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
Porcine reproductive and respiratory syndrome(PRRS)is a problem that has significant economic impact on the global pig industry.In recent years,there has been an increased importation of pork into China,contributing t...Porcine reproductive and respiratory syndrome(PRRS)is a problem that has significant economic impact on the global pig industry.In recent years,there has been an increased importation of pork into China,contributing to the emergence of novely imported porcine reproductive and respiratory syndrome virus(PRRSV)sub-types.Nevertheless,codon usage patterns and their effects on the evolution and adaptation of these new input PRRSV sub-types in hosts remain elusive.To investigate this,we employed a Bayesian approach to analyze two novel imported PRRSV sub-types,namely,NADC30-like and NADC34-like viruses.These sub-types have different codon preferences.Besides,the Effective Number of Codon(ENC)analysis revealed that both NADC30-like and NADC34-like fall within the expected curve distribution,describing a balanced codon usage for both NADC30-like and NADC34-like virus.Based on the Codon Adaptation Index(CAI),NADC30-like showed the highest similarity to the host,aligning with the main prevalence trend of the host.In contrast,NADC34-like exhibited the highest frequency of optimal codon usage;this analysis is based on Frequency of Optimal Codons(FOP).Moreover,the Relative Codon Deoptimization Index(RCDI)indicates that NADC30-like sub-types have a greater degree of inverse optimization sub-type.These findings suggest that mutational pressure affects codon usage preferences of genes in newly imported PRRSV,and that natural selection plays a vital role in determining PRRSV gene codon preferences.Our study provides new insights into the disease,origin,evolutionary patterns,and host adaptation of these newly imported PRRSV sub-types in China.It also contributes to the development of theoretical frameworks for studying genetics and the evolution of PRRSV.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 Postdoctoral Science Foundation 72nd Grant of China(2022M723906)Projects of Jilin Province Science and Technology Development Plan(20220508051RC).
文摘Porcine reproductive and respiratory syndrome(PRRS)is a problem that has significant economic impact on the global pig industry.In recent years,there has been an increased importation of pork into China,contributing to the emergence of novely imported porcine reproductive and respiratory syndrome virus(PRRSV)sub-types.Nevertheless,codon usage patterns and their effects on the evolution and adaptation of these new input PRRSV sub-types in hosts remain elusive.To investigate this,we employed a Bayesian approach to analyze two novel imported PRRSV sub-types,namely,NADC30-like and NADC34-like viruses.These sub-types have different codon preferences.Besides,the Effective Number of Codon(ENC)analysis revealed that both NADC30-like and NADC34-like fall within the expected curve distribution,describing a balanced codon usage for both NADC30-like and NADC34-like virus.Based on the Codon Adaptation Index(CAI),NADC30-like showed the highest similarity to the host,aligning with the main prevalence trend of the host.In contrast,NADC34-like exhibited the highest frequency of optimal codon usage;this analysis is based on Frequency of Optimal Codons(FOP).Moreover,the Relative Codon Deoptimization Index(RCDI)indicates that NADC30-like sub-types have a greater degree of inverse optimization sub-type.These findings suggest that mutational pressure affects codon usage preferences of genes in newly imported PRRSV,and that natural selection plays a vital role in determining PRRSV gene codon preferences.Our study provides new insights into the disease,origin,evolutionary patterns,and host adaptation of these newly imported PRRSV sub-types in China.It also contributes to the development of theoretical frameworks for studying genetics and the evolution of PRRSV.
