Giada Rossini

West Nile virus in Europe: emergence, epidemiology, diagnosis, treatment, and prevention

West Nile virus (WNV), a mosquito-borne flavivirus in the Japanese encephalitis antigenic group, has caused sporadic outbreaks in humans, horses and birds throughout many of the warmer regions of Europe for at least 20 years. Occasional cases of West Nile encephalitis have also been associated with infected blood transfusions and organ donations. Currently, WNV appears to be expanding its geographical range in Europe and causing increasing numbers of epidemics/outbreaks associated with human morbidity and mortality. This brief review reports on the current epidemic situation regarding WNV in Europe, highlighting the clinical, diagnostic and preventive measures available for controlling this apparently emerging human pathogen.

Inflammatory Cytokine Expression Is Associated with Chikungunya Virus Resolution and Symptom Severity

The Chikungunya virus infection zones have now quickly spread from Africa to parts of Asia, North America and Europe. Originally thought to trigger a disease of only mild symptoms, recently Chikungunya virus caused large-scale fatalities and widespread economic loss that was linked to recent virus genetic mutation and evolution. Due to the paucity of information on Chikungunya immunological progression, we investigated the serum levels of 13 cytokines/chemokines during the acute phase of Chikungunya disease and 6- and 12-month post-infection follow-up from patients of the Italian outbreak. We found that CXCL9/MIG, CCL2/MCP-1, IL-6 and CXCL10/IP-10 were significantly raised in the acute phase compared to follow-up samples. Furthermore, IL-1β, TNF-α, Il-12, IL-10, IFN-γ and IL-5 had low initial acute phase levels that significantly increased at later time points. Analysis of symptom severity showed association with CXCL9/MIG, CXCL10/IP-10 and IgG levels. These data give insight into Chikungunya disease establishment and subsequent convalescence, which is imperative to the treatment and containment of this quickly evolving and frequently re-emerging disease.

Mosquito, bird and human surveillance of West Nile and Usutu viruses in Emilia-Romagna Region (Italy) in 2010.

Background In 2008, after the first West Nile virus (WNV) detection in the Emilia-Romagna region, a surveillance system, including mosquito- and bird-based surveillance, was established to evaluate the virus presence. Surveillance was improved in following years by extending the monitoring to larger areas and increasing the numbers of mosquitoes and birds tested. Methodology/Principal Findings A network of mosquito traps, evenly distributed and regularly activated, was set up within the surveyed area. A total of 438,558 mosquitoes, grouped in 3,111 pools and 1,276 birds (1,130 actively sampled and 146 from passive surveillance), were tested by biomolecular analysis. The survey detected WNV in 3 Culex pipiens pools while Usutu virus (USUV) was found in 89 Cx. pipiens pools and in 2 Aedes albopictus pools. Two birds were WNV-positive and 12 were USUV-positive. Furthermore, 30 human cases of acute meningoencephalitis, possibly caused by WNV or USUV, were evaluated for both viruses and 1,053 blood bags were tested for WNV, without any positive result. Conclusions/Significance Despite not finding symptomatic human WNV infections during 2010, the persistence of the virus, probably due to overwintering, was confirmed through viral circulation in mosquitoes and birds, as well as for USUV. In 2010, circulation of the two viruses was lower and more delayed than in 2009, but this decrease was not explained by the relative abundance of Cx. pipiens mosquito, which was greater in 2010. The USUV detection in mosquito species confirms the role of Cx. pipiens as the main vector and the possible involvement of Ae. albopictus in the virus cycle. The effects of meteorological conditions on the presence of USUV-positive mosquito pools were considered finding an association with drought conditions and a wide temperature range. The output produced by the surveillance system demonstrated its usefulness and reliability in terms of planning public health policies.

A neutralizing monoclonal antibody targeting the acid-sensitive region in chikungunya virus E2 protects from disease.

The mosquito-borne alphavirus, chikungunya virus (CHIKV), has recently reemerged, producing the largest epidemic ever recorded for this virus, with up to 6.5 million cases of acute and chronic rheumatic disease. There are currently no licensed vaccines for CHIKV and current anti-inflammatory drug treatment is often inadequate. Here we describe the isolation and characterization of two human monoclonal antibodies, C9 and E8, from CHIKV infected and recovered individuals. C9 was determined to be a potent virus neutralizing antibody and a biosensor antibody binding study demonstrated it recognized residues on intact CHIKV VLPs. Shotgun mutagenesis alanine scanning of 98 percent of the residues in the E1 and E2 glycoproteins of CHIKV envelope showed that the epitope bound by C9 included amino-acid 162 in the acid-sensitive region (ASR) of the CHIKV E2 glycoprotein. The ASR is critical for the rearrangement of CHIKV E2 during fusion and viral entry into host cells, and we predict that C9 prevents these events from occurring. When used prophylactically in a CHIKV mouse model, C9 completely protected against CHIKV viremia and arthritis. We also observed that when administered therapeutically at 8 or 18 hours post-CHIKV challenge, C9 gave 100% protection in a pathogenic mouse model. Given that targeting this novel neutralizing epitope in E2 can potently protect both in vitro and in vivo, it is likely to be an important region both for future antibody and vaccine-based interventions against CHIKV.

