Is a virus considered to be alive?

Sure

Nope. Viruses aren't alive.

The way I learned it, is that you could argue either way.
It has some properties of life -- but on the other hand, it lacks others.
My biology teacher said you could argue either way.

"Viruses straddle the definition of life. They lie somewhere between supra molecular complexes and very simple biological entities. Viruses contain some of the structures and exhibit some of the activities that are common to organic life, but they are missing many of the others. In general, viruses are entirely composed of a single strand of genetic information encased within a protein capsule. Viruses lack most of the internal structure and machinery which characterize 'life', including the biosynthetic machinery that is necessary for reproduction. In order for a virus to replicate it must infect a suitable host cell".
From The Bacteriophage T4 Virus"alive = organism:

Nature of Earth's organisms: temporary self-replicable constrained-energy genetic systems that support and maintain Earth's biosphere by maintenance of genes.

Every "self-replicable" genetic system has a unique package of essentials for replication...and viruses are not different in this respect than other organisms."
-Dov Henis

So, the general consensus is that viruses can be considered to be either alive or not alive. In my personal opinion, they're not alive, but that's just what I think. Pweeze give best answer for sources

Viruses are not considered my most scientists to be alive.

They do kind of "straddle a grey area," as the previous answerer said, in that they can perform some, but not all, of the functions used to define living organisms. For example, they can reproduce--sort of. That is, they cannot reproduce independently, but if they infect living cells they can hijack those cells into making more of them. So you can see how this has been a sticky question through the ages. Yes, they do basically reproduce if mixed with living cells. But no, they do not reproduce independently, so they're not a self-perpetuating species.

A surprisingly useful analogy is the analogy of the computer viruses. Computer viruses are not organisms, or, in this case, computers themselves. They're just lines of code that a computer will read and reproduce. This doesn't require any consciousness on the viruses part; it's just a stray piece of programming that happens to have the effect of making more viruses when it's carried out. Biological viruses are just the same way. They're not really life forms, but rather complex organic chemicals which happen to be read by a cell in the same way that the instructions of a computer virus are read.

Hope this helps!

viruses are both non-living as well as living.They are living because when they enter a living body they start multiplying and when they are outside a living organism they are just like dead particles.Living: core material is DNA. Non-living:lack cellular structure, can be crystallized and stored for any length of  time