Year-end Sale % OFF 
Abstract
BackgroundThe Leishmania protozoan parasites cause devastating human diseases. Leishmania have been considered to replicate clonally, without genetic exchange. However, an accumulation of evidence indicates that there are inter-specific and intra-specific hybrids among natural populations. The first and so far only experimental proof of genetic exchange was obtained in 2009 when double drug resistant Leishmania major hybrids were produced by co-infecting sand flies with two strains carrying different drug resistance markers. However, the location and timing of hybridisation events in sand flies has not been described.Methodology/Principal FindingsHere we have co-infected Phlebotomus perniciosus and Lutzomyia longipalpis with transgenic promastigotes of Leishmania donovani strains carrying hygromycin or neomycin resistance genes and red or green fluorescent markers. Fed females were dissected at different times post bloodmeal (PBM) and examined by fluorescent microscopy or fluorescent activated cell sorting (FACS) followed by confocal microscopy. In mixed infections strains LEM3804 and Gebre-1 reached the cardia and stomodeal valves more rapidly than strains LEM4265 and LV9. Hybrids unequivocally expressing both red and green fluorescence were seen in single flies of both vectors tested, co-infected with LEM4265 and Gebre-1. The hybrids were present as short (procyclic) promastigotes 2 days PBM in the semi-digested blood in the endoperitrophic space. Recovery of a clearly co-expressing hybrid was also achieved by FACS. However, hybrids could not sustain growth in vitro.Conclusions/SignificanceFor the first time, we observed L. donovani hybrids in the sand fly vector, 2 days PBM and described the morphological stages involved. Fluorescence microscopy in combination with FACS allows visualisation and recovery of the progeny of experimental crosses but on this occasion the hybrids were not viable in vitro. Nevertheless, genetic exchange in L. donovani has profound epidemiological significance, because it facilitates the emergence and spread of new phenotypic traits.
Highlights
Protozoan parasites of the genus Leishmania (Kinetoplastida: Trypanosomatidae) cause the leishmaniases - severe human diseases that may be mutilating or fatal
Experimental co-infections Three pairs of GFP/RFP transfected L. donovani strains were used for experimental infections in two sand fly vector species, P. perniciosus and L. longipalpis: LEM3804 (RFP) and LV9 (GFP), LV9 (GFP) and Gebre-1 (RFP) and LEM4265 (GFP) and Gebre-1 (RFP) (Table 1)
In 2009, the landmark experiments of Akopyants et al [22] proved that two strains of L. major carrying different drug resistance markers could undergo genetic exchange, and that this process occurred in the sand fly vector, with an approximate frequency of 2.561025
Summary
Protozoan parasites of the genus Leishmania (Kinetoplastida: Trypanosomatidae) cause the leishmaniases - severe human diseases that may be mutilating or fatal. Intracellular amastigotes taken up in the sand fly bloodmeal undergo transformation to short procyclic promastigotes with short flagellum. These forms divide and later transform to elongated nectomonads that escape through broken peritrophic matrix [6] and attach to the midgut epithelium to prevent expulsion during defecation of bloodmeal remnants. The Leishmania protozoan parasites cause devastating human diseases. The first and so far only experimental proof of genetic exchange was obtained in 2009 when double drug resistant Leishmania major hybrids were produced by co-infecting sand flies with two strains carrying different drug resistance markers. The location and timing of hybridisation events in sand flies has not been described
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
