Biology subjects

Vo, T. T.

Publications and source records attributed to Vo, T. T..

4 recordsLinked to original sources

bioRxiv2025

Versatile HIV Rev-dependent reporter cell system for stringent and sensitive quantification of viral reservoirs, neutralizing antibodies, and restriction factors

Detecting and measuring HIV reservoirs, neutralizing antibodies, and restriction factors are important for HIV cure research and the development of new therapeutics and vaccines. Here we describe the development and validation of several HIV Rev-dependent indicator cell lines for these purposes. These reporter cells come from different T-lymphoblast cell lines, including MOLT-4-R5, SupT1-R5, CEM-SS, A3R5, and from the adherent TZM cell platform based on HeLa clone JC53. These cells express CD4, CXCR4, and various levels of CCR5. We compared these cell lines for responsiveness to both X4 and R5-tropic viruses, and confirmed that reporter expression in these cells is not affected by stimulation from mitogens but is responsive to HIV Tat and Rev, reducing non-specific reporter induction from the leaky LTR promoter. To validate the sensitivity of the Rev-dependent reporter cell systems, we conducted a viral dilution assay with three primary HIV-1 clade C swarms from an adult in Malawi. We also validated the systems for quantifying antibody neutralization and screening restriction factors; these systems are also sensitive for viral outgrowth assays for quantifying viral reservoirs in clinical and basic research settings. Given that the systems can measure HIV accurately in complex environments with mitogens or other substances, they can be used for versatile applications, such as quantifying latent reservoirs, testing inhibitory compounds, conducting neutralizing antibody assays, and identifying new restriction factors.

microbiology↗

bioRxiv2024

Cytosolic bacterial pathogens activate TLR pathways in tumors that synergistically enhance STING agonist cancer therapies

Bacterial pathogens that invade the eukaryotic cytosol are distinctive tools for fighting cancer, as they preferentially target tumors and can deliver cancer antigens to MHC-I. Cytosolic bacterial pathogens have undergone extensive preclinical development and human clinical trials, yet the molecular mechanisms by which they are detected by innate immunity in tumors is unclear. We report that intratumoral delivery of phylogenetically distinct cytosolic pathogens, including Listeria, Rickettsia, and Burkholderia species, elicited anti-tumor responses in established, poorly immunogenic melanoma and lymphoma in mice. We were surprised to observe that although the bacteria required entry to the cytosol, the anti-tumor responses were largely independent of the cytosolic sensors cGAS/STING and instead required TLR signaling. Combining pathogens with TLR agonists did not enhance anti-tumor efficacy, while combinations with STING agonists elicited profound, synergistic anti-tumor effects with complete responses in >80% of mice after a single dose. Small molecule TLR agonists also synergistically enhanced the anti-tumor activity of STING agonists. The anti-tumor effects were diminished in Rag2-deficient mice and upon CD8 T cell depletion. Mice cured from combination therapy developed immunity to cancer rechallenge that was superior to STING agonist monotherapy. Together, these data provide a framework for enhancing the efficacy of microbial cancer therapies and small molecule innate immune agonists, via the co-activation of STING and TLRs.

cancer biology↗

bioRxiv2023

Host glutathione is required for Rickettsia parkeri to properly septate, avoid ubiquitylation, and survive in macrophages.

Spotted fever group Rickettsia obligately reside in the cytosol where they parasitize over fifty metabolites from their hosts. However, the role for metabolite acquisition in pathogenesis remains unclear. Here, we find that depletion of the abundant low molecular weight thiol glutathione led to an impaired ability of Rickettsia parkeri to form plaques. Super-resolution microscopy revealed that glutathione depletion with buthionine sulfoximine (BSO) in endothelial or epithelial cells led to the formation of bacterial chains that increased in length over time. Chained bacteria had fewer actin-tails and were impeded for their ability to spread from cell to cell. Glutathione depletion also caused an increased frequency of colocalization between the bacterial surface and polyubiquitin. R. parkeri was significantly more restricted upon glutathione depletion in primary macrophages than in epithelial cells in a mechanism that avoided activating the inflammasome and the production of type I interferon. Together, these data suggest that host glutathione is critical for rickettsial septation, actin-based motility, avoiding ubiquitylation, and survival in immune cells.

microbiology↗

bioRxiv2022

Whole-brain mapping of effective connectivity by fMRI with cortex-wide patterned optogenetics

Functional magnetic resonance imaging (fMRI) with optogenetic neural manipulation is a powerful tool that enables brain-wide mapping of effective functional networks. To achieve flexible manipulation of neural excitation throughout the mouse cortex, we incorporated spatiotemporal programmable optogenetic stimuli generated by a digital micromirror device into an MR scanner via an optical fiber bundle for the first time. This approach offered versatility in space and time in planning the photostimulation pattern, combined with in situ optical imaging and cell-type or circuit-specific genetic targeting in individual mice. Brain-wide effective connectivity obtained by fMRI with optogenetic stimulation of atlas-based cortical regions is generally congruent with anatomically defined axonal tracing data but is affected by the types of anesthetics that act selectively on specific connections. fMRI combined with flexible optogenetics opens a new path to investigate dynamic changes in functional brain states in the same animal through high-throughput brain-wide effective connectivity mapping.

neuroscience↗