NVS evidently passed on GNLB’s NS5A program: see the bold-faced section of this PR about ¾ of the way down: #msg-11431616.
GNLB is still nominally partnered with NVS on a non-nuke HCV polymerase inhibitor (#msg-30203067), but this program is in the ultra-slow lane and it’s doubtful that it was the impetus for the GSK buyout.
I think GSK is almost certainly buying GNLB for the NS5A program. The HEV vaccine is perhaps a modest kicker.
“The efficient-market hypothesis may be the foremost piece of B.S. ever promulgated in any area of human knowledge!”