Where did viruses come from?

[Incendia]

Hello probable human.

 

I want to know where virus came from.

[Moontanman]

Hello probable human.

 

I want to know where virus came from.

 

You can start looking here.

 

http://en.wikipedia.org/wiki/Virus

 

 

Regressive hypothesis

Viruses may have once been small cells that parasitised larger cells. Over time, genes not required by their parasitism were lost. The bacteria rickettsia and chlamydia are living cells that, like viruses, can reproduce only inside host cells. They lend support to this hypothesis, as their dependence on parasitism is likely to have caused the loss of genes that enabled them to survive outside a cell. This is also called the degeneracy hypothesis.[38][39]

Cellular origin hypothesis

Some viruses may have evolved from bits of DNA or RNA that "escaped" from the genes of a larger organism. The escaped DNA could have come from plasmids (pieces of naked DNA that can move between cells) or transposons (molecules of DNA that replicate and move around to different positions within the genes of the cell).[40] Once called "jumping genes", transposons are examples of mobile genetic elements and could be the origin of some viruses. They were discovered in maize by Barbara McClintock in 1950.[41] This is sometimes called the vagrancy hypothesis.[38][42]

Coevolution hypothesis

Viruses may have evolved from complex molecules of protein and nucleic acid at the same time as cells first appeared on earth and would have been dependent on cellular life for billions of years. Viroids are molecules of RNA that are not classified as viruses because they lack a protein coat. However, they have characteristics that are common to several viruses and are often called subviral agents.[43] Viroids are important pathogens of plants.[44] They do not code for proteins but interact with the host cell and use the host machinery for their replication.[45] The hepatitis delta virus of humans has an RNA genome similar to viroids but has a protein coat derived from hepatitis B virus and cannot produce one of its own. It is therefore a defective virus and cannot replicate without the help of hepatitis B virus.[46] Similarly, the virophage 'sputnik' is dependent on mimivirus, which infects the protozoan Acanthamoeba castellanii.[47] These viruses that are dependent on the presence of other virus species in the host cell are called satellites and may represent evolutionary intermediates of viroids and viruses.[48][49]

Prions are infectious protein molecules that do not contain DNA or RNA.[50] They cause an infection in sheep called scrapie and cattle bovine spongiform encephalopathy ("mad cow" disease). In humans they cause kuru and Creutzfeldt-Jakob disease.[51] They are able to replicate because some proteins can exist in two different shapes and the prion changes the normal shape of a host protein into the prion shape. This starts a chain reaction where each prion protein converts many host proteins into more prions, and these new prions then go on to convert even more protein into prions. Although they are fundamentally different from viruses and viroids, their discovery gives credence to the idea that viruses could have evolved from self-replicating molecules.[52]

[Guest Emma]

Thx for sharing, Primate

[Incendia]

I like the coevolution one...Thank-you...

[jimfaster]

There is a thoery over there that the original virus was made by defense mechanisms among agencies earlier for other organisms competing for the same niche. In other words, genes and functions have been "eliminated" in the environment to which is attached to something else, in particular, and destroy a host. Over time, we believe that evolution has given new hosts to survive these infections is still an infection that gave the rising generation to be divorced from their original decision makers. He then directed against the virus that could develop independently of the legacy organizations.

[lemur]

Thx for sharing, Primate

What's with the categorical appellations in this thread, mammals?

 

 

 

[KagakuOtaku]

That depends on the type of virus. If it's a genetic virus, it could of come from multiple things: interbreeding, genetic mutations, damages to the psychological mind. If it's the physical virus, it's from external subjects, like: bacteria, harmful chemicals, and whatnot.

Edited March 16, 2011 by KagakuOtaku

[mississippichem]

That depends on the type of virus. If it's a genetic virus, it could of come from multiple things: interbreeding, genetic mutations, damages to the psychological mind. If it's the physical virus, it's from external subjects, like: bacteria, harmful chemicals, and whatnot.

 

Or not. Very roughly a virus is an "almost living thing" that is comprised of a nucleic acid surrounded by a protein capsid that uses other host cells to reproduce. I don't know what you're talking about honestly, viruses don't come from harmful chemicals or "damages to the psychological mind".

