Vaccination against clinical Mycobacterium tuberculosis isolates
(2014) MOBT13 20132Degree Projects in Molecular Biology
- Abstract
- Hybrid 56 (H56) is a new vaccine candidate against pulmonary tuberculosis (TB) developed by Staten Serum Institut (SSI) and currently being tested in clinical trial phase IIa. The vaccine consists of three mycobacterial proteins ESAT-6, Ag85B, and Rv2660c that are fused together in a poly-protein. When formulated in a cationic adjuvant (CAF01), Hybrid56 has shown consistent protective efficacy in various TB animal models including mice, guinea pigs, cattle and non-human primates. However, in all the models the animals were experimentally infected with either Mycobacterium tuberculosis (M.tb) Erdman or H37Rv strains.
Previous work had shown that the protective efficacy of H56 vaccine, after infection with a range of phylogenetically... (More) - Hybrid 56 (H56) is a new vaccine candidate against pulmonary tuberculosis (TB) developed by Staten Serum Institut (SSI) and currently being tested in clinical trial phase IIa. The vaccine consists of three mycobacterial proteins ESAT-6, Ag85B, and Rv2660c that are fused together in a poly-protein. When formulated in a cationic adjuvant (CAF01), Hybrid56 has shown consistent protective efficacy in various TB animal models including mice, guinea pigs, cattle and non-human primates. However, in all the models the animals were experimentally infected with either Mycobacterium tuberculosis (M.tb) Erdman or H37Rv strains.
Previous work had shown that the protective efficacy of H56 vaccine, after infection with a range of phylogenetically different M.tb strains isolated from TB patients coming from different parts of the world, was equally protective as against M.tb Erdman or H37Rv. However, there was one M.tb isolate - originating from the Danish town Thisted - where the protective efficacy of H56 was significantly less than for the Mycobacterium bovis BCG control vaccine.
In this work, I have investigated the reason behind and tried to obtain better protection by broadening the epitope profile. The later was done by priming an immune response with H56 and boosting with the H64 fusion protein. H64 consist of six proteins and shares only the ESAT-6 protein with H56. The protection was, by enlarge, identical to the H56 results. Using culture filtrate and antibodies against ESAT-6, I show that the reason behind the low protective efficacy of H56 and H64 against M.tb Thisted isolate was due to a significant reduction in the secretion of the ESAT-6 protein by this M.tb isolate. When ESAT-6 is not secreted efficiently from the Mycobacteria the epitopes in the protein are not presented on the surface of antigen presenting cells (APCs) and the specific CD4+ T cells expanded during vaccination cannot recognize or activate the APCs and the growth of the Mycobacteria is therefore not limited. (Less) - Popular Abstract
- Fighting for survival; Human vs. Mycobacterium tuberculosis
Tuberculosis (TB) is considered as the second leading cause of death after HIV. Mycobacterium tuberculosis (M.tb) is the bacteria responsible for causing infection. One-third of humans are infected with TB and it kills more than one million people every year making TB as a devastating life thread disease. The only available vaccine against TB is BCG and it is given short time after birth. However, the protection of BCG is limited meaning that the battle of survival between us and M.tb is getting more complicated and the need to develop new vaccine as soon as possible is very urgent.
Hybrid 56 is a new vaccine candidate against TB developed by Staten Serum Institut (SSI) and... (More) - Fighting for survival; Human vs. Mycobacterium tuberculosis
Tuberculosis (TB) is considered as the second leading cause of death after HIV. Mycobacterium tuberculosis (M.tb) is the bacteria responsible for causing infection. One-third of humans are infected with TB and it kills more than one million people every year making TB as a devastating life thread disease. The only available vaccine against TB is BCG and it is given short time after birth. However, the protection of BCG is limited meaning that the battle of survival between us and M.tb is getting more complicated and the need to develop new vaccine as soon as possible is very urgent.
