A model of laboratory surveillance for neuro-arbovirosis applied during 2012 in the Emilia-Romagna region, Italy

Usutu virus in cerebrospinal fluid: A 2-year survey in a Tertiary Care Hospital, Geneva, Switzerland

In 2009, the Usutu virus (USUV) was first reported as a cause of human neuroinvasive disorders. In Switzerland, USUV has been detected in wild birds with a seroprevalence of up to 6.59% in captive specimens sampled from zoo enclosures. This study investigates the clinical prevalence of USUV in human acute neuroinvasive disorders in Switzerland. Two hundred and fifty-eight cerebrospinal fluid samples collected between 2015 and 2017 for routine clinical care in a tertiary level hospital (Geneva) were tested for USUV by rRT-PCR. No samples were found positive, suggesting the absence, or the extremely low circulation of USUV in Western Switzerland.

Use of a physiologically based pharmacokinetic model to simulate drug-drug interactions between antineoplastic and antiretroviral drugs

Background

Co-administration of antineoplastics with ART is challenging due to potential drug-drug interactions (DDIs). However, trials specifically assessing such DDIs are lacking. Our objective was to simulate DDIs between the antineoplastics erlotinib and gefitinib with key antiretroviral drugs and to predict dose adjustments using a physiologically based pharmacokinetic (PBPK) model.

Methods

In vitro data describing chemical properties and pharmacokinetic processes of each drug and their effect on cytochrome P450 isoforms were obtained from the literature. Plasma drug-concentration profiles were simulated in a virtual population of 50 individuals receiving erlotinib or gefitinib alone or with darunavir/ritonavir, efavirenz or etravirine. Simulated pharmacokinetic parameters and the magnitude of DDIs with probe drugs (midazolam, maraviroc) were compared with literature values. Erlotinib and gefitinib pharmacokinetics with and without antiretrovirals were compared and dose-adjustment strategies were evaluated.

Results

Simulated parameters of each drug and the magnitude of DDIs with probe drugs were in agreement with reference values. Darunavir/ritonavir increased erlotinib and gefitinib exposure, while efavirenz and etravirine decreased erlotinib and gefitinib concentrations. Based on our predictions, dose-adjustment strategies may consist of once-daily dosing erlotinib at 25 mg and gefitinib at 125 mg with darunavir/ritonavir; or erlotinib at 200 mg and gefitinib at 375 mg with etravirine. The interaction with efavirenz was not overcome even after doubling erlotinib or gefitinib doses.

Conclusions

PBPK models predicted the in vivo pharmacokinetics of erlotinib, gefitinib and the antiretrovirals darunavir/ritonavir, efavirenz and etravirine, and the DDIs between them. The simulated dose-adjustments may represent valuable strategies to optimize antineoplastic therapy in HIV-infected patients.

Characterization of antibody response in neuroinvasive infection caused by Toscana virus

OBJECTIVES

Among sandfly-borne pathogens, Toscana virus (TOSV) is a prominent cause of summer meningitis in Mediterranean Europe. Here, we assessed the kinetics of anti-TOSV antibodies over time in 41 patients diagnosed with TOSV meningitis or meningoencephalitis in northeastern Italy.

METHODS

Acute and follow-up serum samples were collected up to 20 months after diagnosis of TOSV infection and tested for the presence of specific antibody using immunoenzymatic and indirect immunofluorescence assays. In addition, maturation of anti-TOSV IgG over time was evaluated as well as production of neutralizing antibodies.

RESULTS

Specific IgM and IgG response was present at diagnosis in 100% of patients; TOSV-specific IgM and IgG were detected in patients' sera up to 6 and 20 months after diagnosis, respectively. The avidity index (AI) increased over the first month after infection in 100% of patients and most cases exceeded 60% by Day 30 post infection. The AI subsequently plateaued then declined at 20 months after diagnosis. Finally, neutralization assay to TOSV was performed in 217 sera collected from 41 patients; 69.6% of tested samples resulted in reactive and moderate levels of neutralizing antibodies observed during all phases of infection despite high titres of total anti-TOSV IgG.

CONCLUSIONS

Specific antibody response develops rapidly and is long-lasting for neuroinvasive TOSV infection. Serodiagnosis of neuroinvasive TOSV requires simultaneous detection of specific IgM and IgG. Moderate levels of neutralizing antibodies were maintained over the study period, while the protective role of antibodies lacking neutralizing activity is unclear and requires further evaluation.

