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Nairobi sheep disease (NSD), caused by the viral agent NSD virus (NSDV), is a haemorrhagic fever disease affecting and inducing high mortality in sheep and goat populations. NSDV belongs to the genus Orthonairovirus of the Nairoviridae family from the order Bunyavirales. Other viruses circulating in livestock such as Crimean–Congo haemorrhagic fever virus (CCHFV) and Dugbe virus (DUGV) are members of the same genus and are reported to share antigenic features. There are very few available materials to study NSDV infection both in vitro and in vivo. In the present work, we characterised two monoclonal antibodies generated in mice that recognise NSDV specifically but not CCHFV or DUGV, along with a potential use to define virus-infected cells, using flow cytometry. We believe this tool can be useful for research, but also NSDV diagnostics, especially through immunological staining. [ABSTRACT FROM AUTHOR]

Shrews (Soricidae) are common small wild mammals. Some species of shrews, such as Asian house shrews (Suncus murinus), have a significant overlap in their habitats with humans and domestic animals. Currently, over 190 species of viruses in 32 families, including Adenoviridae, Arenaviridae, Arteriviridae, Astroviridae, Anelloviridae, Bornaviridae, Caliciviridae, Chuviridae, Coronaviridae, Filoviridae, Flaviviridae, Hantaviridae, Hepadnaviridae, Hepeviridae, Nairoviridae, Nodaviridae, Orthoherpesviridae, Orthomyxoviridae, Paramyxoviridae, Parvoviridae, Phenuiviridae, Picobirnaviridae, Picornaviridae, Polyomaviridae, Poxviridae, Rhabdoviridae, Sedoreoviridae, Spinareoviridae, and three unclassified families, have been identified in shrews. Diverse shrew viruses, such as Borna disease virus 1, Langya virus, and severe fever with thrombocytopenia syndrome virus, cause diseases in humans and/or domestic animals, posing significant threats to public health and animal health. This review compiled fundamental information about shrews and provided a comprehensive summary of the viruses that have been detected in shrews, with the aim of facilitating a deep understanding of shrews and the diversity, epidemiology, and risks of their viruses. [ABSTRACT FROM AUTHOR]

Dugbe virus (DUGV) is a tick-borne arbovirus first isolated in Nigeria in 1964. It has been detected in many African countries using such diverse methods as serological tests, virus isolation, and molecular detection. In Senegal, reports of DUGV isolates mainly occurred in the 1970s and 1980s. Here, we report a contemporary detection of three novel DUGV isolates upon screening of a total of 2877 individual ticks regrouped into 844 pools. The three positive pools were identified as Amblyomma variegatum, the main known vector of DUGV, collected in the southern part of the country (Kolda region). Interestingly, phylogenetic analysis indicates that the newly sequenced isolates are globally related to the previously characterized isolates in West Africa, thus highlighting potentially endemic, unnoticed viral transmission. This study was also an opportunity to develop a rapid and affordable protocol for full-genome sequencing of DUGV using nanopore technology. The results suggest a relatively low mutation rate and relatively conservative evolution of DUGV isolates. [ABSTRACT FROM AUTHOR]

In this study, we describe the viral composition of adult Antricola delacruzi ticks collected in a hot bat cave in the state of Rondônia, Western Amazonia, Brazil. A. delacruzi ticks, are special, compared to many other ticks, in that they feed on both bats (larval blood feeding) and bat guano (nymphal and adult feeding) instead of feeding exclusively on vertebrate hosts (blood feeding). Considering this unique life-cycle it is potentially possible that these ticks can pick up/be infected by viruses not only present in the blood of viremic bats but also by virus shed through the bat guano. The viral metagenomic investigation of adult ticks showed that single-stranded negative-sense RNA viruses were the dominant group of viruses identified in the investigated ticks. Out of these, members of the Nairoviridae family were in clear majority constituting 88% of all viral reads in the data set. Genetic and phylogenetic analyses indicate the presence of several different orthonairoviruses in the investigated ticks with only distant relationship to previously described ones. In addition, identification of viral sequences belonging to Orthomyxoviridae, Iflaviridae, Dicistroviridae, Polycipiviridae, Reoviridae and different unclassified RNA viruses showed the presence of viruses with low sequence similarity to previously described viruses. [ABSTRACT FROM AUTHOR]

