Isolation of Serratia marcescens in the midgut of Rhodnius prolixus: impact on the establishment of the parasite Trypanosoma cruzi in the vector

• Published in: Experimental parasitology 2004-05, Vol.107 (1), p.89-96
• Main Authors: Azambuja, P, Feder, D, Garcia, E.S
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chagas disease; Erythrocytes - microbiology; Erythrocytes - parasitology; Fundamental and applied biological sciences. Psychology; Hemolysis; Host-Parasite Interactions; Humans; Insect Vectors - microbiology; Insect Vectors - parasitology; Larva - microbiology; Larva - parasitology; Life cycle. Host-agent relationship. Pathogenesis; Prodigiosin; Prodigiosin - metabolism; Protozoa; Reduviidae; Rhodnius - microbiology; Rhodnius - parasitology; Rhodnius prolixus; Serratia marcescens - isolation & purification; Serratia marcescens - physiology; Trypanolytic activity; Trypanosoma cruzi; Trypanosoma cruzi - physiology
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2004.04.007

The effects of resident bacteria in the stomach of 5th-instar larvae of Rhodnius prolixus on the erythrocyte lysis and Trypanosoma cruzi infection were studied. The bacteria population increased approximately 10,000-fold after feeding. Hemolysis rose to approximately 28% within 24 h postfeeding and then linearly grew until day 4 attaining almost 100%. The number of surviving Y strain of T. cruzi in the stomach declined drastically, while the infection with Dm28c clone was maintained stable. Five days after feeding, few different types of bacterial colonies were obtained when stomach content suspensions were spread onto BHI agar plates. The hemolytic bacteria were isolated and identified as Serratia marcescens biotype A1a (referenced as RPH), which produces the pigment prodigiosin. In vitro experiments, comparing incubations of RPH with S. marcescens SM365, a prodigiosin pigment producer, and S. marcescens DB11, a nonpigment variant, as a control, with erythrocytes and T. cruzi demonstrated that: (i) at 30 °C, SM365 and RPH diminished the populations of Y strain, but not DM28c clone, and DB11 was unable to lyse both T. cruzi strains; (ii) at 0 °C, SM263 and RPH killed the flagellates, but DB11 did not; and (iii) all three strains of S. marcescens were able to lyse erythrocytes. These results suggest that S. marcescens trypanolytic activity from the SM365 and RPH strains is distinct from the hemolytic activity and that prodigiosin is an important factor for the trypanolytic action of the bacteria.