Role of protein deficiency on the course of trypanosoma cruzi infection and on the degree of protection conferred by a flagellar fraction

In order to determine if dietary proteins are responsible for alterations seen in the course of T. cruzi infection in calorie depleted mice, the effects of chemically defined diets with reduced protein contents were measured in the same animal model. BALB/c mice receiving 20% (NP) or 2% (LP) protein diets were injected with 100 blood trypomastigotes 15 days after the initiation of the diet. Onset of parasitemia was detected earlier in the LP group, but by day 13 post infection (pi), parasitemia levels, as well as survival time, were not statistically different from NP animals. Although a chronic state could not be reached with animals infected with 15 blood trypomastigotes receiving a 6% (SP) protein diet, those sacrificed 30 days pi showed statistically different DTH indexes, but not different specific antibody titers, compared to NP animals. To determine the effect of the moderate protein deficiency upon the degree of protection conferred by a flagellar fraction (FF) of T. cruzi which protects well nourished animals against a lethal challenge of the parasite, SP and NP mice immunized with 5 weekly doses of FF were challenged with 1000 metacyclic trypomastigotes. Parasitemias were higher for vaccinated SP animals with respect to NP controls. Survival was also significantly lower for animals receiving the low protein diet.