HP Lecture 6

• leishmaniasis: 3 clinical diseases

  VL (visceral): potentially fatal

  CL (cutaneous): self curing (most common clinical form)- 8 months- 2 years

  MCL (mucocutaneous)

  10 mil global prevalence

  50,000 annual deaths

  350 mil. at risk
• Leishmaniasis

  • .2-.7 mil VL cases yearly
  • .7 to 1.2 mil CL cases yearly
  • endemic in 98 countries
  • Bangladesh: 1st country globally eliminate leishmaniasis or kala-azar (VL)
• leishmaniasis

  • 50 species known
  • 20 are human pathogens
  • amastigotes and promastigotes
  • major parasites species
  • VL: leishmania Donovani, L. infantum
  • CL: L. major, L. topica, L. mexicana
  • MCL: L. braziliensis, L. guyanensis
• Leishmania insect vectors

  • sandfly
  • phlebotomus- old world
  • lutzomyia- new world
  • further classification of the protozoan parasites
  • leishmania developed in foregut
  • vianna developed in hind gut
  • leishmania braziliensis becomes leishmania
  • vianna braziliensis L. (V.) braziliensis
• leishmania origin: 3 hypo

  palearctic origin; neotropical origin; supercontinent origin
• complex disease

  • affecting poor and neglected pop
  • many parasite species, many vector species, many mammalian hosts (zoonosis)
  • socioeconomic, environ. and social factors
  • possible vector adaptation to urban environ.
• history

  • amber in myanmar- paleoleishmania
  • oriental sore (baghdad boil)- 1898 borovsky
  • kala azar (dum dum fever)- 1903 william leishman and charles donovan
  • BMJ- ronald ross
  • Ld bodies
• human volunteer transmission- 1942 at assam, india, henry short, CS swaminath, LAP anderson
• Pathology

  • leishmania RNA virus leads to more severe mucocutaneous leishmaniasis
  • cellular immunity
  • inbred mice and L. major infection
  • C57BL/6 and BALBlc strains
  • T helper 1 and T helper 2
  • NFkB- induce inflammatory response
  • PPARy- supress immune response
• T helper 2: can promote infection or irrelevant to disease progression
• immune subversion strategy: target host cell epigenetic regulation to establish conditions beneficial for parasite survival, via a decreased exp. of activating and high exp. of de-activating components pro-inflammatory pathways
• diagnosis

  • presence of amastigoles (skin lesion: CL/MCL, liver/spleen/bone marrow biopsy: VL)
• culture- NNN medium (novy, macneal, nicolle)
• leshmanin skin test (LST)- montengro test 1926- DTH test
• other diagnosis:

  • whole blood stimulation test (WBA)
  • serological test- immunochromatographic test (ICT)
  • rk28 antigen based rapid agglutination test (RDT)
  • molecular tests- PCR, qPCR
• Therapy

  • pentavalent antimony- sodium stibogluconate (Pentostam), meglumine antimoniate (glucantime): 2 drugs
  • amphotericin 13 w/in liposome (AmBisome) original antifungal
  • miltefosine (impavido)- 2002: newer drug
• Therapy 2:

  • paromomycin- institute for 1 world health: approved in India, 2006
  • pkdl: post-kala-azar dermal leishmaniasis
  • sdAB: single domain antibody, came, llama (nanobodies)
• Genome:

  1st genome: 2005, haploid genome (36 chr)

  leishmania major friedlin strain

  prtn coding genes; RNA genes; pseudogenes
• L. infontum- 36 chr

  L. braziliensis- 35 chr

  200 gene diff (CL, MCL, VL)

  L. tarentolae- sauroleishmania

  typical genome 32-35 ub

  24-36 chr

  leishmania as eukaryotic prtn exp, sys: Jena Bioscience
• kinetoplast genome

  • maxicircle 18,998 bp
  • minicircles 97, avg size 691 bp
• post-genome

  • test w/ 7 cloned L. infantum genes as exp. vectors and transfect into L. major; a single gene induces visceralization in a mouse model
• cross-species mating: drug resistance markers, L. major and L. infantum both in Lutzomyia sand-fly
• leishmania exosomes- from L. infantum Am/Pm conditioned medium, in vitro, induces Th2 environ. for macrophages
• vaccines: not available

  • leishmanization (LZ)- intradermal inoculation of live leishmania to induce an artificial (L lesion in a covered part of human body (protect against further natural CL lesion develop)
  • CHM: controlled human infection model
• cani leish- for dogs, based in prtn w/ saponin adjuvant
• live attenuated vaccine

  • antibiotic selection by gentamicin
  • L. major works in VL, L. donovani by sand fly bites in a hamster model
• GM leishmania-

  • knocking out dihydrofolate reductase/thymidylate synthase (DHFR/TS), lipophosphodlycans- 2 (LPG)
• vaccine candiates- subunit vacines, glycosomal phospoenol pyruvate carboxykinase (PEPCK), amastin
• phase I

  • ChAd63 vector for haspb (hydrophilic acylated surface prtn B), kmpll fusion prtn- CD8 T cell response and IFNy production
  • COVID- 19- modified chimpanzee adenovirus vaccine w/ Ag the viral spike prtn
• Trifluralin

  • leishmania tubulin seq. closer to plant than to animal tubulins
  • dinitroaniline herbicide selectively kills leishmania amastigotes and promastigotes
  • otehr parasitic protozoa can also be killed by the herbicides
• macrophage histone modification

  • parasitic persistence at amastigote differentiation
• Therapeutic vaccine ChAd63-KH

  • worked in phase 1 and 2a