| 1. |
- Bálint, Adám, et al.
(författare)
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Characterization of two low pathogenic avian influenza viruses isolated in Hungary in 2007
- 2010
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Ingår i: Veterinary Microbiology. - : Elsevier BV. - 0378-1135 .- 1873-2542. ; 145, s. 142-147
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Tidskriftsartikel (refereegranskat)abstract
- Two low pathogenic (LP) avian influenza virus strains, A/mallard/Hungary/19616/07 (H3N8) and A/mute swan/Hungary/5973/07 (H7N7), isolated as part of the National Surveillance Program in Hungary, were fully sequenced and characterized. The two viruses showed the closest phylogenetic relationship regarding their acidic polymerase genes. The H7N7 Hungarian virus and some H5N2 influenza viruses isolated from Korean pigs appeared to have their basic polymerase gene 1 from a relatively recent common ancestor. The matrix gene nucleotide sequence of each Hungarian virus showed close relationship with contemporaneous Czech H3N8 mallard isolates, which belonged to distinct phylogenetic branches. The non-structural protein genes belonged to different alleles, rendering a peculiar characteristic to the H7N7 isolate compared to the so far analyzed Eurasian H7 viruses. The surface glycoprotein genes of the H3N8 isolate showed a close phylogenetic relationship and high nucleotide identities to H3N8 subtype isolates from Northern Europe collected in 2003-2006, and to an H3N2 isolate in Italy in 2006, extending the perceptions of this HA subtype across Northern and Southern Europe close to this period. These findings provide further data to the diversity of influenza viruses found in wild migratory birds and present useful information for large scale studies on influenza virus evolution. (c) 2010 Elsevier B.V. All rights reserved.
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| 2. |
- Bálint, Adám, et al.
(författare)
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Swine influenza viruses isolated in 1983, 2002 and 2009 in Sweden exemplify different lineages
- 2010
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Ingår i: Acta Veterinaria Scandinavica. - : Springer Science and Business Media LLC. - 0044-605X .- 1751-0147. ; 52, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Swine influenza virus isolates originating from outbreaks in Sweden from 1983, 2002 and 2009 were subjected to nucleotide sequencing and phylogenetic analysis. The aim of the studies was to obtain an overview on their potential relatedness as well as to provide data for broader scale studies on swine influenza epidemiology. Nonetheless, analyzing archive isolates is justified by the efforts directed to the comprehension of the appearance of pandemic H1N1 influenza virus. Interestingly, this study illustrates the evolution of swine influenza viruses in Europe, because the earliest isolate belonged to 'classical' swine H1N1, the subsequent ones to Eurasian 'avian-like' swine H1N1 and reassortant 'avian-like' swine H1N2 lineages, respectively. The latter two showed close genetic relatedness regarding their PB2, HA, NP, and NS genes, suggesting common ancestry. The study substantiates the importance of molecular surveillance for swine influenza viruses.
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| 3. |
- Bálint, Adám, et al.
(författare)
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The first Swedish H1N2 swine influenza virus isolate represents an uncommon reassortant
- 2009
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Ingår i: Virology Journal. - 1743-422X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The European swine influenza viruses (SIVs) show considerable diversity comprising different types of H1N1, H3N2, and H1N2 strains. The intensifying full genome sequencing efforts reveal further reassortants within these subtypes. Here we report the identification of an uncommon reassortant variant of H1N2 subtype influenza virus isolated from a pig in a multisite herd where H1N2 swine influenza was diagnosed for the first time in Sweden during the winter of 2008-2009. The majority of the European H1N2 swine influenza viruses described so far possess haemagglutinin (HA) of the human-like H1N2 SIV viruses and the neuraminidase (NA) of either the European H1N2 or H3N2 SIV-like viruses. The Swedish isolate has an avian-like SIV HA and a H3N2 SIV-like NA, which is phylogenetically more closely related to H3N2 SIV NAs from isolates collected in the early '80s than to the NA of H3N2 origin of the H1N2 viruses isolated during the last decade, as depicted by some German strains, indicative of independent acquisition of the NA genes for these two types of reassortants. The internal genes proved to be entirely of avian-like SIV H1N1 origin. The prevalence of this SIV variant in pig populations needs to be determined, as well as the suitability of the routinely used laboratory reagents to analyze this strain.The description of this H1N2 SIV adds further information to influenza epidemiology and supports the necessity of surveillance for influenza viruses in pigs.
