 1940s I can tell you !
see:
http://en.wikipedia.org/wiki/Robert_Edgar_Hope-Simpson
Oh god I havent covered the skin transplantation experiments: they transplanted skin subject to herpes to - you know the ear or the shoulder and then waited for reactivation. Would it be shoulder ? shows the virus was latent in the skin cells - or would it be the same original place where the rash was ? implying latency somewhere else perhaps the nerve.
and and and herpes was reactivated in the original place - and everyone fell about wondering what the hell was going on.
we did all this because the Govt of the day wanted to know if the vaccine supply was infected with unknown latent viruses. A question that has resurfaced recently - you know with the great unwashed screaming down a Beeb microphone: 'and if we give the kids killer MMR, we don't know if they will later grow horns, spawn frogs instead of kids etc etc.'
we knew the answer in the seventies - they won't
the vaccine cell supplies are clean.
very interesting series of experiments in cell culture with cell fusion and sendai virus........