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Identification of variable region differences in Neisseria meningitidis class 3 protein sequences among five group B
G A Zapata1, W F Vann, Y Rubinstein
1Center for Biologics Evaluation and Research, Division of Bacterial Products, Bethesda, Maryland 20892.
Abstract:
Strains of Neisseria meningitidis express one of two porin proteins. These porins have been identified as the class 2 and class 3 proteins, and express serotype-specific epitopes. The gene for the class 3 protein was amplified by the polymerase chain reaction from the DNA of a serotype 4 strain as a 1025 bp fragment. The nucleotide sequence of this gene was determined and compared with two recently published sequences. On the basis of this comparison we have identified two major variable regions in the translated protein sequence, VR1 and VR2, that may be associated with serotype specificity. Three other variable regions were also identified. The sequences in the VR1 and VR2 regions from five additional group B N. meningitidis strains of serotypes 1, 4, 8, 12, and 15, all expressing class 3 proteins, were determined. The VR1 and VR2 regions were variable and were flanked by highly conserved regions among eight different class 3 sequences. These two variable regions of 15 and 9 amino acids are predicted to be in surface-exposed loops.
Insights
Neisseria meningitidis porin proteins show variable regions linked to serotype specificity. These variable regions (VR1 and VR2) in class 3 porins may determine specific epitopes.
Area of Science:
- Microbiology
- Molecular Biology
- Immunology
Background:
- Neisseria meningitidis strains express class 2 or class 3 porin proteins.
- These porins possess serotype-specific epitopes, crucial for immune recognition.
- Understanding porin variability is key to meningococcal disease research.
Purpose of the Study:
- To identify and characterize variable regions within the class 3 porin gene of Neisseria meningitidis.
- To investigate the association of these variable regions with serotype specificity.
- To compare sequences across different serotypes to find conserved and variable domains.
Main Methods:
- Polymerase chain reaction (PCR) amplification of the class 3 porin gene.
- DNA sequencing of the amplified gene fragments.
- Bioinformatic analysis and comparison of nucleotide and translated protein sequences.
Main Results:
- Identified two major variable regions (VR1 and VR2) in the translated class 3 porin sequence.
- These variable regions are flanked by highly conserved regions across different serotypes.
- VR1 (15 amino acids) and VR2 (9 amino acids) are predicted to be surface-exposed loops.
Conclusions:
- The identified variable regions VR1 and VR2 in class 3 porins are likely associated with serotype specificity.
- Conserved flanking regions suggest functional importance, while variable loops may mediate host-pathogen interactions.
- Further research into these regions could aid in vaccine development and diagnostics.