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Diefenbacher M, Tan TJC, Bauer DLV, Stadtmueller BM, Wu NC, Brooke CB. Interactions between Influenza A Virus Nucleoprotein and Gene Segment Untranslated Regions Facilitate Selective Modulation of Viral Gene Expression. J Virol 2022; 96:e0020522. [PMID: 35467364 PMCID: PMC9131868 DOI: 10.1128/jvi.00205-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/29/2022] [Indexed: 11/20/2022] Open
Abstract
The influenza A virus (IAV) genome is divided into eight negative-sense, single-stranded RNA segments. Each segment exhibits a unique level and temporal pattern of expression; however, the exact mechanisms underlying the patterns of individual gene segment expression are poorly understood. We previously demonstrated that a single substitution in the viral nucleoprotein (NP:F346S) selectively modulates neuraminidase (NA) gene segment expression while leaving other segments largely unaffected. Given what is currently known about NP function, there is no obvious explanation for how changes in NP can selectively modulate the replication of individual gene segments. In this study, we found that the specificity of this effect for the NA segment is virus strain specific and depends on the untranslated region (UTR) sequences of the NA segment. While the NP:F346S substitution did not significantly alter the RNA binding or oligomerization activities of NP in vitro, it specifically decreased the ability of NP to promote NA segment viral RNA (vRNA) synthesis. In addition to NP residue F346, we identified two other adjacent aromatic residues in NP (Y385 and F479) capable of similarly regulating NA gene segment expression, suggesting a larger role for this domain in gene-segment specific regulation. Our findings reveal a novel role for NP in selective regulation of viral gene segment replication and provide a framework for understanding how the expression patterns of individual viral gene segments can be modulated during adaptation to new host environments. IMPORTANCE Influenza A virus (IAV) is a respiratory pathogen that remains a significant source of morbidity and mortality. Escape from host immunity or emergence into new host species often requires mutations that modulate the functional activities of the viral glycoproteins hemagglutinin (HA) and neuraminidase (NA), which are responsible for virus attachment to and release from host cells, respectively. Maintaining the functional balance between the activities of HA and NA is required for fitness across multiple host systems. Thus, selective modulation of viral gene expression patterns may be a key determinant of viral immune escape and cross-species transmission potential. We identified a novel mechanism by which the viral nucleoprotein (NP) gene can selectively modulate NA segment replication and gene expression through interactions with the segment UTRs. Our work highlights an unexpected role for NP in selective regulation of expression from the individual IAV gene segments.
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Affiliation(s)
- Meghan Diefenbacher
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Timothy J. C. Tan
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - David L. V. Bauer
- RNA Virus Replication Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Beth M. Stadtmueller
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Nicholas C. Wu
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Christopher B. Brooke
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Synergistic Effect between 3'-Terminal Noncoding and Adjacent Coding Regions of the Influenza A Virus Hemagglutinin Segment on Template Preference. J Virol 2021; 95:e0087821. [PMID: 34190596 DOI: 10.1128/jvi.00878-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influenza A virus genome is comprised of eight single-stranded negative-sense viral RNA (vRNA) segments. Each of the eight vRNA segments contains segment-specific nonconserved noncoding regions (NCRs) of similar sequence and length in different influenza A virus strains. However, in the subtype-determinant segments, encoding hemagglutinin (HA) and neuraminidase (NA), the segment-specific noncoding regions are subtype specific, varying significantly in sequence and length at both the 3' and 5' termini among different subtypes. The significance of these subtype-specific noncoding regions (ssNCR) in the influenza virus replication cycle is not fully understood. In this study, we show that truncations of the 3'-end H1-subtype-specific noncoding region (H1-ssNCR) resulted in recombinant viruses with decreased HA vRNA replication and attenuated growth phenotype, although the vRNA replication was not affected in single-template RNP reconstitution assays. The attenuated viruses were unstable, and point mutations at nucleotide position 76 or 56 in the adjacent coding region of HA vRNA were found after serial passage. The mutations restored the HA vRNA replication and reversed the attenuated virus growth phenotype. We propose that the terminal noncoding and adjacent coding regions act synergistically to ensure optimal levels of HA vRNA replication in a multisegment environment. These results provide novel insights into the role of the 3'-end nonconserved noncoding regions and adjacent coding regions on template preference in multiple-segmented negative-strand RNA viruses. IMPORTANCE While most influenza A virus vRNA segments contain segment-specific nonconserved noncoding regions of similar length and sequence, these regions vary considerably both in length and sequence in the segments encoding HA and NA, the two major antigenic determinants of influenza A viruses. In this study, we investigated the function of the 3'-end H1-ssNCR and observed a synergistic effect between the 3'-end H1-ssNCR nucleotides and adjacent coding nucleotide(s) of the HA segment on template preference in a multisegment environment. The results unravel an additional level of complexity in the regulation of RNA replication in multiple-segmented negative-strand RNA viruses.
