Project description:BackgroundSugarcane mosaic virus (SCMV) is responsible for large-scale economic losses in the global production of sugarcane, maize, sorghum, and some other graminaceous species. To understand the evolutionary mechanism of SCMV populations, this virus was studied in Shanxi, China. A total of 86 maize leaf samples (41 samples in 2012 and 45 samples in 2013) were collected from 4 regions of Shanxi.ResultsDouble-antibody sandwich (DAS)-ELISA and RT-PCR showed 59 samples (30 samples in 2012 and 29 samples in 2013) to be positive for SCMV, from which 10 new isolates of SCMV were isolated and sequenced. The complete genomes of these isolates are 9610 nt long, including the 5' and 3' non-coding regions, and encode a 3063-amino acid polyprotein. Phylogenetic analyses revealed that 24 SCMV isolates could be divided on the basis of the whole genome into 2 divergent evolutionary groups, which were associated with the host species. Among the populations, 15 potential recombination events were identified. The selection pressure on the genes of these SCMV isolates was also calculated. The results confirmed that all the genes were under negative selection.ConclusionsNegative selection and recombination appear to be important evolutionary factors shaping the genetic structure of these SCMV isolates. SCMV is distributed widely in China and exists as numerous strains with distinct genetic diversity. Our findings will provide a foundation for evaluating the epidemiological characteristics of SCMV in China and will be useful in designing long-term, sustainable management strategies for SCMV.
Project description:Alfalfa (Medicago sativa L.) is one of the most important quality forages worldwide and is cultivated throughout China. Alfalfa is susceptible to a variety of viral diseases during its growth, which has caused huge amounts of commercial losses. However, the profile of the alfalfa virus in China remains ambiguous and the viruses transmitted by Odontothrips loti (Haliday), dominant insect pests in alfalfa, are also poorly understood. In the present study, virus diversity was investigated in the primary alfalfa-growing areas in China. A total of 18 alfalfa viruses were identified through RNA-sequencing (RNA-seq) and reverse transcription-polymerase chain reaction (RT-PCR). Two new plant viruses, Medicago sativa virus 1 (MsV1) and Medicago sativa luteovirus 1 (MsLV1), were detected for the first time. Another four viruses, including the Alfalfa ringspot-associated virus (ARaV), Alfalfa virus F (AVF), Alfalfa enamovirus 1 (AEV1), and Alfalfa deltaparitivirus (ADPV), were reported in China for the first time as well. Both Alfalfa mosaic virus (AMV) and Medicago sativa alphapartitivirus 2 (MsAPV2) are the dominant pathogens, with an infection incidence of 91.7-100%, and 74.4-97.2%, respectively. Additionally, O. loti with first- and second-instar nymphs were shown to acquire the AMV within 0.25 h of feeding on a virus-infected alfalfa. Transmission by thrips to healthy alfalfa plants was also demonstrated. Additionally, we clarified the dynamic changes in the AMV in pre-adult stages of O. loti, which indicated that the AMV is propagated in the nymph stage of O. loti. These findings provide valuable information for understanding the alfalfa virome, confirm the role thrips O. loti plays in alfalfa virus transmission, and improve our fundamental knowledge and management of diseases in China.
