Factors influencing the formaldehyde treatment of viral antigens.

Abstract

An investigation has been made of the use of formaldehyde for the preparation of stable non-infective viral antigens of influenza (PR8) and mumps (Enders). The stability of the antigen to formaldehyde treatment was influenced by the pH, the suspending medium of the virus, the formaldehyde concentration, and the duration and temperature of treatment. The following procedure was found to be the most satisfactory. The supernatant liquid of allantoic fluid which had been frozen and allowed to thaw slowly was centrifuged and the virus was resuspended in isotonic phosphate buffer at pH 6.0. A hemagglutination titer of about 10,000 was attained before the process of treatment was started. This viral antigen was filtered through coarse filter paper and treated with 0.1% formaldehyde at 45 °C. for 12 hr. The excess formaldehyde was neutralized by the addition of 0.25 cc. of 30% dibasic ammonium phosphate per 10 cc. of antigen. After 30 min. at room temperature, 5% (w/v) of arginine was added and the antigen was lyophilized in ampoules. These antigens have been found to be non-infective, satisfactory in the complement-fixation and hemagglutination-inhibition tests as specific diagnostic antigens, and show greater stability than liquid viral antigens.