Nairobi Sheep Disease Virus: A Historical and Epidemiological Perspective

Identification and phylogenetic analysis of Nairobi sheep disease virus from Haemaphysalis longicornis ticks in Shandong Province, China

Nairobi Sheep Disease (NSD) is a typical tick-borne syndrome characterized by severe hemorrhagic gastroenteritis, spontaneous abortion, and a high case fatality rate in small ruminants. The pathogenic agent, Nairobi sheep disease virus (NSDV), has also been associated with human infections, indicating its possible zoonotic potential. Prior to this study, NSDV has been detected from ticks collected in Jilin, Hubei, and Liaoning provinces in China. In the present study, a total of 343 ticks (Haemaphysalis longicornis) were collected in Shandong province, China in 2020, and pooled into 16 libraries. Analysis of the meta-transcriptomic sequencing data identified NSDV strains SDWL07, SDWL08, and SDWL16 from three pools. The SDWL07 and SDWL16 strains were detected from unfed ticks, while SDWL08 was detected from cattle-feeding ticks. Phylogenetic analyses showed higher sequence identities between the three strains and other Chinese NSDV strains than those from India and Kenya. Phylogenetic analyses also revealed that they clustered together and fell within the China lineage, suggesting no potential genetic reassortment among them. In summary, this is the first report of the identification of NSDV in Shandong province, highlighting the continually expanding endemic regions of this pathogen. Surveillance of NSDV should be intensified in China, especially in areas where H. longicornis is endemic.

The Adaptive Immune Response against Bunyavirales

The Bunyavirales order includes at least fourteen families with diverse but related viruses, which are transmitted to vertebrate hosts by arthropod or rodent vectors. These viruses are responsible for an increasing number of outbreaks worldwide and represent a threat to public health. Infection in humans can be asymptomatic, or it may present with a range of conditions from a mild, febrile illness to severe hemorrhagic syndromes and/or neurological complications. There is a need to develop safe and effective vaccines, a process requiring better understanding of the adaptive immune responses involved during infection. This review highlights the most recent findings regarding T cell and antibody responses to the five Bunyavirales families with known human pathogens (Peribunyaviridae, Phenuiviridae, Hantaviridae, Nairoviridae, and Arenaviridae). Future studies that define and characterize mechanistic correlates of protection against Bunyavirales infections or disease will help inform the development of effective vaccines.

Establishment of a lethal mouse model of emerging tick-borne orthonairovirus infections

Emerging and reemerging tick-borne virus infections caused by orthonairoviruses (family Nairoviridae), which are genetically distinct from Crimean-Congo hemorrhagic fever virus, have been recently reported in East Asia. Here, we have established a mouse infection model using type-I/II interferon receptor-knockout mice (AG129 mice) both for a better understanding of the pathogenesis of these infections and validation of antiviral agents using Yezo virus (YEZV), a novel orthonairovirus causing febrile illnesses associated with tick bites in Japan and China. YEZV-inoculated AG129 mice developed hepatitis with body weight loss and died by 6 days post infection. Blood biochemistry tests showed elevated liver enzyme levels, similar to YEZV-infected human patients. AG129 mice treated with favipiravir survived lethal YEZV infection, demonstrating the anti-YEZV effect of this drug. The present mouse model will help us better understand the pathogenicity of the emerging tick-borne orthonairoviruses and the development of specific antiviral agents for their treatment.

Diversity of species and geographic distribution of tick-borne viruses in China

Introduction

Tick-borne pathogens especially viruses are continuously appearing worldwide, which have caused severe public health threats. Understanding the species, distribution and epidemiological trends of tick-borne viruses (TBVs) is essential for disease surveillance and control.

Methods

In this study, the data on TBVs and the distribution of ticks in China were collected from databases and literature. The geographic distribution of TBVs in China was mapped based on geographic locations of viruses where they were prevalent or they were detected in vector ticks. TBVs sequences were collected from The National Center for Biotechnology Information and used to structure the phylogenetic tree.

