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Susceptibility of pathogenic and nonpathogenic Naegleria ssp

Thesis/Dissertation ·
OSTI ID:7165209
The susceptibility of four species of Naegleria amoebae to complement-mediated lysis was determined. The amoebicidal activity of normal human serum (NHS) and normal guinea pig serum (NGPS) for Naegleria amoebae was measured by an in vitro cytotoxicity assay. Release of radioactivity from amoebae labeled with {sup 3}H-uridine and visual observation with a compound microscope were used as indices of lysis. Susceptibility or resistance to complement-mediated lysis in vitro correlated with the in vivo pathogenic potential. Nonpathogenic Naegleria amoebae were lysed at a faster rate and at higher cell concentrations than were pathogenic amoebae. Electrophoretic analysis of NHS incubated with pathogenic or nonpathogenic Naegleria spp. demonstrated that amoebae activate the complement cascade resulting in the production of C3 and C5 complement cleavage products. Treatment with papain or trypsin for 1 h, but not with sialidase, increase the susceptibility of highly pathogenic, mouse-passaged N. fowleri to lysis. Treatment with actinomycin D, cycloheximide or various protease inhibitors for 4 h did not increase susceptibility to lysis. Neither a repair process involving de novo protein synthesis nor a complement-inactivating protease appear to account for the increase resistance of N. fowleri amoebae to complement-mediated lysis. A binding study with {sup 125}I radiolabeled C9 indicated that the terminal complement component does not remain stably bound to the membrane of pathogenic amoebae.
Research Organization:
Virginia Commonwealth Univ., Richmond, VA (USA)
OSTI ID:
7165209
Country of Publication:
United States
Language:
English

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Related Subjects

550201* -- Biochemistry-- Tracer Techniques
550701 -- Microbiology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMOEBA
ANIMALS
AZINES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL VARIABILITY
COMPLEMENT
ELECTROPHORESIS
ENZYME INHIBITORS
GENETIC VARIABILITY
GUINEA PIGS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INVERTEBRATES
ISOTOPE APPLICATIONS
KINETICS
LYSIS
MAMMALS
MAN
MICROORGANISMS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PATHOGENESIS
PRIMATES
PROTEINS
PROTOZOA
PYRIMIDINES
REACTION KINETICS
RESPONSE MODIFYING FACTORS
RIBOSIDES
RODENTS
SARCODINA
SENSITIVITY
TRACER TECHNIQUES
TRITIUM COMPOUNDS
URACILS
URIDINE
VERTEBRATES