However, BPV13 was also implicated as a possible causative factor of urothelial tumors in cattle both in single infections and in coinfecting urinary bladder tissue with BPV2 in an investigation performed more recently in the southern region of Italy, where a high rate of BPV13 DNA and E5 oncoprotein expression was demonstrated in tumoral tissues (8). The gene discussed is ARHGEF15; the disease is infection.