why all mutations are favorable for hiv ?

Question

we know that mutations occur in hiv.. but why all are in favourable for virus.i mean why its stucture is not changing? . i heard env gene is the most mutated gene in hiv... then its stucture should change and its capacity to bind to t lymphocyte should change no?????

Answer 1

MOST VIRAL MUTATIONS ARE NOT FAVORABLE FOR HIV! they nearly always result in a loss of fitness in one way or another. Scientist know this when the create specific mutations in the virus- most of them flop.

THE ONLY MUTATIONS WHICH ARISE IN A POPULATION OVER TIME ARE THE ONES WHICH CONFER AN ADVANTAGE- you simply never see the disadvantgeous mutations because they are selected AGAINST. This is the law of mutation and natural selection.

there is good evidence that even drug resistance mutations reduce other replication kinetics of HIV, making the emergent viruses less fit in another way.

Regarding ENV mutations: you will see more rapid evolution (more mutation and substitution) in a protein which is not highly CONSTRAINED- that is- almost any change in POL might seriously cripple the virus, but ENV is relativley free to change without critical damage. Clearly, however, if you alter the essential properties of ENV like CD4 binding, the virus fails.

http://en.wikipedia.org/wiki/Natural_selection
http://www.stanford.edu/~siegelr/philhsu.htm

Answer 2

Viruses and bacteria multiply frequently making mutations frequent as well. Mutations are even more frequent because the replication process is rather "sloppy" and it allows for mutations to occur. It does seem that all mutations are favorable, but the simplest way to account for that is that the less favorable mutations result in virus that cannot replicate, think survival of the fittest. Additionally, as we medicate and treat HIV patients our anti-virals kill those virus that have not mutated but have little effect on the mutated viruses almost selecting for the mutated virus to continue to thrive. You're right in thinking that if the structure of the virus continually changes, eventually the virus should be ineffective, but because it replicates so frequently and not, rapidly there is always a generation to carry on the virus. A final account for the continued survival is that virus can go into a remission of sorts and stay dorminate for years until becoming clinically detectable in the blood. Mutations are minimized by using several medications that all work differently to prevent replication.

Answer 3

Maybe, but those mutations just die out and the other successful mutations keep ravaging. It is favorable to mutate because it is very difficult to treat something that is always changing. You may find "the cure" to one strain of HIV and then the virus mutates and the cure no longer works.

Answer 4

for some reason, the HIV virus just seems to keep improving itself, which for us is bad, but which for the virus, is favorable. it seems to just keep getting trickier and trickier to treat, and adapting itself to changes in environment, drugs, everything...you would think that somehow with all the medications we have now to treat HIV that it would somehow mutate for the worse, but it hasnt, and from anything i have read, researchers dont have a very good idea why - it surely is puzzling.