NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV),which first appeared in China in 2017,is currently one of the main epidemic strains in China.In this study,we found that a new variant of NADC34-l...NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV),which first appeared in China in 2017,is currently one of the main epidemic strains in China.In this study,we found that a new variant of NADC34-like PRRSV evolved,named the L1A variant.The phylogenetics,epidemic status,and pathogenicity of the LA variants were subsequently comprehensively evaluated.Based on the results of the ORF5 phylogenetic analysis,the L1A variants were classified as NADC34-like PPRSV.All the strains had the same discontinuous 131-aa deletion in the NSP2 region(similar to that in the NADC30).Recombination analysis revealed that the L1A variants were recombinant viruses that contained an NADC30-like PRRSV skeleton,a nonstructural protein-encoding gene region obtained in part from JXA1-like PRRSV and a ORF2-ORF6 gene region partly obtained from NADC34-like PRRSV and that exhibited similar recombination patterns.We successfully isolated the L1A variant TZJ2756 from PAMs and Marc-145 cells.In animal experiments,TZJ2756 exhibited moderate pathogenicity in piglets,causing obvious clinical symptoms,namely,persistent fever,significantly reduced body weight,interstitial edema and severe interstitial pneumonia in the lungs,and prolonged high-load viremia.L1A variants have been detected in at least 12 provinces in China and share many similar epidemiological characteristics with the American L1C variant.This research will enhance our understanding of the prevalence of L1A variants and furnish valuable data for the ongoing monitoring of NADC34-like PRRSV in China.展开更多
HPPD(4-hydroxyphenylpyruvate dioxygenase)inhibitor are widely used in agriculture due to their high efficacy and environmental friendliness.However,many important crops,such as rice,wheat,and soybean,are naturally sen...HPPD(4-hydroxyphenylpyruvate dioxygenase)inhibitor are widely used in agriculture due to their high efficacy and environmental friendliness.However,many important crops,such as rice,wheat,and soybean,are naturally sensitive to these herbicides.In this study,we employed a directed evolution strategy to enhance the metabolic capacity of OsHSL2,OsHSL4,OsHSL6,and SbHSL1 proteins toward HPPD inhibitors,providing a new technological approach as well as theoretical foundation for molecular breeding of herbicide-resistant crops.By combining AlphaFold 3 protein models with crystal structures,we systematically redesigned key residues to resemble the active residues found in HIS1.Catalytic activity assays demonstrated that specific mutations significantly improved the metabolic activity of HSLs proteins toward various HPPD inhibitors.Notably,the OsHSL2-M4 mutant exhibited enhanced metabolic activity for BBC-OH and methyl-benquitrione,while the OsHSL4-M5 mutant completely metabolized BBC-OH and topramezone.Additionally,the SbHSL1-M4 mutant showed significant improvement in the metabolism of BBC-OH and several other herbicides,providing strong evidence to support the use of structure-guided HSL mutations to enhance crop resistance to HPPD inhibitors.展开更多
基金supported by grants from the National Natural Science Foundation of China(32172890 and 32002315)the National Key Research and Development Program of China(2022YFF0711004)+3 种基金the Natural Science Foundation of Heilongjiang Province,China(YQ2022C042)the State Key Laboratory of Veterinary Biotechnology Foundation of China(SKLVBF202208)the Postdoctoral Fellowship Program of CPSF,China(GZC20233062)the National Center of Technology Innovation for Pigs,China(NCTIP-XD/C09)。
文摘NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV),which first appeared in China in 2017,is currently one of the main epidemic strains in China.In this study,we found that a new variant of NADC34-like PRRSV evolved,named the L1A variant.The phylogenetics,epidemic status,and pathogenicity of the LA variants were subsequently comprehensively evaluated.Based on the results of the ORF5 phylogenetic analysis,the L1A variants were classified as NADC34-like PPRSV.All the strains had the same discontinuous 131-aa deletion in the NSP2 region(similar to that in the NADC30).Recombination analysis revealed that the L1A variants were recombinant viruses that contained an NADC30-like PRRSV skeleton,a nonstructural protein-encoding gene region obtained in part from JXA1-like PRRSV and a ORF2-ORF6 gene region partly obtained from NADC34-like PRRSV and that exhibited similar recombination patterns.We successfully isolated the L1A variant TZJ2756 from PAMs and Marc-145 cells.In animal experiments,TZJ2756 exhibited moderate pathogenicity in piglets,causing obvious clinical symptoms,namely,persistent fever,significantly reduced body weight,interstitial edema and severe interstitial pneumonia in the lungs,and prolonged high-load viremia.L1A variants have been detected in at least 12 provinces in China and share many similar epidemiological characteristics with the American L1C variant.This research will enhance our understanding of the prevalence of L1A variants and furnish valuable data for the ongoing monitoring of NADC34-like PRRSV in China.
基金supported by the National Key Research and Development Program of China(No.2024YFE0214300)Hubei Provincial Science and Technology Plan Project(2022BEC051)selfdetermined research funds of CCNU from the colleges'basic research and operation of MOE(No.CCNU24JCPT023).
文摘HPPD(4-hydroxyphenylpyruvate dioxygenase)inhibitor are widely used in agriculture due to their high efficacy and environmental friendliness.However,many important crops,such as rice,wheat,and soybean,are naturally sensitive to these herbicides.In this study,we employed a directed evolution strategy to enhance the metabolic capacity of OsHSL2,OsHSL4,OsHSL6,and SbHSL1 proteins toward HPPD inhibitors,providing a new technological approach as well as theoretical foundation for molecular breeding of herbicide-resistant crops.By combining AlphaFold 3 protein models with crystal structures,we systematically redesigned key residues to resemble the active residues found in HIS1.Catalytic activity assays demonstrated that specific mutations significantly improved the metabolic activity of HSLs proteins toward various HPPD inhibitors.Notably,the OsHSL2-M4 mutant exhibited enhanced metabolic activity for BBC-OH and methyl-benquitrione,while the OsHSL4-M5 mutant completely metabolized BBC-OH and topramezone.Additionally,the SbHSL1-M4 mutant showed significant improvement in the metabolism of BBC-OH and several other herbicides,providing strong evidence to support the use of structure-guided HSL mutations to enhance crop resistance to HPPD inhibitors.
