Oncolytic and protective effects of strain 100 of a new group of non-classified rotavirus of reoviridae family on B16/F10 melanoma growth in experiment.

Abstract

e21587 Background: The purpose of this study was to assess the effect of a strain 100 of a new group of rotavirus of Reoviridae family on the growth of transplantable B16/F10 melanoma in mice and the survival of the animals. Methods: We studied the strain 100 of a new group of rotavirus of Reoviridae family (RVK) ( http://jbks.ru/archive/issue-10/article-6 ). RVK 100 is a live attenuated non-pathogenic virus growing on pig embryo kidney cell culture with concentration 5·109 per 1 ml. The dynamics of melanoma growth and the survival of tumor-bearing animals receiving RVK were studied in 25 male mice divided into 5 equal groups, each n = 5. RVK was administered intramuscularly and orally once a week 0.3 mL and 25 µL, respectively: 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 onset of tumor nodes, a total of 3 injections (“treatment” regimen); group 5 included controls receiving 0.85% NaCl solution. Groups 1 and 3 received live RVK, groups 2 and 4 - RVK inactivated by UV radiation. Results: Survival of mice in groups 1-2 receiving both live and inactivated RVK in the “vaccination” regimen was increased statistically significantly: in group 1, Me = 25 days after melanoma transplantation (LQ 24; UQ 30), in group 2 Me = 26 days (LQ 25; UQ 30), in controls Me = 14 days (LQ 10; UQ 22); p = 0.032 and p = 0.0079, respectively. RVK administration in the “treatment” regimen did not cause such changes. While mice of group 3 receiving the live strain 100 showed a tendency to higher survival, compared to controls (Me = 23 days, LQ 22; UQ 24, p = 0.056), the administration of inactivated RVK (group 4) did not significantly improve the survival of animals, compared to controls (Me = 22 days (LQ 21; UQ 33, p = 0.151). Conclusions: Improved survival of animals with B16/F10 melanoma after the RVK administration indicates the virus ability to slow down tumor growth and confirms our previously published data on the RVK strain 228, although, in contrast to it, the strain 100 is able to increase the survival rate of tumor-bearing mice only when used in the “vaccination” regimen, which refers mainly to the inactivated virus. Since the inactivation of the RVK strain 100 eliminates its effect when used in the “treatment”, but not “vaccination” regimen, it seems to be associated with an immunostimulatory effect but not with an oncolytic one.