Viral co-infection, autoimmunity, and CSF HIV antibody profiles in HIV central nervous system escape

Antiretroviral therapy (ART) suppresses plasma and cerebrospinal fluid (CSF) HIV replication. Neurosymptomatic (NS) CSF escape is a rare exception in which CNS HIV replication occurs in the setting of neurologic impairment. The origins of NS escape are not fully understood. We performed a case-control study of asymptomatic (AS) escape and NS escape subjects with HIV-negative subjects as controls in which we investigated differential immunoreactivity to self-antigens in the CSF of NS escape by employing neuroanatomic CSF immunostaining and massively multiplexed self-antigen serology (PhIP-Seq). Additionally, we utilized pan-viral serology (VirScan) to deeply profile the CSF anti-viral antibody response and metagenomic next-generation sequencing (mNGS) for pathogen detection. We detected Epstein-Barr virus (EBV) DNA more frequently in the CSF of NS escape subjects than in AS escape subjects. Based on immunostaining and PhIP-Seq, there was evidence for increased immunoreactivity against self-antigens in NS escape CSF. Finally, VirScan revealed several immunodominant epitopes that map to the HIV envelope and gag proteins in the CSF of AS and NS escape subjects. Whether these additional inflammatory markers are byproducts of an HIV-driven process or whether they independently contribute to the neuropathogenesis of NS escape will require further study.

Cerebrospinal fluid abacavir concentrations in HIV-positive patients following once-daily administration

Abacavir is a widely used nucleotide reverse transcriptase inhibitor, for which cerebrospinal fluid (CSF) exposure has been previously assessed in twice-daily recipients. We studied abacavir CSF concentrations in 61 and nine HIV-positive patients taking abacavir once daily and twice daily, respectively. Patients on once-daily abacavir had higher plasma and CSF concentrations (96 vs. 22 ng ml^-1 , P = 0.038 and 123 vs. 49 ng ml^-1 , P = 0.038) but similar CSF-to-plasma ratios (0.8 vs. 0.5, P = 0.500). CSF abacavir concentrations were adequate in patients receiving once-daily treatment.

Biomarkers of HIV-1 CNS infection and injury

While it is clear that HIV-1 can cause CNS dysfunction, current approaches to classification and diagnosis of this dysfunction rely on syndromic definitions or measures of abnormality on neuropsychological testing in the background context of HIV-1 infection. These definitions have been variably applied, offer only limited sensitivity or specificity, and do not easily distinguish active from static brain injury. Supplanting or augmenting these approaches with objective biologic measurements related to underlying disease processes would provide a major advance in classification, diagnosis, epidemiology, and treatment assessment. Two major avenues are now actively pursued to this end: 1) analysis of soluble molecular markers in CSF and, to a lesser degree, in blood, and 2) neuroimaging markers using anatomic, metabolic, and functional measurements. This review considers the rationale and prospects of these approaches.

Updated research nosology for HIV-associated neurocognitive disorders

In 1991, the AIDS Task Force of the American Academy of Neurology published nomenclature and research case definitions to guide the diagnosis of neurologic manifestations of HIV-1 infection. Now, 16 years later, the National Institute of Mental Health and the National Institute of Neurological Diseases and Stroke have charged a working group to critically review the adequacy and utility of these definitional criteria and to identify aspects that require updating. This report represents a majority view, and unanimity was not reached on all points. It reviews our collective experience with HIV-associated neurocognitive disorders (HAND), particularly since the advent of highly active antiretroviral treatment, and their definitional criteria; discusses the impact of comorbidities; and suggests inclusion of the term asymptomatic neurocognitive impairment to categorize individuals with subclinical impairment. An algorithm is proposed to assist in standardized diagnostic classification of HAND.

Kinetics of HIV-1 in Cerebrospinal Fluid and Serum After Zidovudine Treatment

Two patients with HIV-1 infection associated with neurological complications were repeatedly followed with cerebrospinal fluid (CSF) and serum analyses before, and 1 to 2.5 years after single zidovudine treatment. Retrospectively, HIV-RNA levels were analyzed with quantitative PCR assay. The number of HIV-RNA copies in CSF was decreased already 1 week after initiation of zidovudine, and continued to decrease during 5 months of follow up, while the serum levels increased during the same period. The difference between HIV levels in CSF and serum compartments following zidovudine treatment indicates that the CSF viral load does not merely reflect blood levels. Single zidovudine treatment did not reduce the viral load in CSF to non-detectable levels but had a better and more long-lasting anti-HIV effect in CSF than in peripheral blood.

Intrathecal immunoactivation in patients with HIV-1 infection is reduced by zidovudine but not by didanosine

The effect of zidovudine and didanosine on the cerebrospinal fluid (CSF) concentrations of neopterin was studied in 12 patients with human immunodeficiency virus type-1 (HIV-1) infection 3-12 months after initiation of antiretroviral therapy. Ten treatment periods on zidovudine and 7 on didanosine were analysed. The CSF concentrations of neopterin decreased by 63% (from 29.6 to 12.9 nmol/l, p < 0.01) during zidovudine but increased by 15% (from 22.6 to 25.9 nmol/l, not significant during didanosine treatment. The CSF monocytic cell count decreased during zidovudine but increased during didanosine treatment. The results suggest that zidovudine but not didanosine reduces intrathecal immunoactivation during HIV-1 infection.