14-3-3 Protein in CSF: An early predictor of SIV CNS disease

In neurons, 14-3-3 proteins regulate diverse processes, including signal transduction, neurotransmitter production, and apoptosis by binding to target proteins, but the role 14-3-3 proteins play in the pathogenesis of central nervous system (CNS) disease remains unclear. To examine the relationship between presence of 14-3-3 protein in cerebrospinal fluid (CSF) and encephalitis in the SIV/macaque model of HIV CNS disease, CSF levels of 14-3-3 protein were measured by quantitative immunoblotting throughout infection in 6 SIV-infected pigtailed macaques. Beginning during asymptomatic infection and continuing until death, CSF levels of 14-3-3 were elevated in 4 of 6 SIV-infected animals. Animals with 14-3-3 protein in CSF had the highest viral loads in the CSF after acute infection and the highest levels of both viral RNA and protein in brain (p < 0.001). In contrast, the presence of 14-3-3 protein in CSF was not associated with CNS microglial/macrophage activation measured by quantitative immunohistochemical staining for CD68 (p = 0.13). CSF levels of 14-3-3 protein may be a valuable marker of early neuronal damage, CNS viral replication, and CNS disease progression in HIV-infected individuals.