Intraindividually, plasma TFV concentrations significantly decreased while cell associated TFV-DP concentrations significantly increased after switching from a TDF to a TAF-containing antiretroviral therapy regimen.

Occasional zoonotic viral attacks on immunologically naive populations result in massive death tolls that are capable of threatening human survival. Currently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the infectious agent that causes coronavirus disease (COVID-19), has spread from its epicenter in Wuhan China to all parts of the globe. Real-time mapping of new infections across the globe has revealed that variable transmission patterns and pathogenicity are associated with differences in SARS-CoV-2 lineages, clades, and strains. Thus, we reviewed how changes in the SARS-CoV-2 genome and its structural architecture affect viral replication, immune evasion, and transmission within different human populations. We also looked at which immune dominant regions of SARS-CoV-2 and other coronaviruses are recognized by Major Histocompatibility Complex (MHC)/Human Leukocyte Antigens (HLA) genes and how this could impact on subsequent disease pathogenesis. Efforts were also placed on understanding immunological changes that occur when exposed individuals either remain asymptomatic or fail to control the virus and later develop systemic complications. Published autopsy studies that reveal alterations in the lung immune microenvironment, morphological, and pathological changes are also explored within the context of the review. Understanding the true correlates of protection and determining how constant virus evolution impacts on host-pathogen interactions could help identify which populations are at high risk and later inform future vaccine and therapeutic interventions.

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Quantification of antiretroviral (ARV) drug concentrations in peripheral blood mononuclear cells (PBMCs) and tissue isolated mononuclear cells (TIMCs) from lymph node (LNMC) and rectum (RMC) is an important measure of bio-distribution. Normalization of drug concentrations is critical to represent tissue drug concentrations and to analyze both intra-individual and inter-individual variability in drug distribution. However, a molecular method to normalize intracellular drug concentrations in PBMCs and TIMCs methanol extracts is currently unavailable. In this study, a novel droplet digital PCR (ddPCR) assay was designed to amplify RPP30 gene sequence conserved in human and non-human primates (NHP). Genomic DNA (gDNA) isolated from 70 percent methanol embedded PBMCs and TIMCs was used as ddPCR template to quantitate precise RPP30 copies to derive cell counts. The novel molecular method quantitated RPP30 copies in human and rhesus macaque gDNA templates with greater accuracy and precision than qPCR. RPP30 ddPCR derived cell counts are strongly correlated with automated cytometer based cell counts in PBMC (R = 0.90, p = 0.001 and n = 20); LNMC (R = 0.85 p = 0.0001 and n = 22) and RMC (R = 0.92, p = 0.0001 and n = 20) and achieved comparable normalized drug concentrations. Therefore, the RPP30 ddPCR assay is an important normalization method in drug bio-distribution and pharmacokinetic studies in humans and NHPs.

Summary Microglia play a key role in brain development, normal homeostasis, and neurodegenerative disorders. Single-cell technologies have led to important findings about microglia, with many animal model studies using single-cell RNA sequencing (scRNA-seq), whereas most human specimen studies using archived frozen brains for single-nucleus RNA sequencing (snRNA-seq). However, microglia compose a small proportion of the total brain tissue; snRNAseq depletes expression of microglia activation genes that characterize many diseases. Here we examine the use of purified, cryopreserved microglia for scRNA-seq. Comparison of scRNA-seq on paired fresh and cryopreserved microglia from rhesus monkeys revealed a high level of correlation of gene expression between the two conditions. Disease-related genes were relatively unaffected, but an increase in immediate-early gene expression was present in cryopreserved cells. Regardless, changes in immediate-early gene expression are still detectable. Cryopreservation of microglia is a suitable procedure for prospectively archiving samples.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) is the causative agent of Corona Virus Disease 2019 (COVID-19). Lower production of type I and III interferons and higher levels of inflammatory mediators upon SARS-CoV2 infection contribute to COVID-19 pathogenesis. Optimal interferon production and controlled inflammation are essential to limit COVID-19 pathogenesis. However, the aggravated inflammatory response observed in COVID-19 patients causes severe damage to the host and frequently advances to acute respiratory distress syndrome (ARDS). Toll-like receptor 7 and 8 (TLR7/8) signaling pathways play a central role in regulating induction of interferons (IFNs) and inflammatory mediators in dendritic cells. Controlled inflammation is possible through regulation of TLR mediated response without influencing interferon production and may reduce COVID-19 pathogenesis. This review focuses on inflammatory mediators contribute to pathogenic effects and the role of TLR pathways in the induction of interferon and inflammatory mediators and their contribution to COVID-19 pathogenesis. We conclude that potential TLR7/8 agonists inducing antiviral interferon response and control inflammation are important therapeutic options to effectively eliminate SARS-CoV2 induced pathogenesis. Ongoing and future studies may provide additional evidence on their safety and efficacy to treat COVID-19 pathogenesis.

