Plays a role in modulating the host immune response and affecting host cytokine production. Structurally and functionally homolog of host CEACAM1, induces endothelial cell angiogenesis (PubMed:21670740). Ligands for host FLT3 receptor, activates the PI3K/AKT and MAPK/ERK pathways. In turn, triggers hematopoietic progenitor cell and monocyte differentiation leading to virus reactivation (PubMed:29691342). Interacts with host FLT3. Highly glycosylated. Belongs to the RL11 family.