Mutations of novel influenza A(H10N8) virus in chicken eggs and MDCK cells.
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ABSTRACT:
SUBMITTER: Yang J
PROVIDER: S-EPMC4178415 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The Madin-Darby canine kidney (MDCK) cell line is an in vitro model for influenza A virus (IAV) infection and propagation. MDCK-SIAT1 (SIAT1) and humanized MDCK (hCK) cell lines are engineered MDCK cells that express N-glycans with elevated levels of sialic acid (Sia) in α2,6-linkage (α2,6-Sia) that are recognized by many human IAVs. To characterize the N-glycan structures in these cells and the potential changes compared to the parental MDCK cell line resulting from engineering, we analyzed the N-glycans from these cells at different passages, using both mass spectrometry and specific lectin and antibody binding. We observed significant differences between the three cell lines in overall complex N-glycans and terminal galactose modifications. MDCK cells express core fucosylated, bisected complex-type N-glycans at all passage stages, in addition to expressing α2,6-Sia on short N-glycans and α2,3-Sia on larger N-glycans. By contrast, SIAT1 cells predominantly express α2,6-Sia glycans and greatly reduced level of α2,3-Sia glycans. Additionally, they express bisected, sialylated N-glycans that are scant in MDCK cells. The hCK cells exclusively express α2,6-Sia glycans. Unexpectedly, hCK glycoproteins bound robustly to the plant lectin MAL-1, indicating α2,3-Sia glycans, but such binding was not Sia-dependent and closely mirrored that of an antibody that recognizes glycans with terminal 3-O-sulfate galactose (3-O-SGal). The 3-O-SGal epitope is highly expressed in N-glycans on multiple hCK glycoproteins. These results indicate vastly different N-glycomes between MDCK cells and the engineered clones that could relate to IAV infectivity.
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Project description:Three human cases of H10N8 virus infections were initially reported in China in late 2013 and early 2014, two of which were fatal. This was the first time the H10N8 subtype has been detected in humans, and the pathogenicity of this virus remains under characterized. We first assessed its pathogenicity by infecting BALB/c mice with two H10N8 isolates, A/Jiangxi-Donghu/346-1/2013 and A/Chicken/Jiangxi/102/2013. The human isolate (H346-1) demonstrated stronger capability of replication and induced higher cytokine response in vivo than the chicken isolate (C102). In addition, H346-1 was fatal to mice, while all mice (N = 14) in C102-infected group survived during the infection course without weight loss. We hypothesized that the 627K mutation in the PB2 gene (PB2-K627) in H346-1 was associated with high pathogenicity in mice. Taken together, this study based on mouse model provides some insight into understanding the pathogenicity of the emerging viruses in mammals.
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Project description:Several live attenuated influenza virus A/California/7/09 (H1N1) (CA09) candidate vaccine variants that possess the hemagglutinin (HA) and neuraminidase (NA) gene segments from the CA09 virus and six internal protein gene segments from the cold-adapted influenza virus A/Ann Arbor/6/60 (H2N2) virus were generated by reverse genetics. The reassortant viruses replicated relatively poorly in embryonated chicken eggs. To improve virus growth in eggs, reassortants expressing the HA and NA of CA09 were passaged in MDCK cells and variants exhibiting large-plaque morphology were isolated. These variants replicated at levels approximately 10-fold higher than the rate of replication of the parental strains in embryonated chicken eggs. Sequence analysis indicated that single amino acid changes at positions 119, 153, 154, and 186 were responsible for the improved growth properties in MDCK cells and eggs. In addition, the introduction of a mutation at residue 155 that was previously shown to enhance the replication of a 1976 swine influenza virus also significantly improved the replication of the CA09 virus in eggs. Each variant was further evaluated for receptor binding preference, antigenicity, attenuation phenotype, and immunogenicity. Mutations at residues 153, 154, and 155 drastically reduced viral antigenicity, which made these mutants unsuitable as vaccine candidates. However, changes at residues 119 and 186 did not affect virus antigenicity or immunogenicity, justifying their inclusion in live attenuated vaccine candidates to protect against the currently circulating 2009 swine origin H1N1 viruses.
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Project description:The Madin-Darby Canine Kidney (MDCK) cell line is among the most commonly used cell lines for the production of influenza virus vaccines. As cell culture-based manufacturing is poised to replace egg-based processes, increasing virus production is of paramount importance. To shed light on factors affecting virus productivity, we isolated a subline, H1, which had twice the influenza virus A (IAV) productivity of the parent (P) through cell cloning, and characterized H1 and P in detail on both physical and molecular levels. Transcriptome analysis revealed that within a few hours after IAV infection, viral mRNAs constituted over one fifth of total mRNA, with several viral genes more highly expressed in H1 than P. Functional analysis of the transcriptome dynamics showed that H1 and P responded similarly to IAV infection, and were both subjected to host shutoff and inflammatory responses. Importantly, H1 was more active in translation and RNA processing intrinsically and after infection. Furthermore, H1 had more subdued inflammatory and antiviral responses. Taken together, we postulate that the high productivity of IAV hinges on the balance between suppression of host functions to divert cellular resources and the sustaining of sufficient activities for virus replication. Mechanistic insights into virus productivity can facilitate the process optimization and cell line engineering for advancing influenza vaccine manufacturing.
