Comparative Usutu and West Nile virus transmission potential by local Culex pipiens mosquitoes in north-western Europe

Originating from Africa, Usutu virus (USUV) first emerged in Europe in 2001. This mosquito-borne flavivirus caused high mortality rates in its bird reservoirs, which strongly resembled the introduction of West Nile virus (WNV) in 1999 in the United States. Mosquitoes infected with USUV incidentally transmit the virus to other vertebrates, including humans, which can result in neuroinvasive disease. USUV and WNV co-circulate in parts of southern Europe, but the distribution of USUV extends into central and northwestern Europe. In the field, both viruses have been detected in the northern house mosquito Culex pipiens, of which the potential for USUV transmission is unknown. To understand the transmission dynamics and assess the potential spread of USUV, we determined the vector competence of C. pipiens for USUV and compared it with the well characterized WNV. We show for the first time that northwestern European mosquitoes are highly effective vectors for USUV, with infection rates of 11% at 18. °C and 53% at 23. °C, which are comparable with values obtained for WNV. Interestingly, at a high temperature of 28. °C, mosquitoes became more effectively infected with USUV (90%) than with WNV (58%), which could be attributed to barriers in the mosquito midgut. Small RNA deep sequencing of infected mosquitoes showed for both viruses a strong bias for 21-nucleotide small interfering (si)RNAs, which map across the entire viral genome both on the sense and antisense strand. No evidence for viral PIWI-associated RNA (piRNA) was found, suggesting that the siRNA pathway is the major small RNA pathway that targets USUV and WNV infection in C. pipiens mosquitoes

Arbovirus-Derived piRNAs Exhibit a Ping-Pong Signature in Mosquito Cells

The siRNA pathway is an essential antiviral mechanism in insects. Whether other RNA interference pathways are involved in antiviral defense remains unclear. Here, we report in cells derived from the two main vectors for arboviruses, Aedes albopictus and Aedes aegypti, the production of viral small RNAs that exhibit the hallmarks of ping-pong derived piwi-associated RNAs (piRNAs) after infection with positive or negative sense RNA viruses. Furthermore, these cells produce endogenous piRNAs that mapped to transposable elements. Our results show that these mosquito cells can initiate de novo piRNA production and recapitulate the ping-pong dependent piRNA pathway upon viral infection. The mechanism of viral-piRNA production is discussed

SARS-CoV-2 infects the human kidney and drives fibrosis in kidney organoids

Kidney failure is frequently observed during and after COVID-19, but it remains elusive whether this is a direct effect of the virus. Here, we report that SARS-CoV-2 directly infects kidney cells and is associated with increased tubule-interstitial kidney fibrosis in patient autopsy samples. To study direct effects of the virus on the kidney independent of systemic effects of COVID-19, we infected human-induced pluripotent stem-cell-derived kidney organoids with SARS-CoV-2. Single-cell RNA sequencing indicated injury and dedifferentiation of infected cells with activation of profibrotic signaling pathways. Importantly, SARS-CoV-2 infection also led to increased collagen 1 protein expression in organoids. A SARS-CoV-2 protease inhibitor was able to ameliorate the infection of kidney cells by SARS-CoV-2. Our results suggest that SARS-CoV-2 can directly infect kidney cells and induce cell injury with subsequent fibrosis. These data could explain both acute kidney injury in COVID-19 patients and the development of chronic kidney disease in long COVID

Small RNA Profiling in Dengue Virus 2-Infected Aedes Mosquito Cells Reveals Viral piRNAs and Novel Host miRNAs

Contains fulltext : 171518.PDF (publisher's version ) (Open Access)In Aedes mosquitoes, infections with arthropod-borne viruses (arboviruses) trigger or modulate the expression of various classes of viral and host-derived small RNAs, including small interfering RNAs (siRNAs), PIWI interacting RNAs (piRNAs), and microRNAs (miRNAs). Viral siRNAs are at the core of the antiviral RNA interference machinery, one of the key pathways that limit virus replication in invertebrates. Besides siRNAs, Aedes mosquitoes and cells derived from these insects produce arbovirus-derived piRNAs, the best studied examples being viruses from the Togaviridae or Bunyaviridae families. Host miRNAs modulate the expression of a large number of genes and their levels may change in response to viral infections. In addition, some viruses, mostly with a DNA genome, express their own miRNAs to regulate host and viral gene expression. Here, we perform a comprehensive analysis of both viral and host-derived small RNAs in Aedes aegypti Aag2 cells infected with dengue virus 2 (DENV), a member of the Flaviviridae family. Aag2 cells are competent in producing all three types of small RNAs and provide a powerful tool to explore the crosstalk between arboviral infection and the distinct RNA silencing pathways. Interestingly, besides the well-characterized DENV-derived siRNAs, a specific population of viral piRNAs was identified in infected Aag2 cells. Knockdown of Piwi5, Ago3 and, to a lesser extent, Piwi6 results in reduction of vpiRNA levels, providing the first genetic evidence that Aedes PIWI proteins produce DENV-derived small RNAs. In contrast, we do not find convincing evidence for the production of virus-derived miRNAs. Neither do we find that host miRNA expression is strongly changed upon DENV2 infection. Finally, our deep-sequencing analyses detect 30 novel Aedes miRNAs, complementing the repertoire of regulatory small RNAs in this important vector species

