Eleonora Lalle

Association of Profoundly Impaired Immune Competence in H1N1v-Infected Patients with a Severe or Fatal Clinical Course

BACKGROUND Pandemic A/H1N1v influenza is characterized by a mild clinical course. However, a small subset of patients develops a rapidly progressive course caused by primary viral pneumonia or secondary bacterial infections that, in many cases, lead to death due to respiratory failure. The aim of the present study was to analyze the involvement of the immune response in the clinical presentation of H1N1v influenza. METHODS The differentiation and functional capability of T cells from H1N1v-infected patients presenting with either mild disease (n=22) or severe or fatal disease (n=6) were compared. Moreover, plasma cytokines and chemokines were quantified. RESULTS T cells from H1N1v-infected patients presenting with a severe clinical course resulted in impaired effector cell differentiation and failed to respond to mitogenic stimulation. T cell anergy was strictly associated with a severe acute phase of infection, but T cells could be restored in patients able to recover. Of interest, massive expression of CD95 marker was found on anergic T cells, suggesting an apoptosis-related mechanism. Finally, lower plasma levels of interferon-alpha and monocyte chemoattractant protein-1 were found in patients with a worse clinical course of influenza, suggesting impaired production of these cytokines. CONCLUSIONS Our results show a strict association between host immune competence and the severity of the clinical course of H1N1v infection. By monitoring host functional response, patients with an enhanced risk of developing influenza-associated severe complications could be identified in a timely manner.

Frequency of Detection of Upper Respiratory Tract Viruses in Patients Tested for Pandemic H1N1/09 Viral Infection

ABSTRACT Molecular testing of 270 consecutive nasopharyngeal swab samples taken in May and June 2009 and 274 samples from patients hospitalized between July and December 2009 showed similar findings of respiratory viruses, with influenza A pandemic virus H1N1/09 being the most represented, followed by human parainfluenza virus type 3 and rhinoviruses. Statistical analyses suggested virus cocirculation in the absence of viral interference.

Activation of interferon response genes and of plasmacytoid dendritic cells in HIV-1 positive subjects with GB virus C co-infection.

GB virus C (GBV-C) coinfection has a protective role in Human Immunodeficiency Virus (HIV) infection, and increases the duration of suppression of HIV-1 viremia in patients under Highly Active Anti-Retroviral Therapy (HAART). Since innate antiviral response may be involved in the protection, we analyzed the possible role of GBV-C as activator of innate immunity. To this aim, we measured the extent of activation of the interferon (IFN) system and of circulating Dendritic Cells (DC) in vivo, and the ability of GBV-C to activate these functions in vitro. Activation of IFN system and of circulating DC was compared in GBV-positive and -negative HIV-1 co-infected patients with HAART-driven suppression of HIV-1 viremia. Endogenous levels of IFN-γ and RNA-dependent protein kinase (PKR) mRNA were significantly higher in peripheral blood mononuclear cells (PBMC) from GBV-C-positive when compared to GBV-C-negative patients. IFN-γ expression was correlated with all the Interferon response genes (IRGs) and with GBV-C viremia. The frequency of circulating plasmacytoid DC (pDC) expressing the CD80 activation marker was increased in GBV-C-positive patients, and was correlated with GBV-C viral load. In vitro experiments indicated that GBV-C is able to induce IFN-γ expression in PBMC. In addition, in PBMC cultures GBV-C induced an increase of CD80 expression by pDC, that was reduced by antibody to IFN-γ. Our data indicate that in HIV-positive patients GBV-C coinfection promotes the activation of IFN-γ and downstream IRG expression, as well as with the activation/maturation of circulating pDC. GBV-C-driven IFN-γ activation is, at least in part, responsible for the increased maturation of pDC. This crosstalk may suggest a role for GBV-C coinfection in boosting the innate antiviral response to HIV infection.

