Mc. Bash et al., ANALYSIS OF NEISSERIA-MENINGITIDIS CLASS-3 OUTER-MEMBRANE PROTEIN GENE VARIABLE REGIONS AND TYPE IDENTIFICATION USING GENETIC TECHNIQUES, Infection and immunity, 63(4), 1995, pp. 1484-1490
The class 3 porin proteins of Neisseria meningitidis stimulate bacteri
cidal antibodies and express serotype-specific antigenic epitopes. Seq
uence analysis of porB genes for the class 3 proteins revealed regions
of variability that map to surface-exposed loops, To evaluate the rel
ationship between serotype and variable-region (VR) genotype, sequence
s from the 11 class 3-expressing serotype strains and 3 additional ser
otype 3 strains were analyzed by molecular techniques, Multiple-sequen
ce alignment revealed a limited number of unique sequences at each of
four VRs (VR1 to VR4), ranging from four unique sequences at VR1 to se
ven sequence patterns at VR2 and VR4, Serotype-specific VR sequences w
ere found in each of the four VRs, suggesting that each VR has immunol
ogic importance, Five serotypes had at least one VR sequence that was
unique. Three serotypes which had sequences in common with other serot
ypes at each VR were distinguished by examining multiple VRs, Serotype
3 was identical to serotype 19 at each VR, and serotype 8 was identic
al to serotype 18 at each VR, Serotypes 4 and 21 were identical at VR1
and significantly different at VR3 and VR4, A subpopulation of seroty
pe 4 strains with a unique VR2 sequence was identified, The serotypes
which were grouped with closely related or identical sequences at one
VR were grouped with different serotypes at other VRs consistent with
the pattern of genetic mosaicism described for the porA (class 1 prote
in) gene. Hybridization assays demonstrated the ability to identify VR
genotypes and distinguish serotypes using biotin-labelled oligonucleo
tide probes, This information may be useful in strain selection for va
ccine development, in epidemiologic studies to determine the prevalenc
e of the individual VR genotype (especially among nonserotypeable stra
ins) and, combined with PCR, in the identification of culture-negative
suspected meningococcal cases.