Residual virulence, antigenic properties, survivability duration and contagiosity of B. abortus strain 82-TR

The purpose of research is to study the residual virulence, antigenic properties, duration of survival and contagiousness of the strain B. abortus 82-Tr. Determination of residual virulence was carried out on 45 guinea pigs divided into 9 groups of 5 animals each. Animals of the first group were immunized with a culture from the 82-Tr strain subcutaneously in the groin area in a volume of 1 ml with a content of 10 m.c.; the second - 50; the third - 100; the fourth - 500; fifth - 1000; sixth - 10 thousand; seventh - 100 thousand; eighth - 1 million; ninth - 9 billion m.c. To study the duration of survival of the B. abortus 82-Tr strain in the body of guinea pigs, its harmlessness and contagiousness, 21 animals were used, the first half of which were vaccinated with a culture of the 82-Tr strain at a dose of 1.5 billion m.c., and the second half (unvaccinated) were placed next to them. Within 4 months after the introduction of culture once a month, 3 guinea pigs from each group of animals were taken blood from the heart for serological studies, and then subjected to euthanasia, followed by bacteriological examination. It was found that the culture of the strain begins to take root at a concentration of 1000 m.k. With an increase in the concentration of the injected culture, there was a slight decrease in the infection index (II) to (42.0 ± 5.8) at 1 million m.c. and (40.0 ± 15.3) at a dose of 1 billion m.c. Studies give reason to believe that the culture of strain 82-Tr has weak residual virulence.