dna-dna hybridization experiments , performed under stringent conditions , showed that these viruses represent nine new types , hpvs 14 ( with subtypes a and b ) , 15 , 17 ( with subtypes a and b ) , 19 , 20 , 21 , 22 , 23 , and 24 .
C0042776
viruses
C0021344
hpvs