Non-Invasive In Vivo Study of the Trypanosoma vivax Infectious Process Consolidates the Brain Commitment in Late Infections

Abstract

Trypanosoma vivax, one of the leading parasites responsible for Animal African Trypanosomosis (Nagana), is generally cyclically transmitted by Glossina spp. but in areas devoid of the tsetse flies in Africa or in Latin American countries is mechanically transmitted across vertebrate hosts by other haematophagous insects, including tabanids. We followed on from our recent studies on the maintenance of this parasite in vivo and in vitro, and its genetic manipulation, by constructing a West African IL1392 T. vivax strain that stably expresses firefly luciferase and is fully virulent for immunocompetent mice. We report here on a study where murine infection with this strain was monitored in vivo using a non-invasive method. Study findings fully support the use of this strain in the assessment of parasite dynamics in vivo since a strong correlation was found between whole body light emission measured over the course of the infection and parasitemia determined microscopically. In addition, parasitemia and survival rates were very similar for mice infected by the intraperitoneal and sub-cutaneous routes, except for a longer prepatent period following sub-cutaneous inoculation with the parasite. Our results clearly show that when administered by the subcutaneous route, the parasite is retained few days in the skin close to the inoculation site where it multiplies before passing into the bloodstream. Ex vivo bioluminescence analyses of organs isolated from infected mice corroborated our previous histopathological observations with parasite infiltration into spleen, liver and lungs. Finally, our study reinforces previous observations on the presence of the parasite in the central nervous system and consequently the brain commitment in the very late phases of the experimental infection.

Comparative clinico-pathological observations in young Zebu (Bos indicus) cattle experimentally infected with Trypanosoma vivax isolates from tsetse infested and non-tsetse areas of Northwest Ethiopia

“…Similar to our finding splenomegaly and hepatomegaly were reported by Fatihu et al [ 37 ] in experimental infected goats with T. vivax . The various forms of congestion and necrosis observed were also in consonance with findings of Archivio et al [ 39 ] and Silva et al [ 40 ].…”

The animal trypanosomiases and their chemotherapy: a review

“…lymph nodes, eyes and cerebrospinal fluid) where they may directly damage tissues and where they are less accessible to drug treatment (Whitelaw et al 1988; Osorio et al 2008; D'Archivio et al 2013). …”

A new chimeric triple reporter fusion protein as a tool for in vitro and in vivo multimodal imaging to monitor the development of African trypanosomes and Leishmania parasites

“…At the same time, together with colleagues from Glasgow, Conakry and Kinshasa, we have demonstrated that the majority of T. b. gambiense parasites were actually rather developing in the extravascular matrix of the dermis of murine models, where they were seen actively swimming and dividing (Capewell et al, 2016). In another study by D'Archivio and co-workers, the importance of the late brain invasion by T. vivax parasites was assessed in a dynamic manner by intravital imaging of a bioluminescent strain (D'Archivio et al, 2013).…”