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Holwerda M, Laloli L, Wider M, Schönecker L, Becker J, Meylan M, Dijkman R. Establishment of a Reverse Genetic System from a Bovine Derived Influenza D Virus Isolate. Viruses 2021; 13:v13030502. [PMID: 33803792 PMCID: PMC8003313 DOI: 10.3390/v13030502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 11/23/2022] Open
Abstract
The ruminant-associated influenza D virus (IDV) has a broad host tropism and was shown to have zoonotic potential. To identify and characterize molecular viral determinants influencing the host spectrum of IDV, a reverse genetic system is required. For this, we first performed 5′ and 3′ rapid amplification of cDNA ends (RACE) of all seven genomic segments, followed by assessment of the 5′ and 3′ NCR activity prior to constructing the viral genomic segments of a contemporary Swiss bovine IDV isolate (D/CN286) into the bidirectional pHW2000 vector. The bidirectional plasmids were transfected in HRT-18G cells followed by viral rescue on the same cell type. Analysis of the segment specific 5′ and 3′ non-coding regions (NCR) highlighted that the terminal 3′ end of all segments harbours an uracil instead of a cytosine nucleotide, similar to other influenza viruses. Subsequent analysis on the functionality of the 5′ and 3′ NCR in a minireplicon assay revealed that these sequences were functional and that the variable sequence length of the 5′ and 3′ NCR influences reporter gene expression. Thereafter, we evaluated the replication efficiency of the reverse genetic clone on conventional cell lines of human, swine and bovine origin, as well as by using an in vitro model recapitulating the natural replication site of IDV in bovine and swine. This revealed that the reverse genetic clone D/CN286 replicates efficiently in all cell culture models. Combined, these results demonstrate the successful establishment of a reverse genetic system from a contemporary bovine IDV isolate that can be used for future identification and characterization of viral determinants influencing the broad host tropism of IDV.
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Affiliation(s)
- Melle Holwerda
- Institute of Virology and Immunology, 3012 Bern, Switzerland;
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, 3001 Bern, Switzerland; (L.L.); (M.W.)
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Laura Laloli
- Institute for Infectious Diseases, University of Bern, 3001 Bern, Switzerland; (L.L.); (M.W.)
- Graduate School for Cellular and Biomedical Sciences, University of Bern, 3012 Bern, Switzerland
| | - Manon Wider
- Institute for Infectious Diseases, University of Bern, 3001 Bern, Switzerland; (L.L.); (M.W.)
| | - Lutz Schönecker
- Institute of Veterinary Bacteriology, Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland;
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; (J.B.); (M.M.)
- Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Jens Becker
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; (J.B.); (M.M.)
- Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Mireille Meylan
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; (J.B.); (M.M.)
- Department of Clinical Veterinary Science, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Ronald Dijkman
- Institute of Virology and Immunology, 3012 Bern, Switzerland;
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
- Institute for Infectious Diseases, University of Bern, 3001 Bern, Switzerland; (L.L.); (M.W.)