Coordinate induction of IFN-α and -γ by SARS-CoV also in the absence of virus replication

Abstract Background: Severe acute respiratory syndrome (SARS) is an emerging infection caused by a novel coronavirus known as SARS-CoV, characterized by an over-exuberant immune response with lung lymphomononuclear cells infiltration and proliferation that may account for tissue damage more than the direct effect of viral replication. This study is aimed at investigating the capability of SARS-CoV to activate IFN-α and -γ expression in lymphomonocytes (PBMC) from healthy donors, evaluating whether viral replication is necessary for this activation. Results: SARS-CoV virus is able to induce both IFN-α and -γ mRNA accumulation and protein release in a dose-dependent manner, MOI 10 being the most effective. The time course curve indicated that IFN-α mRNA induction peaked at 24 h.p.i,. whereas IFN-γ mRNA was still increasing at 48 h.p.i. Released IFN (both types) reached a plateau after 24–48 h.p.i. and remained rather stable over a 5-day period. A transient peak of negative strand viral RNA was detected after 1–2 days of infection, but neither infectious virus progeny yield nor newly produced viral genomic RNA could be evidenced in infected cultures, even after prolonged observation time (up to 13 days). Cocultivation of PBMC with fixed SARS-CoV-infected Vero cells was even more efficient than exposure to live virus in eliciting IFN-α and -γ induction. A combination of IFN-α and -γ strongly inhibited SARS-CoV replication in Vero cells, while the single cytokines were much less effective. Conclusions: This study provides evidence that SARS-CoV is able to induce in normal PBMC a coordinate induction of IFN-α and -γ gene expression. Virus replication is not necessary for IFN induction since efficient IFN expression could be obtained also by the cocultivation of normal PBMC with fixed SARS-CoV-infected cells. Concomitant activation of IFN-α and -γ gene expression by SARS-CoV in vivo may be relevant for the pathogenesis of the disease, both for the possible involvement in immunomediated damage of the tissues and for the strong inhibition of SARS-CoV replication as a result of combined cytokine action.

Design and clinical application of a molecular method for detection and typing of the influenza A/H1N1pdm virus

In March/April 2009, Mexico experienced an outbreak of respiratory illness, due to a new influenza of swine origin virus, which spread rapidly via human-to-human transmission, and became pandemic (A/H1N1pdm). Because of its unique genome composition, which includes gene segments of swine, avian and human origin, and to the considerable differences to the human influenza A viruses that have circulated so far, the currently used molecular methods proved inadequate. Based on published sequences, a primer set targeting the nucleoprotein gene was designed, which provided enhanced sensitivity for the new strain and proved suitable for sequence-based strain identification. The novel nucleoprotein reverse-transcription-PCR showed higher sensitivity for A/H1N1pdm than a commercial test for influenza A, and was comparable to the real-time-based method developed by the Centers for Disease Control and Prevention. It was used to screen 177 clinical samples referred to the laboratory for suspected A/H1N1pdm infection, detecting 17 (9.6%) infections that were confirmed by sequence analysis (100% sensitivity as compared to the real-time kit). The novel method is suitable for the diagnosis of A/H1N1pdm, and is also suitable, at least in the screening phase, for laboratories not equipped with the real-time PCR technology.

Longitudinal characterization of dysfunctional T cell-activation during human acute Ebola infection

Data on immune responses during human Ebola virus disease (EVD) are scanty, due to limitations imposed by biosafety requirements and logistics. A sustained activation of T-cells was recently described but functional studies during the acute phase of human EVD are still missing. Aim of this work was to evaluate the kinetics and functionality of T-cell subsets, as well as the expression of activation, autophagy, apoptosis and exhaustion markers during the acute phase of EVD until recovery. Two EVD patients admitted to the Italian National Institute for Infectious Diseases, Lazzaro Spallanzani, were sampled sequentially from soon after symptom onset until recovery and analyzed by flow cytometry and ELISpot assay. An early and sustained decrease of CD4 T-cells was seen in both patients, with an inversion of the CD4/CD8 ratio that was reverted during the recovery period. In parallel with the CD4 T-cell depletion, a massive T-cell activation occurred and was associated with autophagic/apoptotic phenotype, enhanced expression of the exhaustion marker PD-1 and impaired IFN-gamma production. The immunological impairment was accompanied by EBV reactivation. The association of an early and sustained dysfunctional T-cell activation in parallel to an overall CD4 T-cell decline may represent a previously unknown critical point of Ebola virus (EBOV)-induced immune subversion. The recent observation of late occurrence of EBOV-associated neurological disease highlights the importance to monitor the immuno-competence recovery at discharge as a tool to evaluate the risk of late sequelae associated with resumption of EBOV replication. Further studies are required to define the molecular mechanisms of EVD-driven activation/exhaustion and depletion of T-cells.

