Lactobacillus casei ssp. rhamnosus enhances non specific protection against Plasmodium chabaudi AS in mice

Objective. To evaluate the capacity of Lactobacillus casei ssp. rhamnosus to enhance resistance against Plasmodium chabaudi chabaudi AS. Material and Methods. NIH mice were IP injected with viable lactobacillus casei seven days (LC1 group) or 7 and 14 days (LC2 group) before the challenge (day 0) with Plasmodium chabaudi parasitized red blood cells (pRBC). Control mice were inoculated with pRBC only. When parasitaemia was resolved, naive mice were injected with spleen cells from each group. The parasitaemia was measured. Nitric oxide (NO^.) in serum was determined. Results. Mice from the LC1 group presented a reduction in parasitaemia, with a prepatent period of five days, parasitaemia lasted 11 days, and the peak was (36.3 % pRBC) on the 12^th day post-infection. Mice from the LC2 group showed a prepatent period of five days, parasitaemia lasted eight days, and the peak (30 % pRBC) was of on the 11^th day. In the control, the prepatent period was three days, the parasitaemia lasted 15 days, and the peak (51% pRBC) was on day nine. Mice inoculated with spleen cells from the LC2 group showed a prepatent period of 21 days, parasitaemia lasted seven days, and the peak (13.5% pRBC) was on the 26^th day. Conclusion. L. casei enhanced nonspecific resistance to P. chabaudi, as indicated by longer prepatent periods, reduced parasitaemia, and reduction in the viability of the parasites recovered from the spleen of infected mice, along with high concentrations of NO^. in serum.