Transboundary and Emerging Diseases最新文献

Rotavirus A (RVA) is a prevalent cause of enteric diarrhea in infants, bovine, pigs, and sheep globally. Currently, the G6P[1]-type rotaviruses are prevalent in sheep or goat in Bangladesh, Turkey, and Uganda. However, this genotype has not been reported in Chinese sheep or goat. Therefore, 12 anal swabs were collected from diarrheal sheep in Gansu Province, China, in 2023 and tested for rotavirus using reverse transcription-polymerase chain reaction (RT-PCR). Pathological sections and immunohistochemistry were used to observe pathological changes and rotavirus antigens in the duodenum, respectively. The sheep rotavirus was isolated in MA-104 cells and characterized through indirect immunofluorescence and transmission electron microscopy. The genes of the strain were obtained using the next-generation sequencing technology and analyzed phylogenetically. One sheep was positive for rotavirus by RT-PCR, and immunohistochemistry revealed numerous rotavirus antigens in the apical portion of the duodenal villi. Transmission electron microscopy revealed that the strain was characterized by virus particles that were “wheel-shaped” and measured 70–80 nm in size. The gene constellations of this strain is G6-P[1]-I2-R2-C2-M2-A11-N2-T6-E2-H3. BLASTn and phylogenetic tree analyses suggest that this strain is likely a recombinant of human rotavirus, goat rotavirus, and bovine rotavirus. The comparison of amino acid similarities revealed three differences in the key antigenic epitopes of the VP7 and VP4 proteins between the GO34 strain and this study strain despite the identical gene constellations of the two strains. To date, this is the first report of this constellation of RVA being found in sheep.

Lumpy skin disease (LSD) is a viral disease caused by lumpy skin disease virus (LSDV), which mainly infects cattle and can cause huge economic losses. In May 2023, yaks, cattle-yaks, and cattle in Tibet (Xizang), China, developed fever, skin nodules, and severe discharges and were suspected to be cases of LSD. Samples from these animals were analyzed using molecular biology and serological methods. The RPO30, P32, and GPCR genes were amplified by PCR and sequenced, and the whole genome of the virus was determined using viral metagenomics technology. Sequencing results showed that it was indeed an LSDV infection, and enzyme-linked immunosorbent assay results confirmed the presence of LSDV antibodies. The whole genome phylogenetic tree shows that LSDV/CHINA/Tibet/2023 is different from the previous epidemic strains in China, but clusters with India 2022 strain. This is the first report of LSD in yaks, cattle-yaks, and cattle on the highest altitude plateau in the world.

The epizootic hemorrhagic disease virus (EHDV) is a novel emerging threat for the European livestock sector. First detected in Sardinia and southern Spain at the end of 2022, this transboundary disease emerged in France in September 2023 despite restrictions on animal movement and enhanced surveillance protocols. Although virus spread is believed to be mediated by the dispersal of Culicoides vectors by the wind, prediction is difficult due to the large number of meteorological parameters that must be considered. Using simulations of atmospheric trajectories, we developed a model to investigate the long-distance dispersal risk zone of Culicoides in Europe, starting from different source zones. Our model predicted with good sensitivity the newly EHDV-infected areas in France over a period of 5 weeks after its first introduction in the country. Prospectively, we predicted that the midge dispersal zone of early 2024 could expand toward most of the western half of France and could sporadically reach new countries under favorable spring conditions. The wind dispersal risk maps provided are intended to support better preparedness and response to Culicoides-borne diseases.

Influenza A virus (IAV) can rapidly disseminate among animals through various transmission routes, with emerging evidence suggesting the ocular surface as an important entrance. However, it remains unclear how the virus invades the respiratory tract after ocular exposure. Here, we demonstrated that H1N1 (A/swine/Guangdong/1/2011) utilizes the nasolacrimal system to rapidly spread from the ocular surface to the respiratory tract in the porcine model. In vivo and ex vivo, IAV could efficiently attach and replicate in conjunctiva epithelium, which has abundance of α-2,6-linked and α-2,3-linked sialic acid. After ocular inoculation, infectious virions swiftly migrate to the nasolacrimal duct of piglets and, via continual drainage, disseminate to the respiratory tract. Moreover, the detection of continual virus shedding as well as the successful isolation of virus from conjunctiva and respiratory tract tissue indicated the establishment of productive infection after the transocular route. This study presents evidence suggesting that IAVs could utilize the nasolacrimal system to swiftly spread to the respiratory tract following ocular exposure, which contributes to understanding the modes of transocular transmission of IAVs.