Project description:Alfalfa (Medicago sativa L.) is one of the most widely cultivated forage crops in the world. China is the second largest producer of alfalfa in terms of the planting area worldwide, with Gansu, Henan, Inner Mongolia, and Shaanxi provinces being the production hubs. Alfalfa viruses have been reported on a small-scale survey in some of these areas, but they have not been well characterized. In the present study, seven viruses were detected in 12 fields of 10 cities/counties of the four abovementioned provinces by high-throughput sequencing and assembly of small RNA. Their incidence, distribution, and genetic diversity were analyzed by enzyme-linked immunosorbent assay, polymerase chain reaction (PCR)/reverse transcription-PCR and clone sequencing. The results showed that alfalfa mosaic virus (AMV), pea streak virus (PeSV), lucerne transient streak virus (LTSV), alfalfa dwarf virus (ADV), Medicago sativa alphapartitivirus 1 (MsAPV1), MsAPV2, and alfalfa leaf curl virus (ALCV) were the main viruses infecting alfalfa in four examined provinces. AMV and MsAPV1 had the highest incidences in all 4 provinces. SDT analysis of the 7 viruses isolated in China revealed a highly conserved among AMV, LTSV, ADV, MsAPV1, MsAPV2, and ALCV, but the sequence was a high variation between China isolates to abroad isolates in PeSV, ADV, and ALCV. To our knowledge, this is the first report of ADV in Inner Mongolia and Gansu, ALCV in Inner Mongolia, MsAPV1 and MsAPV2 in all 4 provinces, and PeSV and LTSV in China. These findings provide a basis for future research on the genetic evolution of alfalfa viruses in China and on strategies to prevent diseases in alfalfa caused by these viruses.
Project description:With worldwide cultivation, the faba bean (Vicia faba L.) stands as one of the most vital cool-season legume crops, serving as a major component of food security. China leads global faba bean production in terms of both total planting area and yield, with major production hubs in Yunnan, Sichuan, Jiangsu, and Gansu provinces. The faba bean viruses have caused serious yield losses in these production areas, but previous researches have not comprehensively investigated this issue. In this study, we collected 287 faba bean samples over three consecutive years from eight provinces/municipalities of China. We employed small RNA sequencing, RT-PCR, DNA sequencing, and phylogenetic analysis to detect the presence of viruses and examine their incidence, distribution, and genetic diversity. We identified a total of nine distinct viruses: bean yellow mosaic virus (BYMV, Potyvirus), milk vetch dwarf virus (MDV, Nanovirus), vicia cryptic virus (VCV, Alphapartitivirus), bean common mosaic virus (BCMV, Potyvirus), beet western yellows virus (BWYV, Polerovirus), broad bean wilt virus (BBWV, Fabavirus), soybean mosaic virus (SMV, Potyvirus), pea seed-borne mosaic virus (PSbMV, Potyvirus), and cucumber mosaic virus (CMV, Cucumovirus). BYMV was the predominant virus found during our sampling, followed by MDV and VCV. This study marks the first reported detection of BCMV in Chinese faba bean fields. Except for several isolates from Gansu and Yunnan provinces, our sequence analysis revealed that the majority of BYMV isolates contain highly conserved nucleotide sequences of coat protein (CP). Amino acid sequence alignment indicates that there is a conserved NAG motif at the N-terminal region of BYMV CP, which is considered important for aphid transmission. Our findings not only highlight the presence and diversity of pathogenic viruses in Chinese faba bean production, but also provide target pathogens for future antiviral resource screening and a basis for antiviral breeding.
Project description:This report describes the genetic characterization of 297 wild-type measles viruses that were isolated in 24 provinces of China between 1995 and 2003. Phylogenetic analysis of the N gene sequences showed that all of the isolates belonged to genotype H1 except 3 isolates, which were genotype A. The nucleotide sequence and predicted amino acid homologies of the 294-genotype H1 strains were 94.7%-100% and 93.3%-100%, respectively. The genotype H1 isolates were divided into 2 clusters, which differed by approximately 2.9% at the nucleotide level. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Even though other measles genotypes have been detected in countries that border China, this report shows that genotype H1 is widely distributed throughout the country and that China has a single, endemic genotype. This important baseline data will help to monitor the progress of measles control in China.
