scholarly journals Ac23, an Envelope Fusion Protein Homolog in the Baculovirus Autographa californica Multicapsid Nucleopolyhedrovirus, Is a Viral Pathogenicity Factor

2003 ◽  
Vol 77 (1) ◽  
pp. 328-339 ◽  
Author(s):  
Oliver Y. Lung ◽  
Marilyn Cruz-Alvarez ◽  
Gary W. Blissard
Keyword(s):  
Fusion Protein ◽  
Viral Entry ◽  
Fusion Proteins ◽  
Autographa Californica ◽  
Viral Envelope ◽  
Evolutionary Divergence ◽  
Pathogenicity Factor ◽  
Group I ◽  
Group Ii ◽  
Contrast Group

ABSTRACT Viral envelope fusion proteins are important structural proteins that mediate viral entry and may affect or determine the host range of a virus. The acquisition, exchange, and evolution of such envelope proteins may dramatically affect the success and evolutionary divergence of viruses. In the family Baculoviridae, two very different envelope fusion proteins have been identified. Budded virions of group I nucleopolyhedroviruses (NPVs) such as the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), contain the essential GP64 envelope fusion protein. In contrast group II NPVs and granuloviruses have no gp64 gene but instead encode a different envelope protein called F. F proteins from group II NPVs can functionally substitute for GP64 in gp64null AcMNPV viruses, indicating that GP64 and these F proteins serve a similar functional role. Interestingly, AcMNPV (and other gp64-containing group I NPVs) also contain an F gene homolog (Ac23) but the AcMNPV F homolog cannot compensate for the loss of gp64. In the present study, we show that Ac23 is expressed and is found in budded virions. To examine the function of F protein homologs from the gp64-containing baculoviruses, we generated an Ac23null AcMNPV genome by homologous recombination in E. coli. We found that Ac23 was not required for viral replication or pathogenesis in cell culture or infected animals. However, Ac23 accelerated the mortality of infected insect hosts by approximately 28% or 26 h. Thus, Ac23 represents an important viral pathogenicity factor in larvae infected with AcMNPV.

scholarly journals The F-Like Protein Ac23 Enhances the Infectivity of the Budded Virus of gp64-Null Autographa californica Multinucleocapsid Nucleopolyhedrovirus Pseudotyped with Baculovirus Envelope Fusion Protein F

2008 ◽  
Vol 82 (19) ◽  
pp. 9800-9804 ◽  
Author(s):  
Manli Wang ◽  
Ying Tan ◽  
Feifei Yin ◽  
Fei Deng ◽  
Just M. Vlak ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Fusion Proteins ◽  
Spodoptera Exigua ◽  
Autographa Californica ◽  
Pseudotyped Virus ◽  
F Protein ◽  
Group I ◽  
Protein F ◽  
Budded Virus ◽  
Functional Envelope

ABSTRACT The GP64 and F proteins were previously identified as the sole functional envelope fusion proteins in Baculoviridae. F-like proteins, present only in group I nucleopolyhedroviruses (NPVs), are remnant, nonfunctional F proteins. In this report, we describe the effect of the presence or absence of the F-like protein Ac23 in a gp64-null Autographa californica multinucleocapsid NPV pseudotyped with the F protein from Spodoptera exigua multicapsid NPV (SeF). We found that the presence of Ac23 elevates the infectivity of the pseudotyped virus. This is in contrast to the results of Lung et al. (J. Virol. 76:5729-5736, 2002), who found no such effect. The possible reasons for the differing results are discussed.

scholarly journals GP64 of group I nucleopolyhedroviruses cannot readily rescue infectivity of group II f-null nucleopolyhedroviruses

2008 ◽  
Vol 89 (2) ◽  
pp. 424-431 ◽  
Author(s):  
Marcel Westenberg ◽  
Just M. Vlak
Keyword(s):  
Fusion Protein ◽  
Selective Advantage ◽  
Autographa Californica ◽  
Viral Attachment ◽  
F Protein ◽  
Group I ◽  
The Family ◽  
Protein Group ◽  
Group Ii ◽  
Budded Virus

