Integrated HIV Successfully Cut Out of Human Genome 185
Chris writes "German scientists have succeeded in snipping HIV out of human cells after it has integrated itself into a patient's DNA. The procedure is a breakthrough in bio-technology and fuels hope of a cure for AIDS. The group is only cautiously optimistic, though, as treating a full-on infection would be substantially different than succeeding in a controlled lab environment. 'Researchers ... began with the bacterial enzyme Cre recombinase, which exchanges any two pieces of DNA flanked on either end by a certain pattern of nucleotides (DNA subunits) known as loxP. HIV does not naturally contain loxP sites, so the team created a hybrid of the two DNA molecules, which they used to select a series of mutated Cre enzymes that were increasingly able to recognize the combined DNA. The final enzyme, Tre, removed all traces of HIV from cultured human cervical cells after about three months, the researchers report online today in Science.'"
Re:Translation, please. (Score:5, Informative)
Re:Seems like cheating (Score:5, Informative)
Re:Seems like cheating (Score:5, Informative)
Re:wild idea (Score:4, Informative)
Your method has been tried, in a way. A patient's blood was essentially flushed with healthy blood from donors, so his whole blood was exchanged. It did no good in the long term, because the HIV infects also macrophages in other tissues than blood. The next wave of the infection came from those macrophages.
Re:Translation, please. (Score:4, Informative)
Re:Translation, please. (Score:2, Informative)
beckerist
What exactly is this "Tre" then? I see it's an enzyme, but I guess I'm still a bit confused. Cre acted as a catalyst to procure a specific reaction for a specific DNA sequence? Is that an attribute of the chemical composition of the enzyme, or, well...I guess I really don't understand where that came from. Is it a specific enzyme, or is "Cre" the name attributed to ANY enzyme that acts in this way?
Tre is simply their name for the "evolved" Cre enzyme. Cre is a one of many site specific recombinases/integrases. others include FlpE and PhiC31. they each have specific dna sequences that they recognise and most are derived from bateriophages (a kind of virus that infects bacteria). the bacteriophages use these enzymes to insert dna into the genome of the bacteria that they infect.
OK, so with that, what is Tre? The same type of enzyme with a different chemical composition? The reason I'm asking this is because, if I'm interpreting this correctly, this could have very far reaching ramifications! I can imagine this (enzyme? process?) being used to cure just about ANY virus infection....
These enzymes are encoded by proteins. they made alterations to the amino acids coding for the cre protein and then selected for modifications which could cut the HIV coding sequence as well. in theory, yes the process could be used to generate enzymes which can recognise dna sequences coding for a whole range of viruses but as usual life is not that simple. for a start delivering the enzyme to all the infected cells is a huge challenge. secondly, you would have to be pretty certain that the enzyme recognised with extremely high fidelity the sequence that you wished to cut out or you would end up chopping chunks out of the host genome at random (many of these enzymes have what are called psuedo recognition sites cattered around the genome of most mammals - phiC31 is particularly bad for this.
Lux
But I have to say that I disagree about needing to be careful about the number of infections in the host cell. HIV infects differentiated cells that do not naturally reproduce, so mutagenesis leading to cancer is unlikely, and killing infected cells is very nearly as useful as curing them. The body can/will always make more.
you are correct that hiv is very good at infecting non dividing cells (for this reason viruses based on hiv are used routinely by researchers to infect a range of cells, both dividing and non-dividing). however the translocations which I mentioned earlier are capable of generating oncogenes (essentially cancer initiating genes) by bringing a gene on one chromosome next to a gene on another chromosome to form a fusion of the pair. the philadelphia chromosome present in some leukemias is a good example of this (BCR-ABL gene). such translocations appear to be able to initiate proliferation in non-dividing cells