Monroe D. Eaton

Demonstration in Cotton Rats and Rabbits of a Latent Virus Related to Pneumonia Virus of Mice.

Summary and Comment Fourteen rabbits in a total of 28 developed neutralizing antibodies to the pneumonia virus of mice (PVM) either before or during the time they were under experiment in this laboratory. The appearance of these antibodies could not be correlated with the kind of material injected or with the development of antibodies to the atypical pneumonia virus 5 or to other agents. The incidence of antibodies to PVM was definitely higher in rabbits which had been kept in the laboratory for 2 to 10 months, and thus exposed to this agent carried by other rodents in active or latent form, than in normal rabbits newly received from an outside source or in those under experiment for a short interval of time. An agent related to PVM has been isolated from the lungs of apparently normal cotton rats, but as yet no attempt has been made to isolate a similar agent from rabbits. Human serums frequently contain neutralizing antibodies to PVM, 2 but an increase in these antibodies has not been observed. Although these results do not exclude the possibility that a virus antigenically related to PVM may be carried in the human respiratory tract, they do suggest that previous experiments 3 have failed to establish the relationship of such an agent to the virus isolated in our laboratory from persons with atypical pneumonia. 5

Action of acridines on agents of the psittacosis-lymphogranuloma group.

Summary Acriflavine; 3-nitro-6, 7-dimethoxy 9 - (2-phenyl-4-diethylaminobutylamino) acridine; and 3-nitro-6, 7-dimethoxy 9 - (2-hydroxy-3-diethylaminopropylamino) acridine inhibited yolk sac infections of chick embryos with the agents of feline pneumonitis, lymphogranuloma venereum, and meningopneumonitis. The first two compounds were less active against the virus of mouse pneumonitis, but the last-named inhibited this agent in chick embryos. Proflavine, atabrine, and drugs closely related to the above-mentioned nitroacridines, except for substitution of C1 for NO2, had no significant inhibitory action. 3-nitro-9-aminoacridine was intermediate in its effect. Respiratory infections in mice caused by the agent of feline pneumonitis were retarded by the two nitroacridines, but these drugs showed slight or no effect in mice against intranasal infection with the agents of mouse pneumonitis, lymphogranuloma venereum, and meningopneumonitis.

Complement-Fixation in Human Pneumonitis with Group-Reactive Virus Antigens.

Summary Complement fixation tests were done with sera from cases of pneumonitis and acute upper respiratory disease and antigens from the viruses of lymphogranuloma ven-ereum, meningopneumonitis, and the mouse pneumonia virus of Nigg. 4 Positive reactions of a group-specific character were obtained in 10 to 15% of cases of pneumonitis and in about 2% of cases of upper respiratory disease.

Serological Differentiation of Primary Atypical Pneumonia from Virus Pneumonia of the Psittacosis Group.

Summary In 11 cases of primary atypical pneumonia with increases in neutralizing antibodies for the virus propagated in chick embryos no significant development of complement-fixing antibodies for agents of the psittacosis group were found. Ten of the patients had cold hemagglutinins and 7 showed significant titers of agglutinins for the indifferent streptococcus No. 344. In an additional 10 cases of virus pneumonia where the presence of an agent of the psittacosis group was demonstrated by virus isolation or complement fixation, no significant development of neutralizing antibodies for the virus of atypical pneumonia occurred. The serum of one of the latter 10 patients showed streptococcal agglutination at a dilution of 1:20 without change in titer.

A New Strain of Virus of Influenza B Isolated During an Epidemic in California.

Summary A new strain of the virus of influenza B was isolated from the throat washing of a case of influenza during an epidemic in California in January, 1940. The difficulties of isolating this virus by the usual methods of passage in ferrets and mice are noted. The new strain was not identical in antigenic composition with the Lee strain isolated by Francis, but was closely related to it.

Effect of the Host in Action of Sulfonamides on Elementary-Body Agents of Murine and Feline Pneumonitis.

Summary The effect of sulfamerazine on pulmonary infections in mice, hamsters, rats, and cotton rats, and on yolk sac infections in chick embryos with the agents of murine and feline pneumonitis was studied. The drug inhibited the action of the mouse virus in all the species tested and was effective in very small doses, 0.0025 mg per gram of body weight in mice and somewhat larger doses, 0.1 mg/g, in hamsters. With the agent of feline pneumonitis, large doses of sulfamerazine, near the toxic limits, produced moderate inhibition of the lung lesions in hamsters and white rats, slight inhibition in cotton rats, and no effect in mice or chick embryos.

Experiments on Immunization of Human Beings against Influenza A.

Summary Studies were conducted at two large institutions during an outbreak of influenza A which was proven by complement-fixation tests. Persons at both institutions received a living virus and complex formalinized vaccine previous to the outbreak. An epidemiological survey revealed some protection at one institution, but none at the other. There was no obvious difference in the prophylactic efficacy of the two vaccines in the relatively small group of 829 individuals studied.

A Comparison of various Methods of demonstrating Influenza Virus in Throat Washings.

Summary During the epidemic of influenza A in 1943-44, throat washings from military personnel were tested in ferrets or hamsters, or in both species, and a smaller number of the same washings were inoculated into chick embryos. None of the throat washings from 23 persons in whom response to serological tests for influenza A virus was negative produced antibodies to that virus after intranasal inoculation in ferrets. Of 30 throat washings from persons showing positive response to serological tests for influenza A virus, 17 (56.7 ± 9.05%) produced in ferrets an increase in antibodies to the virus. With 2 exceptions all ferrets showing an increase in antibodies also developed fever 2 to 3 days after inoculation. Four of 41 ferrets showing no increase in antibodies had similar febrile reaction. Thirty, or 56.6 ± 6.81% of 53 throat washings from persons with known cases of influenza A were positive in hamsters, a result identical with that obtained in ferrets. Twelve throat washings that were negative in ferrets produced no antibody response in hamsters. Seventeen throat washings shown to contain influenza A virus by tests in ferrets or hamsters were inoculated into chick embryos by the amniotic route. Of these, 7 (41.2 ± 11.9%) infected the embryos. Virus was demonstrated in 4 throat washings in the first passage and in 3 in the second, but usually 1 or 2 additional amniotic or allantoic passages were necessary before the virus reached sufficient titer to be positively identified as influenza A. In 2 of 13 unfiltered throat washings inoculated into the allantois of chick embryos, virus was demonstrated on first passage.

Precipitation and Concentration of Influenza Virus With Alum.

Summary The virus of influenza grown in allantoic fluid of chick embryos can be pre-cipitated in a stable form with alum and the precipitate redissolved in sodium citrate. This procedure does not alter the infective, anti-genic, or hemagglutinating properties of the virus. Adsorption on sterile chicken cells was also used to concentrate the virus before inactivation and precipitation with alum. The immunizing power of formalinized and alum-precipitated virus in mice was slightlv less than that of active fluid. Inactive con-centrated alum precipitates inoculated sub-cutaneously produced a satisfactory antibodv response in human beings. The suspensions of alum precipitates freed of formaldehyde and acid retain their antigenicity when stored at 4°C for at least three months.