Research Article Construction of a Chimeric Secretory IgA and Its Neutralization Activity against Avian Influenza Virus H5N1

permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Secretory immunoglobulin A (SIgA) acts as the first line of defense against respiratory pathogens. In this assay, the variable regions of heavy chain (VH) and Light chain (VL) genes from a mouse monoclonal antibody against H5N1 were cloned and fused with human IgA constant regions. The full-length chimeric light and heavy chains were inserted into a eukaryotic expressing vector and then transfected into CHO/dhfr-cells.The chimeric monomeric IgA antibody expression was confirmed by using ELISA, SDS-PAGE, andWestern blot. In order to obtain a dimeric secretory IgA, another two expressing plasmids, namely, pcDNA4/His A-IgJ and pcDNA4/His A-SC, were cotransfected into the CHO/dhfr-cells.The expression of dimeric SIgAwas confirmed by using ELISA assay andnative gel electrophoresis. Inmicroneutralization assay on 96-well immunoplate, the chimeric SIgA showedneutralization activity against H5N1 virus onMDCK cells and the titer was determined to be 1: 64. On preadministrating intranasally, the chimeric SIgA could prevent mice from lethal attack by using A/Vietnam/1194/04 H5N1 with a survival rate of 80%. So we concluded that the constructed recombinant chimeric SIgA has a neutralization capability targeting avian influenza virus H5N1 infection in vitro and in vivo. 1