Increased production of human immunodeficiency virus (HIV) in HIV-induced syncytia formation: An efficient infection process

Self-DNA driven inflammation in COVID-19 and after mRNA-based vaccination: lessons for non-COVID-19 pathologies

The coronavirus disease 2019 (COVID-19) pandemic triggered an unprecedented concentration of economic and research efforts to generate knowledge at unequalled speed on deregulated interferon type I signalling and nuclear factor kappa light chain enhancer in B-cells (NF-κB)-driven interleukin (IL)-1β, IL-6, IL-18 secretion causing cytokine storms. The translation of the knowledge on how the resulting systemic inflammation can lead to life-threatening complications into novel treatments and vaccine technologies is underway. Nevertheless, previously existing knowledge on the role of cytoplasmatic or circulating self-DNA as a pro-inflammatory damage-associated molecular pattern (DAMP) was largely ignored. Pathologies reported 'de novo' for patients infected with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 to be outcomes of self-DNA-driven inflammation in fact had been linked earlier to self-DNA in different contexts, e.g., the infection with Human Immunodeficiency Virus (HIV)-1, sterile inflammation, and autoimmune diseases. I highlight particularly how synergies with other DAMPs can render immunogenic properties to normally non-immunogenic extracellular self-DNA, and I discuss the shared features of the gp41 unit of the HIV-1 envelope protein and the SARS-CoV 2 Spike protein that enable HIV-1 and SARS-CoV-2 to interact with cell or nuclear membranes, trigger syncytia formation, inflict damage to their host's DNA, and trigger inflammation - likely for their own benefit. These similarities motivate speculations that similar mechanisms to those driven by gp41 can explain how inflammatory self-DNA contributes to some of most frequent adverse events after vaccination with the BNT162b2 mRNA (Pfizer/BioNTech) or the mRNA-1273 (Moderna) vaccine, i.e., myocarditis, herpes zoster, rheumatoid arthritis, autoimmune nephritis or hepatitis, new-onset systemic lupus erythematosus, and flare-ups of psoriasis or lupus. The hope is to motivate a wider application of the lessons learned from the experiences with COVID-19 and the new mRNA vaccines to combat future non-COVID-19 diseases.

A Universal CAR-NK Cell Targeting Various Epitopes of HIV-1 gp160

Engineering T cells and natural killer (NK) cells with anti-HIV chimeric antigen receptors (CAR) has emerged as a promising strategy to eradicate HIV-infected cells. However, current anti-HIV CARs are limited by targeting a single epitope of the HIV envelope glycoprotein gp160, which cannot counter the enormous diversity and mutability of viruses. Here, we report the development of a universal CAR-NK cell, which recognizes 2,4-dinitrophenyl (DNP) and can subsequently be redirected to target various epitopes of gp160 using DNP-conjugated antibodies as adaptor molecules. We show that this CAR-NK cell can recognize and kill mimic HIV-infected cell lines expressing subtypes B and C gp160. We additionally find that anti-gp160 antibodies targeting membrane-distal epitopes (including V1/V2, V3, and CD4bs) are more likely to activate universal CAR-NK cells against gp160⁺ target cells, compared with those targeting membrane-proximal epitopes located in the gp41 MPER. Finally, we confirm that HIV-infected primary human CD4⁺ T cells can be effectively killed using the same approach. Given that numerous anti-gp160 antibodies with different antigen specificities are readily available, this modular universal CAR-NK cell platform can potentially overcome HIV diversity, thus providing a promising strategy to eradicate HIV-infected cells.

A quantitative assessment of dynamical differences of RSV infections in vitro and in vivo

Experimental results in vitro and in animal models are used to guide researchers in testing vaccines or treatment in humans. However, viral kinetics are different in vitro, in animals, and in humans, so it is sometimes difficult to translate results from one system to another. In this study, we use a mathematical model to fit experimental data from multiple cycle respiratory syncytial virus (RSV) infections in vitro, in african green monkey (AGM), and in humans in order to quantitatively compare viral kinetics in the different systems. We find that there are differences in viral clearance rate, productively infectious cell lifespan, and eclipse phase duration between in vitro and in vivo systems and among different in vivo systems. We show that these differences in viral kinetics lead to different estimates of drug effectiveness of fusion inhibitors in vitro and in AGM than in humans.

