Lack of protective efficacy in buffaloes vaccinated with Fasciola gigantica leucine aminopeptidase and peroxiredoxin recombinant proteins

• Published in: Acta tropica 2011-06, Vol.118 (3), p.217-222
• Main Authors: Raina, O.K., Nagar, Gaurav, Varghese, Anju, Prajitha, G., Alex, Asha, Maharana, B.R., Joshi, P.
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Helminth - blood; antigens; Antigens, Helminth - genetics; Antigens, Helminth - immunology; Biological and medical sciences; Buffaloes; Cloning, Molecular; DNA, Helminth - chemistry; DNA, Helminth - genetics; Escherichia coli; Escherichia coli - genetics; Fasciola - genetics; Fasciola - immunology; Fasciola gigantica; Fasciola hepatica; Fascioliasis - immunology; Fascioliasis - prevention & control; Gene Expression; General aspects; genes; hydrogen peroxide; immune response; Leucine aminopeptidase; leucyl aminopeptidase; Leucyl Aminopeptidase - genetics; Leucyl Aminopeptidase - immunology; liver flukes; Medical sciences; metacercariae; metalloproteinases; Molecular Sequence Data; Peroxiredoxin; Peroxiredoxins - genetics; Peroxiredoxins - immunology; Protection; recombinant proteins; Recombinant Proteins - genetics; Recombinant Proteins - immunology; sequence analysis; Sequence Analysis, DNA; Trematoda; Vaccination; Vaccines - administration & dosage; Vaccines - genetics; Vaccines - immunology; Vaccines, Subunit - administration & dosage; Vaccines, Subunit - genetics; Vaccines, Subunit - immunology; Vaccines, Synthetic - administration & dosage; Vaccines, Synthetic - genetics; Vaccines, Synthetic - immunology
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2011.02.008

Fasciola gigantica leucine aminopeptidase protein (56kDa) expressed in E. coli, characterized and evaluated for its vaccine potential along with recombinant peroxiredoxin (24kDa) in buffaloes. Both proteins failed to give significant level of protection in buffaloes. [Display omitted] ► Leucine aminopeptidase gene was identified in Fasciola gigantica. ► Recombinant leucine aminopeptidase did not evoke protective response in buffaloes. ► Peroxiredoxin recombinant protein in combination with leucine aminopeptidase also failed to evoke protection in buffaloes. Gene coding for leucine aminopeptidase (LAP), a metalloprotease, was identified in the tropical liver fluke, Fasciola gigantica; that on sequence analysis showed a close homology (98.6%) with leucine aminopeptidase of the temperate liver fluke, Fasciola hepatica. The recombinant leucine aminopeptidase protein was expressed in Escherichia coli. F. gigantica peroxiredoxin, a hydrogen peroxide scavenger and an immunomodulating protein, was also cloned and expressed in E. coli. A vaccination trial in buffaloes was conducted with these two recombinant proteins, with 150 and 300μg of leucine aminopeptidase and a cocktail of 150μg each of recombinant leucine aminopeptidase and peroxiredoxin in three groups, respectively. Both Th1- and Th2-associated humoral immune responses were elicited to immunization with these antigens. A challenge study with 400 metacercariae did not show a significant protection in terms of reduction in the worm burden (8.4%) or anti-fecundity/embryonation effect in the immunized groups, as to the non-immunized control animals. Our observations in this buffalo vaccination trial are contrary to the earlier promise shown by leucine aminopeptidase of F. hepatica as a leading candidate vaccine molecule. Identification of leucine aminopeptidase gene and evaluation of the protein for its protective efficacy in buffaloes is the first scientific report on this protein in F. gigantica.