title: Deletion of parasite immune modulatory sequences combined with immune activating signals enhances vaccine mediated protection against filarial nematodes.
abstract: BACKGROUND
  Filarial nematodes are tissue-dwelling parasites that can be killed by Th2-driven immune effectors, but that have evolved to withstand immune attack and establish chronic infections by suppressing host immunity. As a consequence, the efficacy of a vaccine against filariasis may depend on its capacity to counter parasite-driven immunomodulation.
  
  
  RESULTS
  We immunised mice with DNA plasmids expressing functionally-inactivated forms of two immunomodulatory molecules expressed by the filarial parasite Litomosoides sigmodontis: the abundant larval transcript-1 (LsALT) and cysteine protease inhibitor-2 (LsCPI). The mutant proteins enhanced antibody and cytokine responses to live parasite challenge, and led to more leukocyte recruitment to the site of infection than their native forms. The immune response was further enhanced when the antigens were targeted to dendritic cells using a single chain Fv-αDEC205 antibody and co-administered with plasmids that enhance T helper 2 immunity (IL-4) and antigen-presenting cell recruitment (Flt3L, MIP-1α). Mice immunised simultaneously against the mutated forms of LsALT and LsCPI eliminated adult parasites faster and consistently reduced peripheral microfilaraemia. A multifactorial analysis of the immune response revealed that protection was strongly correlated with the production of parasite-specific IgG1 and with the numbers of leukocytes present at the site of infection.
  
  
  CONCLUSIONS
  We have developed a successful strategy for DNA vaccination against a nematode infection that specifically targets parasite-driven immunosuppression while simultaneously enhancing Th2 immune responses and parasite antigen presentation by dendritic cells.
authors.affiliation: Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, United Kingdom. s.babayan@ed.ac.uk
authors.forename: Simon A
authors.initials: SA
authors.lastname: Babayan
authors.forename: Honglin
authors.initials: H
authors.lastname: Luo
authors.forename: Nick
authors.initials: N
authors.lastname: Gray
authors.forename: David W
authors.initials: DW
authors.lastname: Taylor
authors.forename: Judith E
authors.initials: JE
authors.lastname: Allen
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D000947:Antigens, Helminth / Q000235:genetics / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D018509:DNA, Helminth / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D005260:Female; D005368:Filariasis / Q000276:immunology* / Q000517:prevention & control*; D005370:Filarioidea / Q000235:genetics / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D017384:Sequence Deletion; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D022223:Vaccines, Subunit / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D016207:Cytokines; D018509:DNA, Helminth; D019444:Vaccines, DNA; D022223:Vaccines, Subunit