Biology subjects

Hultquist, J. F.

Publications and source records attributed to Hultquist, J. F..

At least 19 recordsLinked to original sources

bioRxiv2026

APOBEC3G Splicing Defects in Nonhuman Primate Models Result in Disparate Viral Mutational Profiles Relative to Humans

Nonhuman primates (NHPs), particularly macaques, are indispensable models for studying human infectious diseases due to their close immunological and physiological similarities. Understanding species-specific molecular differences is essential for maximizing the translational value of these models. Here we report that APOBEC3G (A3G), a potent antiviral restriction factor and the major source of genetic variations in HIV, exhibits a widespread mRNA splicing defect in the Cercopithecinae subfamily, which includes the commonly used NHP models. Driven by intronic polymorphisms, this splicing defect substantially reduces A3G protein levels and consequently results in a markedly reduced A3G-mediated mutation signatures, fewer defective viral genomes, and greater viral diversification in SIV compared to HIV. This species-specific effect is not restricted to lentiviruses: reduced A3G signatures have also been reported in simian foamy virus and simian T-cell leukemia virus, suggesting broader effects across primate retroviruses. These findings reveal a lineage-specific alteration in a major antiviral restriction factor, with important implications for viral restriction, evolution, drug resistance, and immune evasion. They also highlight the importance of incorporating naturally occurring genetic variation into NHP model selection to improve the reproducibility, translational fidelity, and biological relevance of preclinical research.

genomics↗

bioRxiv2026

Functional Characterization of RSV Clades Associated with Prophylactic Breakthrough Infections in Pediatric Transmission Clusters

The recent development of new respiratory syncytial virus (RSV) prophylactics for the prevention of severe lower respiratory tract infections in infants and older adults promises in lowering disease burden in these vulnerable populations. However, it remains unclear if periodic breakthrough infections in these populations may drive the emergence of resistant isolates or clades and what factors might contribute to these breakthroughs. In this retrospective cohort study, we performed whole-genome sequencing of RSV isolates from infants and adults during the past two RSV seasons (2023-2025) to assess viral and clinical correlates of nirsevimab breakthrough. RSV infections from nirsevimab breakthrough cases were associated with less severe clinical outcomes in the first, but not second, season after administration. While breakthrough isolates did not share any Fusion glycoprotein mutations in predicted antigenic sites, they largely belonged to only a few circulating clades that were responsible for driving temporally distinct pediatric transmission clusters. To determine if these transmission clusters and breakthrough infections were in part driven by differences in the Fusion proteins of these clades, we compared the relative fusogenicity and neutralization susceptibility of Fusion proteins from contemporary circulating clades. Notably, RSV-A clade A.D.3 exhibited modestly reduced susceptibility to nirsevimab neutralization, though it wasnt associated with any transmission clusters or breakthrough infections. Collectively, these data suggest that clade associations with prophylactic breakthrough are driven by pediatric transmission clusters rather than clade-associated resistance, though continued surveillance will be vital as prophylactic coverage continues to rise.

microbiology↗

bioRxiv2026

A Tissue Virus Microenvironment with Activated Stress Responses Underlies Durable SIV Persistence

HIV persistence during suppressive antiretroviral therapy (ART) remains a central barrier to cure, with the majority of reservoirs residing in gut-associated lymphoid tissues (GALT). Here, we define a spatially organized viral microenvironment (VME) that sustains reservoir durability and governs early viral rebound by comparing animals initiating ART early after infection (transient reservoirs) versus late (persistent reservoirs). Using immunoPET/CT-guided sampling of SIV-infected rhesus macaques combined with spatial transcriptomics, we interrogated tissue sites of viral production during the eclipse phase following analytical treatment interruption (ATI). Our results revealed that viral rebound from persistent reservoirs arises from discrete, transcriptionally active foci enriched in the mucosa lining the gut lumen. Eclipse phase persistent reservoirs were characterized by increased proviral burden and a distinct tissue state marked by activation of stress-response, metabolic, mitochondrial, and cell cycle programs coupled to repression of cytoplasmic translation and increased cellular senescence. These features co-occurred with immunosuppressive cellular architectures resembling tertiary lymphoid structures enriched for Treg cells, innate lymphoid cells, and mast cells, regulated by Treg-centered cell-cell interaction networks. In contrast, transient reservoirs displayed enhanced translational and metabolic activity and were embedded within immune-active environments enriched for CD8 T cells, Th17, Tfh, and activated CD4 T cells. Machine learning identified stress adaptation, hypoxia, metabolic rewiring, and cytoskeletal remodeling pathways as dominant predictors of viral density within persistent VMEs, with strong convergence on programs observed in tumor microenvironments (TME). Orthogonal validation confirmed activation of the integrated stress response (ISR) at sites of viral production in concurrence with results of immunofluorescent microscopy revealing SIV gag expression in two populations primarily in the mucosa, differentiated by the phosphorylation of eIF2. Together, these findings establish the VME as a critical determinant of reservoir persistence, integrating immune regulation, tissue remodeling, and translational control to enable viral survival. This framework suggests that effective HIV cure strategies will require coordinated disruption of VME-supportive functions in addition to targeting infected cells.