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| 4. |
- Metreveli, Giorgi, et al.
(författare)
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A Size-Exclusion Nanocellulose Filter Paper for Virus Removal
- 2014
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Ingår i: Advanced Healthcare Materials. - : Wiley. - 2192-2640 .- 2192-2659. ; 10:3, s. 1546-1550
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Tidskriftsartikel (refereegranskat)abstract
- This is the first time a 100% natural, unmodified nanofibrous polymer-based membrane is demonstrated capable of removing viruses solely based on the size-exclusion principle, with log10 reduction value (LRV) ≥ 6.3 as limited by the assay lower detection limit and the feed virus titre, thereby matching the performance of industrial synthetic polymer virus removal filters.
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| 5. |
- Metreveli, Giorgi, et al.
(författare)
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Comparison of two H1N2 swine influenza A viruses from disease outbreaks in pigs in Sweden during 2009 and 2010
- 2011
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Ingår i: Virus Genes. - : Springer Science and Business Media LLC. - 0920-8569 .- 1572-994X. ; 42, s. 236-244
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Tidskriftsartikel (refereegranskat)abstract
- The influenza A virus subtypes H1N1, H1N2 and H3N2 are prevalent in pig populations worldwide. In the present study, two relatively uncommon swine influenza virus (SIV) H1N2 subtypes, isolated in Sweden in 2009 and 2010, were compared regarding their molecular composition and biological characteristics. The differences regarding markers purportedly related to pathogenicity, host adaptation or replication efficiency. They included a truncated PB1-F2 protein in the earlier isolate but a full length version in the more recent one; differences in the number of haemagglutinin glycosylation sites, including a characteristic human one; and a nuclear export protein with altered export signal. Of particular interest, the NS1 amino acid sequence of swine H1N2-2009 and 2010 has a 'unique or very unusual' PDZ binding domain (RPKV) at the C-terminal of the protein, a motif that has been implicated as a virulence marker. Concerning biological properties, these viruses reached lower titre and showed reduced cytopathogenicity in MDCK cells compared with an avian-like H1N1 isolate A/swine/Lidkoping/1193/2002 belonging to the same lineage as the 2009 and 2010 isolates. The findings should contribute to better understanding of factors related to the survival/extinction of this uncommon reassortant variant.
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| 6. |
- Metreveli, Giorgi, et al.
(författare)
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Molecular analysis and characterization of swine and human influenza viruses isolated in Hungary in 2006–2007
- 2009
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Ingår i: Virus Genes. - : Springer Science and Business Media LLC. - 0920-8569 .- 1572-994X. ; 39, s. 186-192
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Tidskriftsartikel (refereegranskat)abstract
- In order to provide additional information to the epidemiological situation in Middle Europe and open further possibilities to investigate the transmission of influenza viruses between species, the viral genomes of three influenza A virus isolates (one human and two swine) collected from North-East Hungary in 2006–2007 have been fully sequenced and characterized. The sequence analysis reveals strong geographical relationships between the internal genes of the two swine viruses; the human isolate shows strict conservation to recent H1N1 strains, while the swine strains demonstrate and reflect a mixed avian–human origin, a characteristic of European swine influenza viruses. No evidence of interspecies interaction has been found among the studied isolates
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| 7. |
- Metreveli, Giorgi, et al.
