The immunological relationship of the vaccina and pig pox viruses demonstrated by gel diffusion.

The Ouchterlony double diffusion method in agar gel has been used to study the antigens of the vaccinia and pig pox viruses and their corresponding antibodies. The existence of a common antigenic constituent in the two viruses has been demonstrated. The sensitivity of the method was found to be adequate for sera giving complement fixation titres of 1/80. The complications arising from the presence of antibodies to heterologous (host) antigens are illustrated.