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Smallpox From The Past
An anonymous reader submits "Earlier this year, librarian Susanne Caro was looking through an 1888 book on United States Civil War medicine and discovered a small envelope labeled 'scabs from vaccination of W.B. Yarrington's children' and signed by Dr. W.D. Kelly, the author of the book. After a bit of research, she realized they might be smallpox scabs used in early live vaccination methods and contacted various officials including the Centers for Disease Control and Prevention. The CDC was excited by the find, because it gives them an untreated specimen from over a century ago, and a chance to look at the disease's evolution. Although the FBI had concerns that the smallpox may have been planted in the book, most of the researchers believe the scabs are too old to be dangerous, and they fear they may not even be able to yield live smallpox."
If the virus is nothing but the DNA and a protein coating around it, why are the people wanting it to be live ?
Am I missing something ? What am I missing ?
They are probably referring to whether or not the DNA information is sufficiently in-tact. If the DNA is too far destroyed, the virus probably won't be able to reproduce itself even after infecting a live cell.
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*beware the cute-bunny virus
In this context, "live" virus is able to infect and reproduce. "Killed" virus has been damaged to the point that it cannot infect a cell. Hence the concern over using "live" virus vaccines - the vaccines use a damaged or weakened virus that the body can easily defeat - but occasionally a few full strength particles get through and trigger the disease instead of vaccinating against it. "Killed" virus vaccines use fragments of destroyed viruses, ensuring you can't get sick from them, but possibly not as effective as the live kind.
Clear, Dark Skies
If the virus is nothing but the DNA and a protein coating around it, why are the people wanting it to be live ?
Am I missing something ? What am I missing ?
I think they just mean viable, not really "live", since "live" has a weird meaning for a virus. If they couldn't find live virus samples, then either the virus wasn't there, or it was, but is now "dead", in the sense that it can't work anymore.
True, viruses are just dna and protein, or something like that... Collections of complicated chemicals, basically. They can still degrade, given enough time. Heat them up enough, they will "die", by having their molecules scrambled, etc...
But, IANAChemist, nor a biologist, so take my words with a grain of salt.
But, IANAChemist, nor a biologist, so take my words with a grain of salt
Well, I am a Biologist and your answer is right!
The basic unit of life is the cell. Anything subcellular is not considered "alive" by scientific standards.
-DD
You're missing the point entirely. Their first act was to ask who had the book. They then put the envelope in a PAPER BAG and MAILED it to a laboratory? What kind of idiocy is that? The first thing they should have done, is quarantine the envelope. Then they should have asked who came into contact with it in order to make sure nobody was infected. Asking whether a borrower could have planted it is just kind of dumb. They should use common sense, just like every other damn law enforcement agency out there. I'm sick of these idiotic conclusions the agents immediately draw (think Wen Ho Lee).
If the virus is nothing but the DNA and a protein coating around it, why are the people wanting it to be live?
Am I missing something? What am I missing?
As a card-carrying virologist let me give you a run down on the information you're missing. If you don't consider the type of nucleic acid (RNA or DNA), there are two types of viruses that infect mammalian cells - enveloped and non-enveloped. Enveloped viruses (such as smallpox) have an outer lipid bilayer (the envelope) that is studded with glycoproteins that need to bind specific molecules on the surface of mammalian cells to permit fusion between the viral envelope and the cell membrane. Fusion allows the virus' nucleic acid to enter the cell. The viral envelope is very fragile, and breaks down rapidly when dried. When the envelope breaks down, it spills the contents of the virus out -- i.e. the nucleic acid, which in the absence of the envelope doesn't have a means to specifically enter a cell. This is one reason why wiping surfaces with 100% ethanol (a dehydrating agent) is quite effective against enveloped viruses like HIV.
Even viruses that are not enveloped have protein coats that directly interact with cell surface molecules that act as receptors to mediate the entry of these viruses into cells. The proteins that make up these coats also denature (lose their proper shape) with time, although this is typically a slower process.
Finally, how stable is the viral nucleic acid? Viral nucleic acids are typically not present as naked RNA or DNA, but in a complex of DNA or RNA with proteins that coat them. These coated nucleic acids are quite stable. Nucleic acid from DNA viruses (like smallpox) is likely to be more stable than nucleic acid from RNA viruses, and I'm guessing that they should be able to do phylogenetic studies on the strain of smallpox present in those scabs after amplifying recovered DNA by PCR.
BTW, after many years of Slashdot lurking, a wee bit of horn tooting. My lab works on how the genome of EBV latches on to human chromosomes. Here's a pretty picture from our work that was on the cover of the Journal of Virology last month.