(författare)
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Phylogenetic Analysis of the Hemagglutinin Gene of Low Pathogenic Avian Influenza Virus H7N7 Strains in Mallards in Northern Europe
- 2010
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Ingår i: Avian Diseases. - 0005-2086. ; 54, s. 453-456
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Tidskriftsartikel (refereegranskat)abstract
- The H7 subtype of avian influenza (AI) has the capability to evolve into a highly pathogenic AI (HPAI) virus. In this study, we have characterized the hemagglutinin (HA) genes of three avian H7N7 influenza A viruses isolated from healthy migratory, mallards in Northern Europe in three different years to study the natural variation of these viruses in the natural reservoir. Phylogenetic analysis demonstrated that the H7 HA genes were all closely related to recent H7 isolates responsible for influenza outbreaks in poultry in Europe. The A/mallard/Sweden/S90735/2003 isolate clustered together with the HA gene of A/ mallard/Netherlands/12/00/H7N3 (AY338460), which has been shown to be closely related to the H7N7 responsible for HPAI outbreaks in the Netherlands and Germany in 2003. In contrast, the HA gene of the two mallard strains A/mallard/Sweden/S90597/2005 and A/mallard/Sweden/100993/2008 were more related to the chicken strain isolated in domestic poultry in England in 2006, A/Ch/England/4054/2006/H7N3 (EF467826), and 2008, A/Ch/England/2008/1-17N7 (214011964). Analysis of the deduced HA amino acid sequence shows two different HA cleavage sires in these isolates. Although these HA cleavage sites are consistent with a low pathogenicity AI, the cleavage sites appear to posses an increasing numbers of basic amino acids over time (PEIPKGRGLF in 2003 and 2005 and PEIPKKRGLF in 2008). The conclusion from this study is that H7 subtypes isolated from healthy mallards are closely related to the H7 subtypes that have caused recent influenza outbreaks in poultry, in Europe.
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| 8. |
- Metreveli, Giorgi
(författare)
-
Swine influenza A virus subtype H1N2 in Sweden
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The influenza A virus subtypes H1N1, H1N2 and H3N2 are prevalent in pig populations worldwide. All scientific data point towards swine as the key host species for new human influenza pandemics, which have been suggested to evolve in pigs from viral genes of avian, human and porcine origin. Therefore, it is of major importance to record the evolution of swine influenza viruses in pigs, and in particular monitor hallmarks of adaptation to humans. The scope of this thesis was to increase the understanding of the genetics of swine influenza virus (SIV), and to investigate the importance of different viral gene markers in association with differences in pathogenicity of two viruses of H1N2 subtype in pigs. The results from this study demonstrate, for the first time, natural reassortment in H1N2 viruses in the pig populations of Sweden. These H1N2 viruses have an avian-like SIV H1N1 haemagglutinin (HA) and a European H3N2 SIV-like neuraminidase (NA). Nucleotide sequence comparison revealed significant differences between the two consecutive H1N2 isolates. To be able to understand the genotypic differences observed in the genomes of these H1N2s, and to identify the genetic markers responsible for the differences, a reverse genetic system was developed. Four recombinant SIV H1N2 viruses were constructed that displayed differences in virulence in mice, r1021 (more virulent) and r9706 (less virulent), as well as the same viruses with swapped PB1 segments. Interestingly, the current findings showed that the replacement of the PB1 segment of r9706 by that of r1021 increases the virulence of the virus that replicate with higher titer in mice lungs, while the opposite is true when PB1 r9706 is introduced into r1021. This study demonstrates that differences in virulence of swine influenza virus subtype H1N2 are attributed at least in part to the PB1 segment. The findings presented in this thesis support the observations concerning the continuous reassortment processes of SIVs in pigs, resulting in repeated and independent emergence of certain HA/NA combinations. This may lead to emergence of new viral variants of severe pathogenicity of pigs. Continuous and efficient surveillance and further detailed genetic and phenotypic analysis can help to identify such novel viral variants, having more potential to cross species barriers and to pose health risks even to humans and to other host species.
