Aerodynamic engineering of a pulmonary prime-pull vaccine against Tuberculosis

Student thesis: Doctoral Thesis

Abstract

Tuberculosis (TB) remains the infectious disease with the highest mortality alongside HIV. Despite the existence of the Bacillus Calmette-Guerin (BCG) vaccine there is an unmet need for an effective vaccine against pulmonary TB, the most common form of TB. Traditional vaccines were based on live-attenuated organisms, but nowadays the development of subunit vaccines is attracting the attention of researches largely as a result of the improved safety profile. However, many subunit vaccines lack potent immunogenicity, therefore the inclusion of an adjuvant within the subunit vaccine formulation may be required.Due to the optimal biological properties of the lipids, liposomes are extensively studied as delivery systems along with polymer-based particulate systems such as the well-known poly(lactic-co-glycolic acid) family (PLGA). The cationic liposomal adjuvant formulation (CAF) 01, which is based on the cationic surfactant dimethyldioctadecylammonium (DDA) bromide and the immunopotentiator trehalose 6,6'-dibehenate (TDB) from Mycobacterium tuberculosis, has previously been shown to be a strong adjuvant system against several diseases such as TB. CAF01 is commonly prepared by the thin film method which has several drawbacks including scale-up and reproducibility.In contrast, controllable technologies such as microfluidics have advantages in material preparation such as uniform flow and mixing, high efficiency, continuous operation, easy control and low cost. Therefore, initial studies were focused towards method optimisation of CAF01 through microfluidics, followed by in vivo evaluation of the optimised formulation (biodistribution and immunisation studies). The second part of the thesis was based in the formulation PLGA nano- and microparticles using microfluidics and the double emulsion method respectively.All formulations were characterised according to their size, polydispersity and surface charge as empty particulate systems and incorporating either ovalbumin (OVA) as a model antigen or the vaccine candidate Ag85B-ESAT6-Rv2660c (H56). Selected PLGA particles were formulated as dry powders for inhalation and for the delivery of the H56 tuberculosis antigen into the deep lungs (alveoli). In vitro deposition within the lungs was evaluated using a Pharmacopoeia approved airway simulator, while cell viability, particle uptake and antigen processing was assessed in three macrophages cell lines.Finally, a prime-pull vaccine approach for protection against pulmonary TB was investigated. An immunisation protocol consisting of parenteral (subcutaneous) priming with the TB vaccine candidate H56 alongside CAF01 followed by respiratory mucosal boosting of the H56 within PLGA nano- and micropaticles was carried out in order to elucidate if intranasal administration of the H56 antigen produces the desired immunological responses for the protection against pulmonary TB.The immune responses generated indicate the retention of the immunogenicity of the antigen encapsulated within a lyophilised PLGA delivery system, demonstrating the successful scale independent manufacture of polymer based delivery systems encapsulating antigens for inhalation/aerolisation delivery to the lung mucosa.
Date of Award1 Jul 2018
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorYvonne Perrie (Supervisor) & Paul Hoskisson (Supervisor)

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