Results

Eighteen TBVs from eight genera of five families were prevalent in China. Five genera of ticks played an important role in the transmission of TBVs in China. According to phylogenetic analysis, some new viral genotypes, such as the Dabieshan tick virus (DTV) strain detected in Liaoning Province and the JMTV strain detected in Heilongjiang Province existed in China.

Discussion

TBVs were widely distributed but the specific ranges of viruses from different families still varied in China. Seven TBVs belonging to the genus Orthonairovirus of the family Nairoviridae such as Nairobi sheep disease virus (NSDV) clustered in the Xinjiang Uygur Autonomous Region (XUAR) and northeastern areas of China. All viruses of the family Phenuiviridae except Severe fever with thrombocytopenia syndrome virus (SFTSV) were novel viruses that appeared in the last few years, such as Guertu virus (GTV) and Tacheng tick virus 2 (TcTV-2). They were mainly distributed in the central plains of China. Jingmen tick virus (JMTV) was distributed in at least fourteen provinces and had been detected in more than ten species of tick such as Rhipicephalus microplus and Haemaphysalis longicornis, which had the widest distribution and the largest number of vector ticks among all TBVs. Parainfluenza virus 5 (PIV5) and Lymphatic choriomeningitis virus (LCMV) were two potential TBVs in Northeast China that could cause serious diseases in humans or animals. Ixodes persulcatus carried the highest number of TBVs, followed by Dermacentor nuttalli and H. longicornis. They could carry as many as ten TBVs. Three strains of Tick-borne encephalitis (TBEV) from Inner Mongolia Province clustered with ones from Russia, Japan and Heilongjiang Province, respectively. Several SFTSV strains from Zhejiang Province clustered with strains from Korea and Japan. Specific surveillance of dominant TBVs should be established in different areas in China.

Data release: targeted systematic literature search for tick and tick-borne pathogen distributions in six countries in sub-Saharan Africa from 1901 to 2020

BACKGROUND

Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review.

METHODS

Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap.

RESULTS

Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries.

CONCLUSIONS

These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.

Characterisation of putative novel tick viruses and zoonotic risk prediction

Tick-associated viruses remain a substantial zoonotic risk worldwide, so knowledge of the diversity of tick viruses has potential health consequences. Despite their importance, large amounts of sequences in public data sets from tick meta-genomic and -transcriptomic projects remain unannotated, sequence data that could contain undocumented viruses. Through data mining and bioinformatic analysis of more than 37,800 public meta-genomic and -transcriptomic data sets, we found 83 unannotated contigs exhibiting high identity with known tick viruses. These putative viral contigs were classified into three RNA viral families (Alphatetraviridae, Orthomyxoviridae and Chuviridae) and one DNA viral family (Asfarviridae). After manual checking of quality and dissimilarity towards other sequences in the data set, these 83 contigs were reduced to five contigs in the Alphatetraviridae from four putative viruses, four in the Orthomyxoviridae from two putative viruses and one in the Chuviridae which clustered with known tick-associated viruses, forming a separate clade within the viral families. We further attempted to assess which previously known tick viruses likely represent zoonotic risks and thus deserve further investigation. We ranked the human infection potential of 133 known tick-associated viruses using a genome composition-based machine learning model. We found five high-risk tick-associated viruses (Langat virus, Lonestar tick chuvirus 1, Grotenhout virus, Taggert virus and Johnston Atoll virus) that have not been known to infect human and two viral families (Nairoviridae and Phenuiviridae) that contain a large proportion of potential zoonotic tick-associated viruses. This adds to the knowledge of tick virus diversity and highlights the importance of surveillance of newly emerging tick-associated diseases.

