A “Unitarian” View of Vaccinia Hemagglutinin *

Since Nagler's discovery" of the hemagglutinin obtained from suspensions of vaccinial lesions on the chorio-allantois, a number of investigators have attempted to characterize it more precisely. Nagler"" and others'"" have shown that antibodies which inhibit vaccinia hemagglutinin (V.H.) develop in man, rabbits, mice, and guinea pigs following infection with vaccinia virus, but it is not known if the V.H. itself is antigenic. Burnet and Stone' observed that V.H. was a substance distinct from the virus particle. Since V.H. was inactivated by Clostridium welchii a-tOxin (lecithinase) in the presence of calcium ions, and since citrate, specific antitoxic serum, and lecithin inhibited this inactivation, Stone" concluded that V.H. contains a phospholipid, most probably lecithin, and that the enzymic breakdown of this part of the complex destroys its hemagglutinating properties. On the basis of an analysis of some physico-chemical and immunological properties of V.H., Chu" ' concluded that it is distinct from, and apparently unassociated with, the elementary body, that it is not the L-S antigen, but that it represents a new and distinct antigen occurring in a relatively large particulate state. Since protamine and histones were found to inhibit vaccinia hemagglutination, Fisher8 suggested that the red cell receptors for the phospholipid might be protein in nature. From all of these observations, it would appear that niany of the important properties of V.H. have been established. However, as Gillen, Burr, and Nagler have pointed out, some of the reported findingsg indicate the possibility that two hemagglutinins exist. These may be itemized as follows: (a) although most of the V.H. is found in the supernatant after high speed centrifugation, a trace of V.H. is consistently present in the sediment; (b) crude vaccinia virus suspensions presumably contain a heat labile and a heat stable component. Gillen, Burr, and Nagler,9 in experiments designed to investigate the existence of two hemagglutinins, concluded that there are two hemagglutinating fractions in suspensions of chorio-allantoic membranes infected with vaccinia virus: (a) a soluble V.H. which is heat labile, not retained by Seitz filters, and not sedimented by centrifugation at 17,000 rpm for three hours, and (b) a V.H. which is more closely associated with the elementary body and which is heat stable, sedimented by centrifugation at 17,000 rpm, and retained by Seitz filters. In addition, Gillen, Burr, and Nagler9 found that the two hemagglutinins differed in the type of agglutination which they produced, in the extent to