Detection of Usutu-Virus-Specific IgG in Blood Donors from Northern Italy

We developed a novel enzyme-linked immunosorbent assay to detect the specific IgG response to Usutu virus (USUV) in humans, by evaluating 359 blood donors who were living in northeastern Italy. Our results demonstrate the presence of an anti-USUV response in 4 subjects with no history of other flavivirus infection.

Interplay between Human Cytomegalovirus and Intrinsic/Innate Host Responses: A Complex Bidirectional Relationship

The interaction between human cytomegalovirus (HCMV) and its host is a complex process that begins with viral attachment and entry into host cells, culminating in the development of a specific adaptive response that clears the acute infection but fails to eradicate HCMV. We review the viral and cellular partners that mediate early host responses to HCMV with regard to the interaction between structural components of virions (viral glycoproteins) and cellular receptors (attachment/entry receptors, toll-like receptors, and other nucleic acid sensors) or intrinsic factors (PML, hDaxx, Sp100, viperin, interferon inducible protein 16), the reactions of innate immune cells (antigen presenting cells and natural killer cells), the numerous mechanisms of viral immunoevasion, and the potential exploitation of events that are associated with early phases of virus-host interplay as a therapeutic strategy.

A rapid and specific real-time RT-PCR assay to identify Usutu virus in human plasma, serum, and cerebrospinal fluid

BACKGROUND Usutu virus (USUV), a flavivirus that belongs to the Japanese encephalitis virus (JEV) family, has recently emerged as a human pathogen, necessitating new diagnostic tools. OBJECTIVE The development and assessment of a real-time RT-PCR assay to detect USUV in human samples. STUDY DESIGN Based on USUV genomic sequences from GenBank, USUV-specific primers and probes that target the NS5 gene were designed. The sensitivity was evaluated in a 10-fold dilution series of plasmid that contained the amplicon and in a dilution series of a quantified human USUV isolate. The specificity was determined by testing various concentrations of related ArBo viruses, including flaviviruses and phleboviruses. Human RNAse P was also amplified in the assay. One hundred four human specimens from patients who suffered from viral meningoencephalitis were evaluated. RESULTS The real-time RT-PCR assay had a sensitivity of 50 genomic copies per reaction (corresponding to 2200 copies/ml) and 1 PFU/ml of USUV isolate. USUV isolates from Austria were identified with identical efficiency, and no ArBo viruses, other than USUV, were detected. USUV was also identified in 3 cerebrospinal fluid samples. All human samples were positive for RNAse P. CONCLUSIONS This PCR assay is recommended for all cases in which a rapid and clinically accurate diagnosis of human USUV infection is required.

False-Positive Transcription-Mediated Amplification Assay Detection of West Nile Virus in Blood from a Patient with Viremia Caused by an Usutu Virus Infection

ABSTRACT Detection of West Nile virus (WNV) by nucleic acid amplification technology (NAAT) is used widely to screen blood and organ donations in areas where WNV is endemic. We report a false-positive result of a WNV transcription-mediated amplification assay (TMA) in a patient with viremia that was caused by Usutu virus, a mosquito-borne flavivirus.

Intrauterine cytomegalovirus infection and glycoprotein N (gN) genotypes.

BACKGROUND Human cytomegalovirus (HCMV) clinical isolates display genetic polymorphisms, supposed to be related with strain-specific tissue-tropism and HCMV-induced immunopathogenesis. One recently discovered polymorphic gene is ORF UL73, encoding for the envelope glycoprotein gN. Among HCMV clinical strains, it shows four distinct genomic variants denoted as gN-1, gN-2, gN-3 and gN-4. OBJECTIVES Aims of this study were to assess the prevalence of the different gN types in the populations examined and to investigate the possible relationship between genotypes and severity of congenital CMV disease. STUDY DESIGN The gN genotyping was carried out by sequencing analysis of the HCMV ORF UL73. Comparisons were made by chi-square test and contingency tables. RESULTS All the four gN genotypes can cause congenital infections and the overall distribution was as follows: gN-1, 23.6%; gN-2, 1.1%; gN-3, 12.9%; gN-4, 62.4%. None of them seems to be preferentially associated with vertical transmission or with acute outcome of congenital infection. However, considering the chronic outcome and long-term sequelae, there was a statistically significant (P<0.05) difference between congenitally infected infants with or without adverse chronic outcome. CONCLUSIONS HCMV congenital infections, which displayed a prevalence of the gN-1 variants, seem to be associated with favorable chronic outcome.

Phylogenetic analysis of West Nile virus isolates, Italy, 2008-2009.

To determine the lineage of West Nile virus that caused outbreaks in Italy in 2008 and 2009, several West Nile virus strains were isolated from human specimens and sequenced. On the basis of phylogenetic analyses, the strains isolated constitute a distinct group within the western Mediterranean cluster.