Background: COVID-19 is caused by the severe acute respiratory syndrome virus SARS-CoV-2. It is widely recognized as a respiratory pathogen, but neurologic complications can be the presenting manifestation in a subset of infected patients. Case presentation: We describe a 78-year old immunocompromised woman who presented with altered mental status after witnessed seizure-like activity at home. She was found to have SARS-CoV-2 infection and associated neuroinflammation. In this case, we undertake the first detailed analysis of cerebrospinal fluid (CSF) cytokines during COVID-19 infection and find a unique pattern of inflammation in CSF, but no evidence of viral neuroinvasion. Conclusion: Our findings suggest that neurologic symptoms such as encephalopathy and seizures may be the initial presentation of COVID-19. Central nervous system inflammation may associate with neurologic manifestations of disease.

COVID-19 patients frequently develop neurological symptoms, but the biological underpinnings of these phenomena are unknown. Through single cell RNA-seq and cytokine analyses of CSF and blood from COVID-19 patients with neurological symptoms, we find compartmentalized, CNS specific T cell activation and B cell responses. All COVID-19 cases had CSF anti-SARS-CoV-2 antibodies whose target epitopes diverged from serum antibodies. In an animal model, we find that intrathecal SARS-CoV-2 antibodies are found only during brain infection, and are not elicited by pulmonary infection. We produced CSF-derived monoclonal antibodies from a COVID-19 patient, and find that these mAbs target both anti-viral and anti-neural antigens—including one mAb that reacted to both spike protein and neural tissue. Overall, CSF IgG from 5/7 patients contains anti-neural reactivity. This immune survey reveals evidence of a compartmentalized immune response in the CNS of COVID-19 patients and suggests a role for autoimmunity in neurologic sequelae of COVID-19.

Understanding HIV-1–host interactions can identify the cellular environment supporting HIV-1 reactivation and mechanisms of clonal expansion. We developed HIV-1 SortSeq to isolate rare HIV-1–infected cells from virally suppressed, HIV-1–infected individuals upon early latency reversal. Single-cell transcriptome analysis of HIV-1 SortSeq+ cells revealed enrichment of nonsense-mediated RNA decay and viral transcription pathways. HIV-1 SortSeq+ cells up-regulated cellular factors that can support HIV-1 transcription (IMPDH1 and JAK1) or promote cellular survival (IL2 and IKBKB). HIV-1–host RNA landscape analysis at the integration site revealed that HIV-1 drives high aberrant host gene transcription downstream, but not upstream, of the integration site through HIV-1–to–host aberrant splicing, in which HIV-1 RNA splices into the host RNA and aberrantly drives host RNA transcription. HIV-1–induced aberrant transcription was driven by the HIV-1 promoter as shown by CRISPR-dCas9–mediated HIV-1–specific activation and could be suppressed by CRISPR-dCas9–mediated inhibition of HIV-1 5′ long terminal repeat. Overall, we identified cellular factors supporting HIV-1 reactivation and HIV-1–driven aberrant host gene transcription as potential therapeutic targets to disrupt HIV-1 persistence.

BackgroundIt is largely unknown how frequently low-abundance HIV drug-resistant variants at levels under limit of detection of conventional genotyping (<20% of quasi-species) are present in antiretroviral-experienced persons experiencing virologic failure. Further, the clinical implications of low-abundance drug-resistant variants at time of virologic failure are unknown.Methodology/Principal FindingsPlasma samples from 22 antiretroviral-experienced subjects collected at time of virologic failure (viral load 1380 to 304,000 copies/mL) were obtained from a specimen bank (from 2004–2007). The prevalence and profile of drug-resistant mutations were determined using Sanger sequencing and ultra-deep pyrosequencing. Genotypes were interpreted using Stanford HIV database algorithm. Antiretroviral treatment histories were obtained by chart review and correlated with drug-resistant mutations. Low-abundance drug-resistant mutations were detected in all 22 subjects by deep sequencing and only in 3 subjects by Sanger sequencing. In total they accounted for 90 of 247 mutations (36%) detected by deep sequencing; the majority of these (95%) were not detected by standard genotyping. A mean of 4 additional mutations per subject were detected by deep sequencing (p<0.0001, 95%CI: 2.85–5.53). The additional low-abundance drug-resistant mutations increased a subject's genotypic resistance to one or more antiretrovirals in 17 of 22 subjects (77%). When correlated with subjects' antiretroviral treatment histories, the additional low-abundance drug-resistant mutations correlated with the failing antiretroviral drugs in 21% subjects and correlated with historical antiretroviral use in 79% subjects (OR, 13.73; 95% CI, 2.5–74.3, p = 0.0016).Conclusions/SignificanceLow-abundance HIV drug-resistant mutations in antiretroviral-experienced subjects at time of virologic failure can increase a subject's overall burden of resistance, yet commonly go unrecognized by conventional genotyping. The majority of unrecognized resistant mutations correlate with historical antiretroviral use. Ultra-deep sequencing can provide important historical resistance information for clinicians when planning subsequent antiretroviral regimens for highly treatment-experienced patients, particularly when their prior treatment histories and longitudinal genotypes are not available.

Central nervous system (CNS) immune activation is an important driver of neuronal injury during several neurodegenerative and neuroinflammatory diseases. During HIV infection, CNS immune activation is associated with high rates of neurocognitive impairment, even during sustained long-term suppressive antiretroviral therapy (ART). However, the cellular subsets that drive immune activation and neuronal damage in the CNS during HIV infection and other neurological conditions remain unknown, in part because CNS cells are difficult to access in living humans. Using single-cell RNA sequencing (scRNA-seq) on cerebrospinal fluid (CSF) and blood from adults with and without HIV, we identified a rare (<5% of cells) subset of myeloid cells that are found only in CSF and that present a gene expression signature that overlaps significantly with neurodegenerative disease-associated microglia. This highlights the power of scRNA-seq of CSF to identify rare CNS immune cell subsets that may perpetuate neuronal injury during HIV infection and other conditions.