In HIV-positive patients, myeloid-derived suppressor cells induce T-cell anergy by suppressing CD3ζ expression through ELF-1 inhibition.

Objective:During HIV infection, a down-modulation of CD3&zgr; was found on T cells, contributing to T-cell anergy. In this work, we studied the correlation between myeloid-derived suppressor cells (MDSC) frequency and T-cell CD3&zgr; expression. Moreover, we investigated the mechanisms of CD3&zgr; decrease exploited by MDSC. Design and method:CD3&zgr; expression and MDSC frequency were evaluated by flow cytometry on peripheral blood mononuclear cells from 105 HIV-positive (HIV+) patients. The role of MDSC in the modulation of the HIV-specific T-cell response was evaluated. The level of CD3&zgr; mRNA and ELF-1 protein were analysed by real-time–PCR and western blot, respectively. Results:We found that granulocytic-MDSC (Gr-MDSC) were expanded in HIV+ patients compared with healthy donors; in particular, in cART-treated individuals a higher Gr-MDSC frequency was observed in patients with a CD4+ T-cell count below 400 cells/&mgr;l. We found an inverse correlation between the percentage of Gr-MDSC and CD3&zgr; level. Moreover, in-vitro MDSC depletion induced the up-regulation of CD3&zgr; in T cells, restoring the functionality of &agr;&bgr;, but not &ggr;&dgr; T cells. The in-vitro effect of isolated MDSC on CD3&zgr; expression was found cell contact-dependent, and was not mediated by previously described molecules. CD3&zgr; down-modulation corresponds to the decrease of its mRNA induced by silencing the transcription factor ELF-1. Conclusion:Our data provide new knowledge on mechanisms used by Gr-MDSC in immune-modulation and on their role in the immune reconstitution during antiviral treatments.

Interferon-α improves phosphoantigen-induced Vγ9Vδ2 T-cells interferon-γ production during chronic HCV infection.

In chronic HCV infection, treatment failure and defective host immune response highly demand improved therapy strategies. Vγ9Vδ2 T-cells may inhibit HCV replication in vitro through IFN-γ release after Phosphoantigen (PhAg) stimulation. The aim of our work was to analyze Vγ9Vδ2 T-cell functionality during chronic HCV infection, studying the role of IFN-α on their function capability. IFN-γ production by Vγ9Vδ2 T-cells was analyzed in vitro in 24 HCV-infected patients and 35 healthy donors (HD) after PhAg stimulation with or without IFN-α. The effect of in vivo PhAg/IFN-α administration on plasma IFN-γ levels was analyzed in M. fascicularis monkeys. A quantitative analysis of IFN-γ mRNA level and stability in Vγ9Vδ2 T-cells was also evaluated. During chronic HCV infection, Vγ9Vδ2 T-cells showed an effector/activated phenotype and were significantly impaired in IFN-γ production. Interestingly, IFN-α was able to improve their IFN-γ response to PhAg both in vitro in HD and HCV-infected patients, and in vivo in Macaca fascicularis primates. Finally, IFN-α increased IFN-γ-mRNA transcription and stability in PhAg-activated Vγ9Vδ2 T-cells. Altogether our results show a functional impairment of Vγ9Vδ2 T-cells during chronic HCV infection that can be partially restored by using IFN-α. A study aimed to evaluate the antiviral impact of PhAg/IFN-α combination may provide new insight in designing possible combined strategies to improve HCV infection treatment outcome.

Molecular Characterization of the First Ebola Virus Isolated in Italy, from a Health Care Worker Repatriated from Sierra Leone.

ABSTRACT Here, we report the complete genome sequence of an Ebola virus (EBOV) isolated from a health worker repatriated from Sierra Leone to Italy in November 2014. The sequence, clustering in clade 3 of the Sierra Leone sequences, was analyzed with respect to mutations possibly affecting diagnostic and therapeutic targets as well as virulence.

Molecular Characterization of Autochthonous Chikungunya Cluster in Latium Region, Italy

We report partial molecular characterization of isolates from an autochthonous chikungunya virus cluster in the Latium Region of Italy. E1 sequences from 3 patients differ substantially from sequences from the 2007 outbreak in Italy and lack the A226V substitution associated with increased viral fitness in the Aedes albopictus mosquito vector.