I think the string is refering to a virus signature update. As far as other scanners finding/cleaning this trojan, Antivir and Kaspersky are able to find and remove. (So cleanup is ok, I was just wondering if Avast should have been able to find this file with the right settings in regards to archives) BTW, Mcafee cmd line snanner seemed to miss this trojan as well.
Thanks,
-mark