wook,sumpin'like that. You're right, we've known for some time that Bavi "upregulates" immune response. Don't think we knew it might help confer immunity to re-challenge (2nd set phenomenon?). However, we should remember that the phenom. was presumably only seen in 13%...the survivors. That presupposes a "subset" of test subjects [rats], or some other undetermined variable in the 13%.