Oncolytic and protective effect of strain no. 228 of a new rotavirus group in the Reoviridae family on В16/F10 melanoma growth in experiment.

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e14210 Background: The purpose of the study was to determine the effect of a strain No. 228 of a new rotavirus group of the Reoviridae family on the growth of transplantable В16/F10 melanoma in mice and survival of animals. Methods: The study was performed using a strain No.228 of a new group of rotaviruses (working title «group K», RVK) ( http://jbks.ru/archive/issue-10/article-6 ). RVK is a live attenuated and apathogenic strain growing on the PEKC culture (pig embryo kidney cells) with 5·109 viral particles/mL. The dynamics of melanoma growth and survival of animals receiving RVK were studied on 25 male mice divided equally into 5 groups. RVK was administered intramuscularly and Per os once a week, respectively 0.3 mL and 25 µL to groups 1-2 21 days prior to the tumor inoculation, a total of 4 injections (“vaccination” regimen); to groups 3-4 – 7 days after tumor inoculation with the appearance of tumor nodes, a total of 3 injections (“treatment” regimen); group 5 – controls receiving saline. Groups 1 and 3 received live RVK, groups 2 and 4 - RVK inactivated by UV radiation. Results: Survival in both groups of animals with “vaccination” regimen was improved significantly, compared to controls (group 1 – 25.8±2.2 days after melanoma transplantation; group 2 – 25.4±1.1 days; controls – 14.6±3.08 days, p < 0.05). In groups with “treatment” regimen, survival was 19.2±3.08 days in group 3 and 21.6±3.52 days in group 4, the latter significantly higher than in controls (p < 0.05). Introduction of a live virus in the “vaccination” regimen resulted in significantly better survival compared to the “treatment” regimen (group 1 vs. group 3), while inactivated virus did not caused such a difference (groups 2 and 4). Conclusions: Improved survival of mice with B16/F10 melanoma after administration of RVK demonstrated its ability to inhibit tumor growth and confirmed our previously published data obtained on Guerin's carcinoma in rats. Administration of a live virus prior to the tumor inoculation cause stronger effect than after inoculation. Since inactivation of the virus does not eliminate its effect, apparently, it is associated with immunostimulating action, rather than with oncolytic one.