Interaction of PRRS virus with bone marrow monocyte subsets

Area of Science:

• Veterinary Virology
• Immunology
• Cell Biology

Background:

• Porcine reproductive and respiratory syndrome virus (PRRSV) establishes persistent infections in lymphoid organs.
• Porcine bone marrow contains CD163 and CD169 expressing monocyte subsets crucial for PRRSV entry into macrophages.

Purpose of the Study:

• To investigate the permissiveness of porcine bone marrow monocyte subsets to PRRSV infection.
• To understand the role of these subsets in viral persistence and associated hematological disorders.

Main Methods:

• Isolation and culture of porcine bone marrow monocyte subsets (CD163+ and CD163-).
• Infection of monocyte subsets with PRRSV and quantification of viral titers.
• Analysis of cytokine secretion (IL-8) and monocyte differentiation potential.

Main Results:

• PRRSV replicated efficiently in CD163+ bone marrow monocytes, with delayed kinetics compared to alveolar macrophages.
• CD163- bone marrow monocytes showed variable permissiveness and lower viral titers.
• Both subsets secreted IL-8 upon infection, with CD163+ cells producing higher amounts.
• CD163- monocytes could differentiate into CD163+ CD169+ cells in the presence of M-CSF.

Conclusions:

• Porcine bone marrow CD163+ monocytes are a significant reservoir for PRRSV, contributing to viral persistence.
• PRRSV infection of bone marrow monocytes may underlie hematological changes, including reduced peripheral blood monocyte counts.