Why WARTS are caused by virus?

[A.J.Cann]

Some more information:
http://www-micro.msb.le.ac.uk/335/Papovaviruses.html

Dr Alan J. Cann  PhD,   Department of Microbiology & Immunology,
University of Leicester,  P.O. Box 138,  Medical Sciences Building,
University Road, Leicester LE1 9HN,  UK.
Email: nna at le.ac.uk     http://www-micro.msb.le.ac.uk/AJC/nna.html