microbiology↗

bioRxiv2025

Impact of N6-methyladenosine (m6A) machinery on HIV-1 replication in primary CD4+ T cells

N6-methyladenosine (m6A) is the most prevalent internal modification of cellular and viral RNA and is critical to the regulation of its localization, stability, and translation. Previous studies on the role of m6A during HIV-1 replication have produced conflicting results. Since m6A function can vary dramatically by cell type and state, here we aimed to clarify the role of the m6A machinery during HIV-1 replication in primary CD4+ T cells. Using CRISPR-Cas9 we targeted 46 cellular genes implicated in m6A or 5-methylcytosine (m5C) regulation and measured subsequent HIV-1 replication in primary CD4+ T cells. Only knockout of the m6A writer complex auxiliary proteins VIRMA and WTAP, and the m6A reader YTHDF2 were validated as significantly decreasing HIV-1 replication. In contrast, knockout of METTL3 or METTL14, which form the catalytic core of the writer complex, resulted in only marginal changes in HIV-1 infection, despite significant decreases in total cellular m6A levels. Chemical inhibition of METTL3 led to a dose-dependent decrease in HIV-1 infection, coupled with an increase in protein levels of METTL3 and other writer complex members. Expression of writer proteins was also co-dependent, revealing complex regulatory feedback mechanisms. Overall, these results clarify the role of epitranscriptomic machinery during HIV-1 replication in primary CD4+ T cells and suggest regulation by auxiliary members of the m6A writer complex is more influential than the function of the catalytic core itself on HIV-1 infection in primary CD4+ T cells. IMPORTANCEm6A is the most common chemical modification on cellular and viral RNA and regulates its stability, localization, and translation. m6A modification and its regulation varies dramatically between cell types and cell states. In this study, we investigated the role of m6A factors during HIV-1 infection of physiologically relevant primary CD4+ T cells. Using CRISPR-Cas9 to knockout 46 cellular genes implicated in RNA modification, we found only the m6A writer complex auxiliary members WTAP and VIRMA, and the reader YTHDF2, significantly affected HIV-1 replication in these cells. In contrast, knockout of METTL3 or METTL14, which form the catalytic core of the writer complex, resulted in marginal changes in HIV-1 infection, despite larger reductions in total cellular m6A levels. Our findings suggest regulation by auxiliary members of the m6A writer complex is more influential than the function of the catalytic core itself on HIV-1 infection in primary CD4+ T cells.

microbiology↗

bioRxiv2025

Paracrine Signals from HIV-1 Infected Immune Cells Reprogram Cervical Cancer Pathways

Persistent infection with human papillomavirus (HPV) is the primary cause of cervical cancer worldwide. Notably, women co-infected with HPV and human immunodeficiency virus type 1 (HIV-1) have a six-fold higher lifetime risk of developing cervical cancer compared to those without HIV, even when adhering to antiretroviral therapy (ART) and achieving T-cell reconstitution. While chronic HIV-1 infection is known to cause inflammation, how paracrine signals from immune cells alter signaling in cervical cells remain poorly understood. To address this, we conducted global transcriptomics analysis on cervical swabs from Kenyan women with HPV, stratified by HIV-1 and cancer status. Strikingly, women with HIV-1 showed cancer-like gene expression patterns in non-cancerous cervical epithelial cells. Complementary global mass spectrometry (MS) proteomics of cervical cells exposed to the secretome of HIV-1 infected primary CD4+ T-cells revealed altered expression of proteins in MAPK, PI3K-AKT, and {beta}-catenin signaling pathways. Integrative network analyses of transcriptomic and proteomic datasets revealed that HIV-1 altered gene expression in key pathways known to drive cervical cancer, including genes commonly mutated in HIV-1-naive disease. Notably, IRS-1, a key PI3K-AKT pathway activator, was found to be consistently upregulated in both participant samples and cell culture models, as were interferon-stimulated genes. Phosphoproteomics MS analysis confirmed PI3K-AKT pathway activation in cervical cells exposed to conditioned media from HIV-1-infected T-cells. Together, our findings uncover how HIV-1 reshapes cervical cell signaling via paracrine mechanisms and highlights the PI3K pathway as a potential therapeutic target in HIV-associated cervical cancer.

