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Chang P, Sadeyen JR, Bhat S, Daines R, Hussain A, Yilmaz H, Iqbal M. Risk assessment of the newly emerged H7N9 avian influenza viruses. Emerg Microbes Infect 2023; 12:2172965. [PMID: 36714929 PMCID: PMC9930780 DOI: 10.1080/22221751.2023.2172965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Since the first human case in 2013, H7N9 avian influenza viruses (AIVs) have caused more than 1500 human infections with a mortality rate of approximately 40%. Despite large-scale poultry vaccination regimes across China, the H7N9 AIVs continue to persist and evolve rapidly in poultry. Recently, several strains of H7N9 AIVs have been isolated and shown the ability to escape vaccine-induced immunity. To assess the zoonotic risk of the recent H7N9 AIV isolates, we rescued viruses with hemagglutinin (HA) and neuraminidase (NA) from these H7N9 AIVs and six internal segments from PR8 virus and characterized their receptor binding, pH of fusion, thermal stability, plaque morphology and in ovo virus replication. We also assessed the cross-reactivity of the viruses with human monoclonal antibodies (mAbs) against H7N9 HA and ferret antisera against H7N9 AIV candidate vaccines. The H7N9 AIVs from the early epidemic waves had dual sialic acid receptor binding characteristics, whereas the more recent H7N9 AIVs completely lost or retained only weak human sialic acid receptor binding. Compared with the H7N9 AIVs from the first epidemic wave, the 2020/21 viruses formed larger plaques in Madin-Darby canine kidney (MDCK) cells and replicated to higher titres in ovo, demonstrating increased acid stability but reduced thermal stability. Further analysis showed that these recent H7N9 AIVs had poor cross-reactivity with the human mAbs and ferret antisera, highlighting the need to update the vaccine candidates. To conclude, the newly emerged H7N9 AIVs showed characteristics of typical AIVs, posing reduced zoonotic risk but a heightened threat for poultry.
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Affiliation(s)
| | | | | | | | | | - Huseyin Yilmaz
- Department of Virology, Veterinary Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
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Guan L, Ping J, Lopes TJS, Fan S, Presler R, Neumann G, Kawaoka Y. Development of an Enhanced High-Yield Influenza Vaccine Backbone in Embryonated Chicken Eggs. Vaccines (Basel) 2023; 11:1364. [PMID: 37631932 PMCID: PMC10459923 DOI: 10.3390/vaccines11081364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/28/2023] Open
Abstract
Vaccination is an efficient approach to preventing influenza virus infections. Recently, we developed influenza A and B virus vaccine backbones that increased the yield of several vaccine viruses in Madin-Darby canine kidney (MDCK) and African green monkey kidney (Vero) cells. These vaccine backbones also increased viral replication in embryonated chicken eggs, which are the most frequently used platform for influenza vaccine manufacturing. In this study, to further increase the viral titers in embryonated chicken eggs, we introduced random mutations into the 'internal genes' (i.e., all influenza viral genes except those encoding the hemagglutinin and neuraminidase proteins) of the influenza A virus high-yield virus backbone we developed previously. The randomly mutated viruses were sequentially passaged in embryonated chicken eggs to select variants with increased replicative ability. We identified a candidate that conferred higher influenza virus growth than the high-yield parental virus backbone. Although the observed increases in virus growth may be considered small, they are highly relevant for vaccine manufacturers.
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Affiliation(s)
- Lizheng Guan
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Jihui Ping
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Tiago J. S. Lopes
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Shufang Fan
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Robert Presler
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Gabriele Neumann
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
| | - Yoshihiro Kawaoka
- Department of Pathobiological Sciences, School of Veterinary Medicine, Influenza Research Institute, University of Wisconsin-Madison, Madison, WI 53711, USA (T.J.S.L.); (R.P.)