Introduction of the ectoparasite Rhipicephalus pulchellus (Ixodida: Ixodidae) into Connecticut with a human traveler from Tanzania, and a review of its importation records into the United States

Globalization, increased frequency of travel, and a rise in legal and illegal animal trades can introduce exotic ticks into the United States. We herein report the importation of a male Rhipicephalus pulchellus (Gerstäcker) on a human traveler returning to Connecticut from Tanzania, Africa, and review historical importation records of this species into the United States. This common tick is broadly distributed throughout East Africa, from Eritrea to Tanzania, has a wide host range on domestic animals and wildlife, and has been most frequently introduced into the United States on tick-infested wild animal hosts and animal trophies, but documentation of importation on humans has been rare. Archival records at the United States Department of Agriculture's National Veterinary Services Laboratories show R. pulchellus has been introduced into the United States at least 40 times over the last 62 yr. Rhipicephalus pulchellus has been linked to Rickettsia conorii, the agent of boutonneuse fever in humans, Crimean-Congo hemorrhagic fever orthonairovirus, and Nairobi sheep disease orthonairovirus. Given the potential for this exotic tick to introduce animal or human pathogens, proper surveillance, interception, identification, and reporting of these ticks are vital in protecting human and animal health.

Generation and Characterisation of Monoclonal Antibodies against Nairobi Sheep Disease Virus Nucleoprotein

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.

The proprotein convertase SKI-1/S1P is a critical host factor for Nairobi sheep disease virus infectivity

Nairobi sheep disease virus (NSDV) belongs to the Orthonairovirus genus in the Bunyavirales order and is genetically related to human-pathogenic Crimean-Congo hemorrhagic fever virus (CCHFV). NSDV is a zoonotic pathogen transmitted by ticks and primarily affects naïve small ruminants in which infection leads to severe and often fatal hemorrhagic gastroenteritis. Despite its veterinary importance and the striking similarities in the clinical picture between NSDV-infected ruminants and CCHFV patients, the molecular pathogenesis of NSDV and its interactions with the host cell are largely unknown. Here, we identify the membrane-bound proprotein convertase site-1 protease (S1P), also known as subtilisin/kexin-isozyme-1 (SKI-1), as a host factor affecting NSDV infectivity. Absence of S1P in SRD-12B cells, a clonal CHO-K1 cell variant with a genetic defect in the S1P gene (MBTPS1), results in significantly decreased NSDV infectivity while transient complementation of SKI-1/S1P rescues NSDV infection. SKI-1/S1P is dispensable for virus uptake but critically required for production of infectious virus progeny. Moreover, we provide evidence that SKI-1/S1P is involved in the posttranslational processing of the NSDV glycoprotein precursor. Our results demonstrate the role of SKI-1/S1P in the virus life cycle of NSDV and suggest that this protease is a common host factor for orthonairoviruses and may thus represent a promising broadly-effective, indirect antiviral target.

Virome diversity of ticks feeding on domestic mammals in China

Ticks are considered the second most common pathogen vectors transmitting a broad range of vital human and veterinary viruses. From 2017 to 2018, 640 ticks were collected in eight different provinces in central and western China. Six species were detected, including H.longicornis, De.everestianus, Rh.microplus, Rh.turanicus, Rh.sanguineous, and Hy.asiaticum. Sixty-four viral metagenomic libraries were constructed on the MiSeq Illumina platform, resulting in 13.44 ​G (5.88 ​× ​10⁷) of 250-bp-end reads, in which 2,437,941 are viral reads. We found 27 nearly complete genome sequences, including 16 genome sequences encoding entire protein-coding regions (lack of 3' or 5' end non-coding regions) and complete viral genomes, distributed in the arboviral family (Chuviridae, Rhabdoviridae, Nairoviridae, Phenuiviridae, Flaviviridae, Iflaviridae) as well as Parvoviridae and Polyomaviridae that cause disease in mammals and even humans. In addition, 13 virus sequences found in Chuviridae, Nairoviridae, Flaviviridae, Iflaviridae, Hepeviridae, Parvoviridae, and Polyomaviridae were identified as belonging to a new virus species in the identified viral genera. Besides, an epidemiological survey shows a high prevalence (9.38% and 15.63%) of two viruses (Ovine Copiparvovirus and Bovine parvovirus 2) in the tick cohort.

