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Chaillon, A.

Publications and source records attributed to Chaillon, A..

4 recordsLinked to original sources
bioRxiv2026

Deconvolution of HIV-1 Mutational Signatures Reveals Dominant and Donor-Specific APOBEC3-Associated Mutagenesis Across Anatomical Compartments

HIV-1 persists across multiple anatomical compartments, yet the mutational processes shaping viral diversity within these reservoirs remain incompletely understood. We investigated HIV-1 mutational signatures across blood, spleen, gut, and brain tissues from 21 people with HIV enrolled in the Last Gift rapid autopsy program. Mutations in single-genome HIV-1 env DNA sequences were quantified by trinucleotide context and deconvolved using non-negative matrix factorization. Two APOBEC3-associated signatures were resolved and together accounted for approximately 50% of all mutations; this contribution remained stable after normalization by the number of potential APOBEC3 target sites. Normalization further revealed a minor signature consistent with methylation-induced cytosine deamination. Mutational patterns were driven primarily by donor identity rather than anatomical compartment. Identical APOBEC3-hypermutated sequences were recovered across brain, gut, and blood, consistent with clonal expansion and trafficking of infected cells. These findings establish APOBEC3 activity as a major contributor to HIV-1 mutagenesis across tissue reservoirs and demonstrate that APOBEC3-associated mutagenesis is strongly donor-specific.

genomics↗
bioRxiv2026

A naturally occurring Tat R52W variant in brain-derived HIV attenuates transcription and may contribute to reservoir persistence

HIV-1 persistence under suppressive antiretroviral therapy (ART) remains a major barrier to eradication, yet the contribution of naturally occurring viral variation to transcriptional regulation is incompletely understood. Here, we identify an HIV-1 Tat variant (R52W) that attenuates viral transcription through the disruption of the Tat-TAR RNA interaction. Full-length HIV-1 genomes derived from the brain microglia of a Last Gift donor, together with peripheral viral sequences obtained during suppressive ART, revealed the presence of the R52W variant in vivo. The same R52W variant was found in another virally suppressed donor within the same cohort. Additional analysis of 3,440 clinical blood isolates from people with HIV identified R52W in 73 sequences (2.12%) of individuals, including three on ART and a therapy controller, and across diverse viral subtypes. Structural modeling demonstrated that R52W destabilizes Tat-TAR binding, while functional assays showed markedly reduced Tat-mediated transcriptional activity, which was restored upon tryptophan-to-arginine reversion (W52R) in Tat. These findings establish a direct molecular mechanism by which a naturally occurring HIV-1 variant modulates viral transcriptional output. Together, our results identify transcriptionally attenuated HIV-1 variants in treated individuals and suggest that modulation of Tat-dependent transcription may represent an underappreciated determinant of viral persistence under suppressive ART.

microbiology↗
bioRxiv2026

SPP1+ Microglia Are Associated with Neuroimmune Rewiring and Glutamatergic Neuronal Injury in ART-Suppressed People Living with HIV

Abstract Antiretroviral therapy (ART) effectively suppresses systemic HIV replication but does not eradicate viral reservoirs in the brain, where their identity and contribution to neurological injury remain poorly defined. Using bulk, single-cell, and single-nucleus transcriptomics of postmortem human brain tissue, we identify an activated SPP1 microglial population that expands 5.8-fold during ART and serves as the primary central nervous system (CNS) reservoir, preferentially harboring HIV transcripts. These reservoir microglia adopt a distinct, immune-evasive reprogramming state marked by chronic type I interferon signaling and inflammasome activation, which we recapitulate in primary human microglia via prolonged interferon-{beta} exposure. We show that viral transcription in ART-suppressed brains is dominated by nef, which may sustain the viral reservoir by disrupting host HLA-A and HLA-E presentation machinery. This persistent, immune-evasive state is associated with TREM2-C1QC complement-mediated synaptic pruning and severe DNA damage response dysregulation, culminating in a profound loss of VGLUT1 and GAD67 glutamatergic neurons that persists despite viral suppression. Our findings establish SPP1 microglia as an active, pathogenic CNS reservoir, identifying the SPP1, MHC-I, and complement pathways as therapeutic targets to eliminate viral persistence and reverse HIV-associated neurocognitive dysfunction.

neuroscience↗