iTunes is a completely different thing, it's an application, apps on iPads generally work independently, their is no overall file manager on an ipad. Viruses made for Macs & pc's run on a completely different system from iOS so can no way be transferred. Their is no need to download virrus protection to your ipad as your updates have you covered. Unless your iPad is jailbroken your safe as sausages.
If you can find me a known virus on an iPad I shall eat my cockers left lug 
I'm well aware that there's no file manager as such but iTunes is much more that a simple Application in that it gives access to the core command structure of the operating system. This is how "Firmware updates" and updates to the system are applied. It's also the path through which various devices can be "Jailbroken" or have alterations made to the core operating system. This route has been utilised by some Apps, thankfully most of which have been spotted at the certification stage, to install malicious code....Google is presently under investigation for data harvesting on iOS devices and on Macs through Safari......It's been well reported in the news and trade journals/websites.
Unfortunately most people mistakenly use the term "Virus" to cover any and all malware on computer systems while, in fact, low level attacks making small but significant alterations to the coding structure of the operating system are much more serious.
If you have access to an Apple software developer's kit (iOS SDK) than I'd suggest a review of the security section would be appropriate.
Bob.
