3D visualisation of hepatitis B vaccine in the oral delivery vehicle SBA-15

Abstract

Developing a technology that enables oral vaccines to work efficiently remains a considerable effort since a number of difficulties must be addressed. The key objective being to ensure the safe passage through the harsh conditions within the gastrointestinal tract, promoting delivery that induces enhanced immune response. In the particular case of hepatitis B, the oral formulation in the nanostructured silica SBA-15 is a viable approach. As a result of its porous structure, low toxicity and structural stability, SBA-15 is capable to protect and release the hepatitis B surface antigen (HBsAg), used in the vaccination scheme, at the desired destination. Furthermore, when compared to the currently used injection based delivery method, better or similar antibody response has been observed. However, information about the organisation of the antigen protein remains unknown. For instance, HBsAg is too large to enter the 10 nm ordered mesopores of SBA-15 and has a tendency to agglomerate when protected by the delivery system. Here we report on the pH dependence of HBsAg aggregation in saline solution investigated using small angle X-rays scattering that resulted in an optimisation of the encapsulation conditions. Additionally, X-ray microscopy combined with neutron and X-ray tomography provided full 3D information of the HBsAg clustering (i.e. agglomeration) inside the SBA-15 macropores. This method enables the visualisation of the organisation of the antigen in the interior of the delivery system, where agglomerated HBsAg coexists with its immunological effective uniformly distributed counterpart. This new approach, to be taken into account while preparing the formulation, can greatly help in the understanding of clinical studies and advance new formulations.

Using crystallography tools to improve vaccine formulations

“…SAXS characterization of the pure antigens in PBS solution (pH = 7.4 and T = 25 C) showed that HBsAg is a globular particle with mean diameter of 30 AE 5 nm, hence larger than the silica mean pore diameter D = 10.4 AE 0.6 nm, confirmed by DLS and TEM images (Rasmussen et al, 2019a). Therefore, the HBsAg particles are in the macroporous region of SBA-15, and may also close the entrance of the mesopore and cluster in PBS.…”

Use of Nanostructured Silica SBA-15 as an Oral Vaccine Adjuvant to Control Mycoplasma hyopneumoniae in Swine Production

“…About seven days before the oral vaccination administration, the dry fraction of the vaccine was prepared, measuring the number of proteins suspended in PBS (pH 7.2). The dose used for the production of the oral vaccine was 200 µg per piglet, mixed with silica in the proportion 1:35 defined in previous studies [ 14 , 26 ]. Mycoplasma hyopneumoniae protein lysate was added to SBA-15, previously macerated and activated, and a drying step at 37 °C for 72 h was performed to obtain the dry fraction [ 16 ].…”

The Neutron Imaging Instrument CONRAD—Post-Operational Review

“…The implementation of these new techniques as standard instrument options helped to expand the imaging capabilities of the beamline, allowing for imaging with polarized neutrons [7][8][9], Bragg-edge mapping [10][11][12][13], high-resolution neutron imaging [14] and grating interferometry [15,16]. These methods were offered to the user community as tools to help address scientific problems over a broad range of topics, such as superconductivity [17], materials research [18,19], life sciences [20,21], cultural heritage and paleontology [22,23]. Industrial applications, including fuel cell [24,25] and battery research [26][27][28], have also been fostered by these increased capabilities, which further helped to increase and improve the scientific output of the facility and to attract new users.…”