Unintegrated HIV-1 circular 2-LTR proviral DNA as a marker of recently infected cells: relative effect of recombinant CD4, zidovudine, and saquinavir in vitro

Unintegrated HIV-1 proviral DNA is one of the earliest detectable forms of HIV-1, and the influence of an antiretroviral drug on its appearance may reflect the efficacy of that agent in preventing infection of new cells. We characterized the dynamics of HIV-1 p24 (p24) antigen production, HIV-1 gag DNA, tandem long-terminal-repeat circular unintegrated proviral (2-LTR) HIV-1 DNA, HIV-1 tat mRNA, and cell viability in the presence of three antiretroviral agents: recombinant soluble CD4 (rsCD4), zidovudine, and saquinavir. Interference with HIV-1 entry by rsCD4 decreased p24 antigen levels modestly, decreased HIV-1 gag by twofold, and 2-LTR was detectable at the end of the culture period. Inhibition of reverse transcription by zidovudine decreased p24 antigen levels modestly, decreased HIV-1 gag by 19-fold, and inhibited detection of 2-LTR HIV-1 DNA. The protease inhibitor, saquinavir, had the greatest overall effect, with the lowest levels of p24 antigen and HIV-1 gag, and inhibition of 2-LTR. There was no detection of tat mRNA in the saquinavir-treated cultures. In addition, cell viability was significantly higher in cultures treated with saquinavir. In these experiments, 2-LTR HIV-1 DNA was indicative of the relative inhibitory effects of three antiretroviral agents acting at different steps of the HIV-1 replication cycle. We demonstrated in vitro that 2-LTR HIV-1 DNA was a useful indicator of an antiretroviral drug in preventing new cell infection and could be utilized as a dynamic marker of drug efficacy in HIV-1-infected patients.

Unintegrated circular HIV-1 DNA in the peripheral mononuclear cells of HIV-1-infected subjects: association with high levels of plasma HIV-1 RNA, rapid decline in CD4 count, and clinical progression to AIDS

We observed 36 HIV-infected patients to evaluate whether the presence of tandem 2-long terminal repeat circular unintegrated HIV-1 DNA (2-LTR) in peripheral blood mononuclear cells (PBMC) at baseline was associated with acceleration of HIV disease. Detection of 2-LTR at baseline correlated with high plasma HIV-1 RNA levels (p < .01), recovery of culturable HIV-1 from plasma (p = .02), and progression to AIDS during follow-up (p = .01). More patients with 2-LTR (68%) than without 2-LTR (31%) had a decline in CD4 levels of >50 cells/mm3 over the first 18 months of follow-up (p = .04), and the average annual CD4 decline was 35% in patients with 2-LTR compared with 16% in those without 2-LTR (p = 0.06). Detection of 2-LTR in PBMC at baseline was an independent predictor of high plasma HIV-1 RNA levels and subsequent CD4 cell decline in this cohort of patients with predominantly nonsyncytium-inducing (NSI) isolates at baseline. The presence of 2-LTR in PBMC appears to be reflective of ongoing HIV-1 replication, as measured by plasma HIV-1 RNA levels, and identifies persons at risk for immunologic and clinical decline.

Non-secretory multiple myeloma with multinucleated giant plasma cells

We report a case of non-secretory multiple myeloma with unusual cytological features. The plasma cells were multinucleated and contained up to forty nuclei. All nuclei had regular outlines without multilobulated and convoluted slopes. DNA content measurement demonstrated that all nuclei of uni- and multinucleated cells were diploid. All plasma cells contained cytoplasmic alpha chain but light chains and their corresponding transcripts were absent. There is no clear explanation concerning multinuclearity. In addition, hypotheses regarding non-secretion of immunoglobulin in non-secretory multiple myeloma and in other B-cell neoplasias are discussed.

Intracerebral hemorrhages and syncytium formation induced by endothelial cell infection with a murine leukemia virus

The mechanisms of endothelial cell damage that lead to cerebral hemorrhage are not completely understood. In this study, a cloned murine retrovirus, TR1.3, that uniformly induced stroke in neonatal BALB/c mice is described. Restriction digest mapping suggests that TR1.3 is part of the Friend murine leukemia virus (FMuLV) family. However, unlike mice exposed to other FMuLVs, mice infected with TR1.3 virus developed tremors and seizures within 8 to 18 days postinoculation. This was uniformly followed by paralysis and death within 1 to 2 days. Postmortem examination of TR1.3-inoculated mice revealed edematous brain tissue with large areas of intracerebral hemorrhage. Histologic analysis revealed prominent small vessel pathology including syncytium formation of endothelial cells. Immunohistochemical analysis of frozen brain sections using double fluorescence staining demonstrated that TR1.3 virus specifically infected small vessel endothelial cells. Although infection of vessel endothelial cells was detected in several organs, only brain endothelial cells displayed viral infection associated with hemorrhage. The primary determinant of TR1.3-induced neuropathogenicity was found to reside within a 3.0-kb fragment containing the 3' end of the pol gene, the env gene, and the U3 region of the long terminal repeat. The restricted tropism and acute pathogenicity of this cloned murine retrovirus provide a model for studying virus-induced stroke and for elucidating the mechanisms involved in syncytium formation by retroviruses in vivo.