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| 9. |
- Metreveli, Giorgi
(författare)
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Swine influenza A virus subtype H1N2 in Sweden
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The influenza A virus subtypes H1N1, H1N2 and H3N2 are prevalent in pig populations worldwide. All scientific data point towards swine as the key host species when new human influenza pandemics arise. All previous pandemics have been suggested to evolve in pigs from viral genes of avian, human and porcine origin. Therefore, it is of major importance to monitor the evolution of swine influenza viruses in pigs, and in particular monitor hallmarks of species adaptation to humans.The scope of this project was to increase the understanding of the genetics of swine influenza virus (SIV), with special emphasis on its zoonotic potential, and to investigate the importance of different viral gene markers for species specificity and adaptation. Since clinical manifestation of swine influenza is rare in Sweden, and SIV strains are of particular concern due to the novel human H1N1 epidemic, viruses were isolated in primary swine kidney or Madin Darby Canine Kidney (MDCK) cells, based on standard protocols and the isolates were subjected to full genome sequencing and comparative sequence analysis of the viral genomes. The results describe the analysis of the whole genome sequences from two swine influenza viruses isolated from Sweden in 2009 and 2010. Moreover, this study demonstrates, for the first time, natural reassortment in H1N2 viruses in the pig populations of Sweden. Biological characterization of the two viruses revealed a weaker growing potential, compared to the Swedish 2002 H1N1 isolate. Sequence comparison revealed significant differences between the two consecutive H1N2 isolates. The most remarkable of these was a truncated coding region for PB1-F2 in the earlier isolates and a full length coding region in the more recent isolates. In order to determine the effect of these viruses on the swine industry and on influenza ecology, further surveillance investigations and detailed analyses are needed.
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| 10. |
- Metreveli, Giorgi, et al.
(författare)
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The origin of the PB1 segment of swine influenza A virus subtype H1N2 determines viral pathogenicity in mice
- 2014
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Ingår i: Virus Research. - : Elsevier BV. - 0168-1702 .- 1872-7492. ; 188, s. 97-102
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Tidskriftsartikel (refereegranskat)abstract
- Swine appear to be a key species in the generation of novel human influenza pandemics. Previous pandemic viruses are postulated to have evolved in swine by reassortment of avian, human, and swine influenza viruses. The human pandemic influenza viruses that emerged in 1957 and 1968 as well as swine viruses circulating since 1998 encode PB1 segments derived from avian influenza viruses. Here we investigate the possible role in viral replication and virulence of the PB1 gene segments present in two swine H1N2 influenza A viruses, A/swine/Sweden/1021/2009(H1N2) (sw 1021) and A/swine/Sweden/9706/2010(H1N2) (sw 9706), where the sw 1021 virus has shown to be more pathogenic in mice. By using reverse genetics, we swapped the PB1 genes of these two viruses. Similar to the sw 9706 virus, chimeric sw 1021 virus carrying the sw 9706 PB1 gene was not virulent in mice. In contrast, replacement of the PB1 gene of the sw 9706 virus by that from sw 1021 virus resulted in increased pathogenicity. Our study demonstrated that differences in virulence of swine influenza virus subtype Hi N2 are attributed at least in part to the PB1 segment. (C) 2014 Elsevier B.V. All rights reserved.
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| 11. |
- Munir, Muhammad, et al.
(författare)
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Alleles A and B of non-structural protein 1 of avian influenza A viruses differentially inhibit beta interferon production in human and mink lung cells
- 2011
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Ingår i: Journal of General Virology. - : Microbiology Society. - 0022-1317 .- 1465-2099. ; 92, s. 2111-2121
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Tidskriftsartikel (refereegranskat)abstract
- Non-structural protein 1 (NS1) counteracts the production of host type I interferons (IFN-alpha/beta) for the efficient replication and pathogenicity of influenza A viruses. Here, we reveal another dimension of the NS1 protein of avian influenza A viruses in suppressing IFN-beta production in cultured cell lines. We found that allele A NS1 proteins of H6N8 and H4N6 have a strong capacity to inhibit the activation of IFN-beta production, compared with allele B from corresponding subtypes, as measured by IFN stimulatory response element (ISRE) promoter activation, IFN-beta mRNA transcription and IFN-beta protein expression. Furthermore, the ability to suppress IFN-beta promoter activation was mapped to the C-terminal effector domain (ED), while the RNA-binding domain (RBD) alone was unable to suppress IFN-beta promoter activation. Chimeric studies indicated that when the RBD of allele A was fused to the ED of allele B, it was a strong inhibitor of IFN-beta promoter activity. This shows that well-matched ED and RBD are crucial for the function of the NS1 protein and that the RBD could be one possible cause for this differential IFN-beta inhibition. Notably, mutagenesis studies indicated that the F103Y and Y103F substitutions in alleles A and B, respectively, do not influence the ISRE promoter activation. Apart from dsRNA signalling, differences were observed in the expression pattern of NS1 in transfected human and mink lung cells. This study therefore expands the versatile nature of the NS1 protein in inhibiting IFN responses at multiple levels, by demonstrating for the first time that it occurs in a manner dependent on allele type.
