Respiratory virus infections such as Avian Influenza, infectious laryngotracheitis and infectious bronchitis lead to high morbidity and mortality in chickens globally.
Given the limitations of current control measures against these virus infections, it is a necessity that novel measures are developed leading to enhanced host immune responses against respiratory viruses. The objective of the study was to boost the cell-mediated immunity in chickens post-hatch via pre-hatch delivery of nucleic acids increasing the resistance to respiratory viruses. We delivered CpG DNA or non-CpG DNA (control DNA) or PBS in ovo and collected tissues from the respiratory and immune organs for the purpose of immunostaining of macrophages, T cluster of differentiation (CD)4+, T CD8+ and B IgM+ cells.
In the next experiment, we delivered CpG DNA and non-CpG DNA or PBS as controls in ovo and subsequently infected with infectious laryngotracheitis virus (ILTV), infectious bronchitis virus (IBV) and H4N6 avian influenza virus (AIV) at day 1 post-hatch. We found in ovo CpG DNA increases recruitment of macrophages, T CD4+, T CD8+, B IgM+ cells in lungs and immune organs post-hatch. In correlating with the cellular responses, we also found that in ovo delivered CpG DNA induces protective responses against ILTV and IBV infections in terms of reduced mortality and clinical signs and inhibits AIV replication in lungs and trachea. This study suggests that the CpG DNA is a potential candidate for further investigation in order to boost cell-mediated immune response against respiratory viruses.
Source: From The 2019 International Poultry Scientific Forum.