There is no built-in method to limit file size or scan for viruses but you can do both of these yourself once the file has been uploaded (which is what mamy sites do at least for anti-virus).
What I would generally do is once the file is uploaded, open it (or read the directory) to get its file length. If too large erase the file and advise the client.
As for anti-virus, it all depends on what anti-virus tools you want and have purchased. Most have some form of command line utility you can call to check for viruses, You would need to check with the anti-virus supplier for details.
If you want a free option or need this for Linux have a look at ClamAV.
It is important to make sure whatever you chose to use for anti-virus protection gets updated regularly.