| 1. |
- Agback, Peter, et al.
(författare)
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Multiple Host Factors Interact with the Hypervariable Domain of Chikungunya Virus nsP3 and Determine Viral Replication in Cell-Specific Mode
- 2018
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Ingår i: Journal of Virology. - 0022-538X. ; 92
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Tidskriftsartikel (refereegranskat)abstract
- Alphaviruses are widely distributed in both hemispheres and circulate between mosquitoes and amplifying vertebrate hosts. Geographically separated alphaviruses have adapted to replication in particular organisms. The accumulating data suggest that this adaptation is determined not only by changes in their glycoproteins but also by the amino acid sequence of the hypervariable domain (HVD) of the alphavirus nsP3 protein. We performed a detailed investigation of chikungunya virus (CHIKV) nsP3 HVD interactions with host factors and their roles in viral replication in vertebrate and mosquito cells. The results demonstrate that CHIKV HVD is intrinsically disordered and binds several distinctive cellular proteins. These host factors include two members of the G3BP family and their mosquito homolog Rin, two members of the NAP1 family, and several SH3 domain-containing proteins. Interaction with G3BP proteins or Rin is an absolute requirement for CHIKV replication, although it is insufficient to solely drive it in either vertebrate or mosquito cells. To achieve a detectable level of virus replication, HVD needs to bind members of at least one more protein family in addition to G3BPs. Interaction with NAP1L1 and NAP1L4 plays a more proviral role in vertebrate cells, while binding of SH3 domain-containing proteins to a proline-rich fragment of HVD is more critical for virus replication in the cells of mosquito origin. Modifications of binding sites in CHIKV HVD allow manipulation of the cell specificity of CHIKV replication. Similar changes may be introduced into HVDs of other alphaviruses to alter their replication in particular cells or tissues.IMPORTANCE Alphaviruses utilize a broad spectrum of cellular factors for efficient formation and function of replication complexes (RCs). Our data demonstrate for the first time that the hypervariable domain (HVD) of chikungunya virus nonstructural protein 3 (nsP3) is intrinsically disordered. It binds at least 3 families of cellular proteins, which play an indispensable role in viral RNA replication. The proteins of each family demonstrate functional redundancy. We provide a detailed map of the binding sites on CHIKV nsP3 HVD and show that mutations in these sites or the replacement of CHIKV HVD by heterologous HVD change cell specificity of viral replication. Such manipulations with alphavirus HVDs open an opportunity for development of new irreversibly attenuated vaccine candidates. To date, the disordered protein fragments have been identified in the nonstructural proteins of many other viruses. They may also interact with a variety of cellular factors that determine critical aspects of virus-host interactions.
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| 2. |
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| 3. |
- Ashokkumar, M., et al.
(författare)
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Unique phenotypic characteristics of recently transmitted HIV-1 subtype C envelope glycoprotein gp120 : Use of CXCR6 coreceptor by transmitted founder viruses
- 2018
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 92:9
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Tidskriftsartikel (refereegranskat)abstract
- Adequate information on the precise molecular and biological composition of the viral strains that establish HIV infection in the human host will provide effective means of immunization against HIV infection. In an attempt to identify the transmitted founder (TF) virus and differentiate the biological properties and infectious potential of the TF virus from those of the population of the early transmitted viruses, 250 patient-derived gp120 envelope glycoproteins were cloned in pMN-K7- Luc-IRESs-NefΔgp120 to obtain chimeric viruses. Samples were obtained from eight infants who had recently become infected with HIV through mother-to-child transmission (MTCT) and two adults who acquired infection through the heterosexual route and were in the chronic stage of infection. Among the 250 clones tested, 65 chimeric viruses were infectious, and all belonged to HIV-1 subtype C. The 65 clones were analyzed for molecular features of the envelope, per-infectious-particle infectivity, coreceptor tropism, drug sensitivity, and sensitivity to broadly neutralizing antibodies. Based on genotypic and phenotypic analysis of the viral clones, we identified 10 TF viruses from the eight infants. The TF viruses were characterized by shorter V1V2 regions, a reduced number of potential N-linked glycosylation sites, and a higher infectivity titer compared to the virus variants from the adults in the chronic stage of infection. CXCR6 coreceptor usage, in addition to that of the CCR5 coreceptor, which was used by all 65 chimeric viruses, was identified in 13 viruses. The sensitivity of the TF variants to maraviroc and a standard panel of neutralizing monoclonal antibodies (VRC01, PG09, PG16, and PGT121) was found to be much lower than that of the virus variants from the adults in the chronic stage of infection.