Co-circulation of two Usutu virus strains in Northern Italy between 2009 and 2014

Usutu virus is an arbovirus closely related to West Nile virus (genus Flavivirus), which circulates between mosquitoes and wild birds. This virus has been increasingly reported in Europe, raising concerns for its possible pathogenic potential for wild birds and humans. This study reports the whole genome sequences of 15 strains of USUV, isolated between 2010 and 2014 from mosquitoes and wild birds in the course of West Nile virus surveillance in the Emilia-Romagna and Lombardy regions of Northern Italy. Both whole and 656 partial genome sequences, obtained from isolated viruses and field samples (mosquitoes and wild birds), were analyzed to describe the temporal and geographical spread of USUV in the surveyed area. The detected sequences belonged to two groups, with one circulating primarily in the northwestern part of the area and the other in the southeastern part. This pattern is likely the result of different routes of introduction from the North (over the Alps) and from the East, respectively. The phylogenetic analysis of obtained sequences and other European sequences demonstrated that the majority of European strains belonged to one main clade, while less common strains, mainly from Western Europe, fell in other two clades. This analysis strongly suggested an autochthonous evolution process of strains of the main clade from a common ancestor with an estimated time of arrival in Europe at the beginning of the 1990s. In addition to causing mass mortality in wild birds, Usutu virus can infect humans and can sporadically cause disease. These factors and the endemization of the Usutu virus in a large area of Europe, sustained by the obtained data, strongly support the need to adequately survey Usutu virus in areas in which its circulation is detected.

Hospital-based enhanced surveillance for West Nile virus neuroinvasive disease

Accurate data on the incidence of West Nile virus (WNV) disease are important for directing public health education and control activities. The objective of this project was to assess the underdiagnosis of WNV neuroinvasive disease through laboratory testing of patients with suspected viral meningitis or encephalitis at selected hospitals serving WNV-endemic regions in three states. Of the 279 patients with cerebrospinal fluid (CSF) specimens tested for WNV immunoglobulin M (IgM) antibodies, 258 (92%) were negative, 19 (7%) were positive, and two (1%) had equivocal results. Overall, 63% (12/19) of patients with WNV IgM-positive CSF had WNV IgM testing ordered by their attending physician. Seven (37%) cases would not have been identified as probable WNV infections without the further testing conducted through this project. These findings indicate that over a third of WNV infections in patients with clinically compatible neurological illness might be undiagnosed due to either lack of testing or inappropriate testing, leading to substantial underestimates of WNV neuroinvasive disease burden. Efforts should be made to educate healthcare providers and laboratorians about the local epidemiology of arboviral diseases and the optimal tests to be used in different clinical situations.

Molecular epidemiology, evolution and phylogeny of Chikungunya virus: An updating review

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus belonging to the Togaviridae family, causing a febrile illness associated with severe arthralgia and rash. In this review, we summarized a series of articles published from 2013 to 2016 concerning CHIKV epidemiology, phylogeny, vaccine and therapies, to give an update of our most recent article written in 2014 (Lo Presti et al.,2014). CHIKV infection was first reported in 1952 from Makonde plateaus and since this time caused many outbreaks worldwide, involving the Indian Ocean region, African countries, American continent and Italy. CHIKV infection is still underestimated and it is normally associated with clinical symptoms overlapping with dengue virus, recurring epidemics and mutations within the viral genome. These characteristics promote the geographical spread and the inability to control vector-mediated transmission of the virus. For these reasons, the majority of studies were aimed to describe outbreaks and to enhance knowledge on CHIKV biology, pathogenesis, infection treatment, and prevention. In this review, 16 studies on CHIKV phylogenetic and phylodinamics were considered, during the years 2013-2016. Phylogenetic and phylodinamic analysis are useful tools to investigate how the genealogy of a pathogen population is influenced by pathogen's demographic history, host immunological milieu and environmental/ecological factors. Phylogenetic tools were revealed important to reconstruct the geographic spread of CHIKV during the epidemics wave and to have information on the circulating strains of the virus, that are important for the prediction and control of the epidemics, as well as for vaccines and antiviral drugs development. In conclusion, this updating review can give a critical appraisal of the epidemiology, therapeutic and phylogenesis of CHIKV, reinforcing the need to monitor the geographic spread of virus and vectors.

