Infection with Ebola virus (EBOV) causes hemorrhagic fever in humans with high case-fatality rates. The EBOV-glycoprotein (EBOV-GP) facilitates viral entry and promotes viral release from human cells. African fruit bats are believed not to develop disease upon EBOV infection and have been proposed as a natural reservoir of EBOV. We compared EBOV-GP interactions with human cells and cells from African fruit bats. We found that susceptibility to EBOV-GP-dependent infection was not limited to bat cells from potential reservoir species, and we observed that GP displayed similar biological properties in human and bat cells. The only exception was GP localization, which was to a greater extent intracellular in bat cells as compared to human cells. Collectively, our results suggest that GP interactions with fruit bat and human cells are similar and do not limit EBOV tropism for certain bat species.

Objective To investigate cytokine production patterns of T cell lines (TCL) from patients with Churg‐Strauss syndrome (CSS). Methods Short‐term polyclonal TCL were generated from peripheral blood of patients with CSS or Wegener's granulomatosis (WG) and healthy controls (HC). TCL were established in the presence of interleukin‐2 (IL‐2) and phytohemagglutinin and were phenotypically characterized by flow cytometry. Th1/Th2 cytokine production by stimulated TCL (72 hours) was analyzed by enzyme‐linked immunosorbent assay. Results TCL that represented the progeny of in vivo–activated T cells from CSS patients displayed a heterogeneous immunophenotype, with a predominance of CD4+ T cells when compared with WG TCL, which were predominantly CD8+. All CSS TCL shared the ability to produce large amounts of interferon‐γ (IFNγ), IL‐4, and IL‐13 compared with HC (P = 0.014 for all 3). Production of IL‐4 and IL‐13 was higher in CSS TCL than in WG TCL (P = 0.014 for both). IL‐5 production was up‐regulated in WG TCL compared with CSS TCL (P = 0.014). Compared with HC, WG TCL showed increased production of IFNγ (P = 0.021), IL‐5 (P = 0.043), and IL‐13 (P = 0.021). Conclusion Our results indicate that, while there is evidence for both a type 1 and a type 2 response in CSS, type 2 cytokine production pattern appears to predominate in this disease when compared with WG and HC.

BackgroundPlatelets, anucleate cell fragments abundant in human blood, can capture HIV-1 and platelet counts have been associated with viral load and disease progression. However, the impact of platelets on HIV-1 infection of T cells is unclear.ResultsWe found that platelets suppress HIV-1 spread in co-cultured T cells in a concentration-dependent manner. Platelets containing granules inhibited HIV-1 spread in T cells more efficiently than degranulated platelets, indicating that the granule content might exert antiviral activity. Indeed, supernatants from activated and thus degranulated platelets suppressed HIV-1 infection. Infection was inhibited at the stage of host cell entry and inhibition was independent of the viral strain or coreceptor tropism. In contrast, blockade of HIV-2 and SIV entry was less efficient. The chemokine CXCL4, a major component of platelet granules, blocked HIV-1 entry and neutralization of CXCL4 in platelet supernatants largely abrogated their anti-HIV-1 activity.ConclusionsRelease of CXCL4 by activated platelets inhibits HIV-1 infection of adjacent T cells at the stage of virus entry. The inhibitory activity of platelet-derived CXCL4 suggests a role of platelets in the defense against infection by HIV-1 and potentially other pathogens.

The interferon-induced host cell factor tetherin inhibits release of human immunodeficiency virus (HIV) from the plasma membrane of infected cells and is counteracted by the HIV-1 protein Vpu. Influenza A virus (FLUAV) also buds from the plasma membrane and is not inhibited by tetherin. Here, we investigated if FLUAV encodes a functional equivalent of Vpu for tetherin antagonism. We found that expression of the FLUAV protein NS1, which antagonizes the interferon (IFN) response, did not block the tetherin-mediated restriction of HIV release, which was rescued by Vpu. Similarly, tetherin-mediated inhibition of HIV release was not rescued by FLUAV infection. In contrast, FLUAV infection induced tetherin expression on target cells in an IFN-dependent manner. These results suggest that FLUAV escapes the antiviral effects of tetherin without encoding a tetherin antagonist with Vpu-like activity.

Objective. To investigate cytokine production patterns of T cell lines (TCL) from patients with Churg-Strauss syndrome (CSS).Methods. Short-term polyclonal TCL were generated from peripheral blood of patients with CSS or Wegener's granulomatosis (WG) and healthy controls (HC). TCL were established in the presence of interleukin-2 (IL-2) and phytohemagglutinin and were phenotypically characterized by flow cytometry. Th1/ Th2 cytokine production by stimulated TCL (72 hours) was analyzed by enzyme-linked immunosorbent assay.Results. TCL that represented the progeny of in vivo-activated T cells from CSS patients displayed a heterogeneous immunophenotype, with a predominance of CD4؉ T cells when compared with WG TCL, which were predominantly CD8؉. All CSS TCL shared the ability to produce large amounts of interferon-␥ (IFN␥), IL-4, and IL-13 compared with HC ( P ‫؍‬ 0.014 for all 3). Production of IL-4 and IL-13 was higher in CSS TCL than in WG TCL (P ‫؍‬ 0.014 for both). IL-5 production was up-regulated in WG TCL compared with CSS TCL (P ‫؍‬ 0.014). Compared with HC, WG TCL showed increased production of IFN␥ (P ‫؍‬ 0.021), IL-5 (P ‫؍‬ 0.043), and IL-13 (P ‫؍‬ 0.021).Conclusion. Our results indicate that, while there is evidence for both a type 1 and a type 2 response in CSS, type 2 cytokine production pattern appears to predominate in this disease when compared with WG and HC.