[Show abstract][Hide abstract] ABSTRACT: A genomic library was constructed in a lambda gt11 vector using chromosomal DNA from a meningococcal serogroup A strain and plaques expressing the class 5C protein were recognized by screening with specific monoclonal antibodies. The opc insert was subcloned into a multicopy plasmid which induced expression of that protein in Escherichia coli as a surface-exposed major outer membrane protein. The nucleotide sequence of opc is typical of an outer membrane protein with a promoter and terminator region, a leader peptide which is cleaved during expression and a complete open reading frame. Unlike other meningococcal class 5 proteins or gonococcal P.II proteins, the sequence did not contain any pentanucleotide repeats and the sequence showed little homology to these other functionally related proteins. However, the predicted amino acid sequence of the mature protein for opc showed 27% similarity to that for a second opa gene cloned from the same meningococcal strain. This is the first report of cloning and expression of a functional meningococcal gene encoding a class 5 outer membrane protein in E. coli.
No preview · Article · Nov 1991 · Microbial Pathogenesis
[Show abstract][Hide abstract] ABSTRACT: Serogroup A meningococci were isolated from patients and healthy carriers in The Gambia between 1982 and 1988. The class 5
proteins expressed by these bacteria were identified by electrophoretic migration and by serologic tests. Three protein serologic
groupings (seroclasses) called A (protein 5a),B (proteins 5b, 5d, or 5e), and C (protein 5c or 5C) were found among 331 bacterial
isolates. The number of class 5 proteins expressed per isolate varied from none to four, with a median of two. The class 5
protein composition differed for certain paired isolates obtained from the nasopharynx, blood, and cerebrospinal fluid of
diseased patients and for certain pairs of sequential isolates from the nasopharynx of healthy carriers; the medical relevance
of this variation remains unclear, although the 5C protein was preferentially isolated from the nasopharynx and the 5a protein
from diseased patients. The data show that a large proportion of healthy carriers in The Gambia were exposed to bacteria expressing
each of the three seroclasses and that many people were exposed to two or all three seroclasses during the epidemic of 1982–1983.
No preview · Article · Sep 1991 · The Journal of Infectious Diseases