Distinct phenotype, longitudinal changes of numbers and cell-associated virus in blood dendritic cells in SIV-infected CD8-lymphocyte depleted macaques

The dynamics of simian immunodeficiency virus after depletion of CD8+ cells

Human immunodeficiency virus infection is still one of the most important causes of morbidity and mortality in the world, with a disproportionate human and economic burden especially in poorer countries. Despite many years of intense research, an aspect that still is not well understood is what (immune) mechanisms control the viral load during the prolonged asymptomatic stage of infection. Because CD8+ T cells have been implicated in this control by multiple lines of evidence, there has been a focus on understanding the potential mechanisms of action of this immune effector population. One type of experiment used to this end has been depleting these cells with monoclonal antibodies in the simian immunodeficiency virus-macaque model and then studying the effect of that depletion on the viral dynamics. Here we review what these experiments have told us. We emphasize modeling studies to interpret the changes in viral load observed in these experiments, including discussion of alternative models, assumptions and interpretations, as well as potential future experiments.

Downregulation of Interferon-β and Inhibition of TLR3 Expression are associated with Fatal Outcome of Severe Fever with Thrombocytopenia Syndrome

Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease with high mortality and increasing prevalence in the East Asia. Though the etiological agent has been identified as a novel Bunyavirus, cellular mechanisms of viral pathogenesis and host immune response to SFTS virus infection remain unknown. A comprehensive study was conducted on a cohort of 70 patients on clinical manifestations, viral loads, modulation of cytokines, serum interferon level, immune related gene expression in peripheral blood cells, and dynamic changes of circulating dendritic cells during the acute phase of SFTSV infection. We found that high level viremia, reduced platelets, coagulation dysfunction, multi-organ injuries, elevated IL-6 and TNF-α were closely associated with the aggravation of SFTS. In addition, we demonstrated strong correlations between disease severity and the decline of serum IFN-β and IL-1β level, reduction of myeloid dendritic cells (mDCs) and suppressed Toll like receptor 3 expression in monocytes and mDCs. In general, dysfunction of innate immune response and cytokine storm are both involved in the pathogenesis of SFTS. Reduction of myeloid DCs contributes to the fatal outcome of SFTS virus infection, and the regulation of TLR3 could probably be the mechanism.