Analysis of the diversity of tick-borne viruses at the border areas in Liaoning Province, China

Ticks play a significant role in transmitting arboviruses, which pose a risk to human and animal health. The region of Liaoning Province, China, with abundant plant resources with multiple tick populations, has reported several tick-borne diseases. However, there remains a scarcity of research on the composition and evolution of the tick virome. In this study, we conducted the metagenomic analysis of 561 ticks in the border area of Liaoning Province in China and identified viruses related to known diseases in humans and animals, including severe fever with thrombocytopenia syndrome virus (SFTSV) and nairobi sheep disease virus (NSDV). Moreover, the groups of tick viruses were also closely related to the families of Flaviviridae, Parvoviridae, Phenuiviridae, and Rhabdoviridae. Notably, the Dabieshan tick virus (DBTV) of the family Phenuiviridae was prevalent in these ticks, with the minimum infection rate (MIR) of 9.09%, higher than previously reported in numerous provinces in China. In addition, sequences of tick-borne viruses of the family Rhabdoviridae have first been reported from the border area of Liaoning Province, China, after being described from Hubei Province, China. This research furthered the insight into pathogens carried by ticks in the northeastern border areas of China, offering epidemiological information for possible forthcoming outbreaks of infectious diseases. Meanwhile, we provided an essential reference for assessing the risk of tick bite infection in humans and animals, as well as for exploring into the evolution of the virus and the mechanisms of species transmission.

Metavirome of 31 tick species provides a compendium of 1,801 RNA virus genomes

The increasing prevalence and expanding distribution of tick-borne viruses globally have raised health concerns, but the full repertoire of the tick virome has not been assessed. We sequenced the meta-transcriptomes of 31 different tick species in the Ixodidae and Argasidae families from across mainland China, and identified 724 RNA viruses with distinctive virome compositions among genera. A total of 1,801 assembled and complete or nearly complete viral genomes revealed an extensive diversity of genome architectures of tick-associated viruses, highlighting ticks as a reservoir of RNA viruses. We examined the phylogenies of different virus families to investigate virome evolution and found that the most diverse tick-associated viruses are positive-strand RNA virus families that demonstrate more ancient divergence than other arboviruses. Tick-specific viruses are often associated with only a few tick species, whereas virus clades that can infect vertebrates are found in a wider range of tick species. We hypothesize that tick viruses can exhibit both 'specialist' and 'generalist' evolutionary trends. We hope that our virome dataset will enable much-needed research on vertebrate-pathogenic tick-associated viruses.

Investigation of the Virome and Characterization of Issyk-Kul Virus from Swedish Myotis brandtii Bats

Bats are reservoirs for many different viruses, including some that can be transmitted to and cause disease in humans and/or animals. However, less is known about the bat-borne viruses circulating in Northern European countries such as in Sweden. In this study, saliva from Myotis brandtii bats, collected from south-central Sweden, was analyzed for viruses. The metagenomic analysis identified viral sequences belonging to different viral families, including, e.g., Nairoviridae, Retroviridae, Poxviridae, Herpesviridae and Siphoviridae. Interestingly, through the data analysis, the near-complete genome of Issyk-Kul virus (ISKV), a zoonotic virus within the Nairoviridae family, was obtained, showing 95-99% protein sequence identity to previously described ISKVs. This virus is believed to infect humans via an intermediate tick host or through contact with bat excrete. ISKV has previously been found in bats in Europe, but not previously in the Nordic region. In addition, near full-length genomes of two novel viruses belonging to Picornavirales order and Tymoviridae family were characterized. Taken together, our study has not only identified novel viruses, but also the presence of a zoonotic virus not previously known to circulate in this region. Thus, the results from these types of studies can help us to better understand the diversity of viruses circulating in bat populations, as well as identify viruses with zoonotic potential that could possibly be transmitted to humans.