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| 4. |
- Bálint, Adám, et al.
(författare)
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Molecular Characterization of Feline Infectious Peritonitis Virus Strain DF-2 and Studies of the Role of ORF3abc in Viral Cell Tropism
- 2012
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Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 86, s. 6258-6267
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Tidskriftsartikel (refereegranskat)abstract
- The full-length genome of the highly lethal feline infectious peritonitis virus (FIPV) strain DF-2 was sequenced and cloned into a bacterial artificial chromosome (BAC) to study the role of ORF3abc in the FIPV-feline enteric coronavirus (FECV) transition. The reverse genetic system allowed the replacement of the truncated ORF3abc of the original FIPV DF-2 genome with the intact ORF3abc of the canine coronavirus (CCoV) reference strain Elmo/02. The in vitro replication kinetics of these two viruses was studied in CrFK and FCWF-4 cell lines, as well as in feline peripheral blood monocytes. Both viruses showed similar replication kinetics in established cell lines. However, the strain with a full-length ORF3 showed markedly lower replication of more than 2 log(10) titers in feline peripheral blood monocytes. Our results suggest that the truncated ORF3abc plays an important role in the efficient macrophage/monocyte tropism of type II FIPV.
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| 5. |
- Barrenäs, Fredrik, et al.
(författare)
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Deep Transcriptional Sequencing of Mucosal Challenge Compartment from Rhesus Macaques Acutely Infected with Simian Immunodeficiency Virus Implicates Loss of Cell Adhesion Preceding Immune Activation
- 2014
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Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 88:14, s. 7962-7972
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Tidskriftsartikel (refereegranskat)abstract
- Pathology resulting from human immunodeficiency virus (HIV) infection is driven by protracted inflammation; the primary loss of CD4(+) T cells is caused by activation-driven apoptosis. Recent studies of nonhuman primates (NHPs) have suggested that during the acute phase of infection, antiviral mucosal immunity restricts viral replication in the primary infection compartment. These studies imply that HIV achieves systemic infection as a consequence of a failure in host antiviral immunity. Here, we used high-dose intrarectal inoculation of rhesus macaques with simian immunodeficiency virus (SIV) SIVmac251 to examine how the mucosal immune system is overcome by SIV during acute infection. The host response in rectal mucosa was characterized by deep mRNA sequencing (mRNA-seq) at 3 and 12 days postinoculation (dpi) in 4 animals for each time point. While we observed a strong host transcriptional response at 3 dpi, functions relating to antiviral immunity were absent. Instead, we observed a significant number of differentially expressed genes relating to cell adhesion and reorganization of the cytoskeleton. We also observed downregulation of genes encoding members of the claudin family of cell adhesion molecules, which are coexpressed with genes associated with pathology in the colorectal mucosa, and a large number of noncoding transcripts. In contrast, at 12 dpi the differentially expressed genes were enriched in those involved with immune system functions, in particular, functions relating to T cells, B cells, and NK cells. Our findings indicate that host responses that negatively affect mucosal integrity occur before inflammation. Consequently, when inflammation is activated at peak viremia, mucosal integrity is already compromised, potentially enabling rapid tissue damage, driving further inflammation. IMPORTANCE The HIV pandemic is one of the major threats to human health, causing over a million deaths per year. Recent studies have suggested that mucosal antiviral immune responses play an important role in preventing systemic infection after exposure to the virus. Yet, despite their potential role in decreasing transmission rates between individuals, these antiviral mechanisms are poorly understood. Here, we carried out the first deep mRNA sequencing analysis of mucosal host responses in the primary infection compartment during acute SIV infection. We found that during acute infection, a significant host response was mounted in the mucosa before inflammation was triggered. Our analysis indicated that the response has a detrimental effect on tissue integrity, causing increased permeability, tissue damage, and recruitment of SIV target cells. These results emphasize the importance of mucosal host responses preceding immune activation in preventing systemic SIV infection.
