GP5 and coinfection: For instance, an analysis of the International Agency for Research on Cancer HPV Prevalence Surveys that used GP5+/6+ PCR assays to detect HPV, showed an excess of co-infections with HPV33/58, 18/45, 33/35, and 31/35 that was attributable to the cross-hybridization of highly homologous HPV types using enzyme immunoassay for genotyping [2].