Genomic characterization and phylogenetic analysis of a novel Nairobi sheep disease genogroup Orthonairovirus from ticks, Southeastern China

The increasing prevalence and transmission of tick-borne diseases, especially those emerging ones, have posed a significant threat to public health. Thus, the discovery of neglected pathogenic agents carried and transmitted by ticks is urgently needed. Using unbiased high-throughput sequencing, a novel Orthonairovirus designated as Meihua Mountain virus (MHMV), was identified in bloodsucking ticks collected from cattle and wild boars in Fujian province, Southeastern China. The full-length genome was determined by RT-PCR and RACE. Genomic architecture of MHMV shares typical features with orthonairoviruses. Phylogenetic analyses suggested that MHMV is clustered into the Nairobi sheep disease (NSD) genogroup of the genus Orthonairovirus and is closely related to the Hazara virus. The RdRp, GPC, and N protein of MHMV shares 62.3%–83.5%, 37.1%–66.1%, and 53.4%–77.3% amino acid identity with other NSD genogroup viruses, respectively, representing a novel species. The overall pooled prevalence of MHMV in ticks was 2.53% (95% CI: 1.62%–3.73%, 22 positives of 134 tick pools), with 7.38% (95% CI: 3.84%–12.59%, 11 positives of 18 pools) in Haemaphysalis hystricis, 6.02% (95% CI: 1.85%–14.22%, four positives of eight pools) in H. formosensis, 25.03% (95% CI: 9.23%–54.59%, six positive of eight pools) in Dermacentor taiwanensis, and 0.16% (95% CI: 0.01%–0.72%, one positive of 100 pools) in Rhipicephalus microplus. This study presented the first report of tick-carried Orthonairovirus in Fujian province and highlighted the broad geographic distribution and high genetic diversity of orthonairoviruses in China.

A comprehensive list of the Bunyavirales replication promoters reveals a unique promoter structure in Nairoviridae differing from other virus families

Members of the order Bunyavirales infect a wide variety of host species, including plants, animals and humans, and pose a threat to public health. Major families in this order have tri-segmented negative-sense RNA genomes, the 5′ and 3′ ends of which form complementary strands that serve as a replication promoter. Elucidation of the mechanisms by which viral polymerases recognize the promoter to initiate RNA synthesis is important for understanding viral replication and pathogenesis, and developing antivirals. A list of replication promoter configuration patterns may provide details on the differences in the replication mechanisms among bunyaviruses. By using public sequence data of all known bunyavirus species, we constructed a comprehensive list of the replication promoters comprising 40 nucleotides in both the 5′ and 3′ ends of the genome that form a specific complementary strand. Among tri-segmented bunyaviruses, members of the family Nairoviridae, including the highly pathogenic Crimean-Congo hemorrhagic fever virus, have evolved a GC-rich promoter structure differing from that of other families. The unique promoter structure might be related to the large genome size of the family Nairoviridae among bunyaviruses, and the large genome architecture might confer pathogenic advantages. The promoter list provided in this report is useful for predicting the virus family-specific replication mechanisms of bunyaviruses.

Mapping the viruses belonging to the order Bunyavirales in China

BACKGROUND

Viral pathogens belonging to the order Bunyavirales pose a continuous background threat to global health, but the fact remains that they are usually neglected and their distribution is still ambiguously known. We aim to map the geographical distribution of Bunyavirales viruses and assess the environmental suitability and transmission risk of major Bunyavirales viruses in China.

METHODS

We assembled data on all Bunyavirales viruses detected in humans, animals and vectors from multiple sources, to update distribution maps of them across China. In addition, we predicted environmental suitability at the 10 km × 10 km pixel level by applying boosted regression tree models for two important Bunyavirales viruses, including Crimean-Congo hemorrhagic fever virus (CCHFV) and Rift Valley fever virus (RVFV). Based on model-projected risks and air travel volume, the imported risk of RVFV was also estimated from its endemic areas to the cities in China.

