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RESEARCH ARTICLE
Genome Characteristics and Evolution of Pseudorabies Virus Strains in Eastern China from 2017 to 2019
Xiaofeng Zhai, Wen Zhao, Kemang Li, Cheng Zhang, Congcong Wang, Shuo Su, Jiyong Zhou, Jing Lei, Gang Xing, Haifeng Sun, Zhiyu Shi, Jinyan Gu
, doi: 10.1007/s12250-019-00140-1
Since late 2011, outbreaks of pseudorabies virus (PRV) have occurred in southern China causing major economic losses to the pig industry. We previously reported variant PRV may from recombination in China that could be the source of continued epidemics. Here, we analyzed samples from intensive pig farms in eastern China between 2017 and 2019, and sequenced the main glycoproteins (gB, gC, gD, and gE) to study the evolution characteristics of PRV. Based on the gC gene, we found that PRV variants belong to clade 2 and identified a founder effect by the PRV epidemic process. In addition, we detected inter- and intra-clade recombination, in particular, inter-clade recombination in the gB gene of strains FJ-ZXF and FJ-W2, which were recombinants with clade 1 strains. Specific amino acid changes and positively selected sites possibly associated with functional changes were also observed. The characteristics of PRV emergence in China necessitate continuous monitoring and development of vaccines capable of providing immunity against specific PRV variants.Since late 2011, outbreaks of pseudorabies virus (PRV) have occurred in southern China causing major economic losses to the pig industry. We previously reported variant PRV may from recombination in China that could be the source of continued epidemics. Here, we analyzed samples from intensive pig farms in eastern China between 2017 and 2019, and sequenced the main glycoproteins (gB, gC, gD, and gE) to study the evolution characteristics of PRV. Based on the gC gene, we found that PRV variants belong to clade 2 and identified a founder effect by the PRV epidemic process. In addition, we detected inter- and intra-clade recombination, in particular, inter-clade recombination in the gB gene of strains FJ-ZXF and FJ-W2, which were recombinants with clade 1 strains. Specific amino acid changes and positively selected sites possibly associated with functional changes were also observed. The characteristics of PRV emergence in China necessitate continuous monitoring and development of vaccines capable of providing immunity against specific PRV variants.
Research Article
Cleavage of the Babuvirus Movement Protein B4 into Functional Peptides Capable of Host Factor Conjugation is Required for Virulence
Jun Zhuang, Wenwu Lin, Christopher J. Coates, Pengxiang Shang, Taiyun Wei, Zujian Wu, Lianhui Xie
, doi: 10.1007/s12250-019-00094-4
Banana bunchy top virus (BBTV) poses a serious danger to banana crops worldwide. BBTV-encoded protein B4 is a determinant of pathogenicity. However, the relevant molecular mechanisms underlying its effects remain unknown. In this study, we found that a functional peptide could be liberated from protein B4, likely via proteolytic processing. Site-directed mutagenesis indicated that the functional processing of protein B4 is required for its pathogenic effects, including dwarfism and sterility, in plants. The released protein fragment targets host proteins, such as the large subunit of RuBisCO (RbcL) and elongation factor 2 (EF2), involved in protein synthesis. Therefore, the peptide released from B4 (also a precursor) may act as a non-canonical modifier to influence host–pathogen interactions involving BBTV and plants.
Banana bunchy top virus (BBTV) poses a serious danger to banana crops worldwide. BBTV-encoded protein B4 is a determinant of pathogenicity. However, the relevant molecular mechanisms underlying its effects remain unknown. In this study, we found that a functional peptide could be liberated from protein B4, likely via proteolytic processing. Site-directed mutagenesis indicated that the functional processing of protein B4 is required for its pathogenic effects, including dwarfism and sterility, in plants. The released protein fragment targets host proteins, such as the large subunit of RuBisCO (RbcL) and elongation factor 2 (EF2), involved in protein synthesis. Therefore, the peptide released from B4 (also a precursor) may act as a non-canonical modifier to influence host–pathogen interactions involving BBTV and plants.
