Use of a synthetic foot-and-mouth disease virus peptide conjugated to gold nanoparticles for enhancing immunological response

Abstract

Foot-and-mouth disease is an acute, highly contagious infection of domestic and wild cloven-hoofed animals, which can be transmitted to humans. In many cases, the existing vaccines are not quite effective. The purpose of this study was to test the possibility of using gold nanoparticles as an antigen carrier and an adjuvant. The immunogenic properties of gold nanoparticles were assessed by conjugating the particles to a synthetic peptide of the VP 1 capsid protein of the foot-and-mouth disease virus. The resulting conjugate (with or without the use of complete Freund's adjuvant), a commercial vaccine, and the native peptide served to immunize guinea pigs. The titer and sensitivity of the raised antibodies were maximal for the combination comprising the nanoparticle-peptide conjugate and complete Freund's adjuvant. Antibody biosynthesis was accompanied by increased production of proinflammatory cytokines (especially IFN-γ) and by stimulation of the respiratory activity of peritoneal macrophages. The use of gold nanoparticles as a hapten carrier enhanced the immune response even when complete Freund's adjuvant was not used.

Preparation and in vivo evaluation of glyco-gold nanoparticles carrying synthetic mycobacterial hexaarabinofuranoside

“…Control experiments showed that the observed specificity of antisera against Ara 6 -GNPs 3 and 4 is due to the presence of the Ara 6 -epitope in Ara 6 -GNPs 3 and 4 and is not related to the presence of background anti-mycobacterial antibodies, which could be present in intact rabbit serum used for immunization, or antibodies generated against heat-inactivated M. tuberculosis cells, which are present in CFA ( Figure 6, Supporting Information File 1, Figure S1). The importance of using CFA for the generation of hapten-specific antibodies has been recently demonstrated [77]. The titers of antibodies against haptens amine-linked to GNPs decreased in the following order: (hapten + GNPs + CFA) > (hapten + GNPs) ≫ (hapten + CFA).…”

“…In order to prepare the glyco-GNPs, Ara 6 glycosides 1 and 2 ( Figure 1) were directly conjugated to pre-formed [67,94] freshly prepared citrate-stabilized spherical gold nanoparticles (d = 15 nm, identical to those prepared earlier [77]) to give the corresponding Ara 6 -GNPs 3 and 4 (Figure 1), which have the same size as the parent GNPs according to transmission electron microscopy (TEM) ( Figure 2).…”

“…According to the colorimetric determination of carbohydrates (phenol-sulfuric acid reaction, see the Experimental section for details) in the samples of glyco-GNPs 3 and 4, which were puri- fied from the excess of Ara 6 glycosides 1 and 2 by centrifugation, there are no more than 100 glycoside molecules on each nanoparticle on average. Spherical citrate-stabilized GNPs with 15 nm average diameter (which are often considered as standard GNPs for immunochemical studies due to ease of preparation and conjugation with ligands [48,56,57] and have successfully been used in our previous studies [56,57,77,78,95]) were chosen for the experiments. This is because GNPs of this size, unlike much smaller GNPs (e.g., around 2 nm in diameter), which are often derivatized in situ [32,39,46,48], can be easily prepared in advance and kept for further conjugation with a desired ligand.…”

“…Indeed, the direct conjugation of amino-functionalized antigenic glycans with pre-formed GNPs has not been reported yet, to the best of our knowledge. This is despite the fact that simple amines, amino acids and peptides [68][69][70][71][72][73][74][75][76][77][78], as well as diethylaminoethyl-dextran [79] and chitosan [80] have been reported to bind to GNPs in a pH-dependent manner as the energy of the Au-N interaction is intermediate between those of Au-S and Au-O [81]. The affinity of different functional groups to the surface of GNPs decreases in the series Au-S > Au-NH 2 > Au-COOH [82], which enables the exchange of citrate ligands with amines.…”

“…The affinity of different functional groups to the surface of GNPs decreases in the series Au-S > Au-NH 2 > Au-COOH [82], which enables the exchange of citrate ligands with amines. The amine-capped GNPs are stable enough to be used as targeting agents for drugdelivery applications [75], as antigens for the generation of anti-bodies [77], or as antimicrobial agents [78]. These nanoconjugates are nontoxic, effectively penetrate into the cells and can be used as carriers [83].…”