Regulation of microRNA biogenesis and turnover by animals and their viruses

Item does not contain fulltextMicroRNAs (miRNAs) are a ubiquitous component of gene regulatory networks that modulate the precise amounts of proteins expressed in a cell. Despite their small size, miRNA genes contain various recognition elements that enable specificity in when, where and to what extent they are expressed. The importance of precise control of miRNA expression is underscored by functional studies in model organisms and by the association between miRNA mis-expression and disease. In the last decade, identification of the pathways by which miRNAs are produced, matured and turned-over has revealed many aspects of their biogenesis that are subject to regulation. Studies in viral systems have revealed a range of mechanisms by which viruses target these pathways through viral proteins or non-coding RNAs in order to regulate cellular gene expression. In parallel, a field of study has evolved around the activation and suppression of antiviral RNA interference (RNAi) by viruses. Virus encoded suppressors of RNAi can impact miRNA biogenesis in cases where miRNA and small interfering RNA pathways converge. Here we review the literature on the mechanisms by which miRNA biogenesis and turnover are regulated in animals and the diverse strategies that viruses use to subvert or inhibit these processes

Antiviral RNAi in Insects and Mammals: Parallels and Differences

The RNA interference (RNAi) pathway is a potent antiviral defense mechanism in plants and invertebrates, in response to which viruses evolved suppressors of RNAi. In mammals, the first line of defense is mediated by the type I interferon system (IFN); however, the degree to which RNAi contributes to antiviral defense is still not completely understood. Recent work suggests that antiviral RNAi is active in undifferentiated stem cells and that antiviral RNAi can be uncovered in differentiated cells in which the IFN system is inactive or in infections with viruses lacking putative viral suppressors of RNAi. In this review, we describe the mechanism of RNAi and its antiviral functions in insects and mammals. We draw parallels and highlight differences between (antiviral) RNAi in these classes of animals and discuss open questions for future research

Viral piRNA profiles.

<p>piRNA distributions across the genomes of selected (A) alphaviruses, (B) flaviviruses, and (C) bunyaviruses. The plots depict published genome profiles of Sindbis virus (SINV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref029" target="_blank">29</a>], chikungunya virus (CHIKV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref030" target="_blank">30</a>], Semliki Forest virus (SFV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref031" target="_blank">31</a>], dengue virus serotype 2 (DENV2) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref035" target="_blank">35</a>,<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref036" target="_blank">36</a>], cell fusing agent virus (CFAV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref034" target="_blank">34</a>], Rift Valley fever virus (RVFV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref038" target="_blank">38</a>], and Schmallenberg virus (SBV) [<a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006017#ppat.1006017.ref037" target="_blank">37</a>]. For alphaviruses, the position of the subgenomic promoter is depicted. The piRNA coverage on the sense or antisense strand is shown as peaks above or below the <i>x</i>-axis, respectively. Please note that the plots are representations of piRNA profiles from multiple studies that used different ways of normalizing and presenting read counts. Therefore, the heights of the bars are arbitrary and do not allow a quantitative comparison between the different viruses.</p

Radiological Assessment of the Effects of a Full Rolling Motion Shoe During Asymmetrical Bearing

The authors used a new radiological method to assess asymmetrical articular compression of the interphalangeal joints. This method was based on the measurements of 3 angles obtained on dorsopalmar radiographs. Variations of these angles were studied during experimental asymmetrical bearing on unshod feet. It was concluded that 2 angles were interesting parameters to assess asymmetrical articular compression and to define the position of the phalanx in the horny box. Furthermore, variations of these angles induced by experimental asymmetrical bearing were compared without shoe, with a standard shoe and with an orthopaedic full rolling motion shoe. It was observed that the effects of the asymmetrical bearing were reduced when feet were shod with a full rolling motion shoe