A Comparative Study of Recently Isolated Human Strains and a Passage Strain of Poliomyelitis Virus

Abstract

Since the early days of the discovery of the virus of poliomyelitis it has been known that quantitative differences in virulence for the monkey exist between recently isolated strains, and strains which have passed through successive monkeys. Only within the last few years has it been clearly demonstrated b y the work of Burnet and Macnamara (1) in Australia, that immunologic differences exist between such strains, which might be termed qualitative differences, in that they do not seem to be confined to those of virulence alone.These investigators made a comparative study of two strains; one a local virus recently isolated from a fatal human case, and the other the Rockefeller Institute strain of so called mixed virus (M. V.). They described three instances in which monkeys contracted a fatal attack of poliomyelitis following the intracerebral inoculation of the M. V. strain despite the fact that some weeks previously the monkeys had sustained a typical attack of poliomyelitis produced by the local strain. The reverse of this experiment was also demonstrated in a single instance, in which a recovered monkey, partially paralyzed by the M. V. strain, was subsequently brought down with complete paralysis by the local virus. Furthermore, they found in neutralization tests that, although pooled convalescent serum would neutralize both strains, a few tests with individual samples of convalescent sera failed to show this parallelism, in that only the local virus was neutralized.In corroboration of this work Weyer (2) later described differences in the neutralizing values of human convalescent and antiviral horse serum for recently isolated strains and for a monkey passage strain. Flexner (3) has also pointed out that immune sera prepared from "human" and old passage strains of virus * The expenses of this investigation were defrayed by several grants from: (a) the Fluid Research Fund, Yale University; (b) an anonymous donor; and (c) the 1932 Philadelphia Poliomyelitis Fund. 513

Neutralization Tests in Poliomyelitis. Sera Taken During the Acute and Convalescent Stages of the Disease and Tested With a Passage Virus and a Strain Isolated During the 1935 New York City Outbreak 1

“…The failure to develop protective substances in convalescent sera from paralytic cases also coincided with the findings of Paul and Trask (19) who showed that 6 of 7 sera taken 1% to 10 weeks after the onset failed to neutralize the virus; 2 of them when retested a year later still failed to neutralize. On the other hand, Jensen (24) reported the presence of antibodies in paralytic and non-paralytic cases within a month after the onset.…”

“…Such findings differ from those of Howitt (22) who reported that convalescent serum more often neutralized a recently isolated strain than a passage virus. Likewise, Paul and Trask (19) found that convalescent sera from 6 of 7 paralytic cases neutralized a recently isolated strain, whereas only one serum neutralized the passage virus. It is possible that the strain used in the present work was more closely related to the passage virus than that used by the above workers (19,22) (Table I) in convalescent sera from paralytics obtained years after the disease, than was found in the present work in which the sera were collected within a year of onset.…”

“…Likewise, Paul and Trask (19) found that convalescent sera from 6 of 7 paralytic cases neutralized a recently isolated strain, whereas only one serum neutralized the passage virus. It is possible that the strain used in the present work was more closely related to the passage virus than that used by the above workers (19,22) (Table I) in convalescent sera from paralytics obtained years after the disease, than was found in the present work in which the sera were collected within a year of onset. Our figure was approximately 22 per cent and included neutralizing substances found at the onset of the disease (17 per cent), and those which developed in convalescence (5 per cent).…”

“…Moreover, the sera of 2 individuals which had neutralizing power in the first week of the illness did not show a demonstrable increase during convalescence. Other observers also found that neutralizing substances did not develop readily during convalescence following paralysis (15,19).…”

“…Peabody, Draper and Dochez (4) found no neutralizing power in the serum of a child 7 days after the onset of the disease, while that of another child neutralized at 21 days. Paul and Trask (19) reported the case of a 6 year old non-paralytic child whose serum failed to neutralize both in the acute stage and 1 year later. Harmon and Harkins (15) demonstrated the presence of neutralizing substances in the serum from an 11 year old child obtained 5 days and again 5 months after the onset of the disease.…”