cancer biology↗

bioRxiv2025

CPSF6 Promotes HIV-1 Preintegration Complex Function

Cleavage and polyadenylation specificity factor 6 (CPSF6) is part of the cellular cleavage factor I mammalian (CFIm) complex that regulates mRNA processing and polyadenylation. CPSF6 also functions as a HIV-1 capsid (CA) binding host factor and promotes viral DNA integration targeting into gene dense regions of the host genome. However, the effects of CPSF6 on the activity of the HIV-1 preintegration complex (PIC) - the machinery that carries out viral DNA integration to establish infection - is unknown. To study CPSF6s role in HIV-1 PIC function, we extracted PICs from cells depleted of CPSF6 or expressing a CPSF6 mutant that cannot bind to CA. These PICs exhibited significantly lower integration activity when compared to the control PICs. Addition of recombinant CPSF6 restored the integration activity of PICs extracted from the mutant cells, suggesting a direct role of CPSF6 in PIC function. To solidify CPSF6s effect on PIC function, we inoculated CPSF6-depleted and CPSF6-mutant cells with HIV-1 particles and measured viral DNA integration into the host genome. A significant reduction in viral integration in these cells was detected and this defect was not a consequence of reduced reverse transcription or nuclear entry. Additionally, mutant viruses deficient in CA-CPSF6 binding showed no integration defect in CPSF6 mutant cells. Finally, sequencing analysis revealed that HIV-1 integration in the CPSF6 mutant cells was significantly redirected from the gene dense regions of the host genome. Collectively, these results suggest that CPSF6-CA interaction regulates PIC function both in vitro and in infected cells. IMPORTANCEHIV-1 infection is dependent on the interaction of the virus with host factors. However, the molecular details of virus-host factor interactions are not fully understood. For instance, HIV-1 capsid provides binding interfaces for several host factors. CPSF6 is one such capsid-binding host factor, whose cellular function is to regulate mRNA processing and polyadenylation. Initial work identified a truncated cytosolic form of CPSF6 that restricted HIV infection by blocking viral nuclear entry. However, it is now established that the full-length CPSF6 primarily promotes integration targeting into gene dense regions of the host genome. Here we report that CPSF6-CA interaction promotes the activity of HIV-1 preintegration complexes (PICs). We also observed that disruption of CPSF6-CA binding in target cells significantly reduced viral integration and directed integration targeting away from gene-dense regions. These findings demonstrate a critical role for the CPSF6-CA interaction in PIC function and integration targeting.

biochemistry↗

bioRxiv2025

Structure-based discovery of highly bioavailable, covalent, broad-spectrum coronavirus-MPro inhibitors with potent in vivo efficacy