- Division of Virology, Department of Microbiology and Immunology, International Research Center for Infectious Diseases, The Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
- The Research Center for Global Viral Diseases, National Center for Global Health and Medicine Research Institute, Tokyo 162-8655, Japan
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Gao J, Wan H, Li X, Rakic Martinez M, Klenow L, Gao Y, Ye Z, Daniels R. Balancing the influenza neuraminidase and hemagglutinin responses by exchanging the vaccine virus backbone. PLoS Pathog 2021; 17:e1009171. [PMID: 33872324 PMCID: PMC8084346 DOI: 10.1371/journal.ppat.1009171] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 04/29/2021] [Accepted: 04/05/2021] [Indexed: 01/14/2023] Open
Abstract
Virions are a common antigen source for many viral vaccines. One limitation to using virions is that the antigen abundance is determined by the content of each protein in the virus. This caveat especially applies to viral-based influenza vaccines where the low abundance of the neuraminidase (NA) surface antigen remains a bottleneck for improving the NA antibody response. Our systematic analysis using recent H1N1 vaccine antigens demonstrates that the NA to hemagglutinin (HA) ratio in virions can be improved by exchanging the viral backbone internal genes, especially the segment encoding the polymerase PB1 subunit. The purified inactivated virions with higher NA content show a more spherical morphology, a shift in the balance between the HA receptor binding and NA receptor release functions, and induce a better NA inhibitory antibody response in mice. These results indicate that influenza viruses support a range of ratios for a given NA and HA pair which can be used to produce viral-based influenza vaccines with higher NA content that can elicit more balanced neutralizing antibody responses to NA and HA. Influenza vaccines are produced on a large scale to meet the annual U.S. and global demand. To efficiently produce the required number of influenza vaccine doses, virions are commonly used as the antigen source due to their high viral protein content. A draw-back to using virions is that the final antigen composition of the vaccine is determined by the inherent properties of the vaccine virus. While this approach for influenza vaccines is beneficial for the more abundant HA antigen, it likely limits the protective response generated by the less abundant NA antigen. Our results demonstrate that the NA and HA content in vaccine viruses can be optimized by changing the internal genes of the vaccine virus, thereby preserving the surface antigens. The increase in the virion NA content that was achieved elicited higher NA antibody titres and generated more balanced neutralizing antibody responses to HA and NA. Since HA and NA neutralizing antibodies are both protective, this approach could help to improve the suboptimal efficacy of current influenza vaccines and to generate vaccines that provide broader coverage against circulating strains.
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Affiliation(s)
- Jin Gao
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Hongquan Wan
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Xing Li
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Mira Rakic Martinez
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Laura Klenow
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Yamei Gao
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Zhiping Ye
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Robert Daniels
- Division of Viral Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
- * E-mail:
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Liu L, Li Z, Zhou J, Lu J, Li X, Liu J, Xiao N, Wang D. The effect of single amino acid substitution at position 220 in the hemagglutinin glycoprotein on avian influenza H7N9 candidate vaccine virus. Virus Genes 2021; 57:164-171. [PMID: 33606171 DOI: 10.1007/s11262-021-01827-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 01/18/2021] [Indexed: 11/26/2022]
Abstract
Influenza vaccines represent the most effective preventive strategy to control influenza virus infections; however, adaptive mutations frequently occur in the hemagglutinin (HA) glycoprotein during the preparation of candidate vaccine virus and production of vaccine in embryonated eggs. In our previous study, we constructed candidate vaccine virus (HA-R) to match the highly pathogenic avian influenza H7N9 viruses A/Guangdong/17SF003/2016 as part of a pandemic preparedness program. However, mixed amino acids (R, G, and I) were presented at position 220 (H3 numbering) in HA during passage in embryonated eggs. The residue at position 220 is located close to the receptor-binding site and the biological characteristics of this site remain to be elucidated. Therefore, in this study, using reverse genetics, we constructed two viruses carrying the single substitution in position 220 of HA (HA-G and HA-I) and evaluated the biological effects of substitution (R with G/I) on receptor binding, neuraminidase (NA) activity, growth characteristics, genetic stability, and antigenicity. The results revealed both mutant viruses exhibited lower HA binding affinities to two receptor types (sialic acid in alpha2,3- and alpha2,6-linkage to galactose, P < 0.001) and significant better growth characteristics compared to HA-R in two cells. Moreover, under similar NA enzymatic activity, the two mutant viruses eluted more easily from agglutinated erythrocytes than HA-R. Collectively, these results implied the balance of HA and NA in mutant viruses was a stronger determinant of viral growth than the individual amino acid in the HA position 220 in HA-R without strong binding between HA and sialylated receptors. Importantly, both the substitutions conferred altered antigenicity to the mutant viruses. In conclusion, amino acid substitutions at position 220 can substantially influence viral biological properties.
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Affiliation(s)
- Liqi Liu
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Zi Li
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Jianfang Zhou
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Jian Lu
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Xiyan Li
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Jia Liu
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Ning Xiao
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China
| | - Dayan Wang
- Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China.
