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Fig. 2 | Malaria Journal

Fig. 2

From: Bacterial superglue generates a full-length circumsporozoite protein virus-like particle vaccine capable of inducing high and durable antibody responses

Fig. 2

Characterization of a virus-like particle-based CSP vaccine. a Reduced SDS-PAGE gels loaded with AP205 SpyTag-VLPs (lane 1), CSP-SpyCatcher (lane 2) and the CSP Spy-VLP vaccine (lane 3), demonstrating that SpyCatcher-CSP has been covaltly conjugated to the AP205 capsid protein. Three protein bands formed following the reaction of SpyTag-VLPs with SpyCatcher-CSP. The bands correspond to the size of the CSP-VLP capsid protein conjugate (89 kDa) (lane 3 top), uncoupled CSP vaccine antigen (theoretical size 52 kDa—however it appears as 72 kDa on the SDS gel) (lane 3 middle) and unconjugated SpyTag-VLP capsid protein (16.5 kDa) (lane 3 bottom). Densitometric analysis comparing the protein band intensity of in lane 1 with the bottom band in lane 3 revealed that an average of 112 CSP-SpyCatcher antigens have been covalently attached per VLP. b Transmission electron microscopy of the CSP Spy-VLP vaccine (i.e., CSP-SpyCatcher covalently attached to SpyTag-VLP). CSP Spy-VLP samples were placed on carbon, adsorbed to a grid and negatively stained with 2% phosphotungstic acid. The large image reveals uniformly distributed, non-aggregated particles of approximately 49 nm. The bottom left images show a zoomed-in CSP Spy-VLP (bottom) compared to an unconjugated AP205 Spy-VLP (top)

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