Bacterial wilt is a devastating disease of potato and can cause an 80% production loss. To control wilt using bacteriophage therapy, we isolated and characterized twelve lytic bacteriophages from different water sourc...Bacterial wilt is a devastating disease of potato and can cause an 80% production loss. To control wilt using bacteriophage therapy, we isolated and characterized twelve lytic bacteriophages from different water sources in Kenya and China. Based on the lytic curves of the phages with the pathogen Ralstonia solanacearum, one optimal bacteriophage cocktail, P1, containing six phage isolations was formulated and used for studying wilt prevention and treatment efficiency in potato plants growing in pots. The preliminary tests showed that the phage cocktail was very effective in preventing potato bacterial wilt by injection of the phages into the plants or decontamination of sterilized soil spiked with R. solanacearum. Eighty percent of potato plants could be protected from the bacterial wilt(caused by R. solanacearum reference strain GIM1.74 and field isolates), and the P1 cocktail could kill 98% of live bacteria spiked in the sterilized soil at one week after spraying.However, the treatment efficiencies of P1 depended on the timing of application of the phages, the susceptibility of the plants to the bacterial wilt, as well as the virulence of the bacteria infected,suggesting that it is important to apply the phage therapy as soon as possible once there are early signs of the bacterial wilt. These results provide the basis for the development of bacteriophagebased biocontrol of potato bacterial wilt as an alternative to the use of antibiotics.展开更多
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...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 fluorescens control 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 1×10^9 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.展开更多
As a respiratory tract virus,SARS-CoV-2 infected people through contacting with the upper respiratory tract first.Previous studies indicated that microbiota could modulate immune response against pathogen infection.In...As a respiratory tract virus,SARS-CoV-2 infected people through contacting with the upper respiratory tract first.Previous studies indicated that microbiota could modulate immune response against pathogen infection.In the present study,we performed metagenomic sequencing of pharyngeal swabs from eleven patients with COVID-19 and eleven Non-COVID-19 patients who had similar symptoms such as fever and cough.Through metagenomic analysis of the above two groups and a healthy group from the public data,there are 6502 species identified in the samples.Specifically,the Pielou index indicated a lower evenness of the microbiota in the COVID-19 group than that in the Non-COVID-19 group.Combined with the linear discriminant analysis(LDA)and the generalized linear model,eighty-one bacterial species were found with increased abundance in the COVID-19 group,where 51 species were enriched more than 8 folds.The top three enriched genera were Streptococcus,Prevotella and Campylobacter containing some opportunistic pathogens.More interestingly,through experiments,we found that two Streptococcus strains,S.suis and S.agalactiae,could stimulate the expression of ACE2 of Vero cells in vitro,which may promote SARS-CoV-2 infection.Therefore,these enriched pathogens in the pharynxes of COVID-19 patients may involve in the virus-host interactions to affect SARS-CoV-2 infection and cause potential secondary bacterial infections through changing the expression of the viral receptor ACE2 and/or modulate the host’s immune system.展开更多
During the two-year pandemic of coronavirus disease 2019(COVID-19), its causative agent, severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), has been evolving. SARS-CoV-2 Delta, a variant of concern, has beco...During the two-year pandemic of coronavirus disease 2019(COVID-19), its causative agent, severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), has been evolving. SARS-CoV-2 Delta, a variant of concern, has become the dominant circulating strain worldwide within just a few months. Here, we performed a comprehensive analysis of a new B.1.617.2 Delta strain(Delta630) compared with the early WIV04 strain(WIV04) in vitro and in vivo, in terms of replication, infectivity, pathogenicity, and transmission in hamsters. When inoculated intranasally, Delta630 led to more pronounced weight loss and more severe disease in hamsters. Moreover, 40%mortality occurred about one week after infection with 10^(4)PFU of Delta630, whereas no deaths occurred even after infection with 10^(5)PFU of WIV04 or other strains belonging to the Delta variant. Moreover, Delta630outgrew over WIV04 in the competitive aerosol transmission experiment. Taken together, the Delta630 strain showed increased replication ability, pathogenicity, and transmissibility over WIV04 in hamsters. To our knowledge, this is the first SARS-CoV-2 strain that causes death in a hamster model, which could be an asset for the efficacy evaluation of vaccines and antivirals against infections of SARS-CoV-2 Delta strains. The underlying molecular mechanisms of increased virulence and transmission await further analysis.展开更多
Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobac...Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobacterial genetic systems and have generated tools for the clinical展开更多
The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain ...The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain to be established. In the present study, the lytic activity of the catalytic domain(CD, PlySc) and binding specificity of the cell wall binding domain(CBD, PlySb) of PlySs2 were examined. Our results showed that PlySc alone maintains very limited lytic activity. Enhanced green fluorescent protein(EGFP)-fused PlySb displayed high binding affinity to the streptococcal strains tested, including S.suis, S.dysgalactiae, and S.agalactiae, but not staphylococci, supporting its utility as a good CBD donor for streptococcal-targeted lysin engineering. EGFP-fused intact PlySs2 similarly displayed high affinity for streptococci, but not staphylococci. Notably, four truncated PlySb fragments showed no binding capacity. These findings collectively indicate that integrity of the PlySc and PlySb domains is an essential determinant of the broad lytic activity of PlySs2.展开更多
Pathogenic African swine fever virus(ASFV)remains a lethal causative agent in the domestic pig industry,which poses a burden on the swine market and causes substantial socioeconomic losses worldwide.Currently,there ar...Pathogenic African swine fever virus(ASFV)remains a lethal causative agent in the domestic pig industry,which poses a burden on the swine market and causes substantial socioeconomic losses worldwide.Currently,there are no commercially efcacious vaccines or specifc treatments available for ASF prevention and control.Unfortunately,little is known about the swine immune response upon ASFV infection.Here,we investigated the host immune response discrepancy induced by the feld moderately virulent strain ASFV HB-2208 among healthy,diseased and asymptomatic pigs.In the peripheral blood of diseased swine,lymphopenia is caused by the massive loss of bystander lymphocytes,such asγδT cells,B cells and CD4^(+)T cells.Conversely,ASFV has a strong tropism for the mononuclear phagocyte system(MPS)and partial dendritic cells(DCs),whose antigen-presenting ability is impeded by the downregulation of CD80 and MHC I.However,no signifcant diference in the number of CD8α^(high) T cells was detected,whereas the frequencies of NK cells,NKT cells,and regulatory T cells(Tregs)were signifcantly increased.Additionally,an in vitro model was established with a coculture of primary pulmonary alveolar macrophages(PAMs)and peripheral blood mononuclear cells(PBMCs),which signifcantly reducedγδT cells,B cells and CD4^(+)T cells and increased Tregs.The diferentiated immune response might aid in enhancing the understanding of ASFV pathogenesis in suids and provide insights into the mechanism of ASFV-induced lymphopenia for further studies.展开更多
Dear Editor,The pandemic of COVID-19 continues worldwide with many variants arising,especially SARS-CoV-2 Delta(B.1.617.2)and Omicron(B.1.1.529)variants of concern(VOCs).According to WHO,Omicron has spread in almost a...Dear Editor,The pandemic of COVID-19 continues worldwide with many variants arising,especially SARS-CoV-2 Delta(B.1.617.2)and Omicron(B.1.1.529)variants of concern(VOCs).According to WHO,Omicron has spread in almost all the countries with a doubling time less than Delta VOC.展开更多
基金supported financially by the Sino-Africa Joint Research Center(SAJC201605)the Chinese Academy of Sciences(ZDRW-ZS-2016-4)
文摘Bacterial wilt is a devastating disease of potato and can cause an 80% production loss. To control wilt using bacteriophage therapy, we isolated and characterized twelve lytic bacteriophages from different water sources in Kenya and China. Based on the lytic curves of the phages with the pathogen Ralstonia solanacearum, one optimal bacteriophage cocktail, P1, containing six phage isolations was formulated and used for studying wilt prevention and treatment efficiency in potato plants growing in pots. The preliminary tests showed that the phage cocktail was very effective in preventing potato bacterial wilt by injection of the phages into the plants or decontamination of sterilized soil spiked with R. solanacearum. Eighty percent of potato plants could be protected from the bacterial wilt(caused by R. solanacearum reference strain GIM1.74 and field isolates), and the P1 cocktail could kill 98% of live bacteria spiked in the sterilized soil at one week after spraying.However, the treatment efficiencies of P1 depended on the timing of application of the phages, the susceptibility of the plants to the bacterial wilt, as well as the virulence of the bacteria infected,suggesting that it is important to apply the phage therapy as soon as possible once there are early signs of the bacterial wilt. These results provide the basis for the development of bacteriophagebased biocontrol of potato bacterial wilt as an alternative to the use of antibiotics.