| S-EPMC8620111 | biostudies-literature
Project description:Influenza viruses unable to express NS1 protein (delNS1) replicate poorly and induce large amounts of interferon (IFN). They are therefore considered candidate viruses for live-attenuated influenza vaccines. Their attenuated replication is generally assumed to result from the inability to counter the antiviral host response, as delNS1 viruses replicate efficiently in Vero cells, which lack IFN expression. In this study, delNS1 virus was parallel passaged on IFN-competent MDCK cells, which resulted in two strains that were able to replicate to high virus titers in MDCK cells due to adaptive mutations especially in the M-gene segment but also in the NP and NS gene segments. Most notable were clustered U-to-C mutations in the M segment of both strains and clustered A-to-G mutations in the NS segment of one strain, which presumably resulted from host cell-mediated RNA editing. The M segment mutations in both strains changed the ratio of M1 to M2 expression, probably by affecting splicing efficiency. In one virus, 2 amino acid substitutions in M1 additionally enhanced virus replication, possibly through changes in the M1 distribution between the nucleus and the cytoplasm. Both adapted viruses induced levels of IFN equal to that of the original delNS1 virus. These results show that the increased replication of the adapted viruses is not primarily due to altered IFN induction but rather is related to changes in M1 expression or localization. The mutations identified in this paper may be used to enhance delNS1 virus replication for vaccine production.
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Project description:Vaccines constitute a unique selective pressure, different from natural selection, drives the evolution of influenza virus. In this study, A/Chicken/Shanghai/F/1998 (H9N2) was continually passaged in specific pathogen-free embryonated chicken eggs with or without selective pressures from antibodies induced by homologous maternal antibodies. Genetic mutations, antigenic drift, replication, and pathogenicity of the passaged virus were evaluated.Antigenic drift of the passaged viruses occurred in the 47th generation (vF47) under selective pressure on antibodies and in the 52nd generation (nF52) without selective pressure from antibodies. Seven mutations were observed in the vF47 virus, with three in PB2 and four in HA, whereas 12 mutations occurred in the nF52 virus, with three in PB2, two in PB1, four in HA, one in NP, one in NA, and one in NS. Remarkably, the sequences of the HA segment from vF47 were 100% homologous with those of the nF52 virus. Both the vF47 and nF52 viruses showed enhanced replication compared to the parental virus F/98, but higher levels of replication and pathogenicity were displayed by nF52 than by vF47. An inactive vaccine derived from the parental virus F/98 did not confer protection against challenges by either the vF47 or nF52 virus, but inactive vaccines derived from the vF47 or nF52 virus were able to provide protection against a challenge using F/98.Taken together, the passage of H9N2 viruses with or without selective pressure of the antibodies induced by homologous maternal antibodies showed genetic variation, enhanced replication, and variant antigenicity. Selective pressure of the antibody does not seem to play a key role in antigenic drift in the egg model but may impact the genetic variation and replication ability of H9N2 viruses. These results improve understanding of the evolution of the H9N2 influenza virus and may aid in selecting appropriate vaccine seeds.
| S-EPMC5840701 | biostudies-literature
Project description:Influenza virus isolation in embryonated chicken eggs (ECEs) is not applicable for rapid diagnosis, however it allows the recovery and propagation of the viable virus. A low number of infectious virus particles in the swabs, poor quality of samples or individual strain properties can lead to difficulties during the virus isolation process. We propose to utilize chorioallantoic membranes (CAM) of ECEs with the assistance of real-time RT PCR to facilitate equine influenza virus isolation.Real-time RT PCR was used to detect influenza virus genetic material in amniotic/allantoic fluids (AF) and CAM of ECEs. Haemagglutination assay was used for AF. We used highly diluted virus as a substitute of clinical specimen for ECEs inoculation.Our study demonstrated that real-time RT PCR testing of CAM homogenates was more useful than testing of AF for EIV detection in ECEs. Positive results from CAM allowed to select the embryos from those with haemagglutination assay (HA) - and real-time RT PCR-negative AF for further passages. Using homogenates of CAM for subsequent passages, we finally obtained HA-positive AF, which confirmed virus replication.We postulate that real-time RT PCR testing of CAM homogenates and their subsequent passages may facilitate the isolation of equine influenza viruses.
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Project description:BACKGROUND: Wild birds, especially those in wetlands and aquatic environments, are considered to be natural reservoirs of avian influenza viruses. It is accepted that water is an important component in the transmission cycle of avian influenza virus. Monitoring the water at aggregation and breeding sites of migratory waterfowl, mainly wetland, is very important for early detection of avian influenza virus. The epidemiology investigation of avian influenza virus was performed in Dongting lake wetland which is an international important wetland. RESULTS: An H10N8 influenza virus was isolated from Dongting Lake wetland in 2007. Phylogenetic analysis indicated that the virus was generated by multiple gene segment reassortment. The isolate was lowly pathogenic for chickens. However, it replicated efficiently in the mouse lung without prior adaptation, and the virulence to mice increased rapidly during adaptation in mouse lung. Sequence analysis of the genome of viruses from different passages showed that multiple amino acid changes were involved in the adaptation of the isolates to mice. CONCLUSIONS: The water might be an important component in the transmission cycle of avian influenza virus, and other subtypes of avian influenza viruses (other than H5, H7 and H9) might evolve to pose a potential threat to mammals and even humans.
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Project description:Here, we sequenced the genome of the influenza A/Finland/741 M/2014(H1N1) virus and found that the virus accumulated oseltamivir resistance mutation H275Y in its neuraminidase during propagation in cell culture. This indicates that propagation in cell culture modifies virus genomes. The instability of influenza genomes should be taken into consideration during drug-sensitivity studies.
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Project description: Not available
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