Bacteriophages Isolated in China for the Control of Pectobacterium carotovorum Causing Potato Soft Rot in Kenya
Peter Muturi, Junping Yu, Alice Nyambura Maina, Samuel Kariuki, Francis B. Mwaura, Hongping Wei
, doi: 10.1007/s12250-019-00091-7
Soft rot is an economically significant disease in potato and one of the major threats to sustainable potato production. This study aimed at isolating lytic bacteriophages and evaluating methods for and the efficacy of applying phages to control potato soft rot caused by Pectobacterium carotovorum. Eleven bacteriophages isolated from soil and water samples collected in Wuhan, China, were used to infect P. carotovorum host strains isolated from potato tubers showing soft rot symptoms in Nakuru county, Kenya. The efficacy of the phages in controlling soft rot disease was evaluated by applying individual phage strains or a phage cocktail on potato slices and tubers at different time points before or after inoculation with a P. carotovorum strain. The phages could lyse 20 strains of P. carotovorum, but not Pseudomonas fluorescenscontrol strains. Among the 11 phages, Pectobacterium phage Wc5r, interestingly showed cross-activity against Pectobacterium atrosepticum and two phage-resistant P. carotovorum strains. Potato slice assays showed that the phage concentration and timing of application are crucial factors for effective soft rot control. Phage cocktail applied at a concentration of 1 × 109 plaque-forming units per milliliter before or within an hour after bacterial inoculation on potato slices, resulted in ≥90% reduction of soft rot symptoms. This study provides a basis for the development and application of phages to reduce the impact of potato soft rot disease.
Soft rot is an economically significant disease in potato and one of the major threats to sustainable potato production. This study aimed at isolating lytic bacteriophages and evaluating methods for and the efficacy of applying phages to control potato soft rot caused by Pectobacterium carotovorum. Eleven bacteriophages isolated from soil and water samples collected in Wuhan, China, were used to infect P. carotovorum host strains isolated from potato tubers showing soft rot symptoms in Nakuru county, Kenya. The efficacy of the phages in controlling soft rot disease was evaluated by applying individual phage strains or a phage cocktail on potato slices and tubers at different time points before or after inoculation with a P. carotovorum strain. The phages could lyse 20 strains of P. carotovorum, but not Pseudomonas fluorescenscontrol strains. Among the 11 phages, Pectobacterium phage Wc5r, interestingly showed cross-activity against Pectobacterium atrosepticum and two phage-resistant P. carotovorum strains. Potato slice assays showed that the phage concentration and timing of application are crucial factors for effective soft rot control. Phage cocktail applied at a concentration of 1 × 109 plaque-forming units per milliliter before or within an hour after bacterial inoculation on potato slices, resulted in ≥90% reduction of soft rot symptoms. This study provides a basis for the development and application of phages to reduce the impact of potato soft rot disease.
LETTER
Rift Valley Fever Virus and Yellow Fever Virus in Urine: A Potential Source of Infection
Meng Li, Beibei Wang, Liqiang Li, Gary Wong, Yingxia Liu, Jinmin Ma, Jiandong Li, Hongzhou Lu, Mifang Liang, Ang Li, Xiuqing Zhang, Yuhai Bi, Hui Zeng
, doi: 10.1007/s12250-019-00096-2
In recent years, the incidence of human infections caused by emerging or re-emerging pathogens has rapidly increased. Diseases that were once regional now have the ability to spread globally in a short amount of time and pose a wider threat to public health (Weaver et al. 2018). Yellow fever virus (YFV, family Flaviviridae, genus Flavivirus) is a mosquito-borne flavivirus that causes yellow fever in humans and has been endemic in Africa and Latin America for many years (Domingo et al. 2018). The most recent large-scale outbreak of YFV occurred in Brazil in which the mortality rate as of February 28, 2018 is 32.78% (WHO 2018). Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is another mosquitoborne virus and primarily circulates in Africa and the Middle East, and in recent years in Europe (Mansfield et al. 2015). During the initial stage of infection, most patients infected with YFV or RVFV present nonspecific symptoms such as fever, headache, and vomiting, which often lead to a misdiagnosis (Mansfield et al. 2015; Domingo et al. 2018). The cases of YFV and RVFV in China were first reported in March and July 2016, respectively, in travelers returning from Angola (Chen et al. 2016; Liu et al. 2017).
In recent years, the incidence of human infections caused by emerging or re-emerging pathogens has rapidly increased. Diseases that were once regional now have the ability to spread globally in a short amount of time and pose a wider threat to public health (Weaver et al. 2018). Yellow fever virus (YFV, family Flaviviridae, genus Flavivirus) is a mosquito-borne flavivirus that causes yellow fever in humans and has been endemic in Africa and Latin America for many years (Domingo et al. 2018). The most recent large-scale outbreak of YFV occurred in Brazil in which the mortality rate as of February 28, 2018 is 32.78% (WHO 2018). Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is another mosquitoborne virus and primarily circulates in Africa and the Middle East, and in recent years in Europe (Mansfield et al. 2015). During the initial stage of infection, most patients infected with YFV or RVFV present nonspecific symptoms such as fever, headache, and vomiting, which often lead to a misdiagnosis (Mansfield et al. 2015; Domingo et al. 2018). The cases of YFV and RVFV in China were first reported in March and July 2016, respectively, in travelers returning from Angola (Chen et al. 2016; Liu et al. 2017).