Since Edward Jenner made the cowpox vaccine more than 200 years ago, researchers have been trying to develop new vaccine delivery methods. One of the major issues in vaccine designing is finding a safe method to introduce the immunogenic part of the pathogen to the host body’s immune system. Besides the safety of the delivery system, it should also be able to present the antigen to the cells of the immune system. Recently, bacterial ghost (BG) technology has attracted the attention of vaccine designers, as it has both of these imperative characteristics: safety and efficacy.
BGs are the empty cell wall of Gram negative bacteria that can be constructed easily by introducing E-lysis genes inside the bacteria. This gene encodes a protein which creates some pores on the cell wall of the bacteria. The cell content can be ejected by several washing steps through these pores and finally an empty intact cell wall is what remains. The key point of using BGs is the especial intact proteins and other pathogen related compartments on the surface which stimulate immune cells to engulf them immediately due to the pathogenic figure they have. Now, you can imagine what will happen if you put some drugs or a part of another pathogen (an antigen from HIV or influenza virus, for example) inside these cell walls or present the desired antigen on the surface of BGs. Immune cells will engulf the cell wall which contains some other elements, either inside or at the surface. By this way, we can directly transfer our target antigen, DNA or drug into the host’s immune cells. Besides the efficient way of delivery, these empty cell walls boost the immune response against the target antigen because of the intrinsic pathogenic characteristics they possess.
Nowadays, there are several types of vaccines being researched that are based on BG technology including vaccines against influenza, HIV, Salmonella and E.coli.
References:
Langemann T, Koller VJ, Muhammad A, Kudela P, Mayr UB, Lubitz W. The bacterial ghost platform system: Production and applications. Bioengineered Bugs. 2010;1(5):326-336. doi:10.4161/bbug.1.5.12540.
Chaudhari AA, Jawale CV, Kim SW, Lee JH. Construction of a Salmonella Gallinarum ghost as a novel inactivated vaccine candidate and its protective efficacy against fowl typhoid in chickens. Veterinary Research. 2012;43(1):44. doi:10.1186/1297-9716-43-44.
Jing Wen, Yi Yang, Guangyu Zhao, Shuang Tong, Hong Yu, Xia Jin, Lanying Du, Shibo Jiang, Zhihua Kou, Yusen Zhou, Salmonella typhi Ty21a bacterial ghost vector augments HIV-1 gp140 DNA vaccine-induced peripheral and mucosal antibody responses via TLR4 pathway, Vaccine, Volume 30, Issue 39, 24 August 2012, Pages 5733-5739, ISSN 0264-410X.
Mayr UB, Haller C, Haidinger W, et al. Bacterial Ghosts as an Oral Vaccine: a Single Dose of Escherichia coli O157:H7 Bacterial Ghosts Protects Mice against Lethal Challenge . Infection and Immunity. 2005;73(8):4810-4817. doi:10.1128/IAI.73.8.4810-4817.2005.
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