Hybrid 56 is a new vaccine candidate against TB developed by Staten Serum Institut (SSI) and currently being tested in clinical trial phase IIa. The protective efficacy of H56 against clinical M.tb isolates of patients coming from different parts of the world was tested. Results showed that H56 induced a significant protection except for one clinical isolate of patient coming from Thisted town in Denmark.
In this project I investigated the reason behind the low protective efficacy of H56 against M.tb Thisted. Moreover, I tested prime/boosting vaccination protection by priming with H56 and boosting with new developed vaccine subunit Hybrid 64 (H64).
H56 vaccine consists of three mycobacterial proteins ESAT-6, Ag85B, and Rv2660c that are fused together in a poly-protein and emulsified with CAF01 adjuvant. H56 and H64 vaccine subunits share only ESAT-6 protein in common which is a highly conserved immunogenic protein secreted by M.tb.
After setting up an animal experiment and studying the protection induced by priming with H56 and then boosting with H64 against M.tb Thisted, my results showed that there is no significant protection and still have same low protection level compared to vaccination with H56 alone against M.tb Thisted.
Interestingly, using culture filtrate antibodies against ESAT-6 protein, I have found that the reason behind the low protective efficacy of H56 and H64 against M.tb Thisted isolate was due to a significant reduction in the secretion of the ESAT-6 protein by this M.tb isolate.
When ESAT-6 is not secreted efficiently from the Mycobacteria, the epitopes in the protein are not presented on the surface of antigen presenting cells (APCs) and the specific CD4+ T cells expanded during vaccination cannot recognize or activate the APCs and the growth of the M.tb is therefore not limited.
Further studies should be done in order to investigate the reason behind the reduction of ESAT-6 secretion.
Advisor: Claus Aagaard
Master´s Degree Project 60 credits in Medical Biology. 2014
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4778858
- author
- Ahmad, Ahmad Ibrahim
- supervisor
- organization
- course
- MOBT13 20132
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 4778858
- date added to LUP
- 2014-11-12 13:44:04
- date last changed
- 2014-11-12 13:44:04
@misc{4778858,
abstract = {{Hybrid 56 (H56) is a new vaccine candidate against pulmonary tuberculosis (TB) developed by Staten Serum Institut (SSI) and currently being tested in clinical trial phase IIa. The vaccine consists of three mycobacterial proteins ESAT-6, Ag85B, and Rv2660c that are fused together in a poly-protein. When formulated in a cationic adjuvant (CAF01), Hybrid56 has shown consistent protective efficacy in various TB animal models including mice, guinea pigs, cattle and non-human primates. However, in all the models the animals were experimentally infected with either Mycobacterium tuberculosis (M.tb) Erdman or H37Rv strains.
Previous work had shown that the protective efficacy of H56 vaccine, after infection with a range of phylogenetically different M.tb strains isolated from TB patients coming from different parts of the world, was equally protective as against M.tb Erdman or H37Rv. However, there was one M.tb isolate - originating from the Danish town Thisted - where the protective efficacy of H56 was significantly less than for the Mycobacterium bovis BCG control vaccine.
In this work, I have investigated the reason behind and tried to obtain better protection by broadening the epitope profile. The later was done by priming an immune response with H56 and boosting with the H64 fusion protein. H64 consist of six proteins and shares only the ESAT-6 protein with H56. The protection was, by enlarge, identical to the H56 results. Using culture filtrate and antibodies against ESAT-6, I show that the reason behind the low protective efficacy of H56 and H64 against M.tb Thisted isolate was due to a significant reduction in the secretion of the ESAT-6 protein by this M.tb isolate. When ESAT-6 is not secreted efficiently from the Mycobacteria the epitopes in the protein are not presented on the surface of antigen presenting cells (APCs) and the specific CD4+ T cells expanded during vaccination cannot recognize or activate the APCs and the growth of the Mycobacteria is therefore not limited.}},
author = {{Ahmad, Ahmad Ibrahim}},
language = {{eng}},
note = {{Student Paper}},
title = {{Vaccination against clinical Mycobacterium tuberculosis isolates}},
year = {{2014}},
}