Manuel Schibler

Identification of site-specific adaptations conferring increased neural cell tropism during human enterovirus 71 infection.

Enterovirus 71 (EV71) is one of the most virulent enteroviruses, but the specific molecular features that enhance its ability to disseminate in humans remain unknown. We analyzed the genomic features of EV71 in an immunocompromised host with disseminated disease according to the different sites of infection. Comparison of five full-length genomes sequenced directly from respiratory, gastrointestinal, nervous system, and blood specimens revealed three nucleotide changes that occurred within a five-day period: a non-conservative amino acid change in VP1 located within the BC loop (L97R), a region considered as an immunogenic site and possibly important in poliovirus host adaptation; a conservative amino acid substitution in protein 2B (A38V); and a silent mutation in protein 3D (L175). Infectious clones were constructed using both BrCr (lineage A) and the clinical strain (lineage C) backgrounds containing either one or both non-synonymous mutations. In vitro cell tropism and competition assays revealed that the VP197 Leu to Arg substitution within the BC loop conferred a replicative advantage in SH-SY5Y cells of neuroblastoma origin. Interestingly, this mutation was frequently associated in vitro with a second non-conservative mutation (E167G or E167A) in the VP1 EF loop in neuroblastoma cells. Comparative models of these EV71 VP1 variants were built to determine how the substitutions might affect VP1 structure and/or interactions with host cells and suggest that, while no significant structural changes were observed, the substitutions may alter interactions with host cell receptors. Taken together, our results show that the VP1 BC loop region of EV71 plays a critical role in cell tropism independent of EV71 lineage and, thus, may have contributed to dissemination and neurotropism in the immunocompromised patient.

Astrovirus Infection in Hospitalized Infants with Severe Combined Immunodeficiency after Allogeneic Hematopoietic Stem Cell Transplantation

Infants with severe primary combined immunodeficiency (SCID) and children post-allogeneic hematopoietic stem cell transplantation (HSCT) are extremely susceptible to unusual infections. The lack of generic tools to detect disease-causing viruses among more than 200 potential human viral pathogens represents a major challenge to clinicians and virologists. We investigated retrospectively the causes of a fatal disseminated viral infection with meningoencephalitis in an infant with gamma C-SCID and of chronic gastroenteritis in 2 other infants admitted for HSCT during the same time period. Analysis was undertaken by combining cell culture, electron microscopy and sequence-independent single primer amplification (SISPA) techniques. Caco-2 cells inoculated with fecal samples developed a cytopathic effect and non-enveloped viral particles in infected cells were detected by electron microscopy. SISPA led to the identification of astrovirus as the pathogen. Both sequencing of the capsid gene and the pattern of infection suggested nosocomial transmission from a chronically excreting index case to 2 other patients leading to fatal infection in 1 and to transient disease in the others. Virus-specific, real-time reverse transcription polymerase chain reaction was then performed on different stored samples to assess the extent of infection. Infection was associated with viremia in 2 cases and contributed to death in 1. At autopsy, viral RNA was detected in the brain and different other organs, while immunochemistry confirmed infection of gastrointestinal tissues. This report illustrates the usefulness of the combined use of classical virology procedures and modern molecular tools for the diagnosis of unexpected infections. It illustrates that astrovirus has the potential to cause severe disseminated lethal infection in highly immunocompromised pediatric patients.

Clinical features and viral kinetics in a rapidly cured patient with Ebola virus disease: a case report

BACKGROUND A detailed description of viral kinetics, duration of virus shedding, and intraviral evolution in different body sites is warranted to understand Ebola virus pathogenesis. Patients with Ebola virus infections admitted to university hospitals provide a unique opportunity to do such in-depth virological investigations. We describe the clinical, biological, and virological follow-up of a case of Ebola virus disease. METHODS A 43-year-old medical doctor who contracted an Ebola virus infection in Sierra Leone on Nov 16, 2014 (day 1), was airlifted to Geneva University Hospitals, Geneva, Switzerland, on day 5 after disease onset. The patient received an experimental antiviral treatment of monoclonal antibodies (ZMAb) and favipiravir. We monitored daily viral load kinetics, estimated viral clearance, calculated the half-life of the virus in plasma, and analysed the viral genome via high-throughput sequencing, in addition to clinical and biological signs. FINDINGS The patient recovered rapidly, despite an initial high viral load (about 1 × 10(7) RNA copies per mL 24 h after onset of fever). We noted a two-phase viral decay. The virus half-life decreased from about 26 h to 9·5 h after the experimental antiviral treatment. Compared with a consensus sequence of June 18, 2014, the isolate that infected this patient displayed only five synonymous nucleotide substitutions on the full genome (4901A→C, 7837C→T, 8712A→G, 9947T→C, 16201T→C) despite 5 months of human-to-human transmission. INTERPRETATION This study emphasises the importance of virological investigations to fully understand the course of Ebola virus disease and adaptation of the virus. Whether the viral decay was caused by the effects of the immune response alone, an additional benefit from the antiviral treatment, or a combination of both is unclear. In-depth virological analysis and randomised controlled trials are needed before any conclusion on the potential effect of antiviral treatment can be drawn. FUNDING Geneva University Hospitals, Swiss Office of Public Health, Swiss Agency for Development and Cooperation, and Swiss National Science Foundation.