The main protease (MPro) of SARS-CoV-2 is crucial for viral replication and is the target of nirmatrelvir (the active ingredient of Paxlovid) and ensitrelvir. The identification of new agents with differentiated pharmacokinetic and drug resistance profiles will increase therapeutic options for COVID-19 patients and bolster pandemic preparedness generally. Starting with a lead-like dihydrouracil chemotype from a large-library docking campaign, we improved MPro inhibition >1,000-fold by engaging additional sub-sites in the MPro active site, most notably by employing a latent propargyl electrophile to engage the catalytic Cys145. Advanced leads from this series, including AVI-4516 and AVI-4773 show pan-coronavirus antiviral activity in cells, very low clearance in mice, and for AVI-4773 a rapid reduction in viral titers more than a million-fold after just three doses, more rapidly and effectively than the approved drugs, nirmatrelvir and ensitrelvir. Both AVI-4516 and AVI-4773 are well distributed in mouse tissues, including brain, where concentrations ten or fifteen-thousand times the EC90, respectively, are observed eight hours after an oral dose. As exemplar of the series, AVI-4516 shows minimal inhibition of major CYP isoforms and human cysteine and serine proteases, likely due to its latent-electrophilic warhead. AVI-4516 also exhibits synergy in cellular infection models in combination with the RdRp inhibitor molnupiravir, while related analogs strongly inhibit nirmatrelvir-resistant MPro mutant virus in cells. The in vivo and antiviral properties of this new chemotype are differentiated from existing clinical and pre-clinical MPro inhibitors, and will advance new therapeutic development against emerging SARS-CoV-2 variants and other coronaviruses. One sentence summaryThis manuscript describes the discovery of a new class of potent inhibitors of the SARS-CoV-2 major proteases (MPro) with a unique mechanism of inhibition, pan coronaviral activity in cellulo, exquisite selectivity vs. the human proteome, and exceptional in vivo efficacy in SARS-CoV-2 infection models that surpasses that of currently approved agents.

biochemistry↗

bioRxiv2024

Release of P-TEFb from the Super Elongation Complex promotes HIV-1 latency reversal

The persistence of HIV-1 in long-lived latent reservoirs during suppressive antiretroviral therapy (ART) remains one of the principal barriers to a functional cure. Blocks to transcriptional elongation play a central role in maintaining the latent state, and several latency reversal strategies focus on the release of positive transcription elongation factor b (P-TEFb) from sequestration by negative regulatory complexes, such as the 7SK complex and BRD4. Another major cellular reservoir of P-TEFb is in Super Elongation Complexes (SECs), which play broad regulatory roles in host gene expression. Still, it is unknown if the release of P-TEFb from SECs is a viable latency reversal strategy. Here, we demonstrate that the SEC is not required for HIV-1 replication in primary CD4+ T cells and that a small molecular inhibitor of the P-TEFb/SEC interaction (termed KL-2) increases viral transcription. KL-2 acts synergistically with other latency reversing agents (LRAs) to reactivate viral transcription in several cell line models of latency in a manner that is, at least in part, dependent on the viral Tat protein. Finally, we demonstrate that KL-2 enhances viral reactivation in peripheral blood mononuclear cells (PBMCs) from people living with HIV on suppressive ART, most notably in combination with inhibitor of apoptosis protein antagonists (IAPi). Taken together, these results suggest that the release of P-TEFb from cellular SECs may be a novel route for HIV-1 latency reactivation. AUTHOR SUMMARYSince the start of the HIV pandemic, it is estimated that nearly 86 million people have been infected with the virus, and about 40 million people have died. Modern antiretroviral therapies potently restrict viral replication and prevent the onset of AIDS, saving millions of lives. However, these therapies are not curative due to the persistence of the virus in a silenced or latent state in long-lived cells of the body. One proposed strategy to clear this latent reservoir, termed "shock and kill", is to activate these silenced viruses such that the infected cells can be cleared from the body by the immune system. While several drugs have been developed that can activate latent viruses, none have proven effective at reducing the size of the latent reservoir in patients in clinical trials. Here, we describe a new method for latency reactivation using a small molecule inhibitor of a human protein complex called the Super Elongation Complex (SEC). Inhibiting the SEC enhances viral transcription during active infection and triggers the reactivation of latent viruses, especially when in combination with other latency reversing agents. These results pave the way for developing more effective strategies to reactivate latent viruses towards a functional cure.

microbiology↗

bioRxiv2023

A distinctive evolution of alveolar T cell responses is associated with clinical outcomes in unvaccinated patients with SARS-CoV-2 pneumonia

