You should be able to right click on the Virus Scan icon in the task tray and select the update VirusScan option to manually initiate an update. Also, running the Update Task in the Virus Scan console will do the same thing. These both assume you have a working internet connection.
For manual updates, try downloading the latest xdat and running it on the system with VirusScan on it. The link is here:
You may also want to redownload the latest VirusScan available on your license as your copy is Patch 1 and there have been many patches to 8.5i since then. I think the last supported patch before moving to 8.7i or newer is patch 8 for 8.5i.
Moved to Business > VirusScan Enterprise.
8.5i is no longer supported as of Dec 31, 2011: https://kc.mcafee.com/corporate/index?page=content&id=KB69579 meaning we can't help you with it.
You would have to obtain the current 8.8i version to remain up to date.
Consult with your IT guys or wherever the software is licensed through. It only comes as bulk licensing through grant numbers.