- Correspondence: ; Tel.: +41-31-664-0783
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N-Terminal Acetylation by NatB Is Required for the Shutoff Activity of Influenza A Virus PA-X. Cell Rep 2020; 24:851-860. [PMID: 30044982 DOI: 10.1016/j.celrep.2018.06.078] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 03/26/2018] [Accepted: 06/18/2018] [Indexed: 12/17/2022] Open
Abstract
N-terminal acetylation is a major posttranslational modification in eukaryotes catalyzed by N-terminal acetyltransferases (NATs), NatA through NatF. Although N-terminal acetylation modulates diverse protein functions, little is known about its roles in virus replication. We found that NatB, which comprises NAA20 and NAA25, is involved in the shutoff activity of influenza virus PA-X. The shutoff activity of PA-X was suppressed in NatB-deficient cells, and PA-X mutants that are not acetylated by NatB showed reduced shutoff activities. We also evaluated the importance of N-terminal acetylation of PA, because PA-X shares its N-terminal sequence with PA. Viral polymerase activity was reduced in NatB-deficient cells. Moreover, mutant PAs that are not acetylated by NatB lost their function in the viral polymerase complex. Taken together, our findings demonstrate that N-terminal acetylation is required for the shutoff activity of PA-X and for viral polymerase activity.
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Wang J, Peng Y, Zhao L, Cao M, Hung T, Deng T. Influenza A virus utilizes a suboptimal Kozak sequence to fine-tune virus replication and host response. J Gen Virol 2014; 96:756-766. [PMID: 25519170 DOI: 10.1099/vir.0.000030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The segment-specific non-coding regions (NCRs) of influenza A virus RNA genome play important roles in controlling viral RNA transcription, replication and genome packaging. In this report, we present, for the first time to our knowledge, a full view of the segment-specific NCRs of all influenza A viruses by bioinformatics analysis. Our systematic functional analysis revealed that the eight segment-specific NCRs identified could differentially regulate viral RNA synthesis and protein expression at both transcription and translation levels. Interestingly, a highly conserved suboptimal nucleotide at -3 position of the Kozak sequence, which downregulated protein expression at the translation level, was only present in the segment-specific NCR of PB1. By reverse genetics, we demonstrate that recombinant viruses with an optimized Kozak sequence at the -3 position in PB1 resulted in a significant multiple-cycle replication reduction that was independent of PB1-F2 expression. Our detailed dynamic analysis of virus infection revealed that the mutant virus displays slightly altered dynamics from the wild-type virus on both viral RNA synthesis and protein production. Furthermore, we demonstrated that the level of PB1 expression is involved in regulating type I IFN production. Together, these data reveal a novel strategy exploited by influenza A virus to fine-tune virus replication dynamics and host antiviral response through regulating PB1 protein expression.
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Affiliation(s)
- Jingfeng Wang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, PR China
| | - Yousong Peng
- College of Information Science and Engineering, Hunan University, Changsha 410082, PR China
| | - Lili Zhao
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, PR China
| | - Mengmeng Cao
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, PR China
| | - Tao Hung
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, PR China
| | - Tao Deng
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, PR China
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Abstract
Many replication events are involved in the influenza A virus life cycle, and they are accomplished by different virus proteins with specific functions. However, because the size of the influenza virus genome is limited, the virus uses different mechanisms to express multiple viral proteins from a single gene segment. The M2 and NS2 proteins are produced by splicing, and several novel influenza A virus proteins, such as PB1-F2, PB1-N40, and PA-X, have recently been identified. Here, we identified novel PA-related proteins in influenza A virus-infected cells. These newly identified proteins are translated from the 11th and 13th in-frame AUG codons in the PA mRNA and are, therefore, N-terminally truncated forms of PA, which we named PA-N155 and PA-N182, respectively. The 11th and 13th AUG codons are highly conserved among influenza A viruses, and the PA-N155 and PA-N182 proteins were detected in cells infected with various influenza A viruses isolated from different host species, suggesting the expression of these N-truncated PAs is universal in nature among influenza A viruses. These N-truncated PAs did not show polymerase activity when expressed together with PB1 and PB2; however, mutant viruses lacking the N-truncated PAs replicated more slowly in cell culture and had lower pathogenicity in mice than did wild-type virus. These results suggest that these novel PA-related proteins likely possess important functions in the replication cycle of influenza A virus.