Pathogen clearance and resolution of inflammation in patients with pneumonia require an effective local T cell response. Nevertheless, local T cell activation may drive lung injury, particularly during prolonged episodes of respiratory failure characteristic of severe SARS-CoV-2 pneumonia. While T cell responses in the peripheral blood are well described, the evolution of T cell phenotypes and molecular signatures in the distal lung of patients with severe pneumonia caused by SARS-CoV-2 or other pathogens is understudied. Accordingly, we serially obtained 432 bronchoalveolar lavage fluid samples from 273 patients with severe pneumonia and respiratory failure, including 74 unvaccinated patients with COVID-19, and performed flow cytometry, transcriptional, and T cell receptor profiling on sorted CD8+ and CD4+ T cell subsets. In patients with COVID-19 but not pneumonia secondary to other pathogens, we found that early and persistent enrichment in CD8+ and CD4+ T cell subsets correlated with survival to hospital discharge. Activation of interferon signaling pathways early after intubation for COVID-19 was associated with favorable outcomes, while activation of NF-{kappa}B-driven programs late in disease was associated with poor outcomes. Patients with SARS-CoV-2 pneumonia whose alveolar T cells preferentially targeted the Spike and Nucleocapsid proteins tended to experience more favorable outcomes than patients whose T cells predominantly targeted the ORF1ab polyprotein complex. These results suggest that in patients with severe SARS-CoV-2 pneumonia, alveolar T cell interferon responses targeting structural SARS-CoV-2 proteins characterize patients who recover, yet these responses progress to NF-{kappa}B activation against non-structural proteins in patients who go on to experience poor clinical outcomes.

systems biology↗

bioRxiv2023

Exploiting rodent cell blocks for intrinsic resistance to HIV-1 gene expression in human T cells

HIV-1 virion production is inefficient in cells derived from mice and other rodents reflecting cell-intrinsic defects to interactions between the HIV-1 auxiliary proteins Tat and Rev and host dependency factors CCNT1 (Cyclin T1) and XPO1 (Exportin-1, also known as CRM1), respectively. In human cells, Tat binds CCNT1 to enhance viral RNA transcription and Rev recruits XPO1 to mediate the nuclear export of intron-containing viral RNA. In mouse cells, Tats interactions with CCNT1 are inefficient, mapped to a single species-specific residue Y261 instead of C261 in human. Rev interacts poorly with murine XPO1, mapped to a trio of amino acids T411/V412/S414 instead of P411/M412/F414 in humans. To determine if these discrete species-specific regions of otherwise conserved housekeeping proteins represent viable targets for inhibiting Tat and Rev function in humans, herein we recoded ("mousified") each in human CD4+ T cells using precision CRISPR/Cas9-facilitated gene editing. Both edits yielded cells refractory to Rev or Tat activity, respectively, with isolated, isogenic CCNT1.C261Y cell lines remarkable in their capacity to exhibit near total inactivation of viral gene expression for all X4 and R5-tropic HIV-1 strains tested, and even the more distantly related lentiviruses including HIV-2 and SIVagm. These studies validate minor and naturally-occurring, species-specific differences in otherwise conserved human host factors as compelling targets for achieving broad-acting cell-intrinsic resistance to HIVs post-integration phases. ImportanceUnlike humans, mice are unable to support HIV-1 infection. This is due, in part, to a constellation of defined minor, species-specific differences in conserved host proteins needed for viral gene expression. Here, we used precision CRISPR/Cas9 editing to engineer "mousified" versions of two of these proteins, CCNT1 and XPO1, in human T cells. CCNT1 and XPO1 are essential for efficient HIV-1 transcription and viral RNA transport, respectively, making them intriguing targets for gene-based inactivation of virus replication. Targeting either gene yielded antiviral phenotypes, with isogenic CCNT1-modified cell lines confirmed to exhibit potent, durable, and broad-spectrum resistance to HIV-1 and other pathogenic lentiviruses, and with no discernible impact on host cells. These results provide proof of concept for targeting CCNT1 (and potentially XPO1) in the context of one or more functional HIV-1 cure strategies.

