An overview of tuberculosis plant-derived vaccines

Abstract

Tuberculosis (TB) is a leading fatal infectious disease to which the current BCG vaccine has a questionable efficacy in adults. Thus, the development of improved vaccines against TB is needed. In addition, decreasing the cost of vaccine formulations is required for broader vaccination coverage through global vaccination programs. In this regard, the use of plants as biofactories and delivery vehicles of TB vaccines has been researched over the last decade. These studies are systematically analyzed in the present review and placed in perspective. It is considered that substantial preclinical trials are still required to address improvements in expression levels as well as immunological data. Approaches for testing additional antigenic configurations with higher yields and improved immunogenic properties are also discussed.

Need of cost-effective vaccines in developing countries: What plant biotechnology can offer?

“…The lone existing BCG vaccine, consisting of attenuated bacteria, provides only limited protection during childhood and has less or no effect on the rate of pulmonary diseases in adults (Kaufmann et al 2010 ; Gengenbacher and Kaufmann 2012 ). Few vaccines against TB are under clinical investigation (Rosales-Mendoza et al 2015 ); however, more drugs and vaccines are needed to move from discovery into the development pipeline because of the high rate of drug attrition in clinical development and the potential for post-approval failures (Koul et al 2011 ). In addition, it will also be challenging to ensure the proper access of the vaccines to patients in the resource poor countries where these are more needed (Kaufmann et al 2010 ; Koul et al 2011 ).…”

“…Plant biotechnology has been employed in the development of cost-effective vaccines against TB. Several studies reporting the expression of different antigens against TB has been recently summarised by Rosales-Mendoza et al ( 2015 ). Various antigens that have been expressed in plants include Ag85B, ESAT-6, Mtb72F, MPT83 and MPT64.…”

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

“…Several HIV candidate plant‐based vaccines targeting early HIV proteins and structural HIV proteins have been expressed in plants using transient and stable expression systems. These candidates are reviewed elsewhere (Rosales‐Mendoza et al ., ). The combination of plant vaccine with other (or heterologous prime‐boost vaccination) could be advanced to elicit T‐cell responses.…”

“…However, vaccine formulations remain challenging due to the high costs associated with antigen expression and purification. Efficient and affordable vaccination approaches should rely on low‐cost production systems with facile delivery, which will significantly facilitate massive immunization in limited recourse settings, where the vaccine is urgently required (Rosales‐Mendoza et al ., ). 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 ., ).…”

“…Env complex (gp120 and gp140), Gag, Tat and Nef proteins were immunogenic, but Env complex is the only target protein, which can induce neutralizing antibodies (NAbs) inhibiting viral entry. However, Gag, Tat and Nef structures are able to elicit cellular responses, which are involved in viral load blocking (Klasse et al, 2012;Mascola and Haynes, 2013;Rosales-Mendoza et al, 2015).…”