Recombinational reassortment among opa genes from ET-37 complex Neisseria meningitidis isolates of diverse geographical origins

Abstract

Opacity (Opa) proteins are a family of antigenically variable outer-membrane proteins of Neisseria meningitidis. ET-37 complex meningococci, defined by multilocus enzyme electrophoresis, have been isolated on different continents. Twenty-six different Opa proteins have been observed within strains of the ET-37 complex isolated between the 1960s and the 1980s, although individual strains have only four opa genes per chromosome. In this work the opa genes of four closely related ET-37 complex N. meningitidis strains recently isolated from Mali, West Africa were characterized and compared with the opa genes of strain FAM18, an ET-37 complex isolate from the USA. DNA sequence analysis and Southern blot experiments indicated that recombinational reassortment, including gene duplication and import by horizontal genetic exchange, has occurred in the opa genes within the ET-37 complex, resulting in two partially different Opa repertoires being present in FAM18 and the Mali isolates. Using synthetic peptides derived from the hypervariable (HV) regions of opa genes, the epitopes for nine mAbs were mapped. These bacteria, isolated on different continents, contain both shared and unique opa HV regions encoding epitopes recognized by mAbs and show evidence of recombinational reassortment of the HV regions.

Selection for a CEACAM Receptor-Specific Binding Phenotype during Neisseria gonorrhoeae Infection of the Human Genital Tract

“…Fraction V bovine serum albumin (BSA), 5-bromo-4-chloro-3-indolyl phosphate disodium salt (BCIP), nitrotetrazolium blue chloride (NBT), and G418 sulfate were obtained from Bioshop (Burlington, Ontario, Canada). Monoclonal antibody 4B12/C11, which recognizes all the gonococcal Opa variants described, was generously provided by M. Achtman (Max-Planck-Institut für Infektionsbiologie) (49). The monoclonal antibody against the gonococcal pilus was a kind gift from M. So (Oregon Health Sciences University) (50).…”

“…Due to the phase-variable expression of pilus and Opa proteins, the gonococcal strains were cultured from frozen stock onto GC agar 2 days prior to experimentation, and colonies with the desired Opa and pilus phenotypes were visually identified with a binocular microscope and then subcultured to provide bacteria for experimentation on the subsequent day. Opa expression of gonococcal isolates used for infection experiments was confirmed by immunoblot analyses of total bacterial lysates using monoclonal antibody 4B12/C11, which recognizes all the Opa protein variants described (49), and pilus expression was monitored using 10H5.1.1 antibody, which recognizes the conserved SM1 epitope (50).…”

Evaluation of Pulsed-Field Gel Electrophoresis in Epidemiological Investigations of Meningococcal Disease Outbreaks Caused by Neisseria meningitidis Serogroup C

“…However, a number of genetic events known as genetic drift (point mutations, insertions, deletions, and rearrangements, etc.) can significantly affect the applicability of a particular molecular approach to subtype the organism of interest (10). Horizontal exchange of genetic material in N. meningitidis is common, and it is reasonable to expect that such events would have greater effects on PFGE than on MEE or ribotyping, which are methods that deal with specific well-conserved genes, unlike PFGE.…”

Resolution of a Meningococcal Disease Outbreak from Whole-Genome Sequence Data with Rapid Web-Based Analysis Methods

“…Four of these differences were in adjacent genes (NMC0347 to NMC0350), including fHbp, which encodes the vaccine component factor H binding protein, with a higher number of nucleotide changes observed compared to those in single genes, indicative of a single recombination event. Differences in the Opa1800 coding sequence between the case isolate and the carrier isolate which was epidemiologically presumed to have been acquired from it were a single synonymous mutation near the 3= end and loss of a single pentanucleotide (CTCTT) repeat in the signal peptide-encoding region, which is known to affect phase variation (20,43). Among the four isolates from the later local and remote cases, representing strain 2, Genome Comparator initially identified 77 variable loci (with between 32 and 56 variable loci between pairs of isolates).…”