The thermostability of the RTS,S/AS01 malaria vaccine can be increased by co-lyophilizing RTS,S and AS01.

BACKGROUND: Developing thermostable vaccines is a challenge for pharmaceutical companies due to the inherent instability of biological molecules in aqueous solution. The problem is even more stringent in regions subjected to high temperatures in which protective cold chain is difficult to maintain due to a lack of infrastructure. Here, a simple, cost-effective solution to increase the thermostability of the malaria candidate vaccine RTS,S/AS01 is described. This vaccine currently needs to be stored between 2 and 8  °C due to the sensitivity of liquid AS01 to higher temperatures. The strategy was to increase thermostability by co-lyophilizing the RTS,S antigen and AS01. METHODS: Co-lyophilization was achieved in a solution containing 5% sucrose, 10 mM potassium phosphate and 0.0312% polysorbate 80 at pH 6.1. The physicho-chemical characteristics and immunogenic properties of the resulting solid product, called CL-vac, fresh or stored at high temperature, were compared to those of the candidate RTS,S/AS01. RESULTS: CL-vac proved to be acceptable in terms of visual appearance and physico-chemical characteristics. The structural integrity of both RTS,S and AS01 within CL-vac and its equivalence to the RTS,S/AS01 candidate vaccine were shown. Further, the stability of CL-vac was demonstrated for storage periods including 1 year at 4  °C, 1 year at 30  °C, and up to 6 months at 37  °C. In addition, CL-vac could withstand a heat excursion consisting of 1 month at 45  °C after storage for 1 year at 30  °C. Equivalence and stability were demonstrated by the various analytical tools and the immunogenicity of the samples after storage was also demonstrated in mice. CONCLUSIONS: In conclusion, the co-lyophilization process appeared as a promising approach to increase RTS/AS01 vaccine thermostability.

Hepatitis B surface antigen incorporated in dissolvable microneedle array patch is antigenic and thermostable.

Alternatives to syringe-based administration are considered for vaccines. Intradermal vaccination with dissolvable microneedle arrays (MNA) appears promising in this respect, as an easy-to-use and painless method. In this work, we have developed an MNA patch (MNAP) made of hydroxyethyl starch (HES) and chondroitin sulphate (CS). In swines, hepatitis B surface antigen (HBsAg) formulated with the saponin QS-21 as adjuvant, both incorporated in HES-based MNAP, demonstrated the same level of immunogenicity as a commercially available aluminum-adjuvanted HBsAg vaccine, after two immunizations 28 days apart. MNAP application was associated with transient skin reactions (erythema, lump, scab), particularly evident when the antigen was delivered with the adjuvant. The thermostability of the adjuvanted antigen when incorporated in the HES-based matrix was also assessed by storing MNAP at 37, 45 or 50 °C for up to 6 months. We could demonstrate that antigenicity was retained at 37 and 45 °C and only a 10% loss was observed after 6 months at 50 °C. Our results are supportive of MNAP as an attractive alternative to classical syringe-based vaccination.

Methods to monitor monocytes-mediated amyloid-beta uptake and phagocytosis in the context of adjuvanted immunotherapies.

Antibody-mediated capture of amyloid-beta (Aß) in peripheral blood was identified as an attractive strategy to eliminate cerebral toxic amyloid in Alzheimer's disease (AD) patients and murine models. Alternatively, defective capacity of peripheral monocytes to engulf Aß was reported in individuals with AD. In this report, we developed different approaches to investigate cellular uptake and phagocytosis of Aß, and to examine how two immunological devices--an immunostimulatory Adjuvant System and different amyloid specific antibodies--may affect these biological events. Between one and thirteen months of age, APPswe X PS1.M146V (TASTPM) AD model mice had decreasing concentrations of Aß in their plasma. In contrast, the proportion of blood monocytes containing Aß tended to increase with age. Importantly, the TLR-agonist containing Adjuvant System AS01B primed monocytes to promote de novo Aß uptake capacity, particularly in the presence of anti-Aß antibodies. Biochemical experiments demonstrated that cells achieved Aß uptake and internalization followed by Aß degradation via mechanisms that required effective actin polymerization and proteolytic enzymes such as insulin-degrading enzyme. We further demonstrated that both Aß-specific monoclonal antibodies and plasma from Aß-immunized mice enhanced the phagocytosis of 1 µm Aß-coated particles. Together, our data highlight a new biomarker testing to follow amyloid clearance within the blood and a mechanism of Aß uptake by peripheral monocytes in the context of active or passive immunization, and emphasize on novel approaches to investigate this phenomenon.

Processing of blood samples influences PBMC viability and outcome of cell-mediated immune responses in antiretroviral therapy-naïve HIV-1-infected patients.

Intracellular cytokine staining (ICS) assay is increasingly used in vaccine clinical trials to measure antigen-specific T-cell mediated immune (CMI) responses in cryopreserved peripheral blood mononuclear cells (PBMCs) and whole blood. However, recent observations indicate that several parameters involved in blood processing can impact PBMC viability and CMI responses, especially in antiretroviral therapy (ART)-naïve HIV-1-infected individuals. In this phase I study (NCT01610427), we collected blood samples from 22 ART-naïve HIV-1-infected adults. PBMCs were isolated and processed for ICS assay. The individual and combined effects of the following parameters were investigated: time between blood collection and PBMC processing (time-to-process: 2, 7 or 24 h); time between PBMC thawing and initiation of in vitro stimulation with HIV-1 antigens (resting-time: 0, 2, 6 and 18 h); and duration of antigen-stimulation in PBMC cultures (stimulation-time: 6h or overnight). The cell recovery after thawing, cell viability after ICS and magnitude of HIV-specific CD8(+) T-cell responses were considered to determine the optimal combination of process conditions. The impact of time-to-process (2 or 4 h) on HIV-specific CD8(+) T-cell responses was also assessed in a whole blood ICS assay. A higher quality of cells in terms of recovery and viability (up to 81% and >80% respectively) was obtained with shorter time-to-process (less than 7 h) and resting-time (less than 2 h) intervals. Longer (overnight) rather than shorter (6 h) stimulation-time intervals increased the frequency of CD8(+)-specific T-cell responses using ICS in PBMCs without change of the functionality. The CD8(+) specific T-cell responses detected using fresh whole blood showed a good correlation with the responses detected using frozen PBMCs. Our results support the need of standardized procedures for the evaluation of CMI responses, especially in HIV-1-infected, ART-naïve patients.