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Wise HM, Barbezange C, Jagger BW, Dalton RM, Gog JR, Curran MD, Taubenberger JK, Anderson EC, Digard P. Overlapping signals for translational regulation and packaging of influenza A virus segment 2. Nucleic Acids Res 2011; 39:7775-90. [PMID: 21693560 PMCID: PMC3177217 DOI: 10.1093/nar/gkr487] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Influenza A virus segment 2 mRNA expresses three polypeptides: PB1, PB1-F2 and PB1-N40, from AUGs 1, 4 and 5 respectively. Two short open reading frames (sORFs) initiated by AUGs 2 and 3 are also present. To understand translational regulation in this system, we systematically mutated AUGs 1-4 and monitored polypeptide synthesis from plasmids and recombinant viruses. This identified sORF2 as a key regulatory element with opposing effects on PB1-F2 and PB1-N40 expression. We propose a model in which AUGs 1-4 are accessed by leaky ribosomal scanning, with sORF2 repressing synthesis of downstream PB1-F2. However, sORF2 also up-regulates PB1-N40 expression, most likely by a reinitiation mechanism that permits skipping of AUG4. Surprisingly, we also found that in contrast to plasmid-driven expression, viruses with improved AUG1 initiation contexts produced less PB1 in infected cells and replicated poorly, producing virions with elevated particle:PFU ratios. Analysis of the genome content of virus particles showed reduced packaging of the mutant segment 2 vRNAs. Overall, we conclude that segment 2 mRNA translation is regulated by a combination of leaky ribosomal scanning and reinitiation, and that the sequences surrounding the PB1 AUG codon are multifunctional, containing overlapping signals for translation initiation and for segment-specific packaging.
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Affiliation(s)
- Helen M Wise
- Department of Pathology, University of Cambridge, CB2 1QP, UK
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Girard G, Gultyaev AP, Olsthoorn RCL. Upstream start codon in segment 4 of North American H2 avian influenza A viruses. INFECTION GENETICS AND EVOLUTION 2011; 11:489-95. [PMID: 21232632 DOI: 10.1016/j.meegid.2010.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/22/2010] [Accepted: 12/24/2010] [Indexed: 11/17/2022]
Abstract
H2N2 influenza A virus was the cause of the 1957 pandemic. Due to its constant presence in birds, the H2 subtype remains a topic of interest. In this work, comparison of H2 leader sequences of influenza A segment 4 revealed the presence of an upstream in-frame start codon in a majority of North American avian strains. This AUG is located seven codons upstream of the conventional start codon and is in a good Kozak context. In vivo experiments, using a luciferase reporter gene fused to leader sequences derived from North American avian H2 strains, support the efficient use of the upstream start codon. These results were corroborated by in vitro translation data using full-length segment 4 mRNA. Phylogenic analyses indicate that the upstream AUG, first detected in 1976, is stably nested in the North American avian lineage of H2 strains nowadays. The possible consequences of the upstream AUG are discussed.