RESULTS

Here we mapped all 89 species of Bunyavirales viruses in China from January 1951 to June 2021. Nineteen viruses were shown to infect humans, including ten species first reported as human infections. A total of 447,848 cases infected with Bunyavirales viruses were reported, and hantaviruses, Dabie bandavirus and Crimean-Congo hemorrhagic fever virus (CCHFV) had the severest disease burden. Model-predicted maps showed that Xinjiang and southwestern Yunnan had the highest environmental suitability for CCHFV occurrence, mainly related to Hyalomma asiaticum presence, while southern China had the highest environmental suitability for Rift Valley fever virus (RVFV) transmission all year round, mainly driven by livestock density, mean precipitation in the previous month. We further identified three cities including Guangzhou, Beijing and Shanghai, with the highest imported risk of RVFV potentially from Egypt, South Africa, Saudi Arabia and Kenya.

CONCLUSIONS

A variety of Bunyavirales viruses are widely distributed in China, and the two major neglected Bunyavirales viruses including CCHFV and RVFV, both have the potential for outbreaks in local areas of China. Our study can help to promote the understanding of risk distribution and disease burden of Bunyavirales viruses in China, and the risk maps of CCHFV and RVFV occurrence are crucial to the targeted surveillance and control, especially in seasons and locations at high risk.

Mapping of Antibody Epitopes on the Crimean-Congo Hemorrhagic Fever Virus Nucleoprotein

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.

Characterization of Keterah orthonairovirus and evaluation of therapeutic candidates against Keterah orthonairovirus infectious disease

The species Keterah orthonairovirus is a member of the genus Orthonairovirus. Few studies have focused on this species, and there remains no treatment for Issyk-Kul fever, an infectious disease caused by a Keterah orthonairovirus. This study was performed to characterize this species using two viruses, Issyk-Kul virus (ISKV) and Soft tick bunyavirus (STBV), in cell culture and type I interferon receptor knockout (IFNAR-/-) mice and to evaluate the efficacy of serum transfusion using a mouse model of ISKV infection. The two viruses replicated in many kinds of mammal- and tick-derived cell lines but showed few different characteristics in tropism and antigenicity against anti-viral sera in cell culture. Neither virus caused clinical signs in wild-type mice, but both caused lethal infection in IFNAR-/- mice. ISKV caused more acute death than STBV in IFNAR-/- mice. In both viral infections in IFNAR-/- mice, macroscopic abnormalities were prominent in the liver. Similar levels of viral genome between ISKV- and STBV-infected IFNAR-/- mice were observed in blood, liver, lymphoid tissues and adrenal gland at moribund stages. Hematologic abnormalities in IFNAR-/- mice infected with these viruses, including leukopenia and thrombocytopenia, and biochemical abnormalities indicating liver damage were prominent. In addition, blood levels of many kinds of cytokines and chemokines such as granulocyte colony-stimulating factor, interleukin-6, tumor necrosis factor-α, interferon gamma-induced protein 10 and monocyte chemoattractant protein-1 were elevated. ISKV-immunized serum transfusion after infection delayed the time to death of IFNAR-/- mice. Thus, the present study showed that the species Keterah orthonairovirus could proliferate in most mammal-derived cell lines and cause severe liver lesions and death in IFNAR-/- mice and that serum transfusion might be effective in treatment against Issyk-Kul fever.

Diagnosis and Pathogenesis of Nairobi Sheep Disease Orthonairovirus Infections in Sheep and Cattle

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.

