Hilary Koprowski

Propagation of Hog Cholera Virus in Rabbits

Summary Hog cholera virus has been carried for 12 consecutive passages in rabbits by using infected rabbit spleen as transfer material. Starting from the 8th rabbit spleen passage, the virus was passed back to a pig for one passage and was then carried for 8 further passages in rabbits by using infected rabbit blood as transfer material. Aside from a febrile response, no other symptoms were observed in inoculated rabbits.

Adaptation of type I strain of poliomyelitis virus to mice and cotton rats.

Summary A mixture of 2 strains of Type I poliomyelitis virus was adapted to the PRI strain of mice and to cotton rats. The virus could be propagated in certain sublines when either the intraspinal or intracerebral route of inoculation was used. The infectivity of different sublines for mice and cotton rats varied, but the cytopathic titer in tissue culture was of similar magnitude. The passages in PRI mice resulted in a subline completely avirulent for rhesus and cynomolgus monkeys.

ASCITES TUMORS AS CULTURE MEDIA IN QUANTITATIVE GROWTH STUDIES OF VIRAL AGENTS

The ascites tumor-virus marriage was a prearranged affair. My wife, Doctor Irena Koprowska, and I were the matchmakers.’, The father of the bride (if we consider the word “ascites” as of feminine gender) was Doctor Albert Fischer of the Biologic Institute of the Carlsberg Foundation, Copenhagen, Denmark. The bride, Ehrlicha, was sent over by plane on June 1, 1950, and on August 28 of that year the wedding took place. The West Nile virus (which we shall consider as masculine in gender, and not, as the Romans did, neuter) was the groom. In spite of the immigration laws, monogamy did not prevail; the polyandrous Ehrlicha was subsequently wed to several other viruses. The marriages were not very happy ones. On September 23, 1950, an event took place which hardly anyone could have foreseen. The ascites bride was destroyed by one of the viruses, an exotic individual bearing the name of Bum yamwera after the forest in Uganda, Africa, where he was born.2 During the next five years, many more ascites brides-listed in TABLE 1-were matched with viruses, some of which were from overseas and some of which were of native In all, 14 tumors were used: 11 mouse tumors of different histological origin, with different properties as far as propagation in mouse strains is concerned, and 3 rat tumors-Yoshida and 2 he pa to ma^.^ The origin of all tumors was very carefully investigated, and the identity of a given line carried on in this laboratory was checked by submitting samples to outside investigators who are authorities in the field, as, for instance, Doctor Klein or the consulting editor of this monograph. The stock supply of several tumors was also occasionally “refreshed” by the inclusion of material obtained from other laboratories where the same lines had been carried in parallel. The technique usually employed in the experiments consisted of the following steps: (1) A suspension of free tumor cells was injected intra-abdominally into 12 mice susceptible to a particular tumor line and, three to four days later, these animals were divided into two equal groups. Six mice were inoculated intraperitoneally (or less often by other routes) with a virus suspension of predetermined titer. The other six mice received noiiinfected control material of mouse brain, chick embryo, or tissue culture origin. (2) Four to five days after inoculation with virus, if no signs of sickness were noted before, the abdomens of the animals were tapped and ascitic fluid was withdrawn. Aliquots of the fluid were examined in the following ways: (a) a smear was made and stained for morphological examination; (b) a cell

Immunization of man against poliomyelitis with attenuated preparations of living virus.

There could hardly be a more opportune time for retrospective analysis of live virus immunization against poliomyelitis. This is the fifth anniversary of the day when-after painstaking soul searching-a decision was reached to administer the TN strain of poliomyelitis in live form to a nonimmune individual. This first recipient, who ingested log of 5.8 PD6a of the virus in the form of cotton rat CNS, developed intestinal carriage, followed by the appearance of homologous antibodies.‘ This response, occurring in the absence of any signs or symptoms of illness, spurred a collective effort to continue the study-an endeavor considered, at that time, not only perilous for the subjects of the trial but also as sinful on the part of the investigators, who risked misunderstanding and even downright mistrust by laymen and scientists alike. Five years have not yet changed the Age of Doubt into the Age of Faith, but the administration of live poliomyelitis virus to human subjects is now considered only a minor sin, and anyone professing a milder view may even grant those committing such sin an escape from eternal damnation-though thinking, like Josh Billings, “Give the devil his due, but be very careful that there ain’t much due him.” The present paper is divided into three parts: one summarizes the results of clinical trials with particular emphasis on a comparison of data obtained in the oral administration of types 1 and 2; in the second part, the interference phenomenon between types 1 and 2 in the human alimentary tract will be described; and the rest of the paper deals with speculations concerning criteria of attenuation.

