Hepatitis C virus (HCV) prevalence estimation in the adult general population in Belgium : a meta-analysis.

BACKGROUND AND STUDY AIMS: Although multiple HCV prevalence studies were recently performed in the general population from Belgium, they suffer from a lack of geographical representativeness, an insufficient number of participants or a lack of inclusion of high prevalence groups. The aim of this study is to provide robust information on the HCV burden. METHODS: Recently performed HCV prevalence studies in the general, adult population were included in this study, based on well-defined selection criteria. A meta-analysis was performed to estimate the seroprevalence, the prevalence of participants with viremia and the prevalence estimation for people with viremia which were unaware of their status. RESULTS: Eight studies fulfilled the criteria for inclusion of the quantitative prevalence estimation. Based on the meta-analysis on these 8 studies, we estimated an HCV seroprevalence of 1.01% [95% CI : 0.66-1.42%], representing a total of 90,722 adult, HCV seropositives of which 64,412 individuals (0.71%) were confirmed seropositive. Based on the RNA presence, an estimated viremic prevalence of 0.33% [95% CI : 0.21-0.47 %] was determined, corresponding with 29,642 individuals. This is 46,0% of the true HCV seropositive residents. Further, based on the availability of patient information in 5 out of the 8 studies, a prevalence of 0.18% [95% CI : 0.07-0.33] representing 16,168 individuals from the adult Belgian population are unaware of their HCV status. CONCLUSIONS: We believe that the quantitative measurement by the meta-analysis will be more reliable for their use in the design of a screening strategy or in the development of prevention campaigns as compared to the prevalence estimations performed at local level.

Inhibition of MALT1 Decreases Neuroinflammation and Pathogenicity of Virulent Rabies Virus in Mice.

Rabies virus is a neurovirulent RNA virus, which causes about 59,000 human deaths each year. Treatment for rabies does not exist due to incomplete understanding of the pathogenesis. MALT1 mediates activation of several immune cell types and is involved in the proliferation and survival of cancer cells. MALT1 acts as a scaffold protein for NF-κB signaling and a cysteine protease that cleaves substrates, leading to the expression of immunoregulatory genes. Here, we examined the impact of genetic or pharmacological MALT1 inhibition in mice on disease development after infection with the virulent rabies virus strain CVS-11. Morbidity and mortality were significantly delayed in Malt1-/- compared to Malt1+/+ mice, and this effect was associated with lower viral load, proinflammatory gene expression, and infiltration and activation of immune cells in the brain. Specific deletion of Malt1 in T cells also delayed disease development, while deletion in myeloid cells, neuronal cells, or NK cells had no effect. Disease development was also delayed in mice treated with the MALT1 protease inhibitor mepazine and in knock-in mice expressing a catalytically inactive MALT1 mutant protein, showing an important role of MALT1 proteolytic activity. The described protective effect of MALT1 inhibition against infection with a virulent rabies virus is the precise opposite of the sensitizing effect of MALT1 inhibition that we previously observed in the case of infection with an attenuated rabies virus strain. Together, these data demonstrate that the role of immunoregulatory responses in rabies pathogenicity is dependent on virus virulence and reveal the potential of MALT1 inhibition for therapeutic intervention.IMPORTANCE Rabies virus is a neurotropic RNA virus that causes encephalitis and still poses an enormous challenge to animal and public health. Efforts to establish reliable therapeutic strategies have been unsuccessful and are hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protease that mediates the activation of several innate and adaptive immune cells in response to multiple receptors, and therapeutic MALT1 targeting is believed to be a valid approach for autoimmunity and MALT1-addicted cancers. Here, we study the impact of MALT1 deficiency on brain inflammation and disease development in response to infection of mice with the highly virulent CVS-11 rabies virus. We demonstrate that pharmacological or genetic MALT1 inhibition decreases neuroinflammation and extends the survival of CVS-11-infected mice, providing new insights in the biology of MALT1 and rabies virus infection.

MALT1 Controls Attenuated Rabies Virus by Inducing Early Inflammation and T Cell Activation in the Brain.

