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Morphological differences in Neisseria meningitidis pili
J J Greenblatt1, K Floyd, M E Philipps
1Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892.
Abstract:
Disease and carrier isolates of Neisseria meningitidis were examined for their ability to adhere to human buccal epithelial cells and human cell lines and to hemagglutinate human erythrocytes, properties thought to be associated with the presence of pili. Seventy percent (7 of 10) of carrier isolates were found to be highly adherent to human buccal epithelial cells and to agglutinate human A, B, O, Rh-, and Rh+ erythrocytes. In contrast, 60% of the disease isolates adhered poorly to human buccal epithelial cells and 80% failed to agglutinate human erythrocytes. No adherence of either disease or carrier isolates was observed when several human cell lines were tested. When the meningococcal strains were examined by electron microscopy, 7 of 10 disease isolates were found to possess large bundles of aggregated pili (alpha-type pili), while 7 of 10 carrier isolates were found to have numerous unaggregated pili (beta-type pili). A monoclonal antibody against meningococcal pili and one against gonococcal pili reacted with 6 of 10 piliated carrier isolates and 4 of 10 piliated disease isolates. These results suggest that meningococci, like gonococci, possess different types of pili which differ in morphological, antigenic, and binding properties. In addition, antigenic and morphological differences between pili from carrier and disease isolates were observed as well as differences in adherence and hemagglutinating properties.
Insights
Neisseria meningitidis pili vary between disease and carrier strains. Carrier strains exhibit enhanced adherence and hemagglutination, linked to unaggregated pili, unlike disease strains.
Area of Science:
- Microbiology
- Bacteriology
- Immunology
Background:
- Neisseria meningitidis causes meningitis and sepsis.
- Pili are surface appendages implicated in bacterial adherence and virulence.
- Distinct pili types may correlate with different pathogenic potentials.
Purpose of the Study:
- To investigate the relationship between pili type and the pathogenic properties of Neisseria meningitidis.
- To compare adherence, hemagglutination, and pili morphology in disease and carrier isolates.
- To explore antigenic similarities and differences in meningococcal pili.
Main Methods:
- Adherence assays using human buccal epithelial cells and cell lines.
- Hemagglutination tests with human erythrocytes.
- Electron microscopy for pili visualization and characterization.
- Immunological characterization using monoclonal antibodies.
Main Results:
- Carrier isolates showed significantly higher adherence to buccal cells and hemagglutination compared to disease isolates.
- Electron microscopy revealed distinct pili morphologies: aggregated (alpha-type) in disease strains and unaggregated (beta-type) in carrier strains.
- Monoclonal antibodies showed differential reactivity with pili from carrier and disease isolates.
Conclusions:
- Neisseria meningitidis possesses distinct pili types with differing morphological, antigenic, and binding properties.
- Pili variation in Neisseria meningitidis correlates with differences in adherence and hemagglutination.
- These findings suggest a role for pili heterogeneity in meningococcal pathogenesis and carriage.