Gut Microbiota Perturbation in IgA Deficiency Is Influenced by IgA-Autoantibody Status.

BACKGROUND & AIMS: IgA exerts its primary function at mucosal surfaces, where it binds microbial antigens to regulate bacterial growth and epithelial attachment. One third of individuals with IgA deficiency (IgAD) suffers from recurrent mucosal infections, possibly related to an altered microbiota. We aimed to delineate the impact of IgAD and the IgA-autoantibody status on the composition and functional capacity of the gut microbiota. METHODS: We performed a paired, lifestyle-balanced analysis of the effect of IgA on the gut microbiota composition and functionality based on fecal samples from individuals with IgAD and IgA-sufficient household members (n = 100), involving quantitative shotgun metagenomics, species-centric functional annotation of gut bacteria, and strain-level analyses. We supplemented the data set with 32 individuals with IgAD and examined the influence of IgA-autoantibody status on the composition and functionality of the gut microbiota. RESULTS: The gut microbiota of individuals with IgAD exhibited decreased richness and diversity and was enriched for bacterial species encoding pathogen-related functions including multidrug and antimicrobial peptide resistance, virulence factors, and type III and VI secretion systems. These functional changes were largely attributed to Escherichia coli but were independent of E coli strain variations and most prominent in individuals with IgAD with IgA-specific autoreactive antibodies. CONCLUSIONS: The microbiota of individuals with IgAD is enriched for species holding increased proinflammatory potential, thereby potentially decreasing the resistance to gut barrier-perturbing events. This phenotype is especially pronounced in individuals with IgAD with IgA-specific autoreactive antibodies, thus warranting a screening for IgA-specific autoreactive antibodies in IgAD to identify patients with IgAD with increased risk for gastrointestinal implications.

Cranberry (Vaccinium macrocarpon) Extract Impairs Nairovirus Infection by Inhibiting the Attachment to Target Cells.

Hazara virus (HAZV) belongs to the Nairoviridae family and is included in the same serogroup of the Crimean-Congo hemorrhagic fever virus (CCHFV). CCHFV is the most widespread tick-borne arbovirus. It is responsible for a serious hemorrhagic disease, for which specific and effective treatment and preventive systems are missing. Bioactive compounds derived from several natural products may provide a natural source of broad-spectrum antiviral agents, characterized by good tolerability and minimal side effects. Previous in vitro studies have shown that a cranberry (Vaccinium macrocarpon Ait.) extract containing a high content of A-type proanthocyanidins (PAC-A) inhibits the replication of herpes simplex and influenza viruses by hampering their attachment to target cells. Given the broad-spectrum antimicrobial activity of polyphenols and the urgency to develop therapies for the treatment of CCHF, we investigated the antiviral activity of cranberry extract against HAZV, a surrogate nairovirus model of CCHFV that can be handled in Level 2 Biosafety Laboratories (BSL-2). The results indicate that the cranberry extract exerts an antiviral activity against HAZV by targeting early stages of the viral replication cycle, including the initial adsorption to target cells. Although the details of the molecular mechanism of action remain to be clarified, the cranberry extract exerts a virucidal effect through a direct interaction with HAZV particles that leads to the subsequent impairment of virus attachment to cell-surface receptors. Finally, the antiviral activity of the cranberry extract was also confirmed for CCHFV. As a whole, the evidence obtained suggests that cranberry extract is a valuable candidate to be considered for the development of therapeutic strategies for CCHFV infections.

Type-I interferon signatures in SARS-CoV-2 infected Huh7 cells.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes Coronavirus disease 2019 (COVID-19) has caused a global health emergency. A key feature of COVID-19 is dysregulated interferon-response. Type-I interferon (IFN-I) is one of the earliest antiviral innate immune responses following viral infection and plays a significant role in the pathogenesis of SARS-CoV-2. In this study, using a proteomics-based approach, we identified that SARS-CoV-2 infection induces delayed and dysregulated IFN-I signaling in Huh7 cells. We demonstrate that SARS-CoV-2 is able to inhibit RIG-I mediated IFN-ß production. Our results also confirm the recent findings that IFN-I pretreatment is able to reduce the susceptibility of Huh7 cells to SARS-CoV-2, but not post-treatment. Moreover, senescent Huh7 cells, in spite of showing accentuated IFN-I response were more susceptible to SARS-CoV-2 infection, and the virus effectively inhibited IFIT1 in these cells. Finally, proteomic comparison between SARS-CoV-2, SARS-CoV, and MERS-CoV revealed a distinct differential regulatory signature of interferon-related proteins emphasizing that therapeutic strategies based on observations in SARS-CoV and MERS-CoV should be used with caution. Our findings provide a better understanding of SARS-CoV-2 regulation of cellular interferon response and a perspective on its use as a treatment. Investigation of different interferon-stimulated genes and their role in the inhibition of SARS-CoV-2 pathogenesis may direct novel antiviral strategies.

A DNA-based vaccine protects against Crimean-Congo haemorrhagic fever virus disease in a Cynomolgus macaque model.