Dugbe orthonairovirus (DUGV) is a tick-borne arbovirus within the order Bunyavirales. Although displaying mild pathogenic potential, DUGV is genetically related to the Crimean–Congo hemorrhagic fever virus (CCHFV), another orthonairovirus that causes severe liver dysfunction and hemorrhagic fever with a high mortality rate in humans. As we previously observed that CCHFV infection could massively recruit and lipidate MAP1LC3 (LC3), a core factor involved in the autophagic degradation of cytosolic components, we asked whether DUGV infection also substantially impacts the autophagy machinery in epithelial cells. We observed that DUGV infection does impose LC3 lipidation in cultured hepatocytes. DUGV infection also caused an upregulation of the MAP1LC3 and SQSTM1/p62 transcript levels, which were, however, more moderate than those seen during CCHFV infection. In contrast, unlike during CCHFV infection, the modulation of core autophagy factors could influence both LC3 lipidation and viral particle production: the silencing of ATG5 and/or ATG7 diminished the induction of LC3 lipidation and slightly upregulated the level of infectious DUGV particle production. Overall, the results are compatible with the notion that in epithelial cells infected with DUGV in vitro, the autophagy machinery may be recruited to exert a certain level of restriction on viral replication. Thus, the relationship between DUGV infection and autophagy in epithelial cells appears to present both similarities and distinctions with that seen during CCHFV infection. [ABSTRACT FROM AUTHOR]

Crimean-Congo hemorrhagic fever virus (CCHFV), a nairovirus, is a tick-borne zoonotic virus that causes hemorrhagic fever in humans. The CCHFV nucleoprotein (NP) is the antigen most used for serological screening of CCHFV infection in animals and humans. To gain insights into antibody epitopes on the NP molecule, we produced recombinant chimeric NPs between CCHFV and Nairobi sheep disease virus (NSDV), which is another nairovirus, and tested rabbit and mouse antisera/immune ascites, anti-NP monoclonal antibodies, and CCHFV-infected animal/human sera for their reactivities to the NP antigens. We found that the amino acids at positions 161–320 might include dominant epitopes recognized by anti-CCHFV IgG antibodies, whereas cross-reactivity between anti-CCHFV and anti-NSDV antibodies was limited. Their binding capacities were further tested using a series of synthetic peptides whose sequences were derived from CCHFV NP. IgG antibodies in CCHFV-infected monkeys and patients were reactive to some of the synthetic peptide antigens (e.g., amino acid residues at positions 131–150 and 211–230). Only a few peptides were recognized by IgG antibodies in the anti-NSDV serum. These results provide useful information to improve NP-based antibody detection assays as well as antigen detection tests relying on anti-NP monoclonal antibodies. [ABSTRACT FROM AUTHOR]

This report describes the near complete genomic sequence and subsequent analysis of Vinegar Hill virus (VINHV; tentative member of the genus Orthonairovirus, family Nairoviridae, order Bunyavirales). VINHV is the second nairovirus reported to be isolated on mainland Australia and the first to be sequenced and analysed. Our genetic analysis shows that VINHV belongs to the Dera Ghazi Khan genogroup, a group of viruses previously isolated in other parts of the world including Asia, South Africa, and the USA. We discuss possible routes of entry for nairoviruses into Australia and the need to understand the virome of Australian ticks in the context of new and emerging disease. [ABSTRACT FROM AUTHOR]

