Thesis

Development of a gamma glutamylcysteine synthetase vaccine to protect against Leishmania infection

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Awarding institution
  • University of Strathclyde
Date of award
  • 2014
Thesis identifier
  • T13677
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Abstract
  • Leishmaniasis is a public health problem and development of a vaccine to prevent infection is required. The overall aim of this study was to develop a vaccine to protect against Leishmania infection using L. donovani, L. mexicana and L. major gamma glutamylcysteine synthetase (γGCS) recombinant proteins. Studies to optimise the expression of L. donovani, L. mexicana and L. major γGCS recombinant proteins showed that induction with 0.1 mM isopropyl β-D-1-thiogalactopyranoside produced the highest amounts of recombinant protein, and incubation of bacteria at 18°C after induction increased the amount of soluble protein produced. Recombinant L. mexicana γGCS had significantly higher specific enzyme activity (p <0.001) compared to L. donovani and L. major γGCS. L. mexicana γGCS was the most resistant to L-buthionine sulphoximine (BSO) inhibition, the specific irreversible inhibitor of γGCS, at the maximum concentration tested (1.5 mM) and L. mexicana promastigotes were the most resistant to the cytotoxic effects of BSO compared to L. donovani and L. major promastigotes (p < 0.001). Vaccination with the recombinant γGCS proteins from L. donovani, L. major and L. mexicana (triple vaccine) induced significant parasite-specific Th1 and Th2 immune responses based on antibody titres and cytokine production by in vitro stimulated splenocytes from immunised mice. Vaccination by inhalation or subcutaneous injection with the triple vaccine was similar mean percentage reduction in parasite burdens compared to controls ± SE, was 98% ± 0.02 in L. mexicana infected mice. In L. major infected mice was 70% ± 0.1 by subcutaneous immunisation and 65%± 0.01 for inhalation vaccination. Treatment with the triple vaccine by inhalation failed to protect mice against L. donovani infection but was effective in hamsters, where a significant reduction in liver and bone marrow parasite burdens compared to control values (p < 0.05; mean percentage reduction compared to controls ± SE: spleen 89 ± 1; liver 83 ± 0.3; bone marrow 77 ± 1). In conclusion, the results of this study indicate that vaccination against leishmaniasis is feasible by the pulmonary route and that the triple vaccine is a potential vaccine candidate.
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DOI
Date Created
  • 2014
Former identifier
  • 1027057

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