Fusion to chicken C3d enhances the immunogenicity of the M2 protein of avian influenza virus

Abstract

BackgroundCurrent vaccines to avian influenzae virus (AIV), a highly contagious disease of birds, need to be constantly updated due to the high level of variation in the target antigens. Therefore, a vaccine that could induce broad cross protection against AIV is required. The M2 membrane protein is structurally conserved amongst AIV subtypes but tends in induce a poor immune response, whereas C3d has been shown in many species to enhance immunogenicity. In this study, we investigated the potential of M2-avian C3d fusion proteins to provide effective immunity.ResultsWe fused chicken complement C3d to sM2 (M2 protein with the transmembrane region deleted) of AIV and expressed four fusion proteins, GST (Glutathione S-transferase tagged proteins in pGEX expression vector) -C3d-sM2, GST-C3d-L2-sM2, GST-C3d-L1-C3d-sM2 and GST-C3d-L1-C3d-L2-sM2 were used to immunize mice. In addition, Specific pathogen free (SPF) chickens were inoculated with the plasmids pcDNA-sM2, pcDNA-C3d-L1-C3d-L2-sM2, GST-sM2 and GST-C3d-L1-C3d-L2-sM2. The immune response was monitored by an enzyme-linked immunosorbent assay (ELISA) for sM2 antibody, and all the test animals were challenged with A/chicken/Bei Jing/WD9/98 (H9N2) virus. Results revealed that the anti-sM2 antibody in mice and chickens vaccinated with these proteins was higher than the nonfused forms of sM2, the GST-C3d-L1-C3d-L2-sM2 groups have conferred the highest 30% and 20% protection ratio in mice and chickens respectively. In addition, the pcDNA-C3d-L1-C3d-L2-sM2 also enhances the antibody responses to sM2 compared to pcDNA-sM2 in chickens, and acquired 13.3% protection ratio.ConclusionThese results indicated that chicken C3d enhanced the humoral immunity against AIV M2 protein either fused proteins expressed by the prokaryotic system or with the DNA vaccine. Nevertheless, in view of the poor protection ratio for these animals, we speculated that this is not a worthy developing of vaccine in these constructs.

Vaccination induced antibodies to recombinant avian influenza A virus M2 protein or synthetic M2e peptide do not bind to the M2 protein on the virus or virus infected cells

“…Combined with the positive vaccination experiments in chicken [22,23] this led to the expectation that M2 protein and M2e peptide vaccination would work in chicken as well. Our study shows that it is possible in chicken to raise antibodies against a bacterial expressed avian influenza M2 protein or streptavidin bound M2e peptide in a tetrameric conformation.…”

“…Zhang et al used a plasmid coding for an M2 protein of which the transmembrane region was deleted. They found that chicken C3d enhanced the humoral immunity against AIV M2 protein, be it with a poor protection ratio [22]. In contrast, Layton et al (2009) showed that Salmonella vectored vaccines expressing a M2e epitope in association with CD154 are effective at protecting chickens against LPAI, but not against HPAI [23].…”

Rice‐produced MSP142 of Plasmodium falciparum elicits antibodies that inhibit parasite growth in vitro

“…ELISA titre was expressed as the end point serum dilution that gave an absorbance twofold higher than the value of rabbit pre-immune sera. 38…”

A bioinformatic approach to check the spatial epitope structure of an immunogenic protein coded by DNA vaccine plasmids

“…Because there are receptors for C3d complement component (Li, et al, 2009, Zhang, et al, 2010, Zhang, et al, 2011 and domains 3 and 4 of Fc IgY (Taylor, et al, 2008, Purzel, et al, 2009) on dendritic cells, B lymphocytes and macrophages (antigen presenting cells (APC)), different gene segments such as four or eight repeats of 29 amino acids of C3d complement component (P29C3d) and domains 3 and 4 of the Fc part of IgY (FcIgY) were fused to hemagglutinin 9 (H9) gene in this study. Proteins encoded by DNA vaccines are targeted to the surface of APCs providing better importation into the APCs following likely better processing and more efficiency.…”