Dugbe orthonairovirus (DUGV) and Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV) are tick-borne arboviruses within the order Bunyavirales. Both viruses are endemic in several African countries and can induce mild (DUGV, BSL 3) or fatal (CCHFV, BSL 4) disease in humans. Ruminants play a major role in their natural transmission cycle. Therefore, they are considered as suitable indicator animals for serological monitoring studies to assess the risk for human infections. Although both viruses do not actually belong to the same serogroup, cross-reactivities have already been reported earlier—hence, the correct serological discrimination of DUGV and CCHFV antibodies is crucial. In this study, 300 Nigerian cattle sera (150 CCHFV seropositive and seronegative samples, respectively) were screened for DUGV antibodies via N protein-based ELISA, indirect immunofluorescence (iIFA) and neutralization assays. Whereas no correlation between the CCHFV antibody status and DUGV seroprevalence data could be demonstrated with a newly established DUGV ELISA, significant cross-reactivities were observed in an immunofluorescence assay. Moreover, DUGV seropositive samples did also cross-react in a species-adapted commercial CCHFV iIFA. Therefore, ELISAs seem to be able to reliably differentiate between DUGV and CCHFV antibodies and should preferentially be used for monitoring studies. Positive iIFA results should always be confirmed by ELISAs. [ABSTRACT FROM AUTHOR]

Arthropod-borne infections are a medical and economic threat to humans and livestock. Over the last three decades, several unprecedented viral outbreaks have been recorded in the Western part of the Arabian Peninsula. However, little is known about the circulation and diversity of arthropod-borne viruses in this region. To prepare for new outbreaks of vector-borne diseases, it is important to detect which viruses circulate in each vector population. In this study, we used a metagenomics approach to characterize the RNA virome of ticks infesting dromedary camels (Camelus dromedaries) in Makkah province, Saudi Arabia. Two hundred ticks of species Hyalomma dromedarii (n = 196) and Hyalomma impeltatum (n = 4) were collected from the Alkhurma district in Jeddah and Al-Taif city. Virome analysis showed the presence of several tick-specific viruses and tick-borne viruses associated with severe illness in humans. Some were identified for the first time in the Arabian Peninsula. The human disease-associated viruses detected included Crimean Congo Hemorrhagic fever virus and Tamdy virus (family Nairoviridae), Guertu virus (family Phenuiviridae), and a novel coltivirus that shares similarities with Tarumizu virus, Tai forest reovirus and Kundal virus (family Reoviridae). Furthermore, Alkhurma hemorrhagic virus (Flaviviridae) was detected in two tick pools by specific qPCR. In addition, tick-specific viruses in families Phenuiviridae (phleboviruses), Iflaviridae, Chuviridae, Totiviridae and Flaviviridae (Pestivirus) were detected. The presence of human pathogenetic viruses warrants further efforts in tick surveillance, xenosurveillence, vector control, and sero-epidemiological investigations in human and animal populations to predict, contain and mitigate future outbreaks in the region. [ABSTRACT FROM AUTHOR]

Nairobi sheep disease orthonairovirus (NSDV) is a zoonotic tick-borne arbovirus, which causes severe gastroenteritis in small ruminants. To date, the virus is prevalent in East Africa and Asia. However, due to climate change, including the spread of transmitting tick vectors and increased animal movements, it is likely that the distribution range of NSDV is enlarging. In this project, sheep and cattle (hitherto classified as resistant to NSDV) were experimentally infected with NSDV for a comparative study of the species-specific pathogenesis. For this purpose, several new diagnostic assays (RT-qPCR, ELISA, iIFA, mVNT, PRNT) were developed, which will also be useful for future epidemiological investigations. All challenged sheep (three different doses groups) developed characteristic clinical signs, transient viremia and virus shedding—almost independent on the applied virus dose. Half of the sheep had to be euthanized due to severe clinical signs, including hemorrhagic diarrhea. In contrast, the course of infection in cattle was only subclinical. However, all ruminants showed seroconversion—implying that, indeed, both species are susceptible for NSDV. Hence, not only sheep but also cattle sera can be included in serological monitoring programs for the surveillance of NSDV occurrence and spread in the future. [ABSTRACT FROM AUTHOR]

