Chemosensory responses of Trichomonas to polyamines

Abstract

Trichomonas vaginalis, a sexually transmitted parasitic flagellate of the human urogenital tract, requires the polyamine spermine, which is present in high concentrations in the vagina and the epididymus. We investigated the possibility that these parasites might use spermine or other polyamines as chemical signals in migrating to sites of infection, which in turn would suggest a possible class of chemotherapeutic targets. We tested this possibility with a novel assay method. Log‐phase cells were placed in one of two 2‐ml tubes connected by a glass capillary; the other tube contained a test chemical. Numbers of cells migrating through the capillary into the second chamber were monitored over time by sampling the second tube. Significant migration responses were found to be 0.02 mM for spermine, putrescine, and citrulline. Lesser responses were found to spermidine, arginine and ornithine. Other amino acids did not differ from buffered salt solution controls. Cell behavior and motility were studied by videomicrosopy. A larger percentage of motile cells was observed in the presence of the active polyamines than in controls, where more cells attached to surfaces. These results suggest that this parasite does have chemosensory responses to polyamines specifically, and that the behavioral mechanism may involve a simple kinesis, though the latter possibility needs to be tested further.