0000000000350422
AUTHOR
Andrei Soliakov
Alhydrogel® adjuvant, ultrasonic dispersion and protein binding: A TEM and analytical study
Aluminium-based vaccine adjuvants have been in use since the 1920s. Aluminium hydroxide (alum) that is the chemical basis of Alhydrogel, a widely used adjuvant, is a colloid that binds proteins to the particular surface for efficient presentation to the immune system during the vaccination process. Using conventional TEM and cryo-TEM we have shown that Alhydrogel can be finely dispersed by ultrasonication of the aqueous suspension. Clusters of ultrasonicated aluminium hydroxide micro-fibre crystals have been produced (∼ 10-100 nm), that are significantly smaller than those present the untreated Alhydrogel (∼ 2-12 μm). However, even prolonged ultrasonication did not produce a homogenous susp…
Recombinant anthrax protective antigen: Observation of aggregation phenomena by TEM reveals specific effects of sterols.
Abstract Negatively stained transmission electron microscope images are presented that depict the aggregation of recombinant anthrax protective antigen (rPA83 monomer and the PA63 prepore oligomer) under varying in vitro biochemical conditions. Heat treatment (50 °C) of rPA83 produced clumped fibrils, but following heating the PA63 prepore formed disordered aggregates. Freeze-thaw treatment of the PA63 prepore generated linear flexuous aggregates of the heptameric oligomers. Aqueous suspensions of cholesterol microcrystals were shown to bind small rPA83 aggregates at the edges of the planar bilayers. With PA63 a more discrete binding of the prepores to the crystalline cholesterol bilayer ed…
The structure of Yersinia pestis Caf1 polymer in free and adjuvant bound states
Caf1 of the plague bacterium, Yersinia pestis is a polymeric virulence factor and vaccine component, formed from monomers by a donor strand exchange (DSE) mechanism. Here, EM images of Caf1 reveal flexible polymers up to 1.5 microm long (4MDa). The bead-like structures along the polymer are 5.8 + or - 1 nm long and correspond to single Caf1 proteins. Short polymers often form circles, presumably by DSE. We also provide the first images of proteins bound to alhydrogel adjuvant. Caf1, hemocyanin and anthrax PA are all resolved clearly and Caf1 exhibits adjuvant bound stretches with long intervening loops draped from the edges.