基金supported financially by the Sino-Africa Joint Research Centre (SAJC201605)the Chinese Academy of Sciences (ZDRW-ZS-2016-4)
文摘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 fluorescens control 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 1×10^9 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.
基金financial supports of CAS(project No 153B42KYSB20170004)the Wuhan National Biosafety Lab for this study。
文摘As a respiratory tract virus,SARS-CoV-2 infected people through contacting with the upper respiratory tract first.Previous studies indicated that microbiota could modulate immune response against pathogen infection.In the present study,we performed metagenomic sequencing of pharyngeal swabs from eleven patients with COVID-19 and eleven Non-COVID-19 patients who had similar symptoms such as fever and cough.Through metagenomic analysis of the above two groups and a healthy group from the public data,there are 6502 species identified in the samples.Specifically,the Pielou index indicated a lower evenness of the microbiota in the COVID-19 group than that in the Non-COVID-19 group.Combined with the linear discriminant analysis(LDA)and the generalized linear model,eighty-one bacterial species were found with increased abundance in the COVID-19 group,where 51 species were enriched more than 8 folds.The top three enriched genera were Streptococcus,Prevotella and Campylobacter containing some opportunistic pathogens.More interestingly,through experiments,we found that two Streptococcus strains,S.suis and S.agalactiae,could stimulate the expression of ACE2 of Vero cells in vitro,which may promote SARS-CoV-2 infection.Therefore,these enriched pathogens in the pharynxes of COVID-19 patients may involve in the virus-host interactions to affect SARS-CoV-2 infection and cause potential secondary bacterial infections through changing the expression of the viral receptor ACE2 and/or modulate the host’s immune system.
基金supported by China Natural Science Foundation (82150201)
文摘During the two-year pandemic of coronavirus disease 2019(COVID-19), its causative agent, severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), has been evolving. SARS-CoV-2 Delta, a variant of concern, has become the dominant circulating strain worldwide within just a few months. Here, we performed a comprehensive analysis of a new B.1.617.2 Delta strain(Delta630) compared with the early WIV04 strain(WIV04) in vitro and in vivo, in terms of replication, infectivity, pathogenicity, and transmission in hamsters. When inoculated intranasally, Delta630 led to more pronounced weight loss and more severe disease in hamsters. Moreover, 40%mortality occurred about one week after infection with 10^(4)PFU of Delta630, whereas no deaths occurred even after infection with 10^(5)PFU of WIV04 or other strains belonging to the Delta variant. Moreover, Delta630outgrew over WIV04 in the competitive aerosol transmission experiment. Taken together, the Delta630 strain showed increased replication ability, pathogenicity, and transmissibility over WIV04 in hamsters. To our knowledge, this is the first SARS-CoV-2 strain that causes death in a hamster model, which could be an asset for the efficacy evaluation of vaccines and antivirals against infections of SARS-CoV-2 Delta strains. The underlying molecular mechanisms of increased virulence and transmission await further analysis.