Edited March 16, 2011 by mississippichem

[Rip:20]

Or not. Very roughly a virus is an "almost living thing" that is comprised of a nucleic acid surrounded by a protein capsid that uses other host cells to reproduce. I don't know what you're talking about honestly, viruses don't come from harmful chemicals or "damages to the psychological mind".

 

LOL. I have certainly sustained some damages to my psychological mind.

 

Otherwise, the question of virus origin is truly fascinating because it stretches the canonical definition of life for me. Unlike cellular life, viruses (and virus-like particles) lack a set of conserved genes with which we could infer past evolutionary relationships from. Plus that virus-like behavior can be derived from DNA or RNA with or without proteins, or proteins with out nucleic acids, says to me that it is perhaps an intrinsic property of both protein and nucleic acid polymers above a certain size, and that the extant lineages of viruses (and VLPs) have multiple evolutionary origins. Think about that for a minute. This contrasts with our view of cellular life, all of which appears to have a shared common ancestor.

 

There is a thoery over there that the original virus was made by defense mechanisms among agencies earlier for other organisms competing for the same niche. In other words, genes and functions have been "eliminated" in the environment to which is attached to something else, in particular, and destroy a host. Over time, we believe that evolution has given new hosts to survive these infections is still an infection that gave the rising generation to be divorced from their original decision makers. He then directed against the virus that could develop independently of the legacy organizations.

 

This is legendary.

 

+45

Edited March 16, 2011 by Rip:20

[Kikis]

Hello probable human.

 

I want to know where virus came from.

 

Some of the scientists believed the virus was very ancient material in our universe beside the microorganism like bacteria. Both of them had been fight against each other for a million years to conquer our earth. Until new species like plants, animals, also human was appear in the earth, their attention had been averted to prey those species like that were happen till today

[Widdekind]

Viruses are 'late-pre-Life' RNA-World era, pre-DNA, genetic codes?

 

Pure RNA does not self-assemble, into strands, longer than 50-100 base-pairs (bp) (Lane. Life Ascending, p.50~). However, the basal bacteria, on the earth phylogenetic tree, all have >1.5 Mbp. And, the simplest bacteria, Pelagiobacter ubique, has ~1.2 Mbp. Such suggests, that the Last Universal Common Ancestor (LUCA), of all earth microbes, had ~1 Mbp in its DNA ring. So, pre-Life, in the RNA-world, had ~100 bp ("log 2"); whereas, proto-Life, LUCA, had ~1 Mbp ("log 6"):

 

• pre-Life (RNA-world): ~100 bp ("log 2")
  ...
  proto-Life (LUCA): ~1 Mbp ("log 6")

Now, RNA can combine with Proteins, into RNP complexes. And, 'stabilizer Proteins' can strengthen those structures (Scientific American [April 2011], p.73). And more, RNA has been interacting with Proteins, from the first efforts, of earth life. So, such suggests, that, before DNA evolved, as a "durable deep storage" biochemical 'upgrade' of RNA, protein-stabilized RNPs could have accommodated increasingly complex genetic codes, for increasingly complex bio-chemical life, before the evolution of full-fledged cells, like LUCA, at ~1 Mbp.

 

So, interpolating, between pre-Life & proto-Life, perhaps 'advanced pre-Life' had genomes of ~10 kbp ("log 4"), stored in stabilized RNP complexes. And, genomes of such length, are reminiscent of archaic RNA retro-viruses. And more, a retro-virus 'virion' super-complex, as a (colossal) combination of RNA & Proteins, is, technically, an RNP. Perhaps, then, advanced pre-Life, was (retro-)viral, employing Protein 'plate armor' protected retro-virional-like RNP super-complexes, to stably store their genetic codes, which were then thousands & tens of thousands of bp long.

 

• pre-Life (RNA-world): ~100 bp ("log 2")
  advanced pre-Life (retro-virions): ~10 kbp ("log 4")
  proto-Life (LUCA): ~1 Mbp ("log 6")

The retro-virional RNP super-complexes would have functioned only as genetic code, and would have relied on a surrounding bio-chemical system of pathways, to access and translate said code. If the RNA-world was housed, in the pores of undersea hydrothermal vents, then that bio-chemical 'support system', would have been housed, in those undersea vents.