microbiology↗

bioRxiv2022

Contribution of 6mer seed toxicity to HIV-1 induced cytopathicity

HIV-1 (HIV) infects CD4 positive T cells, the gradual depletion of which can lead to the onset of Acquired Immunodeficiency Syndrome (AIDS) in the absence of antiretroviral therapy (ART). Several forms of cell death have been shown to be involved in HIV-mediated killing of either directly infected or bystander cells. It is still unknown, however, why some cells survive HIV infection and persist as part of the latently infected reservoir that reliably causes recurrent viremia upon ART cessation. Improved understanding of the mechanisms of HIV-mediated cell death could inform innovations designed to clear the latent reservoir. "Death Induced by Survival gene Elimination" (DISE) is an RNA interference (RNAi)-based mechanism that kills cells through short (s)RNAs with toxic 6mer seeds (pos. 2-7 of sRNA). These toxic seeds target reverse complementary seed matches in the 3UTR of mRNA transcripts to decrease expression of hundreds of genes that are critical for cell survival. In most cells under normal conditions, highly expressed cell-encoded non-toxic microRNAs (miRNAs) block access of toxic sRNAs to the RNA-induced silencing complex (RISC) that mediates RNAi, promoting cell survival. We now report that infection of cells with HIV results in RISC-loading of an HIV-encoded miRNA, v-miRNA HIV-miR-TAR-3p, which kills cells by DISE through a noncanonical (pos. 3-8) 6mer seed. In addition, cellular RISC bound sRNAs shift to lower seed viability. Both these effects also occur with latent HIV provirus reactivation in J-Lat cells, a well-established cell model of HIV latency. Cells lacking expression of miRNA biogenesis genes Drosha, Dicer and Exportin 5 cannot produce protective miRNAs and therefore do not block RISC loading of the v-miRNA HIV-miR-TAR-3p. These mutant cells, as well as cells lacking expression of the RISC component Ago2, are hypersensitive to cell death via DISE induced by HIV infection. More precise targeting of the balance between protective and cytotoxic sRNAs could specifically and transiently increase silencing of cell survival genes to increase DISE. This could be a new addition to a "shock and kill" strategy to enhance depletion of the provirus reservoir during suppressive ART.

microbiology↗

bioRxiv2022

Rab11-FIP1C is dispensable for HIV-1 replication in primary CD4+ T cells but its role is cell-type-dependent in immortalized human T-cell lines

The HIV-1 envelope glycoprotein (Env) contains a long cytoplasmic tail harboring highly conserved motifs that direct Env trafficking and incorporation into virions and promote efficient virus spread. The cellular trafficking factor Rab11a family interacting protein 1C (FIP1C) has been implicated in the directed trafficking of Env to sites of viral assembly. In this study, we confirm that siRNA-mediated depletion of FIP1C in HeLa cells modestly reduces Env incorporation into virions. To determine whether FIP1C is required for Env incorporation and HIV-1 replication in physiologically relevant cells, CRISPR/Cas9 technology was used to knock out the expression of this protein in several human T-cell lines - Jurkat E6.1, SupT1 and H9 - and in primary human CD4+ T cells. FIP1C knock-out caused modest reductions in Env incorporation in SupT1 cells but did not inhibit virus replication in SupT1 or Jurkat E6.1 T-cell lines. In H9 cells, FIP1C knock-out caused a cell-density-dependent defect in virus replication. In primary CD4+ T cells, FIP1C knock-out had no effect on HIV-1 replication. Furthermore, HTLV-I transformed cell lines that are permissive for HIV-1 replication do not express FIP1C. Mutation of an aromatic motif in the Env cytoplasmic tail - Y795W - implicated in FIP1C-mediated Env incorporation impaired virus replication independently of FIP1C expression in SupT1, Jurkat E6.1, H9, and primary T cells. Together, these results indicate that while FIP1C may contribute to HIV-1 Env incorporation in some contexts, additional and potentially redundant host factors are likely required for Env incorporation and virus dissemination in T cells. ImportanceThe incorporation of the HIV-1 envelope (Env) glycoproteins, gp120 and gp41, into virus particles is critical for virus infectivity. Gp41 contains a long cytoplasmic tail that has been proposed to interact with host cell factors, including the trafficking factor Rab11a family interacting protein 1C (FIP1C). To investigate the role of FIP1C in relevant cell types - human T-cell lines and primary CD4+ T cells - we used CRISPR/Cas9 to knock out FIP1C expression and examined the effect on HIV-1 Env incorporation and virus replication. We observed that in two of the T-cell lines examined (Jurkat E6.1 and SupT1) and in primary CD4+ T cells, FIP1C knockout did not disrupt HIV-1 replication, whereas FIP1C knockout reduced Env expression and delayed replication in H9 cells. The results indicate that while FIP1C may contribute to Env incorporation in some cell lines, it is not an essential factor for efficient HIV-1 replication in primary CD4+ T cells.

microbiology↗

bioRxiv2022

Bioengineering multifunctional extracellular vesicles for targeted delivery of biologics to T cells