The genus Nucleopolyhedrovirus (NPV) of the family Baculoviridae can be subdivided phylogenetically into two groups. The same division can be made on the basis of their budded virus (BV) envelope fusion protein. Group I NPVs are characterized by the presence of a GP64-like major envelope fusion protein, which is involved in viral attachment and the fusion of virus and cell membrane, and is required for budding of progeny nucleocapsids. Group II NPVs have an envelope fusion protein unrelated to GP64, named F. In contrast to GP64, F proteins are found in all baculoviruses, but they are not functional as envelope fusion proteins in group I NPVs. Autographa californica multiple NPV (AcMNPV) lacking GP64 can be pseudotyped by the F protein of Spodoptera exigua multiple NPV (SeMNPV), suggesting that F proteins are functionally analogous to GP64. GP64 homologues are thought to have been acquired by group I NPVs during evolution, thereby giving these viruses a selective advantage and obviating the need for a functional F protein. To address this supposition experimentally, attempts were made to pseudotype a group II NPV, SeMNPV, with GP64. Transfection of an f-null SeMNPV bacmid into Se301 cells did not result in the production of infectious BVs. This defect was rescued by insertion of SeMNPV f, but not by insertion of AcMNPV gp64. This suggests that the functional analogy between GP64 and F is not readily reciprocal and that F proteins from group II NPVs may provide additional functions in BV formation that are lacking in the GP64 type of fusion protein.

scholarly journals Functional Role of the Cytoplasmic Tail Domain of the Major Envelope Fusion Protein of Group II Baculoviruses

2006 ◽  
Vol 80 (22) ◽  
pp. 11226-11234 ◽  
Author(s):  
Gang Long ◽  
Xiaoyu Pan ◽  
Marcel Westenberg ◽  
Just M. Vlak
Keyword(s):  
Fusion Proteins ◽  
Functional Role ◽  
Cytoplasmic Tail ◽  
Viral Envelope ◽  
Repair System ◽  
Dependent Manner ◽  
Tail Domain ◽  
F Protein ◽  
Group Ii

ABSTRACT F proteins from baculovirus nucleopolyhedrovirus (NPV) group II members are the major budded virus (BV) viral envelope fusion proteins. They undergo furin-like proteolysis processing in order to be functional. F proteins from different baculovirus species have a long cytoplasmic tail domain (CTD), ranging from 48 (Spodoptera litura multicapsid NPV [MNPV]) to 78 (Adoxophyes honmai NPV) amino acid (aa) residues, with a nonassigned function. This CTD is much longer than the CTD of GP64-like envelope fusion proteins (7 aa), which appear to be nonessential for BV infectivity. Here we have investigated the functional role of the CTD of Helicoverpa armigera single-capsid NPV (HearNPV), a group II NPV. We combined a newly constructed HearNPV f-null bacmid knockout-repair system and an Autographa californica MNPV (AcMNPV) gp64-null bacmid knockout-pseudotype system with mutation and rescue experiments to study the functional role of the baculovirus F protein CTD. We show that except for the 16 C-terminal aa, the HearNPV F CTD is essential for virus spread from cell to cell. In addition, the CTD of HearNPV F is involved in BV production in a length-dependent manner and is essential for BV infectivity. The tyrosine residue Y658, located 16 aa from the C terminus, seems to be critical. However, HearNPV F without a CTD still rescues the infectivity of gp64-null AcMNPV BV, indicating that the CTD is not involved in processing and fusogenicity. Altogether, our results indicate that the F protein is essential for baculovirus BV infectivity and that the CTD is important for F protein incorporation into BV.

scholarly journals A Histidine Switch in Hemagglutinin-Neuraminidase Triggers Paramyxovirus-Cell Membrane Fusion

2008 ◽  
Vol 83 (4) ◽  
pp. 1727-1741 ◽  
Author(s):  
Anuja Krishnan ◽  
Santosh K. Verma ◽  
Prashant Mani ◽  
Rahul Gupta ◽  
Suman Kundu ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Membrane Fusion ◽  
Fusion Proteins ◽  
Sendai Virus ◽  
Biological Activities ◽  
Viral Envelope ◽  
Attachment Protein ◽  
Histidine Residues ◽  
Human Parainfluenza Virus ◽  
Mimicking Peptides