The first case of African swine fever (ASF) was confirmed in Sweden in September 2023. This article describes the local epidemiology, including the spatiotemporal dynamics of the outbreak and some of the factors that may have contributed to its apparently successful eradication. Upon detection of the outbreak, strict control measures were put in place in a preliminarily defined infected zone. A carcass search, including geo-localisation, removal, sampling, and destruction of found carcasses, was initiated and a preliminary core area was defined based on the results. Six months after confirmation of the first case, 93 wild boar carcasses had been found in the infected zone, of which 62 tested positive for ASF virus (ASFV). All ASFV-positive carcasses were found inside the core area. Based on two taphonomy methods, it was assumed that the infection was introduced between early May and late June 2023. The data also indicated that the epidemic curve peaked between mid-August and mid-September, with the last death occurring in late September 2023. Based on the average estimated time of death, geo-localisation of carcasses and two-dimensional kernel density estimation, clustering in space and time was identified. An online questionnaire with questions about hunting and the wild boar population was sent to all leaders of hunting groups in the infected zone. The results showed that the wild boar population had increased in the last 10 years but with large variations and geographical heterogeneity in space use. Disease introduction through natural wild boar movements was excluded and it was assumed that the long-distance translocation of the virus had occurred through human activities. A municipal waste collection centre without wild boar-proof fencing is located close to the epicentre of the outbreak, attracting many wild boar and contributing to the spread of the virus once it had been introduced to the population.

The respiratory mucosa serves as a primary entry point for numerous pathogenic microbes, and the respiratory mucosa secretes type I and III interferons (IFNs), the first generation of antiviral cytokines, in response to viral infection. The pseudorabies virus (PRV) causes serious illnesses in many domestic and wild animal species, particularly in pigs and cattle. However, more information is needed about the immunosuppressive properties and evolutionary history of emerging PRV field strains in China’s respiratory system. The PRV field strain JS2022, which was obtained from a cow farm for this investigation, is a spontaneous recombination of early PRV variant strains in the Jiangsu region and is similar to the PRV variations recovered in China in terms of its entire genome sequence. According to sequence analysis, JS2022 has a spontaneous deletion of 1,212 bp in the gE gene, 502 bp in the gI gene, and 192 bp in the glycoprotein (g) C gene. Pathogenicity analysis revealed that intranasal JS2022 causes severe neurological symptoms in calves, but this effect is different from that of ZJ01. In addition, a considerable number of viral antigens in the nasal mucosa were detected by immunohistochemical staining. Therefore, we constructed a bovine nasal mucosal explant model that maintained good cell morphology and activity even after 5 days. In bovine nasal mucosal explants, JS2022 and ZJ01 can cause infection, and the viral load increases dramatically over time. Quantitative research revealed that 24 hr after infection, JS2022 dramatically reduced the expression of downstream interferon-stimulated genes and the innate immune factors IFN-β and IFN-λ3 and bovine nasal mucosal explants. Overall, our results highlight the significance of PRV surveillance in cattle and offer a resource for learning more about the clinical traits and development of PRV.

A PRRSV strain, PRRSV2/CN/FJLX06/2021, with strong homology to an MLV-like strain HeN1201 that evolved from the highly pathogenic PRRSV vaccine virus HuN4-F112, was isolated from a dying piglet in China. BLAST and phylogenetic analyses showed that PRRSV2/CN/FJLX06-2021 was most closely related to HeN1201 and HuN4 (the parental strain of MLV HuN4-F112) and clustered with Chinese HP-PRRSV strains in PRRSV-2 lineage 8.7. Importantly, 29 of the 39 characteristic amino acid mutations in the HuN4-F112 genome were found at the corresponding sites of PRRSV2/CN/FJLX06-2021. Animal studies showed that piglets infected with PRRSV2/CN/FJLX06-2021 had a persistent high fever, higher viremia, presence of interstitial pneumonia, and a higher mortality rate (40%) within 2 weeks than those vaccine-inoculated with HuN4-F112. Taken together, these data suggest that PRRSV2/CN/FJLX06-2021 is an MLV-like strain that has evolved from MLV HuN4-F112 and is highly pathogenic to piglets.

