Single dose novel Salmonella vaccine enhances resistance against visceralizing L. major and L. donovani infection in susceptible BALB/c mice

PLoS Negl Trop Dis. 2011 Dec;5(12):e1406. doi: 10.1371/journal.pntd.0001406. Epub 2011 Dec 27.

Abstract

Visceral leishmaniasis is a major neglected tropical disease, with an estimated 500,000 new cases and more than 50,000 deaths attributable to this disease every year. Drug therapy is available but costly and resistance against several drug classes has evolved. Despite all efforts, no commercial, let alone affordable, vaccine is available to date. Thus, the development of cost effective, needle-independent vaccines is a high priority. Here, we have continued efforts to develop live vaccine carriers based on recombinant Salmonella. We used an in silico approach to select novel Leishmania parasite antigens from proteomic data sets, with selection criteria based on protein abundance, conservation across Leishmania species and low homology to host species. Five chosen antigens were differentially expressed on the surface or in the cytosol of Salmonella typhimurium SL3261. A two-step procedure was developed to select optimal Salmonella vaccine strains for each antigen, based on bacterial fitness and antigen expression levels. We show that vaccine strains of Salmonella expressing the novel Leishmania antigens LinJ08.1190 and LinJ23.0410 significantly reduced visceralisation of L. major and enhanced systemic resistance against L. donovani in susceptible BALB/c mice. The results show that Salmonella are valid vaccine carriers for inducing resistance against visceral leishmaniasis but that their use may not be suitable for all antigens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Disease Models, Animal
  • Drug Carriers / administration & dosage*
  • Female
  • Genetic Vectors
  • Leishmania donovani / genetics
  • Leishmania donovani / immunology
  • Leishmania major / genetics
  • Leishmania major / immunology
  • Leishmaniasis Vaccines / administration & dosage*
  • Leishmaniasis Vaccines / genetics
  • Leishmaniasis Vaccines / immunology*
  • Leishmaniasis, Visceral / immunology
  • Leishmaniasis, Visceral / parasitology
  • Leishmaniasis, Visceral / prevention & control*
  • Mice
  • Mice, Inbred BALB C
  • Salmonella typhimurium / genetics*
  • Vaccines, Synthetic / administration & dosage
  • Vaccines, Synthetic / genetics
  • Vaccines, Synthetic / immunology

Substances

  • Antigens, Protozoan
  • Drug Carriers
  • Leishmaniasis Vaccines
  • Vaccines, Synthetic