To the best of my knowlege, there is no such thing as a virus attack on a router. There is no operating system in a router to attack. You need a computer to access a router, so it would not make sense to disable a router in the first place, as there are no benefit in it for the virus creator, who wants the virus to spread, and a dead router cannot help in that.
There can be attacks on your router by someone that wants to access it, to steal your bandwidth, or to access your computer, that can happen.
The only "antivirus" for this kind of attacks is to make sure you use a very strong username and password to access your router and your internet account, and not the router default passwords.
I think non, because routers only deliver data(transferring, sharing). If there would be problems on the router its definitely not a virus. Might be a wrong connections in pc or etc, something like that. But somehow it is possible that there is a virus that attacks the computer by screwing up the function of routers, for example maybe, automatically sending your files to a computer that is connected by the router. But I haven't heard so far something like that before. It's always been the Central Processing Unit that is always damage by such viruses, it is the one that controls all things in your computer anyway. And also, viruses only infects your pc, not the other external devices, not the mouse, the printer, not the storage devices (but it can do copies and multiply in it), nor the speakers, nor the monitor, and most likely not a ROUTER. Lastly if there a virus that attacks router i think many would've known it because routers today are widely-use. Hope I helped. :)
There is an operating system on the router however it is normally chip based and not easy to hack. Try this site for a discussion on the CISCO-IOS used on CISCO routers and listing of links to other OS's used.