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Affiliation(s)
- Geneviève Girard
- Department of Molecular Genetics, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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A complicated message: Identification of a novel PB1-related protein translated from influenza A virus segment 2 mRNA. J Virol 2009; 83:8021-31. [PMID: 19494001 DOI: 10.1128/jvi.00826-09] [Citation(s) in RCA: 268] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Influenza A virus segment 2 is known to encode two polypeptides in overlapping open reading frames: PB1, the polymerase, and PB1-F2, a proapoptotic virulence factor. We show that a third major polypeptide is synthesized from PB1 mRNA via differential AUG codon usage. PB1 codon 40 directs translation of an N-terminally truncated version of the polypeptide (N40) that lacks transcriptase function but nevertheless interacts with PB2 and the polymerase complex in the cellular environment. Importantly, the expression of N40, PB1-F2, and PB1 are interdependent, and certain mutations previously used to ablate PB1-F2 production affected N40 accumulation. Removal of the PB1-F2 AUG upregulated N40 synthesis, while truncating PB1-F2 after codon 8 (with a concomitant M40I change in PB1) abolished N40 expression. A virus lacking both N40 and PB1-F2 replicated normally. However, viruses that did not express N40 but retained an intact PB1-F2 gene overexpressed PB1 early in infection and replicated slowly in tissue culture. Thus, the influenza A virus proteome includes a 12th primary translation product that (similarly to PB1-F2) is nonessential for virus viability but whose loss, in particular genetic backgrounds, is detrimental to virus replication.
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Crescenzo-Chaigne B, Barbezange C, van der Werf S. Non coding extremities of the seven influenza virus type C vRNA segments: effect on transcription and replication by the type C and type A polymerase complexes. Virol J 2008; 5:132. [PMID: 18973655 PMCID: PMC2590603 DOI: 10.1186/1743-422x-5-132] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2008] [Accepted: 10/30/2008] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND The transcription/replication of the influenza viruses implicate the terminal nucleotide sequences of viral RNA, which comprise sequences at the extremities conserved among the genomic segments as well as variable 3' and 5' non-coding (NC) regions. The plasmid-based system for the in vivo reconstitution of functional ribonucleoproteins, upon expression of viral-like RNAs together with the nucleoprotein and polymerase proteins has been widely used to analyze transcription/replication of influenza viruses. It was thus shown that the type A polymerase could transcribe and replicate type A, B, or C vRNA templates whereas neither type B nor type C polymerases were able to transcribe and replicate type A templates efficiently. Here we studied the importance of the NC regions from the seven segments of type C influenza virus for efficient transcription/replication by the type A and C polymerases. RESULTS The NC sequences of the seven genomic segments of the type C influenza virus C/Johannesburg/1/66 strain were found to be more variable in length than those of the type A and B viruses. The levels of transcription/replication of viral-like vRNAs harboring the NC sequences of the respective type C virus segments flanking the CAT reporter gene were comparable in the presence of either type C or type A polymerase complexes except for the NS and PB2-like vRNAs. For the NS-like vRNA, the transcription/replication level was higher after introduction of a U residue at position 6 in the 5' NC region as for all other segments. For the PB2-like vRNA the CAT expression level was particularly reduced with the type C polymerase. Analysis of mutants of the 5' NC sequence in the PB2-like vRNA, the shortest 5' NC sequence among the seven segments, showed that additional sequences within the PB2 ORF were essential for the efficiency of transcription but not replication by the type C polymerase complex. CONCLUSION In the context of a PB2-like reporter vRNA template, the sequence upstream the polyU stretch plays a role in the transcription/replication process by the type C polymerase complex.