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| 6. |
- Bowen, C. D., et al.
(författare)
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Comparison of Herpes Simplex Virus 1 Strains Circulating in Finland Demonstrates the Uncoupling of Whole-Genome Relatedness and Phenotypic Outcomes of Viral Infection
- 2019
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 93:8
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Tidskriftsartikel (refereegranskat)abstract
- A majority of adults in Finland are seropositive carriers of herpes simplex viruses (HSV). Infection occurs at epithelial or mucosal surfaces, after which virions enter innervating nerve endings, eventually establishing lifelong infection in neurons of the sensory or autonomic nervous system. Recent data have highlighted the genetic diversity of HSV-1 strains and demonstrated apparent geographic patterns in strain similarity. Though multiple HSV-1 genomes have been sequenced from Europe to date, there is a lack of sequenced genomes from the Nordic countries. Finland's history includes at least two major waves of human migration, suggesting the potential for diverse viruses to persist in the population. Here, we used HSV-1 clinical isolates from Finland to test the relationship between viral phylogeny, genetic variation, and phenotypic characteristics. We found that Finnish HSV-1 isolates separated into two distinct phylogenetic groups, potentially reflecting historical waves of human (and viral) migration into Finland. Each HSV-1 isolate harbored a distinct set of phenotypes in cell culture, including differences in the amount of virus production, extracellular virus release, and cell-type-specific fitness. Importantly, the phylogenetic clusters were not predictive of any detectable pattern in phenotypic differences, demonstrating that whole-genome relatedness is not a proxy for overall viral phenotype. Instead, we highlight specific gene-level differences that may contribute to observed phenotypic differences, and we note that strains from different phylogenetic groups can contain the same genetic variations. IMPORTANCE Herpes simplex viruses (HSV) infect a majority of adults. Recent data have highlighted the genetic diversity of HSV-1 strains and demonstrated apparent genomic relatedness between strains from the same geographic regions. We used HSV-1 clinical isolates from Finland to test the relationship between viral genomic and geographic relationships, differences in specific genes, and characteristics of viral infection. We found that viral isolates from Finland separated into two distinct groups of genomic and geographic relatedness, potentially reflecting historical patterns of human and viral migration into Finland. These Finnish HSV-1 isolates had distinct infection characteristics in multiple cell types tested, which were specific to each isolate and did not group according to genomic and geographic relatedness. This demonstrates that HSV-1 strain differences in specific characteristics of infection are set by a combination of host cell type and specific viral gene-level differences.
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| 7. |
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| 8. |
- Clo, E., et al.
(författare)
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Characterization of the Viral O-Glycopeptidome: a Novel Tool of Relevance for Vaccine Design and Serodiagnosis
- 2012
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 86:11, s. 6268-6278
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Tidskriftsartikel (refereegranskat)abstract
- Viral envelope proteins mediate interactions with host cells, leading to internalization and intracellular propagation. Envelope proteins are glycosylated and are known to serve important functions in masking host immunity to viral glycoproteins. However, the viral infectious cycle in cells may also lead to aberrant glycosylation that may elicit immunity. Our knowledge of immunity to aberrant viral glycans and glycoproteins is limited, potentially due to technical limitations in identifying immunogenic glycans and glycopeptide epitopes. This work describes three different complementary methods for high-throughput screening and identification of potential immunodominant O-glycopeptide epitopes on viral envelope glycoproteins: (i) on-chip enzymatic glycosylation of scan peptides, (ii) chemical glycopeptide microarray synthesis, and (iii) a one-bead-one-compound random glycopeptide library. We used herpes simplex virus type 2 (HSV-2) as a model system and identified a simple O-glycopeptide pan-epitope, (501)PPA(GalNAc)TAPG(507), on the mature gG-2 glycoprotein that was broadly recognized by IgG antibodies in HSV-2-infected individuals but not in HSV-1-infected or noninfected individuals. Serum reactivity to the extended sialyl-T glycoform was tolerated, suggesting that self glycans can participate in immune responses. The methods presented provide new insight into viral immunity and new targets for immunodiagnostic and therapeutic measures.
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| 9. |
- Crisci, E., et al.