Genetically modifying T cells can enable applications ranging from cancer immunotherapy to HIV treatment, yet delivery of T cell-targeted therapeutics remains challenging. Extracellular vesicles (EVs) are nanoscale particles secreted by all cells that naturally encapsulate and transfer proteins and nucleic acids, making them an attractive and clinically-relevant platform for engineering biocompatible delivery vehicles. We report a suite of technologies for genetically engineering cells to produce multifunctional EV vehicles--without employing chemical modifications that complicate biomanufacturing. We display high affinity targeting domains on the EV surface to achieve specific, efficient binding to T cells, identify a protein tag to confer active cargo loading into EVs, and display fusogenic glycoproteins to increase EV uptake and fusion with recipient cells. We demonstrate integration of these technologies by delivering Cas9-sgRNA complexes to edit primary human T cells. These approaches could enable targeting vesicles to a range of cells for the efficient delivery of cargo.

bioengineering↗

bioRxiv2022

Blockade of TGF-β signaling reactivates HIV-1/SIV reservoirs and immune responses in vivo

Elevated levels of TGF-{beta}, a potent immunosuppressive factor, are present in HIV-1 infected individuals even after years of antiretroviral therapy (ART). TGF-{beta} plays a critical role in maintaining immune cells in a resting state by inhibiting cell activation and proliferation. Resting HIV-1 target cells represent one of the main cellular reservoirs after long term ART and the low inducibility of the latent provirus constitutes one of the major obstacles to "kick and kill" cure strategies. We hypothesized that releasing cells from TGF-{beta}-driven signaling would promote latency reversal. To test our hypothesis, we compared ex vivo models of HIV-1 latency reactivation with and without TGF-{beta} and a TGF-{beta} type 1 receptor (TGFBR1) inhibitor, galunisertib. We also tested the effect of galunisertib in SIV infected, ART treated macaques by monitoring SIV envelope (env) protein expression via PET/CT using the Cu64-anti gp120 Fab (7D3) probe, along with plasma and tissue viral loads (VL). Exogenous TGF-1{beta} reduced HIV-1 reactivation in U1 and ACH2 latency models. Galunisertib increased HIV-1 latency reversal both in ex vivo models and in PBMC from HIV-1 infected, cART treated aviremic donors. In vivo, oral galunisertib promoted increased SIV env protein total standardized uptake values (SUVtot) in PET/CT images of tissues (gut and lymph nodes) of 5 out of 7 aviremic, long-term ART-treated, SIV-infected, macaques. This increase correlated with an increase in SIV RNA in gut tissue. Two out of 7 animals also exhibited increases in plasma viral load. Higher anti-SIV T cell responses and anti-SIV env antibody titers were detected after galunisertib treatment in most animals. In summary, our data suggest that blocking TGF-{beta} signaling simultaneously increases retroviral reactivation events and enhances anti-SIV immune responses.

immunology↗

bioRxiv2022

An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques

The systemic nature of SARS-CoV-2 infection is highly recognized, but poorly characterized. A non-invasive and unbiased method is needed to clarify whole body spatiotemporal dynamics of SARS-CoV-2 infection after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of three rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we track the 64Cu-labelled CR3022-F(ab)2 probe targeting the spike protein of SARS-CoV-2 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Using this method, we uncovered differences in lung pathology between infection with the WA1 isolate and the delta variant, which were readily corroborated through computed tomography scans. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites. Graphic AbstractPET/CT detected SARS-CoV-2 infection of 4 different tissues in the male genital tract illuminates the cause of COVID-19 clinical sequalae of male sexual health and fertility O_FIG O_LINKSMALLFIG WIDTH=189 HEIGHT=200 SRC="FIGDIR/small/481974v2_ufig1.gif" ALT="Figure 1"> View larger version (74K): org.highwire.dtl.DTLVardef@188c53aorg.highwire.dtl.DTLVardef@4c639forg.highwire.dtl.DTLVardef@120799forg.highwire.dtl.DTLVardef@110edb1_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Diagram shows schematic illustration of the male genital tract of the rhesus macaque. Virus icon shows sites of SARS-CoV-2 PET signal. Text highlighting the clinical sequalae associated with each sight of infection is shown in text adjacent to each infection site. C_FIG

immunology↗

bioRxiv2022

Type I IFN promotes pathogenic inflammatory monocyte maturation during H5N1 infection

