HIV transcription persists in the brain of virally suppressed people with HIV.

HIV persistence in the brain is a barrier to cure, and potentially contributes to HIV-associated neurocognitive disorders. Whether HIV transcription persists in the brain despite viral suppression with antiretroviral therapy (ART) and is subject to the same blocks to transcription seen in other tissues and blood, is unclear. Here, we quantified the level of HIV transcripts in frontal cortex tissue from virally suppressed or non-virally suppressed people with HIV (PWH). HIV transcriptional profiling of frontal cortex brain tissue (and PBMCs where available) from virally suppressed (n = 11) and non-virally suppressed PWH (n = 13) was performed using digital polymerase chain reaction assays (dPCR). CD68+ myeloid cells or CD3+ T cells expressing HIV p24 protein present in frontal cortex tissue was detected using multiplex immunofluorescence imaging. Frontal cortex brain tissue from PWH had HIV TAR (n = 23/24) and Long-LTR (n = 20/24) transcripts. Completion of HIV transcription was evident in brain tissue from 12/13 non-virally suppressed PWH and from 5/11 virally suppressed PWH, with HIV p24+CD68+ cells detected in these individuals. While a block to proximal elongation was present in frontal cortex tissue from both PWH groups, this block was more extensive in virally suppressed PWH. These findings suggest that the brain is a transcriptionally active HIV reservoir in a subset of virally suppressed PWH.

Correlation between evoked neurotransmitter release and adaptive functions in SYT1-associated neurodevelopmental disorder.

BACKGROUND: Pathogenic missense variants in the essential synaptic vesicle protein synaptotagmin-1 (SYT1) cause a neurodevelopmental disorder characterised by motor delay and intellectual disability, hyperkinetic movement disorder, episodic agitation, and visual impairments. SYT1 is the presynaptic calcium sensor that triggers synchronous neurotransmitter release. We have previously shown that pathogenic variants around the calcium-sensing region of the critical C2B domain decrease synaptic vesicle exocytosis in neurons. METHODS: Here, we have used cultured hippocampal neurons transfected with SYT1-pHluorin to examine how variants within the C2A and C2B domain of SYT1 impact evoked exocytosis. FINDINGS: We show that recently identified variants within the facilitatory C2A domain of the protein (L159R, T196K, E209K, E219Q), as well as additional variants in the C2B domain (M303V, S309P, Y365C, G369D), share an underlying pathogenic mechanism, causing a graded and variant-dependent dominant-negative impairment in exocytosis. We establish that the extent of evoked exocytosis observed in vitro in the presence of SYT1 variants correlates with neurodevelopmental impacts of this disorder. Specifically, the severity of motor and communication impairments exhibited by individuals harbouring these variants correlates with multiple measures of exocytic efficiency. INTERPRETATION: Together, this suggests that there is a genotype-function-phenotype relationship in SYT1-associated neurodevelopmental disorder, centring impaired evoked neurotransmitter release as a common pathogenic driver. Moreover, this points toward a direct link between control of neurotransmitter release and development of adaptive functions, providing a tractable target for therapeutic amelioration. FUNDING: Australian National Health and Medical Research Council, UK Medical Research Council, Great Ormond Street Hospital Children's Charity, University of Melbourne.