Background The secondary lymphoid tissues (LTs), lymph nodes (LNs) and gut-associated lymphoid tissue (GALT) are considered reservoirs for HIV. Antiretrovirals (ARVs) have lower penetration into LT. In vitro models predictive of ARV LT penetration have not been established. Objectives To develop an in vitro model of LT bioavailability using human lymphoid endothelial cells (HLECs) and investigate its predictability with in vivo pharmacokinetic (PK) studies in mice. Methods ARV bioavailability in HLECs was evaluated at the maximum plasma concentration (Cmax) observed in HIV-infected patients. ARVs were: abacavir, atazanavir, darunavir, dolutegravir, efavirenz, elvitegravir, emtricitabine, maraviroc, raltegravir, rilpivirine, ritonavir, tenofovir disoproxil fumarate and the PK booster cobicistat. The LT PK of representative drugs showing high (efavirenz), intermediate (dolutegravir) and low (emtricitabine) HLEC bioavailability was investigated in BALB/c mice given 50/10/30 mg/kg efavirenz/dolutegravir/emtricitabine orally, daily for 3 days. The concordance of in vitro and in vivo ARV bioavailability was examined. Results ARVs showed high (>67th percentile; rilpivirine, efavirenz, elvitegravir and cobicistat), intermediate (67th–33rd percentile; ritonavir, tenofovir disoproxil fumarate, dolutegravir and maraviroc) and low (<33rd percentile; atazanavir, darunavir, raltegravir, emtricitabine and abacavir) HLEC bioavailability. The hierarchy of efavirenz, dolutegravir and emtricitabine bioavailability in LN, gut and brain tissues of mice was: efavirenz>dolutegravir>emtricitabine. Conclusions ARVs displayed distinct HLEC penetration patterns. PK studies of representative ARVs in LT of mice were concordant with HLEC bioavailability. These findings support further development of this approach and its translational predictability in humans.

Zinc (Zn) is required for proper immune function and host defense. Zn homeostasis is tightly regulated by Zn transporters that coordinate biological processes through Zn mobilization. Zn deficiency is associated with increased susceptibility to bacterial infections, including Streptococcus pneumoniae, the most commonly identified cause of community-acquired pneumonia. Myeloid cells, including macrophages and dendritic cells (DCs), are at the front line of host defense against invading bacterial pathogens in the lung and play a critical role early on in shaping the immune response. Expression of the Zn transporter ZIP8 is rapidly induced following bacterial infection and regulates myeloid cell function in a Zn-dependent manner. To what extent ZIP8 is instrumental in myeloid cell function requires further study. Using a novel, myeloid-specific, Zip8 knockout model, we identified vital roles of ZIP8 in macrophage and DC function upon pneumococcal infection. Administration of S. pneumoniae into the lung resulted in increased inflammation, morbidity, and mortality in Zip8 knockout mice compared with wild-type counterparts. This was associated with increased numbers of myeloid cells, cytokine production, and cell death. In vitro analysis of macrophage and DC function revealed deficits in phagocytosis and increased cytokine production upon bacterial stimulation that was, in part, due to increased NF-κB signaling. Strikingly, alteration of myeloid cell function resulted in an imbalance of Th17/Th2 responses, which is potentially detrimental to host defense. These results (for the first time, to our knowledge) reveal a vital ZIP8- and Zn-mediated axis that alters the lung myeloid cell landscape and the host response against pneumococcus.