SEQUENCE VARIATION IN CLASS-1 OUTER-MEMBRANE PROTEIN IN NEISSERIA-MENINGITIDIS ISOLATED FROM PATIENTS WITH MENINGOCOCCAL INFECTION AND CLOSE HOUSEHOLD CONTACTS

The meningococcal porA gene encodes the class 1 outer membrane protein which contains the VR1 and VR2 regions responsible for sero-subtype s pecificity. However, sequence variations may occur within these region s which are not recognised by the currently available subtype antibodi es. Since this ''silent'' microheterogeneity represents a potential hi dden source of information, in the current study we have used porA gen e sequence analysis to study strains isolated from cases of meningococ cal infection and close household contacts. With each of the three sub types studied, the index cases could be differentiated from each other by sequence variations within at least one of the VR1, VR2 and SV1 re gions. In addition, although isolates from close household contacts sh owed a high degree of homology significant differences could be detect ed within some family groups. These data demonstrate that it is possib le to use sequence information to differentiate between potential sour ces of infection which appear identical using conventional serological methods.