Abstract
Physico-chemical properties of poliovirus inhibitors in sera of different animal species were investigated. Two kinds of inhibitor, tentatively designated as 7S and 19S types, were distinguished in each animal serum by means of gel filtration with Sephadex G-200. The 7S type inhibitor of equine sera which was eluted from the Sephadex column in the second peak fraction was proven to belong to β globulin by ammonium sulfate fractionation and electrophoresis. It formed a precipitate with poliovirus in agar gel, and withstood treatments with heat, ether, chloroform, sodium periodate, trypsin and 2-mercaptoethanol. The 7S type inhibitor was also present in rabbit and bovine sera. The inhibitor of both animal sera also formed a precipitate with the virus, but its virus-neutralizing activity was generally low.
The 19S type inhibitor eluted from the Sephadex G-200 column in the first peak fraction belonged to γ globulin in the ammonium sulfate precipitation, irrespective of the animal species. It did not precipitate poliovirus, but neutralized the virus in the plaque reduction test. Moreover, it was much more sensitive to heat, trypsin and 2-mercaptoethanol than the 7S type inhibitor.
Physico-chemically, the 7S and 19S type inhibitors resembled antibodies with the same molecular sizes, respectively. The 7S type inhibitor of equine serum was, however, distinguishable from the 7S antibody by the facts that it is β globulin and highly stable to the treatments with heat, sodium periodate and trypsin.