Project description:Seneca Valley virus (SVV), a newly determined etiological agent of vesicular disease in swine, causes porcine idiopathic disease and occasional acute death in piglets. Recently, an increased number of SVV infection cases have been reported in the United States (US) and China, resulting in significant economic losses to the swine industry. The first identification of SVV in China was reported in Guangdong Province, a major swine producing province. The cases of SVV were continuously reported in Guangdong in 2015 and 2016. However, the spread of SVV in Guangdong in 2017 remains unknown. In this study, we determined two new SVV strains, CH-GD-2017-1 and CH-GD-2017-2, from Guangdong. The genetic analysis suggested that the two Guangdong strains showed different characteristics to previous Guangdong strains. They showed lower nucleotide similarity with strains isolated in 2015 and 2016, and were more similar to the US strains. Phylogenetic analyses indicated that the new strains were clustered in a different clade with previous Guangdong strains. We found 28 mutated amino acids in the new strains, compared with the first Guangdong strain, SVV CH-01-2015. In the geographic analysis, we found that the US and China reported more SVV cases than other countries, and most of the SVV cases were reported in east and central China-of which, Guangdong Province is one of the major epidemic regions. In conclusion, our findings indicate that SVV continued to spread in Guangdong Province in 2017, and two different clades of SVVs have emerged in this region.
Project description:BackgroundRecurrent infections of animal hosts with avian influenza viruses (AIVs) have posted a persistent threat. It is very important to understand the avian influenza virus distribution and characteristics in environment associated with poultry and wild bird. The aim of this study was to analyze the geographic and seasonal distributions of AIVs in the 31 provinces, municipalities and autonomous region (PMA) of China, compare the AIVs prevalence in different collecting sites and sampling types, analyze the diversity of AIVs subtypes in environment.MethodsA total of 742 005 environmental samples were collected from environmental samples related to poultry and wild birds in different locations in the mainland of China during 2014-2018. Viral RNA was extracted from the environmental samples. Real-time RT-PCR assays for influenza A, H5, H7 and H9 subtypes were performed on all the samples to identify subtypes of influenza virus. The nucleic acid of influenza A-positive samples were inoculated into embryonated chicken eggs for virus isolation. Whole-genome sequencing was then performed on Illumina platform. SPSS software was used to paired t test for the statistical analysis. ArcGIS was used for drawing map. Graphpad Prism was used to make graph.ResultsThe nucleic acid positivity rate of influenza A, H5, H7 and H9 subtypes displayed the different characteristics of geographic distribution. The nucleic acid positivity rates of influenza A were particularly high (25.96%-45.51%) in eleven provinces covered the Central, Eastern, Southern, Southwest and Northwest of China. The nucleic acid positivity rates of H5 were significantly high (11.42%-13.79%) in two provinces and one municipality covered the Southwest and Central of China. The nucleic acid positivity rates of H7 were up to 4% in five provinces covered the Eastern and Central of China. The nucleic acid positivity rates of H9 were higher (13.07%-2.07%) in eleven PMA covered the Southern, Eastern, Central, Southwest and Northwest of China. The nucleic acid positivity rate of influenza A, H5, H7 and H9 showed the same seasonality. The highest nucleic acid positivity rates of influenza A, H5, H7, H9 subtypes were detected in December and January and lowest from May to September. Significant higher nucleic acid positivity rate of influenza A, H5, H7 and H9 were detected in samples collected from live poultry markets (LPM) (30.42%, 5.59%, 4.26%, 17.78%) and poultry slaughterhouses (22.96%, 4.2%, 2.08%, 12.63%). Environmental samples that were collected from sewage and chopping boards had significantly higher nucleic acid positivity rates for influenza A (36.58% and 33.1%), H5 (10.22% and 7.29%), H7(4.24% and 5.69%)and H9(21.62% and 18.75%). Multiple subtypes of AIVs including nine hemagglutinin (HA) and seven neuraminidase (NA) subtypes were isolated form the environmental samples. The H5, H7, and H9 subtypes accounted for the majority of AIVs in environment.ConclusionsIn this study, we found the avian influenza viruses characteristics of geographic distribution, seasonality, location, samples types, proved that multiple subtypes of AIVs continuously coexisted in the environment associated with poultry and wild bird, highlighted the need for environmental surveillance in China.
