Viral evolution?

[fafalone]

Since the subject still is debatable, where do you stand and why?

[Radical Edward]

I wonder if the mechanism could be in some way be related to the takeup of mitochondria.

[fafalone]

The endosymbiotic theory about mitochondria supports the idea of organisms becoming less complex, but takeup of what by them? Viruses don't take up anything.

[aman]

A driving force for viral evolution sometimes depends on the host infected. Slight differences in hosts like malnutrition or vitamin deficiency can cause a virus genome to change by a small percentage to adapt to host deficiency.

Just aman

[fafalone]

My question is more towards the origin of viruses rather than the driving force of continued evolution. Obviously that force is random mutations during reverse transcription or translation.

[aman]

Since the smallest bacteria genome that can reproduce is over 2X the size of the largest virus, and a virus can't reproduce without parasiting the bacterias structures for reproduction, the first conclusion I see is that virus came second. Is that a good guess?

Just aman

[fafalone]

Good guess, it's the best we have, but like this thread is about, there's other theories

[aman]

Looking at fossil records we can find very ancient and simple bacteria fossils but is there such thing as a virus fossil? It sure would help in figuring this out.

Also maybe bacteria evolved in the rich enviroment on Earth and a virus could have evolved in space.

Is there evidence of proto-bacteria in the fossil record or any found in research of sulfur-acid caves or black smokers?

You'd think a proto-bacteria would resemble a virus.

Thanks Fafalone for the question. I have some research to do.

Just aman:dunno: :dunno: :dunno: :scratch:

[Matzi]

Hallo!

 

I think this is a very interesitng question and answering is not that easy for me.

 

Actually, viruses do not live but they need cells to replicate in (either prokaryotic or eukaryotic) (another question might be: What evolved first: phages or viruses?). I think it's in a way paradoxical that a complex of molecules defined as non-living evolves from a living cell.

On the other hand, I do not think that a combination of molecules is that unlikely since that's the way life evolved and why shouldn't viral complexes have evolved this way, either.

 

Matzi

[Radical Edward]

well the virii are generally too complicted to have merely come about by chance, as in, come about cindependently of life. faf's conjectre is probably the best, since however it happened, a virus that occured as a result of a mutation in some bacterium would have all the nescesary tools to hand in order to manipulate cells, and control the internal cellular machinery.

[Matzi]

Ok, you are probably right. There is a great amount of parallels and details viruses and cells have in common.

[invisiblebrain]

i have my own theory.....

 

i think there was a step in the evolution when something similar to viruses (call them protoviruses)came to existence,but they had the metabolic enzyme machinery.........,they survived and further evolution gave bacteria.............and one day the bacteria gave rise to viruses ......these viruses which had some unique advantage over protoviruses killed them and survived back.....huh seems much related to the 2nd option but still would explain its closeness to 1st one

[Sayonara]

All you people using the word "virii" are going to be beaten to death with a Latin dictionary, I hope you realise that

[Skye]

The origin of plasmids from bacterial genomes is a little easier to accept, and perhaps viruses picked up from other bacteria or luckily evolved some protein coding ability from there. Just a sleepy guess.

[YT2095]

I always thought Virus` came from multicellular organisms like ourselves.

we dump millions of dead cells each day, skin, hair, scat, etc...

each cell contains DNA, either whole or in part.

as we know DNA is the basic building block of life, just like transistors are for radios or computers, with this "rogue" dna or fragments, already in a host, the probability of part of it maintaing itself to form another organism isn`t all that difficult. like cancer cells are just normal cells with a corrupt part in the DNA chain.

that would help explain also why virus` are normaly found in areas of the body that create the most dead cells, feces, nasal etc...

 

I didn`t realise until reading this thread, that no one actualy knows, so my thinking maybe false, it`s just the way I always figured they came about.

Back to the drawing board

[Skye]

K now you have to deal with me a little drunk...hic.

 

There's a few things that make them tricksy. They are too small to have left any fossils we are able to distinguish, which only leaves modern types to deal with. While there's a good chance they originated from cellular life, their rate of evolution make genetic comparisons difficult anyway, especially considering they may have diverged long ago. They probably evolved more than once, as the differences between different types of viruses are pretty substantial. If so, these different types have branched out into parasitising a variety of different types of hosts.

 

So while it seems likely they originated from cellular life, probably several times, it's very difficult to go much beyond conjecture.

[YT2095]

"So while it seems likely they originated from cellular life, probably several times, it's very difficult to go much beyond conjecture"

 

well it just seemed the most logical path to me (I could actualy be quite wrong however).

 

I don`t think we`ve seen the last of the new virus` either, for as long we keep dropping dead cells, there will always be that potential for a new virus`and different strains of already existing ones while there are still hosts to be "had".

[atinymonkey]

Your safe from your dead cells, they aren't going to raise up a viral army against you. They encorage bacteria growth though, so don't stop cleaning them up.

 

But yes, new virus strains appear all the time, hence the thread and the inability to cure the common cold.

[Hades]

Lets take for example that a virus existed before any form of microbial life... what would this virus host itself upon? Another virus? That virus does not have the needed organelles to produce copies of the original virus. The virus, whether alive or not which is not the topic of this, still has the need for self preservation, so to speak. It would not benefit the viral population in any way to feed of one another, it also doesnt explain how if a single virus evolved from simple chemicals that MORE than one virus was spawn in the same manner.....

The genome that codes for a virus is far too complex to have originated uniquely, alone, before dna/rna was used as a coding device in microbial life. My personal opinion? It could be that in some cells, be it bacteria.. protists.. animals... perhaps in one cell of this species, a terrible genetic mutation took place making the cell either undergo lysis, or, as far fetched as this sounds, package the genome into a vesicle and then be released thru exocytosis. It would explain how, and why a virus would be able to undergo recognition with very specific cells, and why their capsid/gp120 containing spikes are compatible with the host cell. Bu who am i to say? I enjoy everyones opinions and hope u do mine as well.

[rakuenso]

Maybe viruses were weapons of mass destruction used by cells against other cells =P

 

Of course on a more serious manner, for a virus to have evolved in the first place. The gene coding reverse transcriptase would have been essential. As to how the gene originated is beyond me. It might have been a mutation of the telomerase gene due to the similarities.

 

The capsids might have came from a malfunction during exocytosis where the mutate reverse transcriptase protein accidentally got in. The malfunction during exocytosis should still allow cells recognize the capsid as one of "its own". However one problem with the exocytosis theory is that it doesnt retain any of the receptors (I think)

 

 

my 2 cents