[Use of immune electron microscopy for detecting the hepatitis A virus].

Attempts were made to isolate and identify hepatitis A virus by the method of immune electron microscopy using also biophysical methods and the transfection procedure of cell cultures by nucleic acid preparations. In fecal specimens from patients with infectious hepatitis A, virus-like particles 25-30 nm in diameter were found which reacted with convalescent antisera and could be detected by the immune electron microscopy method. By the same method virus-like particles 22-25 nm in diameter were detected in the blood serum of the patients collected early in the disease. A method for their purification and concentration in cesium chloride density gradients has been developed. Attempts at transfection of the cell cultures with preparations of nucleic acids failed. In the course of the study, however, data were obtained which would subsequently facilitate isolation of the causative agent of hepatitis A.