Aspects de la pathogenese moleculaire d'une maladie connue depuis l'Antiquite: la polyomyelite paralytique

SIGLEINIST T 74850 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Arboviruses and pregnancy: maternal, fetal, and neonatal effects

International audienceArboviruses are an expanding public health threat, with pregnant women facing unique complications from arbovirus infections. These infections, such as dengue and Crimean–Congo haemorrhagic fever, can be more severe in pregnant women than in the general population. Vertical transmission is reported for many arboviruses and can severely affect pregnancy outcome. Indeed, arboviruses—particularly flaviviruses and alphaviruses—are associated with increased risks of fetal loss and premature birth. Arboviruses can be teratogenic, as is the case for Zika virus and Venezuelan equine encephalitis virus. Finally, intrapartum transmission can result in severe neonatal infections, as is true for chikungunya virus. Although the global burden of arboviruses is well recognised, few studies have provided data on arbovirus infection specifically in the context of maternal and child health. Epidemiological and clinical studies are therefore needed to better assess the burden of arbovirus infections during pregnancy and to improve the prevention and clinical management of these viral infections. In this Review, we analyse the information available and identify gaps in knowledge that require further assessment

An <em>ex vivo</em> murine model to study poliovirus-induced apoptosis in nerve cells

International audienceParalytic poliomyelitis results from destruction of motor neurons owing to poliovirus (PV) replication. Using a mouse model, we have previously shown that PV kills neurons of the central nervous system (CNS) as a result of apoptosis (Girard et al., Journal of Virology 73, 6066-6072, 1999). We report the development of mixed mouse primary nerve cell cultures from the cerebral cortex of neonatal mice transgenic for the human PV receptor. These cultures contained all three main cell types of the CNS, i.e. neurons, astrocytes and oligodendrocytes. All three cell types were susceptible to PV infection and virus replication in the cultures led to DNA fragmentation characteristic of apoptosis. PV-induced apoptosis was inhibited by the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(O-Me) fluoromethyl ketone (Z-VAD.FMK), indicating that this process involved caspases. Thus, these mixed mouse primary nerve cell cultures are a new in vitro model for studying the molecular mechanisms of PV-induced apoptosis in nerve cells

Virus replicon particle based Chikungunya virus neutralization assay using Gaussia luciferase as readout

International audienceBackgroundChikungunya virus (CHIKV) has been responsible for large epidemic outbreaks causing fever, headache, rash and severe arthralgia. So far, no specific treatment or vaccine is available. As nucleic acid amplification can only be used during the viremic phase of the disease, serological tests like neutralization assays are necessary for CHIKV diagnosis and for determination of the immune status of a patient. Furthermore, neutralization assays represent a useful tool to validate the efficacy of potential vaccines. As CHIKV is a BSL3 agent, neutralization assays with infectious virus need to be performed under BSL3 conditions. Our aim was to develop a neutralization assay based on non-infectious virus replicon particles (VRPs).MethodsVRPs were produced by cotransfecting baby hamster kidney-21 cells with a CHIKV replicon expressing Gaussia luciferase (Gluc) and two helper RNAs expressing the CHIKV capsid protein or the remaining structural proteins, respectively. The resulting single round infectious particles were used in CHIKV neutralization assays using secreted Gluc as readout.ResultsUpon cotransfection of a CHIKV replicon expressing Gluc and the helper RNAs VRPs could be produced efficiently under optimized conditions at 32°C. Infection with VRPs could be measured via Gluc secreted into the supernatant. The successful use of VRPs in CHIKV neutralization assays was demonstrated using a CHIKV neutralizing monoclonal antibody or sera from CHIKV infected patients. Comparison of VRP based neutralization assays in 24- versus 96-well format using different amounts of VRPs revealed that in the 96-well format a high multiplicity of infection is favored, while in the 24-well format reliable results are also obtained using lower infection rates. Comparison of different readout times revealed that evaluation of the neutralization assay is already possible at the same day of infection.ConclusionsA VRP based CHIKV neutralization assay using Gluc as readout represents a fast and useful method to determine CHIKV neutralizing antibodies without the need of using infectious CHIKV

