See many recent reviews by R.B. Wickner on Yeast Virology. There are many
viruses or virus-like elements that are cytoplasmically inherited in yeast, and
have been extensively studied in our lab and elsewhere, best reviewed by
Wickner. However, yeast lacks a good plaquing agent. In the late 1950's, Carl
Lindegren (a yeast genetics pioneer) published a description of an apparent
plaquing agent termed "zymophage" in a meetings book, but apparently the
phenomenon could not be reproduced even in his lab. So, there really afre
viruses of yeast, but not plaquing agents. As El-Sherbeini and Bostian showed,
it is possible to transmit purified viruses to uninfected spheroplasts, but the
transmission without human assistance has not been reported. Over a few beers,
it has often been speculated that such transmission might occur in cells under
special circumstances, such as mating, although I have not seen data to support
this plausible notion.
Mike Leibowitz
UMDNJ-RW Johnson Medical School
