[Rotavirus: an ubiquitous infection?]. / Rotavirus: une infection ubiquitaire?

Rotavirus is the most frequent virus found in childhood gastroenteritis. A rotavirus viremia is observed in 19 to 63 % of cases, for three days at the beginning of infection. Then, rotavirus can reach several organs as liver (hepatitis in 1/3 of case), nervous central system (2 % of encephalitis could be linked to rotavirus), or more infrequently mesenteric lymph nodes, lung or heart. However, the link between rotavirus and systemic manifestations has not been well established. Further studies are necessary to confirm the role of rotavirus in these organ's lesions.

Reproductive system impairment of mice fed diets containing beluga whale blubber from the St Lawrence estuary and arctic populations.

The toxic potential of naturally relevant mixtures of PCBs and other organohalogens on the reproductive system of C57Bl/6 female mice was assessed. Mice were fed diets in which lipids were replaced by blubber of beluga whales from a highly contaminated population of the Saint Lawrence River, and a less contaminated population from the Arctic Ocean. Ratios of blubber from both sources were mixed in order to perform a dose-response study. Control mice were fed diets for 90 d in which fat was replaced by corn oil or beef tallow. There were no significant effects of diets on body, liver, spleen or thymus weights. Similarly ovulation occurred in all control and experimental groups. However, Graafian follicles from ovaries of mice fed contaminated diets showed abnormal development of oocytes. Cumulus granulosa cells bind normally to the oocyte prior to ovulation and are essential for sperm penetration and fertilization. These cells were absent in both Graafian follicles and ovulated oocytes in the oviduct of all groups fed contaminated diets. Oviducts of these mice revealed evidence of epithelial degeneration. These results suggest the female mouse reproductive system is sensitive to organohalogens and illustrate the toxic potential of contaminant mixtures as found in the less contaminated Arctic population.

Immunosuppression in mice fed on diets containing beluga whale blubber from the St Lawrence estuary and the Arctic populations.

In order to assess the immunotoxic potential of naturally relevant mixtures of PCBs and other organohalogens, C57Bl/6 mice were fed on diets in which lipids were replaced by blubber of beluga whales from the highly contaminated population of the Saint-Lawrence River, and the less contaminated population from the Arctic. Different ratios of blubber from both sources were mixed in order to allow a dose-response study. Mice were fed for a period of 90 days at the end of which their immunological status was monitored. For general parameters such as body weight, weight of the spleen and the thymus no significant effect of diets were observed. The immunological endpoints such as the blastic transformation of splenocytes and the spleen NK cell activity were not significantly affected by any of the diets compared to control diets. While the different cell subpopulations of peripheral blood and thymus were not affected by the diets, a significant decrease was noted in the CD8+ T cell population in the spleen of mice fed with most of the diets containing beluga blubber. Moreover, the ability of splenic cells to elicit humoral response against sheep red blood cells as well as the potential of peritoneal macrophages to perform phagocytosis were suppressed by all diets containing beluga blubbers. In summary, there was no differences between the groups fed with a blubber diet with low and high organochlorine contamination. However, a clear immunosuppression was demonstrated when these groups were compared to the group fed with beef oil. Despite the fact that we cannot exclude a possible contribution of the fatty acid composition of the beluga blubber to the immunosupression, these results suggest the sensitivity of mouse immune system towards organohalogens, and point out the toxic potential of contaminant mixtures as found in the less contaminated Arctic population.