Transmissible Spongiform Encephalopathies (TSEs) primarily affect which part of animals?

Transmissible Spongiform Encephalopathies (TSEs) are a group of neurodegenerative diseases that primarily target the central nervous system, particularly the brains of infected animals. These diseases are characterized by the accumulation of abnormal prion proteins, which lead to the degeneration of neuronal tissue and cause the characteristic sponge-like appearance in the brain.

Because TSEs affect brain tissue, symptoms typically involve neurological impairments such as changes in behavior, coordination issues, and ultimately death. This highlights the significance of the brain as the main organ impacted by TSEs, distinguishing these diseases from conditions that affect other body parts, like the liver, heart, or lungs, which are not associated with such neurodegenerative processes. Therefore, the correct answer is the brain, as it is the primary site affected by these diseases.