Enhancing protective efficacy of poultry vaccines through targeted delivery of antigens to antigen presenting cells

In recent years, poultry production has been under constant threat of infectious diseases such as avian influenza and Newcastle disease resulting in the poultry trade reduction and zoonotic infection risk. Vaccination has become one of the important measures in controlling such diseases. One way of increasing the efficacy of these vaccines is to deliver specific antigens selectively targeting antigen presenting cells (APCs). This could be achieved by coupling APC receptor-specific antibody to the antigen of choice. To achieve this, we are targeting avian influenza hemagglutinin (HA) protein to the chicken dendritic cell (DC) surface receptors. We have recombinantly produced H9HA antigen fused to single chain fragment variable antibodies (scFv) against the chicken DC surface receptors. To assess the HA activity of our recombinantly produced H9HA fused to scFv antibody, hemagglutination assay was adopted. Our constructs were able to agglutinate chicken red blood cells and therefore retained HA activity. Furthermore, the scFv antibodies fused to HA were able to detect their respective antigens via western blot indicating that these scFv antibodies are functional. To further characterise our H9HA fused scFv antibodies in vitro, their binding ability to chicken DCs will be assessed using flow cytometry. Therefore, we have created functional H9HA antigen targeting to chicken DCs which we aim to use in developing enhanced vaccines towards avian influenza virus. In future, we will clone our constructs into herpesvirus of turkey to generate a recombinant viral vector vaccine which we hypothesise would enhance the immune response in chickens.