Meningitis Caused by Toscana Virus Is Associated with Strong Antiviral Response in the CNS and Altered Frequency of Blood Antigen-Presenting Cells

Toscana virus (TOSV) is a Phlebotomus-transmitted RNA virus and a frequent cause of human meningitis and meningoencephalitis in Southern Europe during the summer season. While evidence for TOSV-related central nervous system (CNS) cases is increasing, little is known about the host defenses against TOSV. We evaluated innate immune response to TOSV by analyzing frequency and activation of blood antigen-presenting cells (APCs) and cytokine levels in plasma and cerebrospinal fluid (CSF) from patients with TOSV neuroinvasive infection and controls. An altered frequency of different blood APC subsets was observed in TOSV-infected patients, with signs of monocytic deactivation. Nevertheless, a proper or even increased responsiveness of toll-like receptor 3 and 7/8 was observed in blood APCs of these patients as compared to healthy controls. Systemic levels of cytokines remained low in TOSV-infected patients, while levels of anti-inflammatory and antiviral mediators were significantly higher in CSF from TOSV-infected patients as compared to patients with other infectious and noninfectious neurological diseases. Thus, the early host response to TOSV appears effective for viral clearance, by proper response to TLR3 and TLR7/8 agonists in peripheral blood and by a strong and selective antiviral and anti-inflammatory response in the CNS.

Comparison of Two Commercial Tick-Borne Encephalitis Virus IgG Enzyme-Linked Immunosorbent Assays

Despite the availability of protective vaccines, tick-borne encephalitis virus (TBEV) infections have been increasingly reported to the European Centre for Disease Prevention and Control in the past 2 decades. Since the diagnosis of TBEV exposure relies on serological testing, we compared two commercial enzyme-linked immunosorbent assays (ELISAs), i.e., Immunozym FSME IgG assay (ELISA-1) and Euroimmun FSME Vienna IgG assay (ELISA-2). Both assays use whole TBEV antigens, but they differ in viral strains (Neudoerfl for ELISA-1 and K23 for ELISA-2) and cutoff values. In testing of samples from 398 healthy blood donors, ELISA-1 showed higher reactivity levels than ELISA-2 (P < 0.001), suggesting different assay properties. This finding was supported by Bland-Altman analysis of the optical density at 450 nm (OD450) (mean bias, +0.32 [95% limits of agreement, -0.31 to +0.95]) and persisted after transformation into Vienna units. Concordant results were observed for 276 sera (69%) (44 positive and 232 negative results). Discordant results were observed for 122 sera (31%); 15 were fully discordant, all being ELISA-1 positive and ELISA-2 negative, and 107 were partially discordant (101 being ELISA-1 indeterminate and ELISA-2 negative and 6 having positive or indeterminate reactivity in both ELISAs). Neutralization testing at a 1:10 dilution yielded positive results for 33 of 44 concordant positive sera, 1 of 15 fully discordant sera, and 1 of 33 partially discordant sera. Indirect immunofluorescence testing revealed high antibody titers of ≥100 for yellow fever virus in 18 cases and for dengue virus in one case, suggesting that cross-reactivity contributed to the ELISA-1 results. We conclude that (i) cross-reactivity among flaviviruses remains a limitation of TBEV serological testing, (ii) ELISA-2 revealed reasonable sensitivity and specificity for anti-TBEV IgG population screening of human sera, and (iii) neutralization testing is most specific and should be reserved for selective questions.

First evidence of simultaneous occurrence of West Nile virus and Usutu virus neuroinvasive disease in humans in Croatia during the 2013 outbreak

PURPOSE

We report on first evidence of simultaneous occurrence of West Nile virus (WNV) and Usutu virus (USUV) neuroinvasive infection in humans in Croatia during the transmission season 2013.

METHODS

From June to December 2013, a total of 95 patients with clinically suspected WNV infection (WNV fever and neuroinvasive disease) were tested for WNV IgM/IgG antibodies using enzyme-linked immunosorbent assay. Twenty-six reactive samples were further tested by virus neutralization test for confirmation.

RESULTS

WNV neuroinvasive infection was confirmed in 20 patients, while in three patients USUV neutralizing antibodies were detected. Cases occurred during the 11-week interval (from 24 July to 07 October 2013). Both WNV and USUV cases were distributed in three north-western Croatian counties. In addition to human cases, recent asymptomatic WNV infection (detection of IgM antibodies) was recorded in 9/3,460 (0.3 %) tested sentinel horses. Infected animals were recorded in two eastern and one north-western county.

CONCLUSIONS

Our results indicate co-circulation of WNV and USUV in Croatia. WNV infection could be misdiagnosed with other emerging infectious diseases presenting with neurological symptoms such as USUV infection.