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Affiliation(s)
- Bernadette Crescenzo-Chaigne
- Unité de Génétique Moléculaire des Virus Respiratoires, URA 3015 CNRS, EA 302 Université Paris Diderot, Institut Pasteur, F-75724 Paris, France
| | - Cyril Barbezange
- Unité de Génétique Moléculaire des Virus Respiratoires, URA 3015 CNRS, EA 302 Université Paris Diderot, Institut Pasteur, F-75724 Paris, France
- UMR 1161 Virologie Afssa Inra Enva, 23 avenue du Général de Gaulle, 94706 Maisons-Alfort cedex, France
| | - Sylvie van der Werf
- Unité de Génétique Moléculaire des Virus Respiratoires, URA 3015 CNRS, EA 302 Université Paris Diderot, Institut Pasteur, F-75724 Paris, France
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Iwatsuki-Horimoto K, Hatta Y, Hatta M, Muramoto Y, Chen H, Kawaoka Y, Horimoto T. Limited compatibility between the RNA polymerase components of influenza virus type A and B. Virus Res 2008; 135:161-5. [PMID: 18455827 DOI: 10.1016/j.virusres.2008.03.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 03/11/2008] [Accepted: 03/12/2008] [Indexed: 11/19/2022]
Abstract
Reassortants between type A and B influenza viruses have not been detected in nature, although both viruses co-circulate in human populations. One explanation for this may be functional incompatibility of RNA transcription and replication between type A and B viruses. To test this possibility, we constructed type A/B mosaic polymerase machinery, containing PB2, PB1, PA and nucleoprotein from each of the two virus types, and assessed their polymerase activities with a type A promoter in a reporter assay. Type B polymerase machinery containing homologous components was functional with the type A promoter albeit to various extents depending on the segments from which the regions downstream of the promoter sequence were derived, indicating functional compatibility between the type A promoter and B polymerase machinery. However, all of the A/B mosaic polymerase machinery, except that containing PA from a type A and the others from a type B virus strain, did not function with the type A promoter, indicating limited compatibility among polymerase components of both types. Taken together, these data suggest that incompatibility among components of the polymerase machinery for RNA transcription and replication alone is not responsible for the lack of heterotypic reassortants.
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Affiliation(s)
- Kiyoko Iwatsuki-Horimoto
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo Japan
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Maeda Y, Hatta M, Takada A, Watanabe T, Goto H, Neumann G, Kawaoka Y. Live bivalent vaccine for parainfluenza and influenza virus infections. J Virol 2005; 79:6674-9. [PMID: 15890905 PMCID: PMC1112122 DOI: 10.1128/jvi.79.11.6674-6679.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza and human parainfluenza virus infections are of both medical and economical importance. Currently, inactivated vaccines provide suboptimal protection against influenza, and vaccines for human parainfluenza virus infection are not available, underscoring the need for new vaccines against these respiratory diseases. Furthermore, to reduce the burden of vaccination, the development of multivalent vaccines is highly desirable. Thus, to devise a single vaccine that would elicit immune responses against both influenza and parainfluenza viruses, we used reverse genetics to generate an influenza A virus that possesses the coding region for the hemagglutinin/neuraminidase ectodomain of parainfluenza virus instead of the influenza virus neuraminidase. The recombinant virus grew efficiently in eggs but was attenuated in mice. When intranasally immunized with the recombinant vaccine, all mice developed antibodies against both influenza and parainfluenza viruses and survived an otherwise lethal challenge with either of these viruses. This live bivalent vaccine has obvious advantages over combination vaccines, and its method of generation could, in principle, be applied in the development of a "cocktail" vaccine with efficacy against several different infectious diseases.
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MESH Headings
- Animals
- Cell Line
- Chick Embryo
- Dogs
- Female
- Genetic Engineering
- Hemagglutinin Glycoproteins, Influenza Virus/genetics
- Hemagglutinin Glycoproteins, Influenza Virus/immunology
- Hemagglutinins, Viral/genetics
- Hemagglutinins, Viral/immunology
- Humans
- Influenza A virus/genetics
- Influenza A virus/immunology
- Influenza A virus/pathogenicity
- Influenza Vaccines/administration & dosage
- Influenza Vaccines/genetics
- Influenza Vaccines/isolation & purification
- Mice
- Mice, Inbred BALB C
- Neuraminidase/genetics
- Neuraminidase/immunology
- Parainfluenza Vaccines/administration & dosage
- Parainfluenza Vaccines/genetics
- Parainfluenza Vaccines/isolation & purification
- Sendai virus/genetics
- Sendai virus/immunology
- Sendai virus/pathogenicity
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/isolation & purification
- Vaccines, Combined/administration & dosage
- Vaccines, Combined/genetics
- Vaccines, Combined/isolation & purification
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/isolation & purification
- Virulence/genetics
- Virulence/immunology
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Affiliation(s)
- Yasuko Maeda
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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