There is currently no specific prophylaxis or vaccine against Crimean-Congo haemorrhagic fever virus (CCHFV). Crimean-Congo haemorrhagic fever (CCHF) is a severe febrile illness transmitted by Hyalomma ticks in endemic areas, handling of infected livestock or care of infected patients. We report here the successful protection against CCHFV-mediated disease in a non-human primate disease model. Cynomolgus macaques were vaccinated with a DNA-based vaccine using in vivo electroporation-assisted delivery. The vaccine contained two plasmids encoding the glycoprotein precursor (GPC) and the nucleoprotein (NP) of CCHFV. Animals received three vaccinations and we recorded potent antibody and T cell responses after vaccination. While all sham-vaccinated animals developed viraemia, high tissue viral loads and CCHF-induced disease, the NP + GPC vaccinated animals were significantly protected. In conclusion, this is evidence of a vaccine that can protect against CCHFV-induced disease in a non-human primate model. This supports clinical development of the vaccine to protect groups at risk for contracting the infection.

Digital Rolling Circle Amplification-Based Detection of Ebola and Other Tropical Viruses.

Emerging tropical viruses have caused serious outbreaks during the recent years, such as Ebola virus (EBOV) in 2014 and the most recent in 2018 to 2019 in Congo. Thus, immediate diagnostic attention is demanded at the point of care in resource-limited settings, because the performance and the operational parameters of conventional EBOV testing are limited. Especially, their sensitivity, specificity, and coverage of other tropical disease viruses make them unsuitable for diagnostic at the point of care. Here, a padlock probe (PLP)-based rolling circle amplification (RCA) method for the detection of EBOV is presented. For this, a set of PLPs, separately targeting the viral RNA and complementary RNA of all seven EBOV genes, was used in the RCA assay and validated on virus isolates from cell culture. The assay was then translated for testing clinical samples, and simultaneous detection of both EBOV RNA types was demonstrated. For increased sensitivity, the RCA products were enriched on a simple and pump-free microfluidic chip. Because PLPs and RCA are inherently multiplexable, we demonstrate the extension of the probe panel for the simultaneous detection of the tropical viruses Ebola, Zika, and Dengue. The demonstrated high specificity, sensitivity, and multiplexing capability in combination with the digital quantification rendered the assay a promising diagnostic tool toward tropical virus detection at the point of care.

HIV-1 Infection Primes Macrophages Through STAT Signaling to Promote Enhanced Inflammation and Viral Replication.

Macrophages play important roles in HIV-1 pathogenesis as targets for viral replication and mediators of chronic inflammation. Similar to IFNγ-priming, HIV-1 primes macrophages, resulting in hyperresponsiveness to subsequent toll-like receptor (TLR) stimulation and increased inflammatory cytokine production. However, the specific molecular mechanism of HIV-1 priming and whether cells must be productively infected or if uninfected bystander cells also are primed by HIV-1 remains unclear. To explore these questions, human macrophages were primed by IFNγ or infected with HIV-1 before activation by TLR ligands. Transcriptome profiling by microarray revealed a gene expression profile for IFNγ-primed cells that was further modulated by the addition of lipopolysaccharide (LPS). HIV-1 infection elicited a gene expression profile that correlated strongly with the profile induced by IFNγ (r = .679, p = .003). Similar to IFNγ, HIV-1 enhanced TLR ligand-induced tumor necrosis factor (TNF) protein expression and release. Increased TNF production was limited to productively infected cells. Specific signal transducer and activator of transcription (STAT)1 and STAT3 inhibitors suppressed HIV-1-mediated enhancement of TLR-induced TNF expression as well as HIV-1 replication. These findings indicate that viral replication and inflammation are linked through a common IFNγ-like, STAT-dependent pathway and that HIV-1-induced STAT1 and STAT3 signaling are involved in both inflammation and HIV-1 replication. Systemic innate immune activation is a hallmark of active HIV-1 replication. Our study shows that inflammation may develop as a consequence of HIV-1 triggering STAT-IFN pathways to support viral replication.

The effects of a ketogenic diet on behavioral outcome after controlled cortical impact injury in the juvenile and adult rat.

The ketogenic diet has been shown to have unique properties that make it a more suitable cerebral fuel under various neuropathological conditions (e.g., starvation, ischemia, and traumatic brain injury (TBI). Recently, age-dependent ketogenic neuroprotection was shown among postnatal day 35 (PND35) and PND45 rats after TBI, but not in PND17 and PND65 animals (Prins et al., 2005). The present study addresses the therapeutic potential of a ketogenic diet on motor and cognitive deficits after TBI. PND35 and PND75 rats received sham or controlled cortical impact (CCI) surgery and were placed on either standard (Std) or ketogenic (KG) diet for 7 days. Beam walking and the Morris water maze (MWM) were used to assess sensory motor function and cognition, respectively. PND35 CCI Std animals showed significantly longer traverse times than sham and CCI KG animals at the beginning of motor training. Footslip analysis revealed better performance among the sham and the CCI KG animals compared to the CCI Std group. In the MWM PND35 CCI KG animals showed significantly shorter escape latencies compared to CCI Std-fed animals. During the same time period there was no significant difference between sham animals and CCI KG animals. The therapeutic effect of the ketogenic diet on beam walking and cognitive performance was not observed in PND75 animals. This finding supports our theory about age-dependent utilization and effectiveness of ketones as an alternative fuel after TBI.