Egyptian Rousette Bat (Rousettus aegyptiacus) TIM-3 (T cell immunoglobulin and mucin domain-containing protein 3, also known as HAVCR2, hepatitis A virus cellular receptor 2) is an immune checkpoint receptor involved in regulation of T cell activity and immune tolerance. TIM-3 is a member of the TIM (T cell immunoglobulin and mucin domain) family of immune regulatory proteins, which includes TIM-1, TIM-3, and TIM-4, molecules that modulate immune responses and maintain immune homeostasis. In Egyptian Rousette bats, TIM-3 is likely expressed on activated T lymphocytes, natural killer (NK) cells, dendritic cells, and macrophages, where it functions as a negative regulator of immune activation. Interaction of TIM-3 with its ligands, such as galectin-9, phosphatidylserine, and HMGB1, transmits inhibitory signals that reduce T cell proliferation, cytokine production, and cytotoxic activity, helping to limit excessive inflammatory responses. Because Egyptian Rousette bats are natural reservoirs for viruses such as Marburg virus, immune checkpoint pathways like TIM-3 may contribute to the controlled immune responses and reduced immunopathology observed in bats during viral infection. Regulation of T cell activation through TIM-3 may help balance antiviral immunity with inflammation control, supporting viral tolerance while preventing tissue damage. Characterization of Egyptian Rousette Bat TIM-3 therefore contributes to research on bat antiviral immunity, immune checkpoint regulation, and host–pathogen interactions, providing insights into mechanisms of immune tolerance and viral persistence in reservoir hosts.