| 1. |
- Crisci, E., et al.
(författare)
-
Complement Opsonization Promotes Herpes Simplex Virus 2 Infection of Human Dendritic Cells
- 2016
-
Ingår i: Journal of Virology. - : American Society for Microbiology. - 0022-538X .- 1098-5514. ; 90:10, s. 4939-4950
-
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.
|
|
| 2. |
- Crisci, Elisa, et al.
(författare)
-
Complement opsonization promotes HSV-2 infection of human dendritic cells
- 2016
-
Ingår i: Journal of Virology. - : American society of microbiology. - 0022-538X .- 1098-5514. ; 90:10, s. 4939-4950
-
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.
|
|
| 3. |
- Dai, Meiling, et al.
(författare)
-
Identification of Residues That Affect Oligomerization and/or Enzymatic Activity of Influenza Virus H5N1 Neuraminidase Proteins
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90:20, s. 9457-9470
-
Tidskriftsartikel (refereegranskat)abstract
- Influenza A virus (IAV) attachment to and release from sialoside receptors is determined by the balance between hemagglutinin (HA) and neuraminidase (NA). The molecular determinants that mediate the specificity and activity of NA are still poorly understood. In this study, we aimed to design the optimal recombinant soluble NA protein to identify residues that affect NA enzymatic activity. To this end, recombinant soluble versions of four different NA proteins from H5N1 viruses were compared with their full-length counterparts. The soluble NA ectodomains were fused to three commonly used tetramerization domains. Our results indicate that the particular oligomerization domain used does not affect the K-m value but may affect the specific enzymatic activity. This particularly holds true when the stalk domain is included and for NA ectodomains that display a low intrinsic ability to oligomerize. NA ectodomains extended with a Tetrabrachion domain, which forms a nearly parallel four-helix bundle, better mimicked the enzymatic properties of full-length proteins than when other coiled-coil tetramerization domains were used, which probably distort the stalk domain. Comparison of different NA proteins and mutagenic analysis of recombinant soluble versions thereof resulted in the identification of several residues that affected oligomerization of the NA head domain (position 95) and therefore the specific activity or sialic acid binding affinity (K-m value; positions 252 and 347). This study demonstrates the potential of using recombinant soluble NA proteins to reveal determinants of NA assembly and enzymatic activity. IMPORTANCE The IAV HA and NA glycoproteins are important determinants of host tropism and pathogenicity. However, NA is relatively understudied compared to HA. Analysis of soluble versions of these glycoproteins is an attractive way to study their activities, as they are easily purified from cell culture media and applied in downstream assays. In the present study, we analyzed the enzymatic activity of different NA ectodomains with three commonly used tetramerization domains and compared them with fulllength NA proteins. By performing a mutagenic analysis, we identified several residues that affected NA assembly, activity, and/or substrate binding. In addition, our results indicate that the design of the recombinant soluble NA protein, including the particular tetramerization domain, is an important determinant for maintaining the enzymatic properties within the head domain. NA ectodomains extended with a Tetrabrachion domain better mimicked the full-length proteins than when the other tetramerization domains were used.
|
|
| 4. |
- Hurt, Aeron C., et al.
(författare)
-
Evidence for the Introduction, Reassortment, and Persistence of Diverse Influenza A Viruses in Antarctica
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90:21, s. 9674-9682
-
Tidskriftsartikel (refereegranskat)abstract
- Avian influenza virus (AIV) surveillance in Antarctica during 2013 revealed the prevalence of evolutionarily distinct influenza viruses of the H11N2 subtype in Adelie penguins. Here we present results from the continued surveillance of AIV on the Antarctic Peninsula during 2014 and 2015. In addition to the continued detection of H11 subtype viruses in a snowy sheathbill during 2014, we isolated a novel H5N5 subtype virus from a chinstrap penguin during 2015. Gene sequencing and phylogenetic analysis revealed that the H11 virus detected in 2014 had a >99.1% nucleotide similarity to the H11N2 viruses isolated in 2013, suggesting the continued prevalence of this virus in Antarctica over multiple years. However, phylogenetic analysis of the H5N5 virus showed that the genome segments were recently introduced to the continent, except for the NP gene, which was similar to that in the endemic H11N2 viruses. Our analysis indicates geographically diverse origins for the H5N5 virus genes, with the majority of its genome segments derived from North American lineage viruses but the neuraminidase gene derived from a Eurasian lineage virus. In summary, we show the persistence of AIV lineages in Antarctica over multiple years, the recent introduction of gene segments from diverse regions, and reassortment between different AIV lineages in Antarctica, which together significantly increase our understanding of AIV ecology in this fragile and pristine environment.
|
|
| 5. |
- Lund, Jennifer M., et al.
