Silvia Meschi

Unique human immune signature of Ebola virus disease in Guinea

Despite the magnitude of the Ebola virus disease (EVD) outbreak in West Africa, there is still a fundamental lack of knowledge about the pathophysiology of EVD. In particular, very little is known about human immune responses to Ebola virus. Here we evaluate the physiology of the human T cell immune response in EVD patients at the time of admission to the Ebola Treatment Center in Guinea, and longitudinally until discharge or death. Through the use of multiparametric flow cytometry established by the European Mobile Laboratory in the field, we identify an immune signature that is unique in EVD fatalities. Fatal EVD was characterized by a high percentage of CD4+ and CD8+ T cells expressing the inhibitory molecules CTLA-4 and PD-1, which correlated with elevated inflammatory markers and high virus load. Conversely, surviving individuals showed significantly lower expression of CTLA-4 and PD-1 as well as lower inflammation, despite comparable overall T cell activation. Concomitant with virus clearance, survivors mounted a robust Ebola-virus-specific T cell response. Our findings suggest that dysregulation of the T cell response is a key component of EVD pathophysiology.

Seroprevalence of dengue infection: a cross-sectional survey in mainland Tanzania and on Pemba Island, Zanzibar

OBJECTIVE Evidence available to date indicates that dengue viruses 1, 2, and 3 could be among the causes of acute fever in eastern Africa. Recently, four reports on dengue infection in travelers and residents have raised concerns over the occurrence of dengue fever in mainland Tanzania and in Zanzibar. The objective of this study was to provide seroprevalence data on dengue infection in Tanzania. METHODS This study was conducted in 2007 at two peripheral hospitals, one on Pemba Island, Zanzibar and one in Tosamaganga, Iringa Region, mainland Tanzania. Two hundred and two consecutive febrile outpatients were studied for antibodies and viral RNA to assess the circulation of dengue virus in Tanzania. RESULTS A seroprevalence of 7.7% was found on Pemba Island and of 1.8% was found in Tosamaganga. No acute cases and no previous infections among patients under 11 years of age were detected. CONCLUSION These findings provide the first baseline data on dengue seroprevalence in the country. No recent dengue virus circulation in Tanzania and in the Zanzibar archipelago up until the early 1990s is reported.

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.

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.

Rapid Increase in Total Torquetenovirus (TTV) Plasma Viremia Load Reveals an Apparently Transient Superinfection by a TTV of a Novel Group 2 Genotype

ABSTRACT An apparently transient infection by a superimposed torquetenovirus (TTV) in a subject who already carried three different genotypes of the virus is described. The superinfection induced a rapid increase in the plasma TTV load and a decline in immunocomplexed virus. The superinfecting TTV was a novel group 2 genotype.

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.

IgG Against Dengue Virus in Healthy Blood Donors, Zanzibar, Tanzania

We conducted a seroprevalence survey among 500 healthy adult donors at Zanzibar National Blood Transfusion Services. Dengue virus IgG seroprevalence was 50.6% and independently associated with age and urban residence. These data will aid in building a surveillance, preparedness, and response plan for dengue virus infections in the Zanzibar Archipelago.

Analysis of Diagnostic Findings From the European Mobile Laboratory in Guéckédou, Guinea, March 2014 Through March 2015

Background. A unit of the European Mobile Laboratory (EMLab) consortium was deployed to the Ebola virus disease (EVD) treatment unit in Guéckédou, Guinea, from March 2014 through March 2015. Methods. The unit diagnosed EVD and malaria, using the RealStar Filovirus Screen reverse transcription–polymerase chain reaction (RT-PCR) kit and a malaria rapid diagnostic test, respectively. Results. The cleaned EMLab database comprised 4719 samples from 2741 cases of suspected EVD from Guinea. EVD was diagnosed in 1231 of 2178 hospitalized patients (57%) and in 281 of 563 who died in the community (50%). Children aged <15 years had the highest proportion of Ebola virus–malaria parasite coinfections. The case-fatality ratio was high in patients aged <5 years (80%) and those aged >74 years (90%) and low in patients aged 10–19 years (40%). On admission, RT-PCR analysis of blood specimens from patients who died in the hospital yielded a lower median cycle threshold (Ct) than analysis of blood specimens from survivors (18.1 vs 23.2). Individuals who died in the community had a median Ct of 21.5 for throat swabs. Multivariate logistic regression on 1047 data sets revealed that low Ct values, ages of <5 and ≥45 years, and, among children aged 5–14 years, malaria parasite coinfection were independent determinants of a poor EVD outcome. Conclusions. Virus load, age, and malaria parasite coinfection play a role in the outcome of EVD.

The prevalence of antibodies to human herpesvirus 8 and hepatitis B virus in patients in two hospitals in Tanzania.

The aim of this study was to determine the seroprevalence of human herpesvirus 8 (HHV‐8) and the immunization status for hepatitis B virus (HBV) infection in febrile patients in two districts of the United Republic of Tanzania. Between February and March 2007, blood samples were collected in Pemba Island and Tosamaganga from 336 outpatients and sent to the Virology Laboratory in Rome (Italy) for testing. HHV‐8 DNA and HBV‐DNA were amplified by two in‐house molecular methods, anti‐HHV‐8 antibody titers were determined by an immunofluorescence assay (IFA), and anti‐HCV, HBsAg, anti‐HBs, and anti‐HBc were evaluated by microplate enzyme immunoassay (MEIA). The seroprevalence of HHV‐8 was 30.7% (96/313). In Pemba Island, the prevalence was lower than in Tosamaganga (14.4% vs. 46.3%). A higher prevalence of low titers of HHV‐8 IgG (<1:80, 81%) was found among those under 5 years of age. HHV‐8 DNA was detected in six seropositive patients (6.7%). The prevalence of HBsAg, anti‐HBs, and anti‐HBc was 4.3%, 37.6%, and 29.3%, respectively. Out of 277 patients, 70 had had a previous infection (25.3%). One case of occult hepatitis was found. The cover of hepatitis B vaccination was higher among children born after 2002 (66.7%) than in patients born before 2002. HHV‐8 infection is endemic in Tanzania and the seroprevalence rate was higher in the mainland than on Pemba Island. The 3.9% percentage of HBsAg in children younger than 4 years of age suggests that increased efforts are required in order to achieve universal and compulsory immunization of children against HBV. J. Med. Virol. 82:1569–1575, 2010.

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.