A virus is a small infectious agent that can replicate only inside the living cells of an organism. Virology is the study of viruses.

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6answers
4k views

Why isn't a virus “alive”?

The recent news about a new supermassive virus being discovered got me thinking about how we define viruses as non-living organisms whilst they are bigger than bacteria, and much more complex than we ...
17
votes
2answers
10k views

Why don't we develop immunity against common cold?

We all suffer from common cold, and that, frequently. Why have we not developed immunity against it till now? By immunity I mean immunity as a species.
3
votes
2answers
346 views

Changing the definition of life?

Viruses at this period of time do not fit the current definition of life. Much of the reasoning behind this is that we currently believe that all life must be made up of cells. Also, many biologist/...
11
votes
5answers
402 views

Why have parasites not evolved to be harmless?

I have yet to understand why so many viruses or bacteria haven't evolved to be harmless (specifically, I don't know of any harmless virus). I think it would be greatly beneficial for a virus to ...
8
votes
2answers
2k views

How does the ebola virus attack?

How does the ebola virus attack and how do some people get away with it? Normally any virus would attack a cell with some kind of receptors and some kind of lock and key mechanism entering the cell ...
1
vote
4answers
902 views

How does HIV mutate into other strains while keeping their virulent phenotype?

How does a virus like HIV mutate into so many strains, and yet all of them are harmful to our immune system? What gives this virus the ability to mutate so efficiently?
27
votes
2answers
1k views

Why doesn't blood remain on a mosquito's proboscis in quantities that could spread blood-borne diseases?

We know that HIV can't be transmitted by mosquitos, and nor can other highly virulent viruses that are transmitted through blood and bodily fluid exchanges, such as Ebola (thankfully!). Marcus Junius ...
5
votes
0answers
52 views

Why do viruses last longer on hard surfaces than porous ones

All the papers I've read about survival of viruses outside of the host refer to longer survival times on hard surfaces without explaination. As a layman I would have thought that a virus (who's main ...
5
votes
2answers
15k views

Why does rabies cause hydrophobia?

What feature of rabies pathophysiology causes hydrophobia? Why is hydrophobia unique to this one particular type of viral infection?
3
votes
2answers
3k views

How long do viruses, such as Zika, stay in the body?

Can a virus stay in your body (after recovery) in a concentration that is sufficient to infect someone? Is it known how long the Zika virus persists in the body?
2
votes
2answers
106 views

Why is HIV so large compared to other viruses?

The HIV-1 virus is about 120-150 nm in size and has a genome only about 10,000 base pairs long. Other viruses are far more efficient, for example lambda phage has something like a tenth the volume ...