(författare)
-
HIV-1-neutralizing IgA detected in genital secretions of highly HIV-1-exposed seronegative women on oral preexposure prophylaxis
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90:21, s. 9855-9861
-
Tidskriftsartikel (refereegranskat)abstract
- Although nonhuman primate studies have shown that simian immunodeficiency virus/simian-human immunodeficiency virus (SIV/SHIV) exposure during preexposure prophylaxis (PrEP) with oral tenofovir can induce SIV immunity without productive infection, this has not been documented in humans. We evaluated cervicovaginal IgA in Partners PrEP Study participants using a subtype C primary isolate and found that women on PrEP had IgA with higher average human immunodeficiency virus type 1 (HIV-1)-neutralizing magnitude than women on placebo (33% versus 7%; P = 0.008). Using a cutoff of ≥90% HIV-1 neutralization, 19% of women on-PrEP had HIV-1-neutralizing IgA compared to 0% of women on placebo (P = 0.09). We also estimated HIV-1 exposure and found that the proportion of women with HIV-1-neutralizing IgA was associated with the level of HIV-1 exposure (P = 0.04). Taken together, our data suggest that PrEP and high levels of exposure to HIV may each enhance mucosal HIV-1-specific humoral immune responses in sexually exposed but HIV-1-uninfected individuals.
|
|
| 6. |
- Mullapudi, Edukondalu, et al.
(författare)
-
Structure and Genome Release Mechanism of the Human Cardiovirus Saffold Virus 3
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90:17, s. 7628-7639
-
Tidskriftsartikel (refereegranskat)abstract
- In order to initiate an infection, viruses need to deliver their genomes into cells. This involves uncoating the genome and transporting it to the cytoplasm. The process of genome delivery is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the uncoating of the nonenveloped human cardiovirus Saffold virus 3 (SAFV-3) of the family Picornaviridae. SAFVs cause diseases ranging from gastrointestinal disorders to meningitis. We present a structure of a native SAFV-3 virion determined to 2.5 angstrom by X-ray crystallography and an 11-angstrom-resolution cryo-electron microscopy reconstruction of an "altered" particle that is primed for genome release. The altered particles are expanded relative to the native virus and contain pores in the capsid that might serve as channels for the release of VP4 subunits, N termini of VP1, and the RNA genome. Unlike in the related enteroviruses, pores in SAFV-3 are located roughly between the icosahedral 3- and 5-fold axes at an interface formed by two VP1 and one VP3 subunit. Furthermore, in native conditions many cardioviruses contain a disulfide bond formed by cysteines that are separated by just one residue. The disulfide bond is located in a surface loop of VP3. We determined the structure of the SAFV-3 virion in which the disulfide bonds are reduced. Disruption of the bond had minimal effect on the structure of the loop, but it increased the stability and decreased the infectivity of the virus. Therefore, compounds specifically disrupting or binding to the disulfide bond might limit SAFV infection. IMPORTANCE A capsid assembled from viral proteins protects the virus genome during transmission from one cell to another. However, when a virus enters a cell the virus genome has to be released from the capsid in order to initiate infection. This process is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the genome release of Human Saffold virus 3. Saffold viruses cause diseases ranging from gastrointestinal disorders to meningitis. We show that before the genome is released, the Saffold virus 3 particle expands, and holes form in the previously compact capsid. These holes serve as channels for the release of the genome and small capsid proteins VP4 that in related enteroviruses facilitate subsequent transport of the virus genome into the cell cytoplasm.
|
|
| 7. |
- Rodrigues De Miranda, Joachim
(författare)
-
Virion structure of Iflavirus Slow bee paralysis virus at 2.6-Angstrom resolution
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90, s. 7444 –7455-
-
Tidskriftsartikel (refereegranskat)abstract
- The western honeybee (Apis mellifera) is the most important commercial insect pollinator. However, bees are under pressure from habitat loss, environmental stress, and pathogens, including viruses that can cause lethal epidemics. Slow bee paralysis virus (SBPV) belongs to the Iflaviridae family of nonenveloped single-stranded RNA viruses. Here we present the structure of the SBPV virion determined from two crystal forms to resolutions of 3.4 angstrom and 2.6 angstrom. The overall structure of the virion resembles that of picornaviruses, with the three major capsid proteins VP1 to 3 organized into a pseudo-T3 icosahedral capsid. However, the SBPV capsid protein VP3 contains a C-terminal globular domain that has not been observed in other viruses from the order Picornavirales. The protruding (P) domains form "crowns" on the virion surface around each 5-fold axis in one of the crystal forms. However, the P domains are shifted 36 angstrom toward the 3-fold axis in the other crystal form. Furthermore, the P domain contains the Ser-His-Asp triad within a surface patch of eight conserved residues that constitutes a putative catalytic or receptor-binding site. The movements of the domain might be required for efficient substrate cleavage or receptor binding during virus cell entry. In addition, capsid protein VP2 contains an RGD sequence that is exposed on the virion surface, indicating that integrins might be cellular receptors of SBPV.IMPORTANCEPollination by honeybees is needed to sustain agricultural productivity as well as the biodiversity of wild flora. However, honey-bee populations in Europe and North America have been declining since the 1950s. Honeybee viruses from the Iflaviridae family are among the major causes of honeybee colony mortality. We determined the virion structure of an Iflavirus, slow bee paralysis virus (SBPV). SBPV exhibits unique structural features not observed in other picorna-like viruses. The SBPV capsid protein VP3 has a large C-terminal domain, five of which form highly prominent protruding "crowns" on the virion surface. However, the domains can change their positions depending on the conditions of the environment. The domain includes a putative catalytic or receptor binding site that might be important for SBPV cell entry.
