Steppe lemmings and Chinese hamsters as new potential animal models for the study of the leishmania subgenusMundinia(Kinetoplastida: Trypanosomatidae)

Abstract

Leishmania, the dixenous trypanosomatid parasites, are the causative agents of leishmaniasis currently divided into four subgenera:Leishmania,Viannia,Sauroleishmania,and the recently describedMundinia, consisting of six species distributed sporadically all over the world infecting humans and/or animals. These parasites infect various mammalian species and also cause serious human diseases, but their reservoirs are unknown. Thus, adequate laboratory models are needed to enable proper research ofMundiniaparasites. In this complex study, we compared experimental infections of fiveMundiniaspecies (L. enriettii,L. macropodum,L.chancei,L. orientalis,and four strains ofL. martiniquensis) in three rodent species: BALB/c mouse, Chinese hamster (Cricetulus griseus)and Steppe lemming (Lagurus lagurus). Culture-derived parasites were inoculated intradermally into the ear pinnae and progress of infection was monitored for 20 weeks, when the tissues and organs of animals were screened for the presence and quantity of leishmania. Xenodiagnoses withPhlebotomus duboscqiwere performed at weeks 5, 10, 15 and 20 post-infection to test the infectiousness of the animals throughout the experiment. BALB/c mice showed no signs of infection and were not infectious to sand flies, while Chinese hamsters and Steppe lemmings proved susceptible to all five species ofMundiniatested, showing a wide spectrum of disease signs ranging from asymptomatic to visceral.Mundiniainduced significantly higher infection rates in Steppe lemmings compared to Chinese hamsters, and consequently Steppe lemmings were more infectious to sand flies: In all groups tested, they were infectious from the 5th to the 20th week post infection. In conclusion, we identified two rodent species, Chinese hamster (Cricetulus griseus)and Steppe lemming (Lagurus lagurus), as candidates for laboratory models forMundiniaallowing detailed studies of these enigmatic parasites. Furthermore, the long-term survival of allMundiniaspecies in Steppe lemmings and their infectiousness to vectors support the hypothesis that some rodents have the potential to serve as reservoir hosts forMundinia.Author SummaryLeishmaniaparasites of the subgenusMundiniaare an emerging health and veterinary problem that should not be ignored. Being the most recent of allLeishmaniadescribed, many aspects ofMundiniabiology are enigmatic. We have very scarce data on their life cycles and biology, thus proper laboratory research must be done to enable their better understanding. One of the most crucial parts of the life cycle ofLeishmaniais the development in the mammalian host. In the past, we worked on establishment of other laboratory models for the subgenus, but eitherArvicanthis,Mastomysor Guinea pigs did not prove to be a good choice. Other authors performed experiments with BALB/c mice using various inoculation techniques, but they also failed. Here we describe the establishment of two new potential laboratory model species, Chinese hamsters and Steppe lemmings, which proved to be susceptible toMundiniaand such findings will enable other scientists to continue in research of these parasites.