Dugbe orthonairovirus (DUGV) is a tick-borne arbovirus within the order Bunyavirales. DUGV was first isolated in Nigeria, but virus isolations in ten further African countries indicate that DUGV is widespread throughout Africa. Humans can suffer from a mild febrile illness, hence, DUGV is classified as a biosafety level (BSL) 3 agent. In contrast, no disease has been described in animals, albeit serological evidence exists that ruminants are common hosts and may play an important role in the transmission cycle of this neglected arbovirus. In this study, young sheep and calves were experimentally inoculated with DUGV in order to determine their susceptibility and to study the course of infection. Moreover, potential antibody cross-reactivities in currently available diagnostic assays for Crimean-Congo hemorrhagic fever orthonairovirus (CCHFV) were assessed as DUGV is distantly related to CCHFV. Following subcutaneous inoculation, none of the animals developed clinical signs or viremia. However, all ruminants seroconverted, as demonstrated by two DUGV neutralization test formats (micro-virus neutralization test (mVNT), plaque reduction (PRNT)), by indirect immunofluorescence assays and in bovines by a newly developed DUGV recombinant N protein ELISA. Sera did not react in commercial CCHFV ELISAs, whereas cross-reactivities were observed by immunofluorescence and immunoblot assays. [ABSTRACT FROM AUTHOR]

The Bunyavirales order accommodates related viruses (bunyaviruses) with segmented, linear, single-stranded, negative- or ambi-sense RNA genomes. Their glycoproteins form capsomeric projections or spikes on the virion surface and play a crucial role in virus entry, assembly, morphogenesis. Bunyavirus glycoproteins are encoded by a single RNA segment as a polyprotein precursor that is co- and post-translationally cleaved by host cell enzymes to yield two mature glycoproteins, Gn and Gc (or GP1 and GP2 in arenaviruses). These glycoproteins undergo extensive N-linked glycosylation and despite their cleavage, remain associated to the virion to form an integral transmembrane glycoprotein complex. This review summarizes recent advances in our understanding of the molecular biology of bunyavirus glycoproteins, including their processing, structure, and known interactions with host factors that facilitate cell entry. [ABSTRACT FROM AUTHOR]

Currently, next generation sequencing (NGS) is the mainly used approach for identification and monitorization of viruses with a potential public health threat in clinical and environmental samples. To facilitate detection in NGS, the sequence-independent, single-primer-amplification (SISPA) is an effective tool for enriching virus sequences. We performed a preliminary assessment of SISPA-nanopore sequencing as a potential approach for screening tick-borne viruses in six specimens with detectable Crimean-Congo hemorrhagic fever virus (CCHFV) and Jingmen tick virus (JMTV) sequences. A comparison of unbiased NGS and SISPA followed by nanopore sequencing was carried out in 4 specimens with single and pooled ticks. The approach was further used for genome sequencing in culture-grown viruses. Overall, total/virus-specific read counts were significantly elevated in cell culture supernatants in comparison to single or pooled ticks. Virus genomes could be successfully characterized by SISPA with identities over 99%. Genome coverage varied according to the segment and total read count. Base calling errors were mainly observed in tick specimens and more frequent in lower viral loads. Culture-grown viruses were phylogenetically-related to previously-reported local viruses. In conclusion, the SISPA + nanopore sequencing was successful in generating data comparable to NGS and will provide an effective tool for broad-range virus detection in ticks. [ABSTRACT FROM AUTHOR]

Bunyavirales are negative-sense segmented RNA viruses infecting arthropods, protozoans, plants, and animals. This study examines the phylogenetic relationships of plant viruses within this order, many of which are recently classified species. Comprehensive phylogenetic analyses of the viral RNA dependent RNA polymerase (RdRp), precursor glycoprotein (preGP), the nucleocapsid (N) proteins point toward common progenitor viruses. The RdRp of Fimoviridae and Tospoviridae show a close evolutional relationship while the preGP of Fimoviridae and Phenuiviridae show a closed relationship. The N proteins of Fimoviridae were closer to the Phasmaviridae, the Tospoviridae were close to some Phenuiviridae members and the Peribunyaviridae. The plant viral movement proteins of species within the Tospoviridae and Phenuiviridae were more closely related to each other than to members of the Fimoviridae. Interestingly, distal ends of 3′ and 5′ untranslated regions of species within the Fimoviridae shared similarity to arthropod and vertebrate infecting members of the Cruliviridae and Peribunyaviridae compared to other plant virus families. Co-phylogeny analysis of the plant infecting viruses indicates that duplication and host switching were more common than co-divergence with a host species. [ABSTRACT FROM AUTHOR]