(författare)
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Complement Opsonization Promotes Herpes Simplex Virus 2 Infection of Human Dendritic Cells
- 2016
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Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 90:10, s. 4939-4950
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Tidskriftsartikel (refereegranskat)abstract
- Herpes simplex virus 2 (HSV-2) is one of the most common sexually transmitted infections globally, with a very high prevalence in many countries. During HSV-2 infection, viral particles become coated with complement proteins and antibodies, both present in genital fluids, which could influence the activation of immune responses. In genital mucosa, the primary target cells for HSV-2 infection are epithelial cells, but resident immune cells, such as dendritic cells (DCs), are also infected. DCs are the activators of the ensuing immune responses directed against HSV-2, and the aim of this study was to examine the effects opsonization of HSV-2, either with complement alone or with complement and antibodies, had on the infection of immature DCs and their ability to mount inflammatory and antiviral responses. Complement opsonization of HSV-2 enhanced both the direct infection of immature DCs and their production of new infectious viral particles. The enhanced infection required activation of the complement cascade and functional complement receptor 3. Furthermore, HSV-2 infection of DCs required endocytosis of viral particles and their delivery into an acid endosomal compartment. The presence of complement in combination with HSV-1- or HSV-2-specific antibodies more or less abolished HSV-2 infection of DCs. Our results clearly demonstrate the importance of studying HSV-2 infection under conditions that ensue in vivo, i.e., conditions under which the virions are covered in complement fragments and complement fragments and antibodies, as these shape the infection and the subsequent immune response and need to be further elucidated. During HSV-2 infection, viral particles should become coated with complement proteins and antibodies, both present in genital fluids, which could influence the activation of the immune responses. The dendritic cells are activators of the immune responses directed against HSV-2, and the aim of this study was to examine the effects of complement alone or complement and antibodies on HSV-2 infection of dendritic cells and their ability to mount inflammatory and antiviral responses. Our results demonstrate that the presence of antibodies and complement in the genital environment can influence HSV-2 infection under in vitro conditions that reflect the in vivo situation. We believe that our findings are highly relevant for the understanding of HSV-2 pathogenesis.
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| 10. |
- Crisci, Elisa, et al.
(författare)
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Complement opsonization promotes HSV-2 infection of human dendritic cells
- 2016
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Ingår i: Journal of Virology. - : American society of microbiology. - 0022-538X .- 1098-5514. ; 90:10, s. 4939-4950
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Tidskriftsartikel (refereegranskat)abstract
- Herpes virus type 2 (HSV2) is one of the most common sexually transmitted infections globally with a very high prevalence in many countries. During HSV2 infection viral particles become coated with complement proteins and antibodies, both existent in the genital fluids, which could influence the activation of the immune responses. In genital mucosa, the primary target cells for HSV2 infection are epithelial cells, but resident immune cells such as dendritic cells (DCs) are also infected. The DCs are the activators of the ensuing immune responses directed against HSV2, and the aim of this study was to examine the effects opsonization of HSV2, either with complement alone or with complement and antibodies, had on the infection of immature DCs and their ability to mount inflammatory and antiviral responses. Complement opsonization of HSV2 enhanced both the direct infection of immature DCs and their production of new infectious viral particles. The enhanced infection required activation of the complement cascade and functional complement receptor 3. Furthermore, HSV2 infection of DCs required endocytosis of viral particles and their delivery into an acid endosomal compartment. The presence of complement in combination with HSV1 or HSV2 specific antibodies more or less abolished the HSV2 infection of DCs.Our results clearly demonstrate the importance of studying HSV2 infection under conditions that ensue in vivo, i.e. when the virions are covered in complement fragments and complement fragments and antibodies, as this will shape the infection and the subsequent immune response and needs to be further elucidated.IMPORTANCE: During HSV2 infection viral particles should become coated with complement proteins and antibodies, both existent in the genital fluids, which could influence the activation of the immune responses. The dendritic cells are the activators of the immune responses directed against HSV2, and the aim of this study was to examine the effects of complement alone or complement and antibodies, on the HSV2 infection of dendritic cells and their ability to mount inflammatory and antiviral responses.Our results demonstrate that the presence of antibodies and complement in the genital environment can influence HSV2 infection under in vitro conditions that reflect the in vivo situation. We believe that our findings are highly relevant for the understanding of HSV2 pathogenesis.
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