Whole Genome or Single Genes? A Phylodynamic and Bibliometric Analysis of PRRSV

Diversity, ecology, and evolution of viruses are commonly determined through phylogenetics, an accurate tool for the identification and study of lineages with different pathological characteristics within the same species. In the case of PRRSV, evolutionary research has divided into two main branches based on the use of a specific gene (i.e., ORF5) or whole genome sequences as the input used to produce the phylogeny. In this study, we performed a review on PRRSV phylogenetic literature and characterized the spatiotemporal trends in research of single gene vs. whole genome evolutionary approaches. Finally, using publicly available data, we produced a Bayesian phylodynamic analysis following each research branch and compared the results to determine the pros and cons of each particular approach. This study provides an exploration of the two main phylogenetic research lines applied for PRRSV evolution, as well as an example of the differences found when both methods are applied to the same database. We expect that our results will serve as a guidance for future PRRSV phylogenetic research.

Development of a Dissemination Platform for Spatiotemporal and Phylogenetic Analysis of Avian Infectious Bronchitis Virus

Infecting large portions of the global poultry populations, the avian infectious bronchitis virus (IBV) remains a major economic burden in North America. With more than 30 serotypes globally distributed, Arkansas, Connecticut, Delaware, Georgia, and Massachusetts are among the most predominant serotypes in the United States. Even though vaccination is widely used, the high mutation rate exhibited by IBV is continuously triggering the emergence of new viral strains and hindering control and prevention measures. For that reason, targeted strategies based on constantly updated information on the IBV circulation are necessary. Here, we sampled IBV-infected farms from one US state and collected and analyzed 65 genetic sequences coming from three different lineages along with the immunization information of each sampled farm. Phylodynamic analyses showed that IBV dispersal velocity was 12.3 km/year. The majority of IBV infections appeared to have derived from the introduction of the Arkansas DPI serotype, and the Arkansas DPI and Georgia 13 were the predominant serotypes. When analyzed against IBV sequences collected across the United States and deposited in the GenBank database, the most likely viral origin of our sequences was from the states of Alabama, Georgia, and Delaware. Information about vaccination showed that the MILDVAC-MASS+ARK vaccine was applied on 26% of the farms. Using a publicly accessible open-source tool for real-time interactive tracking of pathogen spread and evolution, we analyzed the spatiotemporal spread of IBV and developed an online reporting dashboard. Overall, our work demonstrates how the combination of genetic and spatial information could be used to track the spread and evolution of poultry diseases, providing timely information to the industry. Our results could allow producers and veterinarians to monitor in near-real time the current IBV strain circulating, making it more informative, for example, in vaccination-related decisions.

The Impact of Tick-Borne Diseases on the Bone

Tick-borne infectious diseases can affect many tissues and organs including bone, one of the most multifunctional structures in the human body. There is a scarcity of data regarding the impact of tick-borne pathogens on bone. The aim of this review was to survey existing research literature on this topic. The search was performed using PubMed and Google Scholar search engines. From our search, we were able to find evidence of eight tick-borne diseases (Anaplasmosis, Ehrlichiosis, Babesiosis, Lyme disease, Bourbon virus disease, Colorado tick fever disease, Tick-borne encephalitis, and Crimean-Congo hemorrhagic fever) affecting the bone. Pathological bone effects most commonly associated with tick-borne infections were disruption of bone marrow function and bone loss. Most research to date on the effects of tick-borne pathogen infections on bone has been quite preliminary. Further investigation of this topic is warranted.

The Integration of Human and Veterinary Studies for Better Understanding and Management of Crimean-Congo Haemorrhagic Fever

Outbreaks that occur as a result of zoonotic spillover from an animal reservoir continue to highlight the importance of studying the disease interface between species. One Health approaches recognise the interdependence of human and animal health and the environmental interplay. Improving the understanding and prevention of zoonotic diseases may be achieved through greater consideration of these relationships, potentially leading to better health outcomes across species. In this review, special emphasis is given on the emerging and outbreak pathogen Crimean-Congo Haemorrhagic Fever virus (CCHFV) that can cause severe disease in humans. We discuss the efforts undertaken to better understand CCHF and the importance of integrating veterinary and human research for this pathogen. Furthermore, we consider the use of closely related nairoviruses to model human disease caused by CCHFV. We discuss intervention approaches with potential application for managing CCHFV spread, and how this concept may benefit both animal and human health.