Distribution of factor H binding protein beyond serogroup B: variation among five serogroups of invasive Neisseria meningitidis in South Africa.

Factor H binding protein (fHBP) is currently under investigation as a potential vaccine antigen for protection against meningococcal serogroup B (MenB) disease. This study describes the distribution of genotypes among all (n=58) MenB, and a total of 80 representative non-MenB (serogroups A, C, Y and W135) isolates causing invasive disease in South Africa in 2005 using fHBP sequence analysis, PorA, FetA and multilocus sequence typing. There was less fHBP diversity among non-MenB isolates compared to MenB isolates. fHBP subfamily variant A32 was the most common fHBP variant among MenB isolates and was represented by 17% (10/58) of the isolates, while fHBP variant B16 was the most prevalent variant among non-MenB strains and was represented by 40% (32/80) of isolates. Overall, subfamily B domain N6 (modular group I) was most prevalent (57%, 79/138). Twenty PorA and 16 FetA types were identified among MenB isolates whereas non-MenB serogroups were largely associated with specific serosubtypes. The most common MenB clonal complex (ST-41/44/lineage 3) was represented by 29% (17/58) of the MenB isolates, while each of the non-MenB serogroups had a major clone represented by at least 75% of the isolates within the serorogroup. Our data highlight that non-MenB meningococcal isolates also harbor fHBP.