Ly6Chi inflammatory monocytes show high IFN responses, and contribute to both protective and pathogenic functions following influenza virus infection. In order to understand the significance of IFN responses in this subset, we examined monocytes during infection with a lethal H5N1 virus that induces high levels of IFN and a low-pathogenicity H1N1 virus that induces low levels of IFN. We show that H5N1 infection results in early recruitment of high numbers of Ly6Chi monocytes and induction of chemokines and Ifnb1. Using unbiased transcriptomic and proteomic approaches, we also find that monocytes are significantly enriched during H5N1 infection and are associated with chemokine and IFN signatures in mice, and with severity of symptoms after influenza virus infection in humans. Recruited Ly6Chi monocytes subsequently become infected in the lung, produce IFN-{beta}, and mature into FasL+ monocyte-derived cells (FasL+MCs) expressing dendritic cell markers. Both Ccr2-/- and Faslgld mice are protected from lethal infection, indicating that monocytes contribute to pathogenesis. Global loss of type I and type III IFN signaling in Stat2-/- mice results in loss of monocyte recruitment, likely reflecting a requirement for IFN-dependent chemokine induction. Here we show that IFN is not directly required for monocyte recruitment on an IFN-sufficient background, but is required for maturation to FasL+MCs. Loss of IFN signaling skews to a Ly6Clo phenotype associated with tissue repair, suggesting that IFN signaling in monocytes is a critical determinant of influenza virus pathogenesis.

immunology↗

bioRxiv2022

Recognition of HIV-1 capsid licenses innate immune response to viral infection

Cyclic GMP-AMP synthase (cGAS) is a primary sensor of aberrant DNA that governs an innate immune signaling cascade, leading to the induction of the type-I interferon response. We have previously identified polyglutamine binding protein 1, PQBP1, as an adaptor molecule required for cGAS-mediated innate immune response of lentiviruses, including the human immunodeficiency virus 1 (HIV-1), but dispensable for the recognition of DNA viruses. HIV-1- encoded DNA is synthesized as a single copy from its RNA genome, and is subsequently integrated into the host chromatin. HIV-1 then produces progeny through amplification and packaging of its RNA genome, thus, in contrast to DNA viruses, HIV-1 DNA is both transient and of low abundance. However, the molecular basis for the detection and verification of this low abundance HIV-1 DNA pathogen-associated molecular pattern (PAMP) is not understood. Here, we elucidate a two-factor authentication strategy that is employed by the innate immune surveillance machinery to selectively respond to the low concentration of PAMP, while discerning these species from extranuclear DNA molecules. We find that, upon HIV-1 infection, PQBP1 decorates intact viral capsid, which serves as a primary verification step for the viral nucleic acid cargo. As the reverse transcription and capsid disassembly initiate, cGAS protein is then recruited to the capsid in a PQBP1-dependent manner, enabling cGAS molecules to be co-positioned at the site of PAMP generation. Thus, these data indicate that PQBP1 recognition of the HIV-1 capsid sanctions a robust cGAS-dependent response to a limited abundance and short-lived DNA PAMP. Critically, this illuminates a molecular strategy wherein the modular recruitment of co-factors to germline encoded pattern recognition receptors (PRRs) serves to enhance repertoire of pathogens that can be sensed by the innate immune surveillance machinery.

molecular biology↗

bioRxiv2021

ICER controls HIV-1 infection and replication in elite controllers

A rare subset of HIV-infected individuals, termed elite controllers (ECs), can maintain long-term control over HIV replication in the absence of antiretroviral therapy (ART). To elucidate the biological mechanism of resistance to HIV replication at the molecular and cellular levels, we performed RNA sequencing and identified alternative splicing variants from ECs, HIV-infected individuals undergoing ART, ART-naive HIV-infected individuals, and healthy controls. Differential gene expression patterns that are specific to ECs and may influence HIV resistance were identified, including alternative RNA splicing and exon usage variants of the CREM/ICER gene (cAMP-responsive element modulator/inducible cAMP early repressors). The knockout and knockdown of specific ICER exons that were found to be upregulated in ECs resulted in significantly increased HIV infection in CD4+ T cell line and primary CD4+ T cells. Overexpression of ICER isoforms decreased HIV infection in primary CD4+ T cells. Furthermore, ICER regulated HIV-1 LTR promoter activity in a Tat-dependent manner. Together, these results suggest that ICER is an HIV host factor that may contribute to HIV resistance of ECs. These findings will help elucidate the mechanisms of HIV control by ECs and may yield a new approach for treatment of HIV.

immunology↗