Identification of Vaccine Candidates for Experimental Visceral Leishmaniasis by Immunization with Sequential Fractions of a cDNA Expression Library

AUTOR(ES)

Melby, Peter C.

FONTE

American Society for Microbiology

RESUMO

Visceral leishmaniasis caused by the intracellular parasite Leishmania donovani is a significant public health problem in many regions of the world. Because of its large genome and complex biology, developing a vaccine for this pathogen has proved to be a challenging task and, to date, protective recombinant vaccine candidates have not been identified. To tackle this difficult problem, we adopted a reductionist approach with the intention of identifying cDNA sequences in an L. donovani amastigote cDNA library that collectively or singly conferred protection against parasite challenge in a murine model of visceral leishmaniasis. We immunized BALB/c mice with plasmid DNA isolated and pooled from 15 cDNA sublibraries (∼2,000 cDNAs/sublibrary). Following systemic challenge with L. donovani, mice immunized with 6 of these 15 sublibraries showed a significantly reduced (35- to 1,000-fold) hepatic parasite burden. Because of the complexity and magnitude of the sequential fractionation-immunization-challenge approach, we restricted our attention to the two sublibraries that conferred the greatest in vivo protection. From one of these two sublibraries, we identified several groups of cDNAs that afforded protection, including a set of nine novel cDNAs and, surprisingly, a group of five cDNAs that encoded L. donovani histone proteins. At each fractionation step, the cDNA sublibraries or the smaller DNA fractions that afforded in vivo protection against the parasite also induced in vitro parasite-specific T helper 1 immune responses. Our studies demonstrate that immunization with sequential fractions of a cDNA library is a powerful strategy for identifying anti-infective vaccine candidates.

Documentos Relacionados

• High-efficiency identification of genes by functional analysis from a retroviral cDNA expression library.
• Bovine galactosyltransferase: identification of a clone by direct immunological screening of a cDNA expression library.
• Identification of clones that encode chicken tropomyosin by direct immunological screening of a cDNA expression library.
• Identification of Potential Vaccine and Drug Target Candidates by Expressed Sequence Tag Analysis and Immunoscreening of Onchocerca volvulus Larval cDNA Libraries
• Preparation of a differentially expressed, full-length cDNA expression library by RecA-mediated triple-strand formation with subtractively enriched cDNA fragments.