Sequelae of Ebola virus disease: the emergency within the emergency

As the massive outbreak of Ebola virus disease (EVD) in west Africa wanes, it has become increasingly clear that thousands of survivors have many sequelae, some of which might be very severe, such as arthritis and vision-threatening uveitis. The mental health effects of EVD on survivors and other family and community members is similarly profound. Furthermore, it is increasingly being recognised that Ebola virus might persist for weeks or months in selected body compartments of survivors, most notably in the semen of men, bringing risk of renewed transmission where it has previously been eliminated. These challenges to EVD survivors constitute a new emergency in terms of addressing individual patient need and to control the disease spread. In this Review, we assess what is known regarding the sequelae of EVD, including possible delayed virus clearance. We discuss some of the key challenges regarding the provision of care to survivors and implementation of necessary future research.

Astrovirus MLB2, a New Gastroenteric Virus Associated with Meningitis and Disseminated Infection

This virus is an unrecognized cause of central nervous system infection, particularly among immunocompromised patients.

Critical Analysis of Rhinovirus RNA Load Quantification by Real-Time Reverse Transcription-PCR

ABSTRACT Rhinoviruses are the most frequent cause of human respiratory infections, and quantitative rhinovirus diagnostic tools are needed for clinical investigations. Although results obtained by real-time reverse-transcription PCR (RT-PCR) assays are frequently converted to viral RNA loads, this presents several limitations regarding accurate virus RNA quantification, particularly given the need to reliably quantify all known rhinovirus genotypes with a single assay. Using an internal extraction control and serial dilutions of an in vitro-transcribed rhinovirus RNA reference standard, we validated a quantitative one-step real-time PCR assay. We then used chimeric rhinovirus genomes with 5′-untranslated regions (5′UTRs) originating from the three rhinovirus species and from one enterovirus to estimate the impact of the 5′UTR diversity. Respiratory specimens from infected patients were then also analyzed. The assay quantification ability ranged from 4.10 to 9.10 log RNA copies/ml, with an estimated error margin of ±10%. This variation was mainly linked to target variability and interassay variability. Taken together, our results indicate that our assay can reliably estimate rhinovirus RNA load, provided that the appropriate error margin is used. In contrast, due to the lack of a universal rhinovirus RNA standard and the variability related to sample collection procedures, accurate absolute rhinovirus RNA quantification in respiratory specimens is currently hardly feasible.

Ebola virus disease diagnosis by real-time RT-PCR: A comparative study of 11 different procedures.

BACKGROUND The diagnosis of Ebola virus disease relies on the detection of viral RNA in blood by real-time reverse-transcription PCR. While several of these assays were developed during the unprecedented 2013-2015 Ebola virus disease outbreak in West Africa, few were applied in the field. OBJECTIVES To compare technical performances and practical aspects of 11 Ebola virus real-time reverse-transcription PCR procedures. STUDY DESIGN We selected the most promising assays using serial dilutions of culture-derived Ebola virus RNA and determined their analytical sensitivity and potential range of quantification using quantified in vitro transcribed RNA; viral load values in the serum of an Ebola virus disease patient obtained with these assays were reported. Finally, ease of use and turnaround times of these kits were evaluated. RESULTS Commercial assays were at least as sensitive as in-house tests. Five of the former (Altona, Roche, Fast-track Diagnostics, and Life Technologies) were selected for further evaluation. Despite differences in analytical sensitivity and limits of quantification, all of them were suitable for Ebola virus diagnosis and viral load estimation. The Lifetech Lyophilized Ebola Virus (Zaire 2014) assay (Life Technologies) appeared particularly promising, displaying the highest analytical sensitivity and shortest turnaround time, in addition to requiring no reagent freezing. CONCLUSIONS Commercial kits were at least as sensitive as in-house tests and potentially easier to use in the field than the latter. This qualitative comparison of real-time reverse transcription PCR assays may serve as a basis for the design of future Ebola virus disease diagnostics.

