Immunogenicity of Recombinant Proteins Consisting of Plasmodium vivax Circumsporozoite Protein Allelic Variant-Derived Epitopes Fused with Salmonella enterica Serovar Typhimurium Flagellin

Abstract

A Plasmodium falciparum circumsporozoite protein (CSP)-based recombinant fusion vaccine is the first malaria vaccine to reach phase III clinical trials. Resistance to infection correlated with the production of antibodies to the immunodominant central repeat region of the CSP. In contrast to P. falciparum, vaccine development against the CSP of Plasmodium vivax malaria is far behind. Based on this gap in our knowledge, we generated a recombinant chimeric protein containing the immunodominant central repeat regions of the P. vivax CSP fused to Salmonella enterica serovar Typhimurium-derived flagellin (FliC) to activate the innate immune system. The recombinant proteins that were generated contained repeat regions derived from each of the 3 different allelic variants of the P. vivax CSP or a fusion of regions derived from each of the 3 allelic forms. Mice were subcutaneously immunized with the fusion proteins alone or in combination with the Toll-like receptor 3 (TLR-3) agonist poly(I·C), and the anti-CSP serum IgG response was measured. Immunization with a mixture of the 3 recombinant proteins, each containing immunodominant epitopes derived from a single allelic variant, rather than a single recombinant protein carrying a fusion of regions derived from each of 3 allelic forms elicited a stronger immune response. This response was independent of TLR-4 but required TLR-5/MyD88 activation. Antibody titers significantly increased when poly(I·C) was used as an adjuvant with a mixture of the 3 recombinant proteins. These recombinant fusion proteins are novel candidates for the development of an effective malaria vaccine against P. vivax.

Immunogenicity of a Prime-Boost Vaccine Containing the Circumsporozoite Proteins of Plasmodium vivax in Rodents

“…Serum IgG anti-P. vivax CSP antibodies were detected by enzyme-linked immunosorbent assay (ELISA) as previously described (14,15). The recombinant proteins (100 to 200 ng/well) were used as the solid-phase bound antigen.…”

“…The hybridomas used were obtained from the Malaria Research and Reference Reagent Resource Center (MR4). Polyclonal antibodies against the P. vivax-like epitopes were ob-tained from C57BL/6 mice immunized with the His 6 -FliC-PvCSP-Vivaxlike antigen as described previously (14). MAbs to the His tag were purchased from GE Healthcare Systems.…”

Enhancement of vaccine efficacy by expression of a TLR5 ligand in the defined live attenuated Francisella tularensis subsp. novicida strain U112ΔiglB::fljB

“…Flagellin has been successfully used as an adjuvant against a variety of pathogens, including bacteria [9, 14, 36], viruses [10], and protozoans [11]. While effective as an adjuvant in low doses, flagellin also has been shown to lead to an increase in T-cell dependent [14, 37] antibody production [14, 16, 38-40], specifically producing high titers of IgG1 and IgG2a that provide complete protection against a targeted pathogen.…”

“…To this end, flagellin has been used successfully as an adjuvant against a variety of pathogens, including bacteria [9], viruses [10], and protozoans [11]. Flagellin promotes Th1-type immunity [12], and importantly, it has been shown that previous exposure to flagellin does not impair the ability of the host to induce robust immune responses when it is used as an adjuvant [13, 14].…”

Defensins – natural peptide antibiotics of higher eucariotes

“…Ответ прост: полезные свойства данных белков планируется использовать в рамках принципиально нового и оригинального подхода, который, как предполагается, будет в состоянии нивелировать негативный момент, связанный с низкой селективностью и не высокой амфифильностью дефензинов альфа и тета. Этот подход заключается в создании гибридных белков, на основе fusion-технологии, иначе называемой технологией слитных генно-инженерных конструкций [47][48][49][50][51][52]. При этом, в нашем случае, целью является объединение, в единой "рамке", двух функциональных последовательностей: как собственно дефензина, так и того или иного амфифильного домена (LTABD и/или LTABP) (рис.…”