Viruses can attack and infect cells in the brain, spinal cord, and nervous system. For example:

• HIV – infects glia (not neurons) especially microglia and astrocytes and can lead to dementia in the central nervous system; infects Schwann cells in the peripheral nervous system
• Polio – infects and kills motor neurons in the spinal cord
• Herpes – infects sensory neurons (Type 1 above the waist, Type 2 below the waist)

(Fields, R. Douglas, PhD. The Other Brain. p 128-132. NY: Simon & Schuster, 2009.)