Evolution of subpatent parasitaemia in Trypanosoma cruzi chronically infected mice with the help of a cyclophosphamide amplification transfer assay Evolução das parasitemias subpatentes na infecção crônica experimental pelo Trypanosoma cruzi através do ensaio de subinoculação modificado pelo tratamento com ciclofosfamida

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: José M. Alvarez, Ayumi Oshima, Veronica Mozer, Liliane Guimarães, Hércules Menezes
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 1991
• Subjects: Trypanosoma cruzi; Infection in mice; Parasitaemia; Cyclophosphamide amplification transfer assay; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Aguda; Alta; Arctic; The ''Y''
• Online Access: https://doi.org/10.1590/S0036-46651991000600013; https://doaj.org/article/ca4c45816dce47c296c701a3942ff309

We have evaluated the sensitivity of the classical blood subinoculation method, modified through cyclophosphamide treatment of transferred mice, for the detection of occult parasitaemias in Trypanosoma cruzi chronically infected mice. Besides its simplicity, the method was shown to be highly sensitive for both the "chronic" phase parasites (99% of chronic cases were shown to harbour occult parasitaemias) and for the acute phase parasites (T. cruzi could be detected in 53.8% of animals transferred with one Y strain parasite and in 20% of animals transferred with one CL strain parasite). Using acute phase bloodforms, the assay proved to be more sensitive than conventional subinoculation when dealing with the CL, but not the Y strain of the parasite. With the help of this parasite detection tool, we have studied during a one year period, the evolution of subpatent parasitaemias in a group of mice which survived through chemotherapy from lethal acute phase of T. cruzi infection. Cyclophosphamide transfer assay revealed occult parasitaemias in 100% of the chronic animals, nevertheless, continuous and discontinuous patterns of positivity were observed. Avaliamos o potencial do ensaio clássico de subinoculação, modificado pelo tratamento com ciclofosfamida dos animais receptores, na detecção de parasitemias ocultas em camundongos com in-fecção crônica pelo Trypanosoma cruzi. O ensaio, além de simples, mostrou ter uma alta sensibilidade; assim, utilizando-se parasitas da fase aguda, o tratamento com ciclofosfamida revelou parasitemias em 53,8% dos animais infectados com um tripanosoma da cepa y, e em 20% dos animais infectados com um tripanosoma da cepa CL. O tratamento com ciclofosfamida aumentou a sensibilidade do ensaio de subinoculação nas infecções pela cepa CL, e resultou em igual sensibilidade quando utilizada a cepa Y. Nos camundongos de fase crônica, obtidos a partir de diversos esquemas de imunoprofilaxia (BCG, soro de camundongo imune) ou quimioterapia, o ensaio revelou parasitemias ocultas em 99% dos ...