New features on the survival of human-infective Trypanosoma rangeli in a murine model: Parasite accumulation is observed in lymphoid organs

PLoS Negl Trop Dis. 2020 Dec 28;14(12):e0009015. doi: 10.1371/journal.pntd.0009015. eCollection 2020 Dec.

Abstract

Trypanosoma rangeli is a non-pathogenic protozoan parasite that infects mammals, including humans, in Chagas disease-endemic areas of South and Central America. The parasite is transmitted to a mammalian host when an infected triatomine injects metacyclic trypomastigotes into the host's skin during a bloodmeal. Infected mammals behave as parasite reservoirs for several months and despite intensive research, some major aspects of T. rangeli-vertebrate interactions are still poorly understood. In particular, many questions still remain unanswered, e.g. parasite survival and development inside vertebrates, as no parasite multiplication sites have yet been identified. The present study used an insect bite transmission strategy to investigate whether the vector inoculation spot in the skin behave as a parasite-replication site. Histological data from the skin identified extracellular parasites in the dermis and hypodermis of infected mice in the first 24 hours post-infection, as well as the presence of inflammatory infiltrates in a period of up to 7 days. However, qPCR analyses demonstrated that T. rangeli is eliminated from the skin after 7 days of infection despite being still consistently found on circulating blood and secondary lymphoid tissues for up to 30 days post-infection. Interestingly, significant numbers of parasites were found in the spleen and mesenteric lymph nodes of infected mice during different periods of infection and steady basal numbers of flagellates are maintained in the host's bloodstream, which might behave as a transmission source to insect vectors. The presence of parasites in the spleen was confirmed by fluorescent photomicrography of free and cell-associated T. rangeli forms. Altogether our results suggest that this organ could possibly behave as a T. rangeli maintenance hotspot in vertebrates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Central America / epidemiology
  • Chagas Disease / epidemiology
  • Chagas Disease / transmission*
  • Disease Models, Animal
  • Host-Parasite Interactions
  • Humans
  • Insect Bites and Stings / parasitology
  • Insect Vectors / parasitology
  • Lymph Nodes / parasitology*
  • Mice
  • Rhodnius / parasitology
  • Sepsis / parasitology
  • Skin / parasitology*
  • South America / epidemiology
  • Spleen / parasitology*
  • Trypanosoma rangeli / isolation & purification*

Grants and funding

AAG and ATC were supported by CNPq – Brazil productivity grants [AAG grant number 303546/2018-2; ATC grant number 312590/2018-0]. FFA received financial support from CNPq PDS Fellowship Program [grant number 103519/2019-0]. This work was supported by Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, INCT-EM/CNPq [grant number 441999/2014-0] and Programa Estratégico de Apoio a Pesquisa em Saúde, PAPES VI/FIOCRUZ [grant number 407614/2012-5]. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.