You may post your question on STD expert forum for an answer from Medical expert/ doctor paying 15$... please use the link below to connect to export forum:
http://www.medhelp.org/posts/show/116
... but the information you are seeking is very basic:
No, blood donation centers don't test for hpv and they don't have to cause hpv is not a blood virus but it's a skin virus...
Gardisil prevents you from 4 strains of hpv (2 low risk & 2 high risk)... these 2 low risk strains are responsible of 90% of wart infection and the other 2 are responsible of 90% of cervical cancer cases... currently, there are almost 100 known strains of hpv virus not 700...