Engineering of Chlamydomonas reinhardtii chloroplast for mucosal immunotherapeutic against Newcastle disease virus

Newcastle disease virus (NDV) is a devastating virus for the poultry industry, resulting in huge economic losses due to high morbidity and mortality. Commercial vaccines are available, but they are limited because of their high cost, difficult storage and administration system, and poor protection against local rising strains. Microalgal chloroplasts can be used to develop recombinant subunit vaccines having the advantages of scalable growth, quick transformation, and uniform expression levels. These vaccines can be produced on a large scale at an economical cost and are expected to be used to induce antigen-specific responses for a range of human and animal diseases. This study was aimed to develop an algae-based vaccine against NDV and to determine its effect on the immune response in chickens. The NDV HN gene was integrated into the chloroplast of Chlamydomonas reinhardtii to obtain stable and high expression of antigenic HN gene, which was found to be ~ 1000 fold higher than C. reinhardtii TN72 cell lines. The grown algal cell lines containing HN gene were fed to the chickens and their immune responses were evaluated in their blood through real time PCR (RT-PCR) analysis. The expression analysis showed a significant upregulation in the expression of Interleukin-6, Interleukins-8, and Interferon-γ at 16th and 26th day of vaccination with transgenic alga. The success of the study proved that transgenic algae-based vaccines can be used to protect poultry from NDV infection.