Identification of the Receptor and Cellular Ortholog of the Marek's Disease Virus (MDV) CXC Chemokine

Abstract

Marek's disease virus (MDV) is a cell associated alphaherpesvirus that causes fatal lymphoma in chickens. One factor that plays a crucial role in MDV pathogenesis is the viral CXC chemokine vIL-8 that was originally named after chicken interleukin 8 (cIL-8). However, a recent study demonstrated that vIL-8 recruits B cells and a subset of T cells but not neutrophils, suggesting that vIL-8 is not a cIL-8 orthologue. In this study, we set to identify the cellular orthologues and receptor of vIL-8 using in silico analyses, binding and chemotaxis assays. Sequence and phylogenetic analyses of all chicken CXC chemokines present in the recently published chicken genome revealed that vIL-8 shares the highest amino acid similarity with the CXCL13L1 variant. To evaluate if vIL-8 and CXCL13L1 are also functional orthologues, we assessed their binding properties and chemotaxis activity. We demonstrated that both vIL-8 and CXCL13 variants bind B cells and subsets of T cells, confirming that they target the same cell types. In addition, the chemokines not only bound the target cells but also induced chemotaxis. Finally, we identified CXCR5 as the receptor of vIL-8 and CXCL13 variants and confirmed that the receptor is expressed on MDV target cells. Taken together, our data demonstrate the conservation of the receptor-ligand interaction between CXCR5 and CXCL13 and shed light on the origin and function of the MDV-encoded vIL-8 chemokine, which plays a crucial role in the pathogenesis of this highly oncogenic virus.

Revisiting cellular immune response to oncogenic Marek’s disease virus: the rising of avian T-cell immunity

“…Based on the accepted model of the MDV life cycle, after inhalation of cell-free virus particle within contaminated dust and dander, epithelial cells are infected first, followed by phagocytes like macrophages and DCs [4]. At this time, B cells, along with T cells, are recruited to the lung by MDV-encoded viral IL-8, a functional orthologue of chemokine CXCL13L1 but distinct from chicken IL-8 [93,94], which recognizes the C-X-C chemokine receptor type 5 (CXCR5) on B and T cells and induces chemotaxis [94]. Subsequently, B cells become the primary target cell for productive MDV replication after the virus is carried to lymphoid tissues by infected macrophages and DCs.…”

Blocking of the CXCR4-CXCL12 Interaction Inhibits the Migration of Chicken B Cells Into the Bursa of Fabricius

“…Chemotaxis assay were performed as described before (20). Briefly transwell plates (Sigma-Aldrich, Taufkirchen, Germany) were coated with 50 µl fibronectin (10 µg/ml) and then incubated for 1 h at 37 • and 5% CO 2 .…”

“…The same chemokine receptor and ligand have been shown to be key players in many other migration processes, including the mobilization of mammalian hematopoietic stem cells, lymphocytes (14)(15)(16) but also primordial germ cells (17). CXCR4 and its ligand CXCL12 are both expressed in chickens during B cell development (18)(19)(20)(21). It has been suggested that immature B cells might also migrate toward the bursa under the influence of the CXCR4/CXCL12 interaction.…”

Latest Insights into Marek’s Disease Virus Pathogenesis and Tumorigenesis

“…MDV secretes a viral CXC chemokine that was initially termed vIL-8, but recently changed to vCXCL13 based in its biological properties [25][26][27][28]. This chemokine recruits B cells and a subset of Mononuclear phagocytes transfer the virus to lymphoid organs, such as the spleen, thymus, and bursa, where the virus lytically replicates in lymphocytes.…”