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
NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV) has been circulating in China for several years and became the dominant field strain in some provinces.Current commercial vaccines could not provi...NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV) has been circulating in China for several years and became the dominant field strain in some provinces.Current commercial vaccines could not provide complete crossprotection to NADC34-like PRRSV infection,which led to huge economic losses on pig farms.Co-infections of NADC34-like PRRSV with some other PRRSV strains are commonly found in many clinical cases,and successful isolation of NADC34-like PRRSV strain from the clinical samples has been a challenge to study its biological characters and perform animal experiments to evaluate its pathogenicity.In this study,we constructed a NADC34-like PRRSV infectious clone derived from the isolated JS2021 NADC34 PRRSV strain using the reverse genetics technique and investigated its virulence and pathogenicity for nursery pigs.The rescued(rNADC34) strain could proliferate well in porcine alveolar macrophages(PAMs),and the viral copy number and titers were comparable to parental strain.For pathogenicity,the rNADC34 straininfected pigs showed high body temperature and body weight loss.The histopathological results presented interstitial pneumonia and severe hemorrhage,infiltration of neutrophils and lymphocyte in lungs,lymph nodes,and tonsils.The viral proteins were also detectable in rNADC34 strain-infected pigs using immunohistochemistry staining.Moreover,the trends of PRRSV-specific antibody and viremia in PRRSV rNADC34-infected pigs were similar with the parental strain-infected pigs.These data indicated that rNADC34 strain manifested strong virulence and high pathogenicity for nursery pigs.展开更多
Porcine reproductive and respiratory syndrome(PRRS)is one of the most significant diseases affecting the pig industry worldwide.The PRRSV mutation rate is the highest among the RNA viruses.To date,NADC30-like PRRSV an...Porcine reproductive and respiratory syndrome(PRRS)is one of the most significant diseases affecting the pig industry worldwide.The PRRSV mutation rate is the highest among the RNA viruses.To date,NADC30-like PRRSV and highly pathogenic PRRSV(HP-PRRSV)are the dominant epidemic strains in China;however,commercial vaccines do not always provide sufficient cross-protection,and the reasons for insufficient protection are unclear.This study isolated a wild-type NADC30-like PRRSV,SX-YL1806,from Shaanxi Province.Vaccination challenge experiments in piglets showed that commercial modified live virus(MLV)vaccines provided good protection against HP-PRRSV.However,it could not provide sufficient protection against the novel strain SXYL1806.To explore the reasons for this phenomenon,we compared the genomic homology between the MLV strain and HP-PRRSV or NADC30-like PRRSV and found that the MLV strain had a lower genome similarity with NADC30-like PRRSV.Serum neutralization assay showed that MLV-immune serum slightly promoted the homologous HP-PRRSV replication and significantly promoted the heterologous NADC30-like PRRSV strain replication in vitro,suggesting that antibody-dependent enhancement(ADE)might also play a role in decreasing MLV protective efficacy.These findings expand our understanding of the potential factors affecting the protective effect of PRRSV MLV vaccines against the NADC30-like strains.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 Natural Science Foundation of China-CGIAR (32361143511)the National Key Research and Development Program of China (2022YFD1800301)+3 种基金the Natural Science Foundation of Jiangsu Province, China (BK20210804)the Jiangsu Innovative and Entrepreneurial Talent Team Project, China (JSSCTD202224)the 111 Project D18007, and the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)supported by the “LvYangJinfeng Program” of Yangzhou City, China。
文摘NADC34-like porcine reproductive and respiratory syndrome virus(PRRSV) has been circulating in China for several years and became the dominant field strain in some provinces.Current commercial vaccines could not provide complete crossprotection to NADC34-like PRRSV infection,which led to huge economic losses on pig farms.Co-infections of NADC34-like PRRSV with some other PRRSV strains are commonly found in many clinical cases,and successful isolation of NADC34-like PRRSV strain from the clinical samples has been a challenge to study its biological characters and perform animal experiments to evaluate its pathogenicity.In this study,we constructed a NADC34-like PRRSV infectious clone derived from the isolated JS2021 NADC34 PRRSV strain using the reverse genetics technique and investigated its virulence and pathogenicity for nursery pigs.The rescued(rNADC34) strain could proliferate well in porcine alveolar macrophages(PAMs),and the viral copy number and titers were comparable to parental strain.For pathogenicity,the rNADC34 straininfected pigs showed high body temperature and body weight loss.The histopathological results presented interstitial pneumonia and severe hemorrhage,infiltration of neutrophils and lymphocyte in lungs,lymph nodes,and tonsils.The viral proteins were also detectable in rNADC34 strain-infected pigs using immunohistochemistry staining.Moreover,the trends of PRRSV-specific antibody and viremia in PRRSV rNADC34-infected pigs were similar with the parental strain-infected pigs.These data indicated that rNADC34 strain manifested strong virulence and high pathogenicity for nursery pigs.
基金This research was supported by the National Natural Science Foundation of China(32172846)the Earmarked Fund for CARS-35,the Science and Technology Major Project of Gansu Province(22ZD6NA001)+4 种基金the Science Foundation for Distinguished Young Scholars of Shaanxi Province(2021JC-18)the Natural Science Foundation of Gansu Province(23JRRA1153)the Science and Technology Plan Project of Gansu Province(23JRRA561)the Chinese Academy of Agricultural Science and Technology Innovation Project(CAAS-ASTIP-JBGS-20210602)the Strategic Priority Research Program of the National Center of Technology Innovation for Pigs(NCTIP-XD/C03).
文摘Porcine reproductive and respiratory syndrome(PRRS)is one of the most significant diseases affecting the pig industry worldwide.The PRRSV mutation rate is the highest among the RNA viruses.To date,NADC30-like PRRSV and highly pathogenic PRRSV(HP-PRRSV)are the dominant epidemic strains in China;however,commercial vaccines do not always provide sufficient cross-protection,and the reasons for insufficient protection are unclear.This study isolated a wild-type NADC30-like PRRSV,SX-YL1806,from Shaanxi Province.Vaccination challenge experiments in piglets showed that commercial modified live virus(MLV)vaccines provided good protection against HP-PRRSV.However,it could not provide sufficient protection against the novel strain SXYL1806.To explore the reasons for this phenomenon,we compared the genomic homology between the MLV strain and HP-PRRSV or NADC30-like PRRSV and found that the MLV strain had a lower genome similarity with NADC30-like PRRSV.Serum neutralization assay showed that MLV-immune serum slightly promoted the homologous HP-PRRSV replication and significantly promoted the heterologous NADC30-like PRRSV strain replication in vitro,suggesting that antibody-dependent enhancement(ADE)might also play a role in decreasing MLV protective efficacy.These findings expand our understanding of the potential factors affecting the protective effect of PRRSV MLV vaccines against the NADC30-like strains.
