Expression analysis of programmed death ligand 2 in tumors caused by the avian oncovirus Marek's disease virus

Area of Science:

• Immunology
• Veterinary Virology
• Oncology

Background:

• The programmed cell death protein 1 (PD-1) receptor and its ligands (PD-L) are crucial regulators of the immune system.
• Gallid herpesvirus 2 (GaHV-2), also known as Marek's disease virus (MDV), is an oncogenic avian herpesvirus that causes malignant lymphomas in chickens.
• Understanding the role of PD-1/PD-L pathways in avian viral রোগogenesis is essential for developing effective control strategies.

Purpose of the Study:

• To investigate the functional and expression characteristics of chicken PD-L2 in the context of GaHV-2 infection.
• To determine the potential involvement of chicken PD-L2 in immune evasion and tumor formation induced by GaHV-2.

Main Methods:

• Analysis of PD-L2 expression (mRNA and protein) in chicken spleens and tumor lesions post-GaHV-2 infection.
• Functional assays involving co-culturing peripheral blood mononuclear cells (PBMCs) and splenocytes with PD-L2-expressing cells to assess immune responses, specifically Interferon-gamma (IFN-γ) production.

Main Results:

• Significantly higher expression of PD-L2 mRNA was observed in the spleens of GaHV-2 infected chickens during the latent phase and in tumor lesions.
• A decrease in IFN-γ protein expression was noted in PBMCs and splenocytes when co-cultured with PD-L2-expressing cells, indicating an inhibitory effect on immune response.

Conclusions:

• Chicken PD-L2 exhibits immunoinhibitory functions, similar to its mammalian counterparts.
• The elevated expression of PD-L2 in GaHV-2 infected chickens suggests its critical role in facilitating viral latency and promoting tumor development through immune suppression.