Evaluation of antitumor activity in strains of a new rotavirus group in Reoviridae family on a model of transplantable murine melanoma

The purpose was to study antitumor effects of the group K rotaviruses strains No. 228 and No. 100 in the experiment on a model of transplantable murine melanoma. Material and methods. The study included 65 С57Black/6 mice with transplantable B16/F10 melanoma and two strains of the Reoviridae family members characterized as rotaviruses, not belonging to the known groups, with the working title “group K rotaviruses (RVK)”. Animals received RVK in “vaccination” (before tumor transplantation) and “treatment” (after tumor formation) modes. Live and inactivated strains were used. RVK were administered intramuscularly as 0.3 ml of virus-containing culture fluid with at least 5x109 viral particles per 1 ml, with a total of 4 injections. Life span of mice and morphological characteristics of tumors were evaluated. Results. Injections of both strains increased the survival of tumor-bearing mice by 1.7-1.9 times in 4 of 8 experimental groups, compared to controls. The modes of RVK administration showed some differences: the survival was longer in mice with the “vaccination” mode compared to the “treatment” mode. Morphological changes in tumors were similar after application of both modes and inclued dystrophic changes of tumor cells, formation of extensive necrosis areas, and leukocyte infiltration. Discussion. Live and inactivated RVK had unidirectional effects implying its association with immunomodulatory action rather than with a direct lytic effect on the tumor. Conclusions. Both studied strains of rotaviruses in the group K had antitumor effect in the model of transplantable В16/F10 murine melanoma in the «vaccination» mode.