MALT1 is involved in the activation of immune responses, as well as in the proliferation and survival of certain cancer cells. MALT1 acts as a scaffold protein for NF-κB signaling and a cysteine protease that cleaves substrates, further promoting the expression of immunoregulatory genes. Deregulated MALT1 activity has been associated with autoimmunity and cancer, implicating MALT1 as a new therapeutic target. Although MALT1 deficiency has been shown to protect against experimental autoimmune encephalomyelitis, nothing is known about the impact of MALT1 on virus infection in the central nervous system. Here, we studied infection with an attenuated rabies virus, Evelyn-Rotnycki-Abelseth (ERA) virus, and observed increased susceptibility with ERA virus in MALT1-/- mice. Indeed, after intranasal infection with ERA virus, wild-type mice developed mild transient clinical signs with recovery at 35 days postinoculation (dpi). Interestingly, MALT1-/- mice developed severe disease requiring euthanasia at around 17 dpi. A decreased induction of inflammatory gene expression and cell infiltration and activation was observed in MALT1-/- mice at 10 dpi compared to MALT1+/+ infected mice. At 17 dpi, however, the level of inflammatory cell activation was comparable to that observed in MALT1+/+ mice. Moreover, MALT1-/- mice failed to produce virus-neutralizing antibodies. Similar results were obtained with specific inactivation of MALT1 in T cells. Finally, treatment of wild-type mice with mepazine, a MALT1 protease inhibitor, also led to mortality upon ERA virus infection. These data emphasize the importance of early inflammation and activation of T cells through MALT1 for controlling the virulence of an attenuated rabies virus in the brain.IMPORTANCE Rabies virus is a neurotropic virus which can infect any mammal. Annually, 59,000 people die from rabies. Effective therapy is lacking and hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protein involved in innate and adaptive immunity and is an interesting therapeutic target because MALT1-deregulated activity has been associated with autoimmunity and cancers. The role of MALT1 in viral infection is, however, largely unknown. Here, we study the impact of MALT1 on virus infection in the brain, using the attenuated ERA rabies virus in different models of MALT1-deficient mice. We reveal the importance of MALT1-mediated inflammation and T cell activation to control ERA virus, providing new insights in the biology of MALT1 and rabies virus infection.

Hepatitis E virus (HEV): seroprevalence and HEV RNA detection in subjects attending a sexually transmitted infection clinic in Brussels, Belgium.

Men who have sex with men (MSM) have an increased incidence of pathogens transmitted by the oro-fecal route. Hepatitis E virus (HEV) is an emerging cause of acute hepatitis and fecal shedding is observed during primary infection. We investigated whether MSM are at increased risk of HEV infection. Subjects who attended a sexually transmitted infection clinic in Brussels and had an HIV test performed between 1 June 2014 and 15 January 2016 were identified. A total of 576 samples were retrospectively screened for both total HEV IgG and HEV RNA. Samples positive for IgG were tested for IgM. MSM proportion was 31·1% (179/576). Overall HEV IgG prevalence was 9·03% (52/576) and was identical in MSM and heterosexual subjects. Among the IgG positive samples, 2/52 (3·84%) samples (both women) were positive for anti-HEV IgM. No sample was positive for HEV RNA. Age over 35 was the only risk factor significantly associated with HEV seropositivity (OR 2·07; 95% CI 1·16-3·67). In conclusion, MSM were not found to have an increased prevalence of HEV as previously reported in other European countries suggesting distinct dynamics of HEV infection in this group across Europe and increased age was associated with a higher risk of seropositivity.

Impact of caspase-1/11, -3, -7, or IL-1ß/IL-18 deficiency on rabies virus-induced macrophage cell death and onset of disease.