Project description:Infectious bronchitis viruses (IBVs) of GI-13 (793/B) and GI-19 (QX/LX4) lineages have been frequently detected in China in recent years. Naturally recombinant IBVs originating from the GI-13 and GI-19 lineages have also been isolated from chicken flocks with respiratory and renal problems in China. Thorough genetic and biological investigations of these recombinant viruses have led to speculation regarding their origin, evolution, and control. In order to confirm the previous results and further extend our understanding about the characteristics of the four recombinant IBV strains we had previously identified (I0718/17, I0722/17, I0724/17, and I0737/17), we conducted phylogenetic analysis by comparing their complete S1 gene sequences with those of 71 reference strains of different genotypes and lineages. We identified a close relationship between the S1 sequences of the four strains and those of GI-13 strains. The results of complete genome sequence analysis confirmed the previously identified recombination events in the four IBV strains and revealed additional recombination events in different genomic regions of strains I0718/17 and I0724/17, suggesting that the two strains originated from multiple recombination events between 4/91-like and YX10-like viruses. We comparatively evaluated the antigenicity, pathogenicity, and affinity of the four recombinant viruses and their deduced parental strains in the trachea and kidneys. Some of the strains showed comparable antigenic relatedness, pathogenicity, and affinity for the trachea and kidneys among each other and with their parental viruses; however, some of them showed varying biological characteristics. Point mutations observed in the receptor-binding domain and hypervariable region of the S1 subunit of the spike protein likely have an effect on these differences in biological characteristics, although the influence of other factors-such as host innate-immune responses and changes in genomic regions beyond the S1 protein-might also be responsible for such changes.
Project description:We performed whole genome single nucleotide polymorphism (SNP) based analysis of all available Venezuelan equine encephalitis (VEE) virus antigenic complex genomes and developed a high resolution genome-wide SNP microarray. We used the SNP microarray to analyze a broad panel of VEEV isolates, found excellent concordance between array and sequence based genotypes for previously sequenced strains, and genotyped unsequenced strains.
Project description:Tomato is a major vegetable crop that has tremendous popularity. However, viral disease is still a major factor limiting tomato production. Here, we report the tomato virome identified through sequencing small RNAs of 170 field-grown samples collected in China. A total of 22 viruses were identified, including both well-documented and newly detected viruses. The tomato viral community is dominated by a few species, and they exhibit polymorphisms and recombination in the genomes with cold spots and hot spots. Most samples were coinfected by multiple viruses, and the majority of identified viruses are positive-sense single-stranded RNA viruses. Evolutionary analysis of one of the most dominant tomato viruses, Tomato yellow leaf curl virus (TYLCV), predicts its origin and the time back to its most recent common ancestor. The broadly sampled data have enabled us to identify several unreported viruses in tomato, including a completely new virus, which has a genome of ?13.4 kb and groups with aphid-transmitted viruses in the genus Cytorhabdovirus Although both DNA and RNA viruses can trigger the biogenesis of virus-derived small interfering RNAs (vsiRNAs), we show that features such as length distribution, paired distance, and base selection bias of vsiRNA sequences reflect different plant Dicer-like proteins and Argonautes involved in vsiRNA biogenesis. Collectively, this study offers insights into host-virus interaction in tomato and provides valuable information to facilitate the management of viral diseases.IMPORTANCE Tomato is an important source of micronutrients in the human diet and is extensively consumed around the world. Virus is among the major constraints on tomato production. Categorizing virus species that are capable of infecting tomato and understanding their diversity and evolution are challenging due to difficulties in detecting such fast-evolving biological entities. Here, we report the landscape of the tomato virome in China, the leading country in tomato production. We identified dozens of viruses present in tomato, including both well-documented and completely new viruses. Some newly emerged viruses in tomato were found to spread fast, and therefore, prompt attention is needed to control them. Moreover, we show that the virus genomes exhibit considerable degree of polymorphisms and recombination, and the virus-derived small interfering RNA (vsiRNA) sequences indicate distinct vsiRNA biogenesis mechanisms for different viruses. The Chinese tomato virome that we developed provides valuable information to facilitate the management of tomato viral diseases.