ABSTRACT Most paramyxovirus fusion proteins require coexpression of and activation by a homotypic attachment protein, hemagglutinin-neuraminidase (HN), to promote membrane fusion. However, the molecular mechanism of the activation remains unknown. We previously showed that the incorporation of a monohistidylated lipid into F-virosome (Sendai viral envelope containing only fusion protein) enhanced its fusion to hepatocytes, suggesting that the histidine residue in the lipid accelerated membrane fusion. Therefore, we explored whether a histidine moiety in HN could similarly direct activation of the fusion protein. In membrane fusion assays, the histidine substitution mutants of HN (H247A of Sendai virus and H245A of human parainfluenza virus 3) had impaired membrane fusion promotion activity without significant changes in other biological activities. Synthetic 30-mer peptides corresponding to regions of the two HN proteins containing these histidine residues rescued the fusion promoting activity of the mutants, whereas peptides with histidine residues substituted by alanine did not. These histidine-containing peptides also activated F-virosome fusion with hepatocytes both in the presence and in the absence of mutant HN in the virosome. We provide evidence that the HN-mimicking peptides promote membrane fusion, revealing a specific histidine “switch” in HN that triggers fusion.

scholarly journals CLINICAL EFFICACY OF RECOMBINANT FACTOR VIII FC FUSION PROTEIN IN HAEMOPHILIA A PATIENT RECEIVING ON DEMAND TREATMENT ONLY

2021 ◽  
Vol 71 (1) ◽  
pp. 62-66
Author(s):  
Saima Zahir ◽  
Tahira Zafar ◽  
Altaf Hussain ◽  
Hamid Saeed Malik ◽  
Pervez Ahmed ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Factor Viii ◽  
Armed Forces ◽  
Recombinant Factor Viii ◽  
Haemophilia A ◽  
On Demand ◽  
Group I ◽  
Fc Fusion Protein ◽  
Male Patients ◽  
Group Ii

Objective: To evaluate the efficacy of recombinant factor VIII FC fusion protein in haemophilia A patientreceiving on demand treatment only. Study Design: Comparative cross sectional study. Place and Duration of Study: Department of Hematology, Armed Forces Institute of Pathology and PakistanHemophilia Welfare Society, Rawalpindi, from Jun to Dec 2017. Methodology: Eighty-nine male patients of Hemophilia A already receiving recombinant factor VIII (20-30 Units/kg) on demand, with no history of inhibitors were included in study. Patients were divided as per age into paediatric and adult group and also on the basis of their basal factor VIII levels into severe, moderate and mild groups. Same patients were switched to recombinant factor VIII FC fusion protein (20-30 Units/kg) and its efficacy was measured and compared with recombinant Factor VIII in terms of dose requirement, injections, bleeds in six month period, presence of inhibitors and side effects. Results: Eighty nine male patients were studied. There was significant reduction in dose from median value of5750 units for group I to 4000 units for group II. Number of bleed in six month period were reduced from 5.3 ingroup I to 4.5 in group II. Number of injections were reduced on average to 1-2 injection per bleed in group II. No inhibitors were detected in group II. Conclusion: rFVIII Fc fusion protein has prolong activity and results in reduction of total dose, number of bleed,dose per bleed and has reduced antigenecity.

scholarly journals Characterization of an Immunodominant Antigenic Site on GB Virus C Glycoprotein E2 That Is Involved in Cell Binding

2006 ◽  
Vol 80 (24) ◽  
pp. 12131-12140 ◽  
Author(s):  
James H. McLinden ◽  
Thomas M. Kaufman ◽  
Jinhua Xiang ◽  
Qing Chang ◽  
Donna Klinzman ◽  
...  
Keyword(s):  
Antigenic Site ◽  
Group Iv ◽  
Binding Assays ◽  
Cell Binding ◽  
Group Iii ◽  
Group I ◽  
Glycoprotein E2 ◽  
Group Ii ◽  
Virus C ◽  
Contrast Group

ABSTRACT GB virus type C (GBV-C) is a human flavivirus that may cause persistent infection, although most infected individuals clear viremia and develop antibodies to the envelope glycoprotein E2. To study GBV-C E2 antigenicity and cell binding, murine anti-E2 monoclonal antibodies (MAbs) were evaluated to topologically map immunogenic sites on GBV-C E2 and for the ability to detect or block recombinant E2 binding to various cell lines. Five competition groups of MAbs were identified. Groups I and II did not compete with each other. Group III competed with both groups I and II. Group IV did not compete with group I, II, or III. One MAb competed with all of the other MAbs, suggesting that the epitopes bound by these MAbs are intimately related. Individually, none of the MAbs competed extensively with polyclonal human convalescent antibody (PcAb); however, combinations of all five MAb groups completely blocked PcAb binding to E2, suggesting that the epitopes bound by these MAbs form a single, immunodominant antigenic site. Only group I and III MAbs detected purified recombinant E2 bound to cells in binding assays. In contrast, group II MAbs neutralized the binding of E2 to cells. Both PcAb and MAbs were conformation dependent, with the exception of one group II MAb (M6). M6 bound to a five-amino-acid sequence on E2 if the peptide included four C-terminal or eight N-terminal residues, suggesting that the GBV-C E2 protein contains a single immunodominant antigenic site which includes a complex epitope that is involved in specific cellular binding.