Treatment challenges associated with bone echinococcosis

OBJECTIVES In this literature review, we concentrate on epidemiology and therapy of osseous echinococcosis, with an emphasis on the recurrence risk. METHODS Literature review 1930-2012. RESULTS We retrieved 200 publications based upon single case reports or case series, mostly from resource-poor settings. Among the 721 rural patients (22% females; median age 37 years), 60% of all reported cases were from the Mediterranean region and almost all patients were immune competent. Echinococcus granulosus was identified as the most frequent species. Most infections involved a single bone (602/721; 83%) and often the spine (321 cases; 45%). In eight cases (8/702; 1%), a secondary bacterial surgical site infection was reported. Surgical intervention was performed in 702 cases (97%), with single intervention in 687 episodes (95%). Complete excision of the lesion was possible in only 117 episodes (16%). Albendazole was by far the most frequently used agent in monotherapy with various dosages, while mebendazole in monotherapy was less frequent (32 cases). The median duration of antihelminthic therapy was 6 months (range 0.7-144 months). There were 124 recurrences (17%) after a median delay of 2 years (range 0.4-17 years). In multivariate analysis, the presence of visceral organ involvement increased the odds of recurrence by 5.4 (95% CI 3.1-9.4), whereas the number of surgical interventions, the duration of antihelminthic therapy or the use of hypertonic saline did not influence recurrence. CONCLUSIONS Bone echinococcosis is a rare parasitic disease. While treatment modalities vary considerably, combined surgical and medical approaches are the standard of care with a 17% risk of recurrence.

Chimeric Rhinoviruses Obtained via Genetic Engineering or Artificially Induced Recombination Are Viable Only if the Polyprotein Coding Sequence Derives from the Same Species

ABSTRACT Recombination is a widespread phenomenon that ensures both the stability and variation of RNA viruses. This phenomenon occurs with different frequencies within species of the Enterovirus genus. Intraspecies recombination is described frequently among non-rhinovirus enteroviruses but appears to be sporadic in rhinoviruses. Interspecies recombination is even rarer for rhinoviruses and mostly is related to ancient events which contributed to the speciation of these viruses. We reported that artificially engineered 5′ untranslated region (UTR) interspecies rhinovirus/rhinovirus or rhinovirus/non-rhinovirus enterovirus recombinants are fully viable. Using a similar approach, we demonstrated in this study that exchanges of the P1-2A polyprotein region between members of the same rhinovirus species, but not between members of different species, give rise to competent chimeras. To further assess the rhinovirus intra- and interspecies recombination potential, we used artificially induced recombination by cotransfection of 5′-end-deleted and 3′-end-deleted and replication-deficient genomes. In this system, intraspecies recombination also resulted in viable viruses with high frequency, whereas no interspecies rhinovirus recombinants could be recovered. Mapping intraspecies recombination sites within the polyprotein highlighted recombinant hotspots in nonstructural genes and at gene boundaries. Notably, all recombinants occurring at gene junctions presented in-frame sequence duplications, whereas most intragenic recombinants were homologous. Taken together, our results suggest that only intraspecies recombination gives rise to viable rhinovirus chimeras in the polyprotein coding region and that recombination hotspots map to nonstructural genes with in-frame duplications at gene boundaries. These data provide new insights regarding the mechanism and limitations of rhinovirus recombination. IMPORTANCE Recombination represents a means to ensure both the stability and the variation of RNA viruses. While intraspecies recombination is described frequently among non-rhinovirus enteroviruses, it seems to occur more rarely in rhinoviruses. Interspecies recombination is even rarer in this virus group and is mostly related to ancient events, which contributed to its speciation. We used engineered chimeric genomes and artificially induced RNA recombination to study experimentally the recombination potential of rhinoviruses and analyze recombination sites. Our results suggest that only intraspecies recombination gives rise to viable chimeras in the polyprotein coding region. Furthermore, characterization of intraspecies chimeras provides new insight into putative recombination hotspots within the polyprotein. In summary, we applied two powerful and complementary experimental approaches to improve current knowledge on rhinovirus recombination.

The 2014–2015 Ebola outbreak in West Africa: Hands On

The International Consortium for Prevention and Infection Control (ICPIC) organises a biannual conference (ICPIC) on various subjects related to infection prevention, treatment and control. During ICPIC 2015, held in Geneva in June 2015, a full one-day session focused on the 2014–2015 Ebola virus disease (EVD) outbreak in West Africa. This article is a non-exhaustive compilation of these discussions. It concentrates on lessons learned and imagining a way forward for the communities most affected by the epidemic. The reader can access video recordings of all lectures delivered during this one-day session, as referenced. Topics include the timeline of the international response, linkages between the dynamics of the epidemic and infection prevention and control, the importance of community engagement, and updates on virology, diagnosis, treatment and vaccination issues. The paper also includes discussions from public health, infectious diseases, critical care and infection control experts who cared for patients with EVD in Africa, in Europe, and in the United Sates and were involved in Ebola preparedness in both high- and low-resource settings and countries. This review concludes that too little is known about the pathogenesis and treatment of EVD, therefore basic and applied research in this area are urgently required. Furthermore, it is clear that epidemic preparedness needs to improve globally, in particular through the strengthening of health systems at local and national levels. There is a strong need for culturally sensitive approaches to public health which could be designed and delivered by social scientists and medical professionals working together. As of December 2015, this epidemic killed more than 11,000 people and infected more than 28,000; it has also generated more than 17,000 survivors and orphans, many of whom face somatic and psychological complications. The continued treatment and rehabilitation of these people is a public health priority, which also requires an integration of specific medical and social science approaches, not always available in West Africa.