|
|
| 8. |
- Rodrigues De Miranda, Joachim
(författare)
-
Virion Structure of Israeli Acute Bee Paralysis Virus
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90, s. 8150 –8159-
-
Tidskriftsartikel (refereegranskat)abstract
- The pollination services provided by the western honeybee (Apis mellifera) are critical for agricultural production and the diversity of wild flowering plants. However, honeybees suffer from environmental pollution, habitat loss, and pathogens, including viruses that can cause fatal diseases. Israeli acute bee paralysis virus (IAPV), from the family Dicistroviridae, has been shown to cause colony collapse disorder in the United States. Here, we present the IAPV virion structure determined to a resolution of 4.0 angstrom and and the structure of a pentamer of capsid protein protomers at a resolution of 2.7 angstrom. IAPV has major capsid proteins VP1 and VP3 with noncanonical jellyroll beta-barrel folds composed of only seven instead of eight beta-strands, as is the rule for proteins of other viruses with the same fold. The maturation of dicistroviruses is connected to the cleavage of precursor capsid protein VP0 into subunits VP3 and VP4. We show that a putative catalytic site formed by the residues Asp-Asp-Phe of VP1 is optimally positioned to perform the cleavage. Furthermore, unlike many picornaviruses, IAPV does not contain a hydrophobic pocket in capsid protein VP1 that could be targeted by capsid-binding antiviral compounds.IMPORTANCEHoneybee pollination is required for agricultural production and to sustain the biodiversity of wild flora. However, honeybee populations in Europe and North America are under pressure from pathogens, including viruses that cause colony losses. Viruses from the family Dicistroviridae can cause honeybee infections that are lethal, not only to individual honeybees, but to whole colonies. Here, we present the virion structure of an Aparavirus, Israeli acute bee paralysis virus (IAPV), a member of a complex of closely related viruses that are distributed worldwide. IAPV exhibits unique structural features not observed in other picorna-like viruses. Capsid protein VP1 of IAPV does not contain a hydrophobic pocket, implying that capsid-binding antiviral compounds that can prevent the replication of vertebrate picornaviruses may be ineffective against honeybee virus infections.
|
|
| 9. |
- Sabin, Charles, et al.
(författare)
-
Structure of Aichi Virus 1 and Its Empty Particle : Clues to Kobuvirus Genome Release Mechanism
- 2016
-
Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 90:23, s. 10800-10810
-
Tidskriftsartikel (refereegranskat)abstract
- Aichi virus 1 (AiV-1) is a human pathogen from the Kobuvirus genus of the Picornaviridae family. Worldwide, 80 to 95% of adults have antibodies against the virus. AiV-1 infections are associated with nausea, gastroenteritis, and fever. Unlike most picornaviruses, kobuvirus capsids are composed of only three types of subunits: VP0, VP1, and VP3. We present here the structure of the AiV-1 virion determined to a resolution of 2.1 angstrom using X-ray crystallography. The surface loop puff of VP0 and knob of VP3 in AiV-1 are shorter than those in other picornaviruses. Instead, the 42-residue BC loop of VP0 forms the most prominent surface feature of the AiV-1 virion. We determined the structure of AiV-1 empty particle to a resolution of 4.2 angstrom using cryo-electron microscopy. The empty capsids are expanded relative to the native virus. The N-terminal arms of capsid proteins VP0, which mediate contacts between the pentamers of capsid protein protomers in the native AiV-1 virion, are disordered in the empty capsid. Nevertheless, the empty particles are stable, at least in vitro, and do not contain pores that might serve as channels for genome release. Therefore, extensive and probably reversible local reorganization of AiV-1 capsid is required for its genome release. IMPORTANCE Aichi virus 1 (AiV-1) is a human pathogen that can cause diarrhea, abdominal pain, nausea, vomiting, and fever. AiV-1 is identified in environmental screening studies with higher frequency and greater abundance than other human enteric viruses. Accordingly, 80 to 95% of adults worldwide have suffered from AiV-1 infections. We determined the structure of the AiV-1 virion. Based on the structure, we show that antiviral compounds that were developed against related enteroviruses are unlikely to be effective against AiV-1. The surface of the AiV-1 virion has a unique topology distinct from other related viruses from the Picornaviridae family. We also determined that AiV-1 capsids form compact shells even after genome release. Therefore, AiV-1 genome release requires large localized and probably reversible reorganization of the capsid.
|
|
