WHO International Standards for antibodies to HPV6 HPV11 HPV31 HPV33 HPV45 HPV52 and HPV58

Previously established World Health Organization (WHO) International Standards (IS) for anti-HPV16 and HPV18 antibodies are used to harmonize results across human papillomavirus (HPV) serology assays. Here, we present an international collaborative study to establish ISs for antibodies against HPV6 (NIBSC code 19/298), HPV11 (20/174), HPV31 (20/176), HPV33 (19/290), HPV45 (20/178), HPV52 (19/296) and HPV58 (19/300). The candidate standards were prepared using sera from naturally infected individuals. Each candidate was shown to be monospecific for reactivity against its indicated HPV type except for the HPV11 candidate, which was also reactive against other types. Expression of antibody levels relative to the relevant candidate IS reduced inter-laboratory variation allowing greater comparability between laboratories. Based on these results, the WHO Expert Committee on Biological Standardization established each of the 7 candidates as the 1st IS for antiserum to its indicated HPV type for use in the standardization of HPV pseudovirion-based neutralization and antibody-binding assays.