The Significance of Protection Tests with the Serum of Man and Other Animals against the Lansing Strain of Poliomyelitis Virus

Abstract

Summary Seventy-eight per cent of the sera from 55 domestic cows from Western States and Okinawa neutralized the Lansing strain of poliomyelitis virus while of 18 “controls” from Nevada desert range none protected. In fresh bovine sera antiviral substances were frequently present which disappeared after storage for 2 or 3 months. Sixty-seven per cent of a similar group of 48 horses were positive and only one of 15 desert controls protected. Forty-four per cent of 112 domestic or “exposed” chickens were positive while only 2 of 43 controls sheltered in the laboratory protected. Of other domestic mammals 45 per cent of 58 protected while none of 30 from wild species were positive. Of domestic birds other than chickens 30 per cent of 63 protected while 19 per cent of 26 from wild species were positive. None of 31 sera from laboratory monkeys, guinea pigs, rabbits, pigeons or doves were positive. Sera from many of these had high titers to one or more of the encephalitis viruses. Monkeys, cotton rats and hamsters inoculated with monkey cord virus of a strain immunologically related to the Lansing strain (MEF-1) responded with neutralizing antibodies though showing no other signs of infection. Three other strains of virus (Brock, Lemos and Bigelow) produced no such response. Chickens inoculated with MEF-1 and other virus strains did not develop antibodies. Furthermore, serum from chickens frequently behaved in an irregular and unexplainable manner. No virus could be isolated from the feces of chickens which were fed or were inoculated with a freshly isolated poliomyelitis virus. Paired, two phase sera from 102 poliomyelitis patients gave the following results: 84 had a high titer at onset or showed no change; 10 showed an increase and 8 a decrease. Few of the human sera taken at onset gave an equivocal result; they tended to be either definitely negative or positive. Fifty-seven of 84 were positive. It is concluded that some strains of poliomyelitis virus fail to stimulate any or significant titers of antibody to the Lansing strain and that others do, this probably is the result of antigenic differences. However, it is far from being established that all Lansing antiviral substances encountered in man or animals are due to contact with poliomyelitis virus.