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Immune Escape Adaptive Mutations in the H7N9 Avian Influenza Hemagglutinin Protein Increase Virus Replication Fitness and Decrease Pandemic Potential. J Virol 2020; 94:JVI.00216-20. [PMID: 32699084 PMCID: PMC7495387 DOI: 10.1128/jvi.00216-20] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 07/08/2020] [Indexed: 02/06/2023] Open
Abstract
H7N9 avian influenza viruses (AIVs) continue to evolve and remain a huge threat to human health and the poultry industry. Previously, serially passaging the H7N9 A/Anhui/1/2013 virus in the presence of homologous ferret antiserum resulted in immune escape viruses containing amino acid substitutions alanine to threonine at residues 125 (A125T) and 151 (A151T) and leucine to glutamine at residue 217 (L217Q) in the hemagglutinin (HA) protein. These HA mutations have also been found in field isolates in 2019. To investigate the potential threat of serum escape mutant viruses to humans and poultry, the impact of these HA substitutions, either individually or in combination, on receptor binding, pH of fusion, thermal stability, and virus replication were investigated. Our results showed the serum escape mutant formed large plaques in Madin-Darby canine kidney (MDCK) cells and grew robustly in vitro and in ovo They had a lower pH of fusion and increased thermal stability. Of note, the serum escape mutant completely lost the ability to bind to human-like receptor analogues. Further analysis revealed that N-linked glycosylation, as a result of A125T or A151T substitutions in HA, resulted in reduced receptor-binding avidity toward both human and avian-like receptor analogues, and the A125T+A151T mutations completely abolished human-like receptor binding. The L217Q mutation enhanced the H7N9 acid and thermal stability while the A151T mutation dramatically decreased H7N9 HA thermal stability. To conclude, H7N9 AIVs that contain A125T+A151T+L217Q mutations in the HA protein may pose a reduced pandemic risk but remain a heightened threat for poultry.IMPORTANCE Avian influenza H7N9 viruses have been causing disease outbreaks in poultry and humans. We previously determined that propagation of H7N9 virus in virus-specific antiserum gives rise to mutant viruses carrying mutations A125T+A151T+L217Q in their hemagglutinin protein, enabling the virus to overcome vaccine-induced immunity. As predicted, these immune escape mutations were also observed in the field viruses that likely emerged in the immunized or naturally exposed birds. This study demonstrates that the immune escape mutants also (i) gained greater replication ability in cultured cells and in chicken embryos as well as (ii) increased acid and thermal stability but (iii) lost preferences for binding to human-type receptor while maintaining binding for the avian-like receptor. Therefore, they potentially pose reduced pandemic risk. However, the emergent virus variants containing the indicated mutations remain a significant risk to poultry due to antigenic drift and improved fitness for poultry.
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Tzeng TT, Chen PL, Weng TC, Tsai SY, Lai CC, Chou HI, Chen PW, Lu CC, Liu MT, Sung WC, Lee MS, Hu AYC. Development of high-growth influenza H7N9 prepandemic candidate vaccine viruses in suspension MDCK cells. J Biomed Sci 2020; 27:47. [PMID: 32241276 PMCID: PMC7115086 DOI: 10.1186/s12929-020-00645-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/27/2020] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Influenza vaccine manufacturers traditionally use egg-derived candidate vaccine viruses (CVVs) to produce high-yield influenza viruses for seasonal or pandemic vaccines; however, these egg-derived CVVs need an adaptation process for the virus to grow in mammalian cells. The low yields of cell-based manufacturing systems using egg-derived CVVs remain an unsolved issue. This study aimed to develop high-growth cell-derived CVVs for MDCK cell-based vaccine manufacturing platforms. METHODS Four H7N9 CVVs were generated in characterized Vero and adherent MDCK (aMDCK) cells. Furthermore, reassortant viruses were amplified in adherent MDCK (aMDCK) cells with certification, and their growth characteristics were detected in aMDCK cells and new suspension MDCK (sMDCK) cells. Finally, the plaque-forming ability, biosafety, and immunogenicity of H7N9 reassortant viruses were evaluated. RESULTS The HA titers of these CVVs produced in proprietary suspension MDCK (sMDCK) cells and chicken embryos were 2- to 8-fold higher than those in aMDCK cells. All H7N9 CVVs showed attenuated characteristics by trypsin-dependent plaque assay and chicken embryo lethality test. The alum-adjuvanted NHRI-RG5 (derived from the fifth wave H7N9 virus A/Guangdong/SP440/2017) vaccine had the highest immunogenicity and cross-reactivity among the four H7N9 CVVs. Finally, we found that AddaVax adjuvant improved the cross-reactivity of low pathogenic H7N9 virus against highly pathogenic H7N9 viruses. CONCLUSIONS Our study indicates that cell-derived H7N9 CVVs possessed high growth rate in new sMDCK cells and low pathogenicity in chicken embryo, and that CVVs generated by this platform are also suitable for both cell- and egg-based prepandemic vaccine production.
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Affiliation(s)
- Tsai-Teng Tzeng
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Po-Ling Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan.,Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, Taiwan
| | - Tsai-Chuan Weng
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Shin-Yi Tsai
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Chia-Chun Lai
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan.,College of Life Science, National Tsing Hua University, Hsinchu, Taiwan
| | - Hsin-I Chou
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Pin-Wen Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Chia-Chun Lu
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Ming-Tsan Liu
- Centers for Disease Control, Ministry of Health and Welfare, Taipei, 689, Taiwan
| | - Wang-Chou Sung
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Min-Shi Lee
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Alan Yung-Chih Hu
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes (NHRI), 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan.
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