Adenovirus-vectored vaccine containing multidimensionally conserved parts of the HIV proteome is immunogenic in rhesus macaques

An effective vaccine that can protect against HIV infection does not exist. A major reason why a vaccine is not available is the high mutability of the virus, which enables it to evolve mutations that can evade human immune responses. This challenge is exacerbated by the ability of the virus to evolve compensatory mutations that can partially restore the fitness cost of immune-evading mutations. Based on the fitness landscapes of HIV proteins that account for the effects of coupled mutations, we designed a single long peptide immunogen comprising parts of the HIV proteome wherein mutations are likely to be deleterious regardless of the sequence of the rest of the viral protein. This immunogen was then stably expressed in adenovirus vectors that are currently in clinical development. Macaques immunized with these vaccine constructs exhibited T-cell responses that were comparable in magnitude to animals immunized with adenovirus vectors with whole HIV protein inserts. Moreover, the T-cell responses in immunized macaques strongly targeted regions contained in our immunogen. These results suggest that further studies aimed toward using our vaccine construct for HIV prophylaxis and cure are warranted.

Masking terminal neo-epitopes of linear peptides through glycosylation favours immune responses towards core epitopes producing parental protein bound antibodies

Glycosylation of hydrophobic peptides at one terminus effectively increases their water-solubility, and conjugation through the opposing end to a carrier protein, renders them more immunogenic. Moreover, the glycosylation minimizes antibody responses to potentially deleterious, non-productive terminal neo-epitope regions of the peptides, and consequently shifts peptide immunogenicity towards the core amino acid residues. As proof of concept, glycopeptide-protein conjugates related to influenza hemagglutinin (HA), neuraminidase (NA), and the dimerization loop region of human epidermal growth factor receptor 2 (Her2), demonstrated a favorable production of core peptide specific antibodies as determined by ELISA studies. Furthermore, glycosylated Her2 peptide conjugate antisera were also shown to recognize full length Her2 protein by ELISA and at the cell surface through flow cytometry analysis. In contrast, unmasked peptide conjugates generated significant antibody populations that were specific to the terminal neo-epitope of the peptide immunogen that are notably absent in parental proteins. Antibodies generated in this manner to peptides in the dimerization loop of Her2 are also functional as demonstrated by the growth inhibition of Her2 expressing SKBR3 carcinoma cells. This method provides a technique to tailor-make epitope-specific antibodies that may facilitate vaccine, therapeutic and diagnostic antibody development.

Evaluation of recombinant monoclonal antibody SVmab1 binding to NaV1.7 target sequences and block of human NaV1.7 currents

Identification of small and large molecule pain therapeutics that target the genetically validated voltage-gated sodium channel NaV1.7 is a challenging endeavor under vigorous pursuit. The monoclonal antibody SVmab1 was recently published to bind the NaV1.7 DII voltage sensor domain and block human NaV1.7 sodium currents in heterologous cells. We produced purified SVmab1 protein based on publically available sequence information, and evaluated its activity in a battery of binding and functional assays. Herein, we report that our recombinant SVmAb1 does not bind peptide immunogen or purified NaV1.7 DII voltage sensor domain via ELISA, and does not bind NaV1.7 in live HEK293, U-2 OS, and CHO-K1 cells via FACS. Whole cell manual patch clamp electrophysiology protocols interrogating diverse NaV1.7 gating states in HEK293 cells, revealed that recombinant SVmab1 does not block NaV1.7 currents to an extent greater than observed with an isotype matched control antibody. Collectively, our results show that recombinant SVmab1 monoclonal antibody does not bind NaV1.7 target sequences or specifically inhibit NaV1.7 current.

Antibodies to Malaria Peptide Mimics Inhibit Plasmodium falciparum Invasion of Erythrocytes

ABSTRACT Apical membrane antigen 1 (AMA1) is expressed on the surfaces of Plasmodium falciparum merozoites and is thought to play an important role in the invasion of erythrocytes by malaria parasites. To select for peptides that mimic conformational B-cell epitopes on AMA1, we screened a phage display library of >108 individual peptides for peptides bound by a monoclonal anti-AMA1 antibody, 4G2dc1, known to inhibit P. falciparum invasion of erythrocytes. The most reactive peptides, J1, J3, and J7, elicited antibody responses in rabbits that recognized the peptide immunogen and both recombinant and parasite AMA1. Human antibodies in plasma samples from individuals exposed to chronic malaria reacted with J1 and J7 peptides and were isolated using immobilized peptide immunoadsorbents. Both rabbit and human antibodies specific for J1 and J7 peptides were able to inhibit the invasion of erythrocytes by P. falciparum merozoites. This is the first example of phage-derived peptides that mimic an important epitope of a blood-stage malaria vaccine candidate, inducing and isolating functional protective antibodies. Our data support the use of J1 and J7 peptide mimics as in vitro correlates of protective immunity in future AMA1 vaccine trials.