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. Author manuscript; available in PMC: 2014 Apr 17.
Published in final edited form as: Cell Host Microbe. 2013 Apr 17;13(4):379–393. doi: 10.1016/j.chom.2013.03.010

Figure 2. Virus entry routes into the CNS.

Figure 2

(A) Alpha herpesviruses (e.g. HSV-1, VZV, PRV) infect pseudounipolar sensory neurons of PNS ganglia. CNS spread is rare and requires anterograde axonal transport of progeny virions toward the spinal cord. (B) RABV and poliovirus spread via neuromuscular junctions (NMJ) from muscles into somatic motor neurons in the spinal cord. (C) Several viruses may infect receptor neurons in the nasal olfactory epithelium. Spread to the CNS requires anterograde axonal transport along the olfactory nerve into the brain. (D) Infiltration through the blood-brain barrier (BBB). The BBB is composed of brain microvascular endothelium cells (BMVEC) with specialized tight junctions, surrounding basement membrane, pericytes, astrocytes, and neurons. Infected leukocytes can traverse this barrier carrying virus into the brain parenchyma. (E) Alternatively, virus particles in the bloodstream can infect BMVECs, compromising the BBB.