As non-living entities, it is highly unlikely that viruses would serve as
"prey" for other organisms.
One could easily imagine that "non-living" viruses could be broken down for their amino
acids and nucleic acids by bacteria and other microbes. Phagocytosis by mircobes is one of
the most common ways to extract the goodies - as you know.
However, that uptake by the "predator" would result in the
virus being introduced into a living cell and, given the ability of
viruses to take advantage of cellular processes for their own
replication, might give the virus an opportunity to replicate and
(probably) kill that cell.
I think that this is a bit of a host range generalization. Not all viruses are in the least
infectious to cells that take them up. Animal viruses are not infectious to bacteria or
yeast or other lower unicellular critters. A big animal virus is just a mass of molecular
junk to a bacterium or yeast. Really, not a bad food source. The "optimal foraging
strategy" on a nutrient starved surface like a rock or a lab bench is to suck up as many
AA's and NA's as possible. I see no problem with the "viruses as food" hypothesis.
However, it's probably not a terribly abundant source of nutrients.
Anyway, it's an interesting proposition.
Peter C. Angeletti
Department of Biochemistry and Molecular Genetics
University of Alabama at Birmingham
Pangeletti at bmg.bhs.uab.edu