Avian H9N2 viruses have wide host range among the influenza A viruses.However,knowledge of H9N2 mammalian adaptation is limited.To explore the molecular basis of the adaptation to mammals,we performed serial lung pass...Avian H9N2 viruses have wide host range among the influenza A viruses.However,knowledge of H9N2 mammalian adaptation is limited.To explore the molecular basis of the adaptation to mammals,we performed serial lung passaging of the H9N2 strain A/chicken/Hunan/8.27 YYGK3W3-OC/2018(3W3)in mice and identified six mutations in the hemagglutinin(HA)and polymerase acidic(PA)proteins.Mutations L226Q,T511I,and A528V of HA were responsible for enhanced pathogenicity and viral replication in mice;notably,HA-L226Q was the key determinant.Mutations T97I,I545V,and S594G of PA contributed to enhanced polymerase activity in mammalian cells and increased viral replication levels in vitro and in vivo.PA-T97I increased viral polymerase activity by accelerating the viral polymerase complex assembly.Our findings revealed that the viral replication was affected by the presence of PA-97I and/or PA-545V in combination with a triple-point HA mutation.Furthermore,the double-and triple-point PA mutations demonstrated antagonistic effect on viral replication when combined with HA-226Q.Notably,any combination of PA mutations,along with double-point HA mutations,resulted in antagonistic effect on viral replication.We also observed antagonism in viral replication between PA-545V and PA-97I,as well as between HA-528V and PA-545V.Our findings demonstrated that several antagonistic mutations in HA and PA proteins affect viral replication,which may contribute to the H9N2 virus adaptation to mice and mammalian cells.These findings can potentially contribute to the monitoring of H9N2 field strains for assessing their potential risk in mammals.展开更多
Seasonal influenza activity significantly decreased in China during the coronavirus disease 2019(COVID-19)pandemic,yet the H3N2 virus led to three epidemic waves.Understanding the characteristics of H3N2 epidemic viru...Seasonal influenza activity significantly decreased in China during the coronavirus disease 2019(COVID-19)pandemic,yet the H3N2 virus led to three epidemic waves.Understanding the characteristics of H3N2 epidemic viruses is essential for recognizing influenza during COVID-19 and for updating vaccines.In this study,we analyzed 579 respiratory samples from patients exhibiting influenza-like symptoms,collected in 2019–2022,leading to the successful sequencing of 36 complete H3N2 genomes.Genomic analysis indicated that the epidemic strains from these periods belonged to different hemagglutinin(HA)clades and exhibited phylogenetic divergence from the concurrently used vaccine strains.Significant antigenic differences were identified through cross-hemagglutination inhibition(HI)and cross-microneutralization(MN)assays.Furthermore,pathogenicity studies showed that representative strains replicated in Madin-Darby canine kidney(MDCK)cells,with varying abilities,and all replicated more effectively at 37℃ compared to 33℃.These strains also replicated well in the respiratory tracts of mice and guinea pigs.The findings indicate a mismatch between circulating H3N2 viruses and recommended vaccine strains,highlighting the need for improved international cooperation and epidemiological surveillance of influenza viruses post-COVID-19.Optimizing effective vaccine strain update strategy and developing a universal influenza vaccine are crucial for future preparedness.展开更多
基金supported by the National Key Research and Development Program of China(NKPs)(2022YFC2604101)the National Science and Technology Major Project of China(2020ZX10001016-002)。
文摘Avian H9N2 viruses have wide host range among the influenza A viruses.However,knowledge of H9N2 mammalian adaptation is limited.To explore the molecular basis of the adaptation to mammals,we performed serial lung passaging of the H9N2 strain A/chicken/Hunan/8.27 YYGK3W3-OC/2018(3W3)in mice and identified six mutations in the hemagglutinin(HA)and polymerase acidic(PA)proteins.Mutations L226Q,T511I,and A528V of HA were responsible for enhanced pathogenicity and viral replication in mice;notably,HA-L226Q was the key determinant.Mutations T97I,I545V,and S594G of PA contributed to enhanced polymerase activity in mammalian cells and increased viral replication levels in vitro and in vivo.PA-T97I increased viral polymerase activity by accelerating the viral polymerase complex assembly.Our findings revealed that the viral replication was affected by the presence of PA-97I and/or PA-545V in combination with a triple-point HA mutation.Furthermore,the double-and triple-point PA mutations demonstrated antagonistic effect on viral replication when combined with HA-226Q.Notably,any combination of PA mutations,along with double-point HA mutations,resulted in antagonistic effect on viral replication.We also observed antagonism in viral replication between PA-545V and PA-97I,as well as between HA-528V and PA-545V.Our findings demonstrated that several antagonistic mutations in HA and PA proteins affect viral replication,which may contribute to the H9N2 virus adaptation to mice and mammalian cells.These findings can potentially contribute to the monitoring of H9N2 field strains for assessing their potential risk in mammals.
基金supported by the National Key R&D Program of China(2022YFC3500804 and 2023YFC2307500 to Y.L.and Y.B.)the National Natural Science Foundation of China(NSFC)(32261133524 and 32425053 to Y.B.)+7 种基金the Beijing Research Center for Respiratory Infectious Diseases(BJRID2025-007 to Y.B.)the CAS Southeast Asia Biodiversity Research Institute(151C53KYSB20210023 to Y.B.)the Major Project of Guangzhou National Laboratory(GZNL2023A01001 to Y.B.)the National Science and Technology Infrastructure of China(National Pathogen Resource Center-NPRC-32 to Y.B.)the CAS Project for Young Scientists in Basic Research(YSBR-086 to Y.B.)the Youth Innovation Promotion Association of CAS(Y2021034 to Y.B.)the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(ZYYCXTD-D-202208 to Y.B.)the Russian Science Foundation(23-44-00026 to M.G.and A.S.).
文摘Seasonal influenza activity significantly decreased in China during the coronavirus disease 2019(COVID-19)pandemic,yet the H3N2 virus led to three epidemic waves.Understanding the characteristics of H3N2 epidemic viruses is essential for recognizing influenza during COVID-19 and for updating vaccines.In this study,we analyzed 579 respiratory samples from patients exhibiting influenza-like symptoms,collected in 2019–2022,leading to the successful sequencing of 36 complete H3N2 genomes.Genomic analysis indicated that the epidemic strains from these periods belonged to different hemagglutinin(HA)clades and exhibited phylogenetic divergence from the concurrently used vaccine strains.Significant antigenic differences were identified through cross-hemagglutination inhibition(HI)and cross-microneutralization(MN)assays.Furthermore,pathogenicity studies showed that representative strains replicated in Madin-Darby canine kidney(MDCK)cells,with varying abilities,and all replicated more effectively at 37℃ compared to 33℃.These strains also replicated well in the respiratory tracts of mice and guinea pigs.The findings indicate a mismatch between circulating H3N2 viruses and recommended vaccine strains,highlighting the need for improved international cooperation and epidemiological surveillance of influenza viruses post-COVID-19.Optimizing effective vaccine strain update strategy and developing a universal influenza vaccine are crucial for future preparedness.
