Live Bacterial Vectors—A Promising DNA Vaccine Delivery System

Abstract

Vaccination is one of the most successful immunology applications that has considerably improved human health. The DNA vaccine is a new vaccine being developed since the early 1990s. Although the DNA vaccine is promising, no human DNA vaccine has been approved to date. The main problem facing DNA vaccine efficacy is the lack of a DNA vaccine delivery system. Several studies explored this limitation. One of the best DNA vaccine delivery systems uses a live bacterial vector as the carrier. The live bacterial vector induces a robust immune response due to its natural characteristics that are recognized by the immune system. Moreover, the route of administration used by the live bacterial vector is through the mucosal route that beneficially induces both mucosal and systemic immune responses. The mucosal route is not invasive, making the vaccine easy to administer, increasing the patient’s acceptance. Lactic acid bacterium is one of the most promising bacteria used as a live bacterial vector. However, some other attenuated pathogenic bacteria, such as Salmonella spp. and Shigella spp., have been used as DNA vaccine carriers. Numerous studies showed that live bacterial vectors are a promising candidate to deliver DNA vaccines.

The potential of plant systems to break the HIV‐TB link

“…Different systems have been used for delivery of subunit vaccines including recombinant bacterial vector system (Triccas, ), recombinant viral vector system (Sereinig et al ., ) and lipoglycan–protein conjugate system (Hamasur et al ., ). However, the high cost of these systems, as well as concerns related to patient safety particularly in terms of bacterial (Yurina, ) and viral vectors, promoted plant‐based delivery system approach. By using the plant cell as the carrier, subunit vaccines can be delivered through mucosal route such as oral administration.…”

New vaccines on the horizon

“…i virusi (adenovirusi, parvovirusi, paramiksovirusi, poksvirusi) su ispitivani kao vakcinalni vektori. U eksperimentalnim modelima, invazivne intracelularne bakterije, kao što su Salmonella typhimurium i Listeria monocytogenes, su se pokazale kao najbolji nosači vakcinalnih DNK (32). U kliničkim studijama prevashodno se koriste virusni vektori, pa su oni u fokusu ovog rada.…”

Lactococcus lactis expressing sand fly PpSP15 salivary protein confers long-term protection against Leishmania major in BALB/c mice

“…Suitable live delivery systems include Brucella abortus, Salmonella enterica, Listeria monocytogenes, Bacillus subtilis, Lactobacillus plantarum, Lactococcus lactis (L. lactis) and Leishmania tarentolae. These systems offer more stability, amplification, production of heterologous antigens into the cell in natural form and, most importantly, in vivo stimulation of the immune system [18,19]. The advantages of L. lactis (NZ9000 strain) compared with other non-pathogenic expression systems are its less endogenous and no exogenous proteases, being LPS-free, and lack of inclusion bodies and spores [20,21].…”