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Electron microscopy procedure influences detection of rotaviruses
S Nakata1, B L Petrie, E P Calomeni
1Department of Virology, Baylor College of Medicine, Houston, Texas 77030.
Abstract:
Technical parameters of electron microscope staining procedures (type of stain, pH of stain, and time of staining) influence particle integrity for three groups of rotaviruses. Simian rotavirus SA11 (group A), Chinese adult diarrhea rotavirus and porcine rotavirus-like agent (group B), and porcine pararotavirus (group C) were tested. All rotavirus strains were quite stable in uranyl acetate and phosphotungstic acid at pH 4.5 and relatively stable in ammonium molybdate. However, staining with phosphotungstic acid at higher pH values with increased staining time yielded a reduction in the number of particles and particles that were broken or degraded to single-shelled particles or core particles. The different staining procedures were also tested in immunoelectron microscopy experiments. Antibody molecules bound to rotavirus particles were observed clearly only with phosphotungstic acid staining and not with uranyl acetate. We therefore recommend that uranyl acetate and phosphotungstic acid at pH 4.5 be used for negative staining of rotaviruses; phosphotungstic acid at pH 4.5 is optimal for immunoelectron microscopy. These technical points may be critical for rotavirus detection and are important for studies pertaining to the epidemiology and clinical importance of the non-group A rotaviruses.
Insights
Electron microscope staining affects rotavirus particle integrity. Optimal staining with uranyl acetate or phosphotungstic acid at pH 4.5 is recommended for accurate rotavirus detection and research.
Area of Science:
- Virology
- Microscopy techniques
- Biochemistry
Background:
- Rotaviruses are a major cause of gastroenteritis in infants and animals.
- Electron microscopy is crucial for visualizing rotavirus particles and their structure.
- Staining procedures in electron microscopy can significantly impact the observed morphology of viruses.
Purpose of the Study:
- To investigate the effect of different electron microscope staining parameters on the integrity of three rotavirus groups.
- To determine optimal staining conditions for negative staining and immunoelectron microscopy of rotaviruses.
- To assess the impact of staining techniques on rotavirus detection and epidemiological studies.
Main Methods:
- Tested three rotavirus strains (Simian rotavirus SA11, Chinese adult diarrhea rotavirus, porcine rotavirus-like agent, and porcine pararotavirus) with various staining agents (uranyl acetate, phosphotungstic acid, ammonium molybdate) at different pH levels and staining times.
- Evaluated particle integrity using electron microscopy.
- Conducted immunoelectron microscopy experiments to assess antibody binding.
Main Results:
- Rotavirus particles showed stability in uranyl acetate and phosphotungstic acid at pH 4.5.
- Higher pH and longer staining times with phosphotungstic acid led to particle degradation.
- Antibody binding was clearly visualized with phosphotungstic acid but not with uranyl acetate.
Conclusions:
- Recommends uranyl acetate and phosphotungstic acid at pH 4.5 for negative staining of rotaviruses.
- Phosphotungstic acid at pH 4.5 is optimal for immunoelectron microscopy of rotaviruses.
- Optimized staining techniques are critical for accurate rotavirus detection and epidemiological studies, especially for non-group A rotaviruses.