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Ebola Vaccine Human Trials Begin
securitas writes "The Washington Post reports on the first human to be injected with '100 trillion strands of synthetic' Ebola DNA. The DNA in the vaccine has been bioengineered by Vical to remove 'the part that triggers illness and the part that might allow the DNA to recombine with the DNA of some other virus.' The New York Times, AP via ABC and BBC all have stories about the new vaccine as the WHO reports 11 dead in a new Ebola outbreak in Congo this week. If you're interested in participating in the Ebola clinical trials, the NIH needs 27 volunteers. The study only has two. Best quote comes from the NIH vaccine center's nursing director: 'People freak out about Ebola.' Slashdot previously discussed an Ebola/HIV gene therapy."
Deadly yes, but are the chances of contracting it anywhere near the chance of being killed by the vaccine? When the mortality rate from the prevention is greater than for the actual disease NOT taking the vaccine is the rational decision. This is why they stopped giving smallpox vaccine to children in the 1970's - more children were becoming ill and dying from the vaccine than from smallpox.
Well, given that ...
am I the only one that isn't surprised that people "freak out" about it?Avantslash - View Slashdot cleanly on your mobile phone.
The candidate vaccine is synthesized using modified, inactivated genes from Ebola virus. This gives the immune system information about viral structures so that it can mount a rapid defense should the real virus ever be encountered. There is no infectious material in the vaccine, and the virus was not present during any stage of the manufacturing process
It's not made from the virus. Only some genes that cannot induce the disease are used.
Save the bandwidth. Don't use sigs!
apparently you didn't read the article... it's still in the testing stage (read: they're not sure exactly what it will do to a human, it may kill you)
This is a Phase I clinical trial. There are typically 3 phases to each clinical trial, with Phase III being "official" statistical study. Phase III is "gold standard" FDA phase, where you prove statistically that your treatment works.
What is a Phase I trial? It is typically used to determine a maximum tolerable dose (MTD). And how is that done? Something called "dose escalation" is used. That means you start off with a very low dose typically given to 3 patients, and if no toxicities (bad things) happen, you raise the dose. You keep doing this until you observe two toxicities in two consecutive groups (typically). Many times the volunteers in Phase I trials are terminally ill and willing to try anything.
If you are not terminally ill, perhaps waiting for the Phase III trial to join is the best bet, when they have already figured out the "maximum tolerable dose".
Dude, I so knew that Biology degree would pay off.
Ebola, as viruses go, is incredibly hard to contract. It lacks a carrier state, which means that contraction depends entirely on contact with infected secretions. Unless you're exchanging spit, bodily fluids, or blood, you're safe. As for the vaccine, stating that the "part that causes the virus to replicate" is removed if superfluous. A vaccine by its very nature is a pathogen modified to restrict replication, and in the case of Ebola, that means the ability to attch itself to your RNA, and manifest itself. The only danger from the vaccine would be isolated to the vaccine itself, NOT Ebola Hemorrhagic Fever.
>it may kill you
So may anything else. Vaccines are a hell of a lot more safe than the actual virus, obviously, but what you may not realize is that, statistically, experimental vaccines are probably safer than crossing the road.
barzelay.net
Those of us old enough exposed ourselves to the smallpox virus. The fact that most /.ers have NOT had a smallpox vaccine is a testament to the effectiveness of this method of vaccination.
Polio vaccine is the same deal.
We already have a tuberculosis vaccine - the BCG - which is given to all schoolchildren in the UK at around age 14.
What is a Virus? How does it work?
A virus is a protein sheath (called a capsid) covering genetic information. The protein sheath varies in size and shape, the most famous being the T4 Bacteriophage (picture on the bar on the left). Simply put, the genetic information can be in the form of RNA or DNA. The virus latches onto a host cell and injects its genetic material through the plasma membrane.
Viruses all have different strategies at this point, depending on their structure and target cells.
The most insidious, the retroviruses (of HIV fame), incorporate their genome into the host cell's. When the host cell copies its own DNA, in the process of normal cell division, it copies the code for the virus. Each daughter cell resulting from this mitotic division carries the virus latent in its own DNA. They now, in their normal life cycle, become factories for the retrovirus, pumping out more and more protein encased genetic sequences. Propagation is very thorough.
A simpler virus might only borrow the mechanisms of the cell to replicate itself. The virus would use DNA polymerases and associated enzymes to copy the genome for the viral offspring and RNA polymerase to transcribe mRNA molecules to translate to proteins for the viral capsid. The baby virii are then assembled (the DNA wrapped in the protective capsid) and they exit the cell. Sometimes this results in the death of the cell, other times it does not. The virus doesn't much care whether the cell survives once it has been copied.
The body, however, doesn't take kindly to its cells being hijacked. It doesn't matter if the viral infection doesn't result in the death of any cells. An infection is inefficient; a virus uses a lot of the cell's energy, energy that could be better spent in normal functions. Here's where the immune system comes in.
How does my immune system protect me from Ebola ?
Proteins are the real workhorses in cellular biology. As far as molecules go they're about as diverse as it gets; almost everything a cell does it does with proteins. A protein is coded for by a gene, a sequence of base pairs in the genome. When we make a protein we tend to make more than one at a time (one type of protein, multiple copies). One or more copies in the set get paired with another protein. This other protein, called MHC, has the sole purpose of escorting its pair to the surface of the cell and holding it there. The surface of the cell has hundreds of proteins of various types sticking out. When a virus instructs a cell to make its proteins the cell follows normal procedure and sends some of them to the surface.
The immune system is incredibly complicated. A subset of it is the T cells, which are themselves divided into two groups, Helper T Cells and Cytotoxic T Cells. Cytotoxic T cells are easier to describe; they're often called assassin cells or natural killer cells. Their purpose is to kill anything foreign that they find in the body. The Helper T Cells each have proteins on their surface (called antibodies) that recognize one target (called an antigen). They wander around, checking out all of the other cells in the body, looking for a match. If a Helper T Cell was looking for EVP-1(Evil Virus Protein 1) it would ignore every cell that didn't display EVP-1 on its surface.
If they find a match they know that the cell is infected with Evil Virus, and they signal for the Cytotoxic cells to come do their job. They also reproduce. So imagine you have a million Helper T Cells with random antibodies on their surface. You're betting on the one cell that is looking for EVP-1 into a cell that happens to be infected with a Ev
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"Little genetic errors"?
They're removing two whole genes. Viruses only have several to begin with. Your own junk DNA is littered with the DNA of several thousand extinct endogenous retroviruses that have lost one or two critical genes. Ebola, being a filovirus, lacks reverse transcriptase and cannot even look forward to a career as a dormant junk DNA sequence.
Your body sees the proteins expressed by the foreign DNA, creates antibodies, and that's it. The DNA does not replicate. Evolution requires successive copying operations (paired with natural selection) and does not apply to this process.