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| 12. |
- Munir, Muhammad, et al.
(författare)
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Differences in the ability to suppress interferon beta production between allele A and allele B NS1 proteins from H10 influenza A viruses
- 2010
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Ingår i: Virology Journal. - 1743-422X. ; 7, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Conclusions: These studies reveal that different non-structural protein 1 (NS1) of influenza viruses, one from allele A and another from allele B, show different abilities to suppress the type I interferon beta expression. It has been hypothesised that some of the differences in the different abilities of the alleles to suppress ISRE were because of the interactions and inhibitions at later stages from the IFN receptor, such as the JAK/STAT pathway. This might reflect the additional effects of the immune evasion potential of different NS1s.
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| 13. |
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| 14. |
- Widén, Frederik, et al.
(författare)
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Molecular epidemiology of hepatitis E virus in humans, pigs and wild boars in Sweden
- 2011
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Ingår i: Epidemiology and Infection. - 0950-2688 .- 1469-4409. ; 139, s. 361-371
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Tidskriftsartikel (refereegranskat)abstract
- Hepatitis E infections in humans are usually acquired in endemic countries in Asia or Africa. In Sweden 17 cases infected in Europe, between 1993 and 2009, were identified. All had clinical hepatitis E with unknown source of infection. Hepatitis E virus (HEV) was identified in faecal samples from 63 piglets in 12 pig farms in Sweden. HEV was also identified in blood from 13 out of 159 investigated Swedish wild boars from nine counties. Partial HEV genomes from humans, pigs and wild boars were sequenced and compared by phylogeny. The results showed close relatedness between HEY strains from piglets from the same farm and from wild boars from the same county. HEV strains from humans showed relatedness with strains from pigs and wild boars from the same county. This study showed that HEY strains form geographical clusters in the phylogenetic tree. The methods used in this study may thus be used for tracing the origin of an infecting strain. Furthermore, this study indicated that there are endemic sources of human HEY infections in Sweden.
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| 15. |
- Zohari, Siamak, et al.
(författare)
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Full genome comparison and characterization of avian H10 viruses with different pathogenicity in Mink (Mustela vison) reveals genetic and functional differences in the non-structural gene
- 2010
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Ingår i: Virology Journal. - 1743-422X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Background: The unique property of some avian H10 viruses, particularly the ability to cause severe disease in mink without prior adaptation, enabled our study. Coupled with previous experimental data and genetic characterization here we tried to investigate the possible influence of different genes on the virulence of these H10 avian influenza viruses in mink.Results: Phylogenetic analysis revealed a close relationship between the viruses studied. Our study also showed that there are no genetic differences in receptor specificity or the cleavability of the haemagglutinin proteins of these viruses regardless of whether they are of low or high pathogenicity in mink. In poly I: C stimulated mink lung cells the NS1 protein of influenza A virus showing high pathogenicity in mink down regulated the type I interferon promoter activity to a greater extent than the NS1 protein of the virus showing low pathogenicity in mink.Conclusions: Differences in pathogenicity and virulence in mink between these strains could be related to clear amino acid differences in the non structural 1 (NS1) protein. The NS gene of mink/84 appears to have contributed to the virulence of the virus in mink by helping the virus evade the innate immune responses.
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