Rabies virus is a highly neurovirulent RNA virus, which causes about 59000 deaths in humans each year. Previously, we described macrophage cytotoxicity upon infection with rabies virus. Here we examined the type of cell death and the role of specific caspases in cell death and disease development upon infection with two laboratory strains of rabies virus: Challenge Virus Standard strain-11 (CVS-11) is highly neurotropic and lethal for mice, while the attenuated Evelyn-Rotnycki-Abelseth (ERA) strain has a broader cell tropism, is non-lethal and has been used as an oral vaccine for animals. Infection of Mf4/4 macrophages with both strains led to caspase-1 activation and IL-1ß and IL-18 production, as well as activation of caspases-3, -7, -8, and -9. Moreover, absence of caspase-3, but not of caspase-1 and -11 or -7, partially inhibited virus-induced cell death of bone marrow-derived macrophages. Intranasal inoculation with CVS-11 of mice deficient for either caspase-1 and -11 or -7 or both IL-1ß and IL-18 led to general brain infection and lethal disease similar to wild-type mice. Deficiency of caspase-3, on the other hand, significantly delayed the onset of disease, but did not prevent final lethal outcome. Interestingly, deficiency of caspase-1/11, the key executioner of pyroptosis, aggravated disease severity caused by ERA virus, whereas wild-type mice or mice deficient for either caspase-3, -7, or both IL-1ß and IL-18 presented the typical mild symptoms associated with ERA virus. In conclusion, rabies virus infection of macrophages induces caspase-1- and caspase-3-dependent cell death. In vivo caspase-1/11 and caspase-3 differently affect disease development in response to infection with the attenuated ERA strain or the virulent CVS-11 strain, respectively. Inflammatory caspases seem to control attenuated rabies virus infection, while caspase-3 aggravates virulent rabies virus infection.

Favourable outcome in a patient bitten by a rabid bat infected with the European bat lyssavirus-1.

The classic rabies virus (genotype 1) has been eliminated in Western Europe, but related lyssaviruses still circulate in local bats. In August 2010, a Belgian photographer was bitten upon provocation of a disoriented Eptesicus serotinus bat in Spain. The bat was infected with European bat lyssavirus-1 (genotype 5). The isolate proved highly neurovirulent in mice. The patient had received preventive rabies immunisations years before the incident and received two boosters with the HDCV rabies vaccine afterwards. Available vaccines are based on the classic rabies virus, which is significantly divergent from the European bat lyssavirus-1. Fortunately, the patient's serological immune response demonstrated satisfactory neutralisation of the 2010 EBLV-1 isolate, using an intracerebral challenge model in mice. Most likely, the patient's life was saved thanks to vaccination with the classic rabies vaccine, which proved sufficiently protective against European bat lyssavirus-1. This case highlights the need for preventive rabies vaccination in people, who come in contact with bats and to seek medical council after a scratch or bite from a bat.

The caspase-generated fragments of PKR cooperate to activate full-length PKR and inhibit translation.

We have studied the involvement of receptor interacting protein kinase-1 (RIP1) and dsRNA-activated protein kinase (PKR) in external dsRNA-induced apoptotic and necrotic cell death in Jurkat T cell lymphoma. Our results suggest that RIP1 plays an imported role in dsRNA-induced apoptosis and necrosis. We demonstrated that contrary to necrosis, protein synthesis is inhibited in apoptosis. Here, we show that phosphorylation of translation initiation factor 2-alpha (eukaryotic initiation factor 2-alpha (eIF2-alpha)) and its kinase, PKR, occur in dsRNA-induced apoptosis but not in necrosis. These events are caspase-dependent and coincide with the appearance of the caspase-mediated PKR fragments, N-terminal domain (ND) and kinase domain (KD). Our immunoprecipitation experiments demonstrated that both fragments could independently co-precipitate with full-length PKR. Expression of PKR-KD leads to PKR and eIF2-alpha phosphorylation and inhibits protein translation, whereas that of PKR-ND does not. Co-expression of PKR-ND and PKR-KD promotes their interaction with PKR, PKR and eIF2-alpha phosphorylation and suppresses protein translation better than PKR-KD alone. Our findings suggest a caspase-dependent mode of activation of PKR in apoptosis in which the PKR-KD fragment interacts with and activates intact PKR. PKR-ND facilitates the interaction of PKR-KD with full-length PKR and thus the activation of the kinase and amplifies the translation inhibitory signal.