Porcine respiratory and reproductive syndrome (PRRS) caused by Betaarterivirus suid leads to severe economic losses. The emergence of highly pathogenic Betaarterivirus suid 2 (PRRSV-II), such as NADC30 and NADC34, has been reported in the USA and several Asian countries. NADC30-like PRRSV-II was first reported in 2018 in Taiwan. To investigate the PRRSV variants currently circulating in Taiwan, sequences covering ORF2-5 of Taiwan PRRSV isolates collected between 2020 and 2023 were analyzed. Phylogenetic analysis of the ORF5 nucleotide sequence indicated that most of the Taiwan isolates were clustered in lineage 3 and three isolates were grouped in lineage 1 and were closely related to the NADC34 strain. Interestingly, these three NADC34-like Taiwan PRRSV isolates carried amino acid deletions similar to NADC30 and were more closely related to NADC30 strains than the NADC34 strains in the Nsp2 gene. Next-generation sequencing and recombination detection program showed potential recombination of lineage 3 with NADC30- and NADC34-like PRRSV-II. Our results suggest the presence of circulating mosaic recombinants and lineage 3 PRRSV-II in Taiwan during 2020 and 2023.

Porcine reproductive and respiratory syndrome (PRRS) poses a serious threat to the Chinese swine industry. The etiological agent PRRSV can be classified as either PRRSV-1 or PRRSV-2. Recent studies have revealed an increase in the rates of PRRSV-1 detection and a wider PRRSV-1 distribution. However, the PRRSV-1 genome in China has yet to be fully characterized. In this study, 24 whole PRRSV-1 genomes from different swine farms were assembled and subjected to whole-genome analysis. A phylogenetic analysis based on the complete genome and ORF5 sequences revealed that the PRRSV-1 strains from China belonged to Western European Subtype I and could be classified into seven subgroups. Statistical analysis revealed that BJEU06-1-Like PRRSV is currently the predominant PRRSV-1 strain. Moreover, a similarity analysis showed low pairwise similarity between most PRRSV-1 genomes from different pig farms. Amino acid alignments of the Nsp2 gene revealed that the BJEU06-1-Like subgroup had five discontinued aa deletions (4 + 1). The new subgroup 1 had 11 continued aa deletions and an aa insertion, the new subgroup 2 had two discontinued aa deletions (1 + 1), and, except for in the case of HKEU16, the HKEU16-Like subgroup had five discontinuous aa deletions (1 + 4). Recombination analysis revealed that the BJEU06-1-Like and NMEU09-1-Like strains participated extensively in recent recombination events. The analysis of positive selection suggested that there were 15 positively selected codons in site model, and there were five sites under positive selection in the BJEU06-1-Like subgroup in the branch-site model. The mean rate and tMRCA for PRRSV-1 strains from China were 4.11 × 10⁻³ substitutions/site/year and 1,969.63, respectively. Thus, it is crucial to strengthen epidemiological surveys of PRRSV-1 in China, especially those monitoring BJEU06-1-Like PRRSV.

In many Mediterranean ecosystems, animal tuberculosis (TB), caused by Mycobacterium bovis, is maintained by multi-host communities in which cattle and different wildlife species establish interaction networks contributing to M. bovis transmission and persistence. Most studies have addressed wildlife–cattle disease-relevant interactions, focusing on reservoir hosts, while disregarding the potential contribution of the so-called accidental hosts and/or neglecting wildlife–wildlife interactions. In this work, we aimed to characterise interspecies interactions in an endemic TB risk area and identify the ecological drivers of interaction patterns regardless of the pre-attributed role of host species on TB epidemiology. For that purpose, spatial–temporal indirect interactions between wildlife mammals and cattle, and between different wildlife species, were investigated through camera trapping. Second, five ecological hypotheses potentially driving species pair interactions in the wet and dry seasons were tested covering water and control sites: human presence (H1), landscape composition (H2), topography (H3), weather (H4), and natural food and water resources (H5). Wild boar (Sus scrofa), red deer (Cervus elaphus), and red fox (Vulpes vulpes) were the wildlife species mostly involved in indirect interactions. We found that indirect wildlife–cattle interactions were more frequent than wildlife interactions and, for certain species pairs, interaction rates were higher in the wet season in both wildlife–cattle and wildlife groups. Natural food and water resources (H5) was the most supported hypothesis that influenced the abundance of wildlife–cattle interactions, with positive effects during the dry season and negative effects during the wet season. In contrast, the abundance of indirect interactions between wildlife species was mainly supported by the human disturbance hypothesis (H1), with negative effects exerted on the dry season and variable effects on the wet season. Other tested hypotheses also influenced wildlife–cattle and wildlife–wildlife interactions, depending on the season and host species. These results highlight that indirect interactions, and thus conditions potentially favouring the transmission of M. bovis in shared environments, are determined by different ecological backgrounds.