Further Studies on Oral Administration of Living Poliomyelitis Virus to Human Subjects.

Summary sixty-one children who had no antibodies against Type II (Lansing) poliomyelitis virus were fed the TN strain of virus. None showed any clinical signs of illness. Viremia was absent in every case. In 29 individuals the virus was isolated from the stool from the 5th to the 20th day after feeding. Specific antibody rise was onserved in most of the patients.

Administration of an attenuated type I poliomyelitis virus to human subjects.

Summary Two human subjects who had no antibodies against Type I poliomyelitis virus were fed a mouse adapted Type I strain, and one human subject who had no antibodies against Types I and II was fed a mixture of mouse adapted Type I and Type II strains. None of the individuals showed clinical signs of illness as a result of ingestion of the virus. In the absence of viremia, all 3 excreted virus in the stools. Homologous neutralizing antibodies developed in the sera of each person. Virus passaged through the human intestinal tract maintained the very low pathogenicity for monkeys when injected intracerebrally.

Studies on Chick Embryo Adapted Rabies Virus. III. Duration of Immunity in Vaccinated Dogs

Conclusions Hinderssons observations, coupled with the results of the present experiments, seem to indicate that: 1. Vaccination with living rabies virus is perhaps a more effective method of immunization of the canine population than any of the others presently available. 2. Immunity conferred by vaccination with living rabies virus, as exemplified by Flury strain in these experiments, lasts at least 2 years. 3. These observations on the duration of immunity following live virus vaccination indicate the need for reconsidering local ordinance and other regulations concerning rabies vaccination.

Specific Complement-Fixing Diagnostic Antigens for Colorado Tick Fever

Summary and Conclusions Specific diagnostic complement-fixing antigens for Colorado tick fever have been prepared from infected mouse brains. The benzene-extracted antigens employed gave no false positive reactions in the presence of highly positive human syphilitic sera. Cross fixation tests between Colorado tick fever immune serum and the heterologous antigens of viral and rickettsial origin indicate that Colorado tick fever is a distinct entity and the virus is not related to any of the other infectious agents tested. These results confirm those obtained with the mouse neutralization test previously reported.13,14 Close correlation was obtained in the complement-fixation and mouse neutralization tests with human convalescent sera. The complement-fixing and neutralizing antibodies apparently appear in the blood of humans at about the 9th to 14th day after diagnosis of illness and may remain demonstrable as long as 34 months later. The complement-fixation test, as well as the mouse neutralization test, may prove of value in epidemiological studies on the incidence and geographic distribution of Colorado tick fever. Furthermore, if results with animal sera parallel those obtained with human sera, the tests may be applied to study the ecology of Colorado tick fever.Summary and ConclusionsSpecific diagnostic complement-fixing antigens for Colorado tick fever have been prepared from infected mouse brains. The benzene-extracted antigens employed gave no false positive reactions in the presence of highly positive human syphilitic sera. Cross fixation tests between Colorado tick fever immune serum and the heterologous antigens of viral and rickettsial origin indicate that Colorado tick fever is a distinct entity and the virus is not related to any of the other infectious agents tested. These results confirm those obtained with the mouse neutralization test previously reported.13,14 Close correlation was obtained in the complement-fixation and mouse neutralization tests with human convalescent sera. The complement-fixing and neutralizing antibodies apparently appear in the blood of humans at about the 9th to 14th day after diagnosis of illness and may remain demonstrable as long as 34 months later.The complement-fixation test, as well as the mouse neutralization test, may...

Oral Administration of a Rodent-Adapted Strain of Poliomyelitis Virus to Chimpanzees.

Nine chimpanzees were fed the TN strain of rodent-adapted poliomyelitis virus. All developed homotypic antibodies and two became intestinal carriers of the virus. None showed clinical signs of disease. Subsequent oral challenge with Brunhilde virus caused viremia and paralysis in one control chimpanzee and intestinal carriage in all other control animals and in seven of those previously fed TN strain.

Occurrence of rabies virus in the blood of developing chick embryo.

Summary and Comments The Flury strain of rabies virus was inoculated by the yolk-sac route into 7-day-old chick embryos. By means of intracerebral injections into mice, the virus was recovered from the chick-embryo blood secured from the 3rd to the 15th post inoculation day. The similar results obtained in two series of experiments seem to exclude the possibility of a major experimental error. While these experiments do not prove or disprove the infectiousness of mammalian blood from rabies infected animals, they do indicate a completely different mechanism of dissemination of the virus in embryonated eggs.