METHOD OF VI-ANTIGEN PREPARING Russian patent published in 1999 - IPC

FIELD: medicine, biotechnology. SUBSTANCE: bacterial mass is suspended in distilled water up to concentration (0.5-2.5) x 10¹¹ cells/ml, suspension is saturated with sodium chloride and bacterial mass is reprecipitated with an alcohol at the range 27.3-71.5% of saturation. Precipitate is resuspended and obtained suspension is dialyzed against distilled water. Acetic acid is added to the dialyzed suspension to final concentration 0.1 M followed by repeated precipitation with an alcohol at the range 27.3-71.5% of saturation. Precipitate is resuspended in distilled water again, acetic acid is added to concentration 1 M and hydrolysis is carried out at 100 C. Hydrolyzate is neutralized, dialyzed repeatedly against distilled water and represipitated with an alcohol at the range 27.3-52.0% of saturation. Isolated precipitate is dissolved in distilled water and obtained solution is subjected for ultrafiltration on membranes and fraction of biopolymer (molecular mass is above 300 kDa) is separated. Product that induces the complete inhibition or guinea pig erythrocyte direct agglutination with microorganism suspension of culture Escherichia coli (strain 815) at the dose 5-10 mcg/ml by dry weight, not above, is taken off as an antigen. EFFECT: decreased impurity content, improved quality, guarantee of the stable conformation structure. 2 cl, 1 tbl, 1 ex