Immunologic Properties of Purified Sendai Virus Glycoproteins

Abstract

Egg-grown Sendai virus was used for purification of the glycoproteins of the virus. The two glycoproteins, HN glycoprotein (VP 2) and F glycoprotein (VP 4), were separated by filtration on DEAE-Bio-Gel A columns and by sucrose density electrofocusing and were used for preparation of rabbit hyperimmune sera. Rabbit hyperimmune sera directed against the HN and F glycoproteins were immunologically distinct. Antiserum directed against the HN glycoprotein inhibited hemagglutination (HA) and neuraminidase (NA) activity and had high neutralizing capacity. Antiserum against the F glycoprotein inhibited hemolysis but did not inhibit HA, NA activity, or virus infectivity. Rabbit hyperimmune sera against untreated, Tween 80-ether, and formalin-treated purified virions were also studied. These sera contained antibodies against both glycoprotein structures, but antibodies against the F glycoprotein blocking hemolysis could not be demonstrated. The two specific glycoprotein antisera were used to estimate the relative amount of hemagglutinin and hemolysin exposed on the envelope of Sendai virions from Vero cells by means of competition studies with ¹²⁵I-labeled purified rabbit γ-globulin directed against egg-grown whole virions. Anti-HN and anti-F sera gave 60 to 70% and 30 to 40% inhibition, respectively, under conditions of antibody excess. Passive immunization with antisera against the two glycoproteins protected mice against natural Sendai virus infection.