Non-a non-b hepatitis surface antigen useful for the preparation of vaccines and methods of use

A vaccine against viral NANB hepatitis comprising in a physiologically acceptable medium an amount of a purified non infectious fraction containing NANBs antigen in quantities sufficient to cause, on administration, an immunologic response, said NANBs antigen (1) having a density between 1.20 and 1.30 g/ml in a cesium chloride solution and between 1.15 and 1.25 g/ml in a sucrose solution (2) having an electrophoretic migration in the .alpha., .beta.-globulin zone;

• (3) being associated to particles with a viral appearance, spheres or filaments, the most typical of which have a size ranging from 10 to 45 nm in diameter, the complete virion appearing as a double envelope sphere of 35 to 45 nm;(4) when administered to a being having an immune system, said NANBs antigen causes the formation of antibodies with which it provides a precipitation reaction, the said antibodies also being capable of aggregating and/or precipitating the said viral particles including the complete double envelope virions containing a nucleocapside having a size of about 35-45nm, the said antibodies also being capable, when combined with a fluorescence agent, of causing a cytoplasmic and/or membranous fluorescence in liver tissue sections from subjects suffering from NANB hepatitis;
• the said antibodies being neither capable of aggregating the complete B hepatitis virus particles nor of causing a cytoplasmic and/or membranous fluorescence in the liver tissue of subjects suffering from B hepatitis.