基金supported by a grant from the State Key Laboratory of Virology(PR China)Chinese Academy of Sciences(No.KJZD-EW-L02)
文摘Dear Editor,Bacteriophages are powerful tools for investigating and manipulating their hosts(Fernandes et al.,2014).This holds particularly true for mycobacteriophages,which have facilitated the development of mycobacterial genetic systems and have generated tools for the clinical
基金supported by the National Natural Science Foundation of China (No. 31400126)Basic Research Program of the Ministry of Science and Technology of China (No. 2012CB721102)+2 种基金Chinese Academy of Sciences (No. KJZD-EW-L02)Open Research Fund Program of the State Key Laboratory of Virology of China (No. 2014IOV002)Key Laboratory of Emerging Infectious Diseases and Biosafety, Wuhan
文摘The novel phage lysin PlySs2, is reported to be highly active against various bacteria, including staphylococci, streptococci and Listeria. However, the molecular mechanisms underlying its broad lytic spectrum remain to be established. In the present study, the lytic activity of the catalytic domain(CD, PlySc) and binding specificity of the cell wall binding domain(CBD, PlySb) of PlySs2 were examined. Our results showed that PlySc alone maintains very limited lytic activity. Enhanced green fluorescent protein(EGFP)-fused PlySb displayed high binding affinity to the streptococcal strains tested, including S.suis, S.dysgalactiae, and S.agalactiae, but not staphylococci, supporting its utility as a good CBD donor for streptococcal-targeted lysin engineering. EGFP-fused intact PlySs2 similarly displayed high affinity for streptococci, but not staphylococci. Notably, four truncated PlySb fragments showed no binding capacity. These findings collectively indicate that integrity of the PlySc and PlySb domains is an essential determinant of the broad lytic activity of PlySs2.
基金support provided by the National Natural Sciences Foundation of China(Grant Nos.32172873 and 31941005)the National Programme on Key Research Project of China(2021YFD1800105-2)National Natural Sciences Foundation of China,32172873,Min Cui,31941005,Min Cui,National Programme on Key Research Project of China,2021YFD1800105-2,Min Cui。
文摘Pathogenic African swine fever virus(ASFV)remains a lethal causative agent in the domestic pig industry,which poses a burden on the swine market and causes substantial socioeconomic losses worldwide.Currently,there are no commercially efcacious vaccines or specifc treatments available for ASF prevention and control.Unfortunately,little is known about the swine immune response upon ASFV infection.Here,we investigated the host immune response discrepancy induced by the feld moderately virulent strain ASFV HB-2208 among healthy,diseased and asymptomatic pigs.In the peripheral blood of diseased swine,lymphopenia is caused by the massive loss of bystander lymphocytes,such asγδT cells,B cells and CD4^(+)T cells.Conversely,ASFV has a strong tropism for the mononuclear phagocyte system(MPS)and partial dendritic cells(DCs),whose antigen-presenting ability is impeded by the downregulation of CD80 and MHC I.However,no signifcant diference in the number of CD8α^(high) T cells was detected,whereas the frequencies of NK cells,NKT cells,and regulatory T cells(Tregs)were signifcantly increased.Additionally,an in vitro model was established with a coculture of primary pulmonary alveolar macrophages(PAMs)and peripheral blood mononuclear cells(PBMCs),which signifcantly reducedγδT cells,B cells and CD4^(+)T cells and increased Tregs.The diferentiated immune response might aid in enhancing the understanding of ASFV pathogenesis in suids and provide insights into the mechanism of ASFV-induced lymphopenia for further studies.
基金This work was supported by Institutes for Drug Research and Development of New Outbreak of Viral Infectious Diseases(SIMM020101),"One-Three-Five"Strategic Programs,Wuhan Institute of Virology,Chinese Academy of Sciences,China.
文摘Dear Editor,The pandemic of COVID-19 continues worldwide with many variants arising,especially SARS-CoV-2 Delta(B.1.617.2)and Omicron(B.1.1.529)variants of concern(VOCs).According to WHO,Omicron has spread in almost all the countries with a doubling time less than Delta VOC.
