[Moscow Research Institute of Viral Preparations tissue-culture smallpox vaccine in a coded control experiments of adult revaccination by scarification]

Comparative studies of tissue culture and dermal smallpox vaccines were carried out in a strictly controlled coded trial by revaccination of adults by scarification. Two lots of tissue culture and one lot of dermal vaccines with a similar infectious titer (8.0 lg PFU/ml) were used. All the lots tested "took" in 100%. In the group revaccinated with tissue culture vaccine seroconversion was observed in 94.2 +/- 2.8%--95.0 +/- 2.8%, with a 4.6 +/- 5.3-fold rise in geometric mean antibody titer; the dermal smallpox vaccine produced seroconversion in 85.7 +/- 4.4% with 4.3-fold rise in geometric mean antibody titer. Febrile reactions in revaccines with the tissue culture vaccine were observed in 23.1%--26.1% which did not exceed this parameter in the group revaccinated with the dermal vaccine (25.2%); in all the groups febrile ractions were of mild degree (37.1 degrees--38 degrees C). Local reactions of the type of confluent erythema were observed 1.8--5.3-fold more frequently among those revaccinated with the dermal vaccine than among those revaccinated with the tissue culture vaccine. Thus, the tissue culture vaccine used epicutaneously was as good as the dermal one by the take rate and antigenic activity, but had less remarked reactogenic properties which allows to recommend it for public health practice.

Immune responses to measles and smallpox vaccinations in malnourished children

Children with different levels of nutritional status were studied to determine their immune response to, and complications from, immunization with live measles vaccine and lyophilized smallpox vaccine. Two hundred forty-one children between the ages of 5 months and 9 years were examined to assess their nutritional status at the time of immunization. Sero-conversion was defined as a hemagglutination-inhibition titer to measles virus, of greater than or equal to 1:20 6 to 8 weeks after vaccination in initially sero-negative children. Of 111 initially sero-negative children 94% had an adequate immune response, shown by sero-conversion. Of 193 children without a smallpox vaccinationscar 97% were successfully immunized against smallpox. These rates of immune response were independent of age, sex, and nutritional status of the children. The geometric mean titer rise to measles immunization of groups, whose nutritional status was normal (greater than 90% of median weight for age), mildly (75 to 90%), moderately (60 to 75%), or severely (less than 60%) malnourished were 7.5, 8.8, 7.9, and 7.9, respectively. Malnutrition did not affect the children's ability to develop adequate immune response to measles of smallpox vaccine, and there were no major complications during the 8-week period of follow-up. Since measles is a very severe disease, which in malnourished children can carry a case fatality rate as high as 50%, malnutrition should be a prime indication for measles immunization, and certainly not a contraindication.

False positive results in V D R L slide test following smallpox immunization

A study is conducted on the incidence of false positive results in the serological test for syphilis in 300 military recruits following smallpox immunization. It is found that 3.7% of individuals developed false reactivity in the V D R L Slide test. The false reactivity appeared two to four weeks following immunization, and disappeared from two to eight weeks later. All reactive sera were negative in the FTA-ABS test.

Generation of virus-specific cytolytic activity in human peripheral lymphocytes after vaccination with vaccinia virus and measles virus

Human peripheral blood lymphocytes (PBL) harvested after vaccination with vaccinia or measles virus showed a specific activity against virus-infected target cells. This activity peaked on day 7 and was specific for the target cells infected with the virus used for the vaccination. The cytotoxic activity was not related to HLA markers. The cells involved in the cytolytic process were lymphocytes bearing Fc receptors. In addition, the cytotoxic activity was abrogated by more than 90% by rabbit Fab'2 anti-human IgG. It is therefore likely that two subpopulations of lymphocytes are involved: an antibody-secreting cell providing specific antiviral antibody and an effector cell bearing Fc receptor (K cells). Finally, these experiments suggest that antibody-dependent cell cytotoxicity may play a major role in the recovery from virus infection in man.

[Comparative study of the smallpox vaccines from B-51, EM-63 and L-IVP in a controlled epidemiological experiment. II. The characteristiics of the immunogenicity of the smallpox vaccines]

Immunogenicity of smallpox vaccines prepared of EM-63, L-IVP, and B-51 strains was studied under conditions of strict controlled epidemiological trial. Skin reactions to revaccination and vaccines antigenic activity indices were detemined in the persons vaccinated. Changes in the virus-neutralizing and antibodies suppressing hemagglutination was the same in persons vaccinated with any of the preparations tested. The maximal virus-neutralizing antibodies level was determined 1 month after the vaccination and persisted without any essential changes for one year. The titre of hemagglutination inhibiting antibodies also reached the maximum in one month, but diminished gradually by the end of one year after the vaccination. There were found no significant differences in the antigenic activity of the vaccines. The vaccines studied also displayed no difference in the number and character of skin reactions to revaccination. In comparing the antibodies level and the character of skin reactions to revaccination it was found that the titres of hemagglutination inhibiting antibodies and virus-neutralizing antibodies of 1:40 and over were in the great majority of cases determined in the blood sera of the vaccinated persons with the immediate and negative reactions to revaccination, i. e. in those with intensive postvaccinal immunity.

[Nonspecific resistance to heterologous viral infection after immunization with smallpox vaccine]

The level of development of nonspecific resistance to influenza virus infection after immunization with variola vaccine, the dynamics of changes in DNA synthesis in the spleen cells and concentration of nonspecific immunoglobulins in the blood serum of mice after immunization and infection with influenza virus were studied. A close correlation between DNA synthesis, concentration of immunoglobulins, and the level of nonspecific resistance to heterologous virus infection was found.

[Experimental study of cellular immunity after administration of inactivated and live virus vaccine]

Experiments were conducted on guinea pigs with the use of cell migration inhibition test of the peritoneal exudate; stimulation of a definite level of cell immunity in response to the administration of both live and of inactivated vaccine virus was shown. The results obtained are used for the interpretation of the action mechanism of the inactivated preparation in two-stage smallpox vaccination.