Patent ID: 7955817

Claim:
A N. meningitidis serogroup A Serum Bactericidal Activity (SBA) assay comprising the step of determining the SBA titre of a serum sample against a N. meningitidis serogroup A reference strain, the reference strain having the following characteristics: a) the % seropositivity against the reference strain in a group of at least 25 naïve 1-2 year old children is less than the % seropositivity against the F8238 strain, where seropositivity is measured by an rSBA assay with titres of 8 or above; and (b) the % seroconversion against the reference strain in a group of at least 25 year old children immunized with a unconjugated N. meningitidis ACWY capsular polysaccharide vaccine is more than 50%, where seroconversion is measured by assessing the % of subjects with at least a 4 fold increase in rSBA titre when sera is compared just before immunization and one month after immunization with the vaccine.