Isolation and characterization of a toxic intracellular protein from Vibrio parahaemolyticus
1Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria.
Abstract:
A toxic factor released from disrupted cells of Vibrio parahaemolyticus was partially purified by gel filtration after precipitation with (NH4)2SO4 at 40% saturation. The factor, which was a thermostable protein of 63 kDa, lysed human erythrocytes at a concentration of 0.15 μg ml(-1). Its LD50 by intravenous injection into mice was 6.4 μg. Fluid accumulated in suckling mice force-fed with the toxic material (1 to 25 μg). Haemolytic activity, which occurred maximall at 37°C and pH 7.0 was enhanced by Ca(2+), Cu(2+) and Zn(2+), each at 1 mM. Anti-toxic-factor serum agglutinated V. parahaemolyticus cells. The factor may play a role in the pathogenesis of V. parahaemolyticus infections and in the host's defence mechanisms against infection by the microorganism.
Insights
Researchers purified a toxic protein from Vibrio parahaemolyticus. This 63 kDa protein causes red blood cell lysis and fluid accumulation in mice, indicating its role in bacterial infection pathogenesis.
Area of Science:
- Microbiology
- Biochemistry
- Toxicology
Background:
- Vibrio parahaemolyticus is a significant cause of seafood-borne gastroenteritis.
- Understanding the virulence factors of V. parahaemolyticus is crucial for developing effective treatments.
Purpose of the Study:
- To isolate and characterize a toxic factor released from Vibrio parahaemolyticus.
- To investigate the hemolytic and toxic properties of the purified factor.
Main Methods:
- Partial purification of the toxic factor using (NH4)2SO4 precipitation and gel filtration.
- Determination of protein molecular weight (63 kDa) and thermostability.
- Assay of hemolytic activity against human erythrocytes.
- LD50 determination in mice via intravenous injection.
- Assessment of fluid accumulation in suckling mice.
- Evaluation of hemolytic activity under varying temperature and pH conditions.
- Analysis of enhancement by divalent cations (Ca2+, Cu2+, Zn2+).
- Agglutination assay using anti-toxic-factor serum.
Main Results:
- A thermostable, 63 kDa protein toxic factor was isolated.
- The factor exhibited potent hemolytic activity (0.15 μg/ml) and a low LD50 (6.4 μg) in mice.
- Intragastric administration induced fluid accumulation in suckling mice.
- Optimal hemolytic activity was observed at 37°C and pH 7.0, enhanced by Ca2+, Cu2+, and Zn2+.
- The anti-toxic-factor serum demonstrated agglutination of V. parahaemolyticus cells.
Conclusions:
- The purified toxic factor is a potent hemolysin and cytotoxin.
- This factor likely contributes to the pathogenesis of Vibrio parahaemolyticus infections.
- The factor may also be involved in the host's immune response to V. parahaemolyticus.