Chikungunya Virus Pathogenesis and Immunity

International audienceChikungunya virus (CHIKV) is an arbovirus associated with acute and chronic arthralgia that re-emerged in the Indian Ocean islands in 2005–2006 and is currently responsible for the ongoing outbreaks in the Caribbean islands and the Americas. We describe here the acute and chronic clinical manifestations of CHIKV in patients that define the disease. We also review the various animal models that have been developed to study CHIKV infection and pathology and further strengthened the understanding of the cellular and molecular mechanisms of CHIKV infection and immunity. A complete understanding of the immunopathogenesis of CHIKV infection will help develop the needed preventive and therapeutic approaches to combat this arbovirosis

Zika virus infects human testicular tissue and germ cells

International audienceZika virus (ZIKV) is a teratogenic mosquito-borne flavivirus that can be sexually transmitted from man to woman. The finding of high viral loads and prolonged viral shedding in semen suggests that ZIKV replicates within the human male genital tract, but its target organs are unknown. Using ex vivo infection of organotypic cultures, we demonstrated here that ZIKV replicates in human testicular tissue and infects a broad range of cell types, including germ cells, which we also identified as infected in semen from ZIKV-infected donors. ZIKV had no major deleterious effect on the morphology and hormonal production of the human testis explants. Infection induced a broad antiviral response but no IFN upregulation and minimal proinflammatory response in testis explants, with no cytopathic effect. Finally, we studied ZIKV infection in mouse testis and compared it to human infection. This study provides key insights into how ZIKV may persist in semen and alter semen parameters, as well as a valuable tool for testing antiviral agents

Therapeutics and Vaccines Against Chikungunya Virus

Erratum in Correction to: Vector Borne Zoonotic Dis 2015;15(4):250-257 DOI: 10.1089/vbz.2014.1681. [Vector Borne Zoonotic Dis. 2015]International audienceCurrently, there are no licensed vaccines or therapies available against chikungunya virus (CHIKV), and these were subjects discussed during a CHIKV meeting recently organized in Langkawi, Malaysia. In this review, we chart the approaches taken in both areas. Because of a sharp increase in new data in these fields, the present paper is complementary to previous reviews by Weaver et al. in 2012 and Kaur and Chu in 2013. The most promising antivirals so far discovered are reviewed, with a special focus on the virus-encoded replication proteins as potential targets. Within the vaccines in development, our review emphasizes the various strategies in parallel development that are unique in the vaccine field against a single disease

Mapping of Chikungunya Virus Interactions with Host Proteins Identified nsP2 as a Higly Connected Viral Component

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that has been responsible for an epidemic outbreak of unprecedented magnitude in recent years. Since then, significant efforts have been made to better understand the biology of this virus but we still have a poor knowledge of CHIKV interactions with host cell components at the molecular level. Here we describe the extensive use of high-throughput yeast two-hybrid (HT-Y2H) to characterize interactions between CHIKV and human proteins. A total of 22 high-confidence interactions, which essentially involved the viral non-structural protein nsP2, were identified and further validated by protein complementation assay (PCA). These results were integrated to a larger network obtained by extensive mining of literature for alphavirus-host interactions. To investigate the role of cellular proteins interacting with nsP2, gene silencing experiments were performed in cells infected by a recombinant CHIKV expressing Renilla luciferase as a reporter. Collected data involve heterogeneous nuclear ribonucleoprotein K (hnRNP-K) and ubiquilin 4 (UBQLN4) in CHIKV replication in vitro. In addition, we showed that CHIKV nsP2 induces a cellular shut-off as previously reported for other Old-World alphaviruses, and determined that among binding partners identified by yeast two-hybrid, the tetratricopeptide repeat protein 7B (TTC7B) plays a significant role in this activity. Altogether, this report provides a first interaction map between CHIKV and human proteins, and involves new host cell proteins in the replication cycle of this virus.info:eu-repo/semantics/publishe