scholarly journals Function, oligomerization and N-linked glycosylation of the Helicoverpa armigera single nucleopolyhedrovirus envelope fusion protein

2006 ◽  
Vol 87 (4) ◽  
pp. 839-846 ◽  
Author(s):  
Gang Long ◽  
Marcel Westenberg ◽  
Hualin Wang ◽  
Just M. Vlak ◽  
Zhihong Hu
Keyword(s):  
Fusion Protein ◽  
Helicoverpa Armigera ◽  
Disulfide Bonds ◽  
Attractive Alternative ◽  
Present Observation ◽  
Reading Frame ◽  
Group I ◽  
The Family ◽  
Helicoverpa Armígera ◽  
Group Ii

In the family Baculoviridae, two distinct envelope fusion proteins are identified in budded virions (BVs). GP64 is the major envelope fusion protein of group I nucleopolyhedrovirus (NPV) BVs. An unrelated type of envelope fusion protein, named F, is encoded by group II NPVs. The genome of Helicoverpa armigera (Hear) NPV, a group II NPV of the single nucleocapsid or S type, also encodes an F-like protein: open reading frame 133 (Ha133). It was demonstrated by N-terminal sequencing of the major 59 kDa protein present in HearNPV BV that this protein is one of the two F subunits: F1 (transmembrane subunit of 59 kDa) and F2 (surface subunit of 20 kDa), both the result of cleavage by a proprotein convertase and disulfide-linked. The HearNPV F protein proved to be a functional analogue of GP64, as the infectivity of an AcMNPV gp64-deletion mutant was rescued by the introduction of the HearNPV F gene. It was also demonstrated by chemical cross-linking that HearNPV F is present in BVs as an oligomer whereby, unlike GP64, disulfide bonds are not involved. Deglycosylation assays indicated that both F1 and F2 possess N-linked glycans. However, when F was made in Hz2E5 cells, these glycans did not have an α-1-3 core fucose modification that usually occurs in insect cells. As α-1-3 core fucose is a major inducer of an allergic response in humans, the present observation makes the HearNPV–Hz2E5 system an attractive alternative for the production of recombinant glycoproteins for therapeutic use in humans.

scholarly journals Sequence and organization of the Spodoptera exigua multicapsid nucleopolyhedrovirus genome

1999 ◽  
Vol 80 (12) ◽  
pp. 3289-3304 ◽  
Author(s):  
Wilfred F. J. IJkel ◽  
Elisabeth A. van Strien ◽  
Jacobus G. M. Heldens ◽  
René Broer ◽  
Douwe Zuidema ◽  
...  
Keyword(s):  
Spodoptera Exigua ◽  
Autographa Californica ◽  
Recent Common Ancestor ◽  
Computer Assisted ◽  
Glycoprotein Gene ◽  
Orgyia Pseudotsugata ◽  
Group I ◽  
Group Ii ◽  
Budded Virus ◽  
Assisted Analysis

The nucleotide sequence of the DNA genome of Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV), a group II NPV, was determined and analysed. The genome contains 135611 bp and has a G+C content of 44 mol%. Computer-assisted analysis revealed 139 ORFs of 150 nucleotides or larger; 103 have homologues in Autographa californica MNPV (AcMNPV) and a further 16 have homologues in other baculoviruses. Twenty ORFs are unique to SeMNPV. Major differences in SeMNPV gene content and arrangement were found compared with the group I NPVs AcMNPV, Bombyx mori (Bm) NPV and Orgyia pseudotsugata (Op) MNPV and the group II NPV Lymantria dispar (Ld) MNPV. Eighty-five ORFs were conserved among all five baculoviruses and are considered as candidate core baculovirus genes. Two putative p26 and odv-e66 homologues were identified in SeMNPV, each of which appeared to have been acquired independently and not by gene duplication. The SeMNPV genome lacks homologues of the major budded virus glycoprotein gene gp64, the immediate-early transactivator ie-2 and bro (baculovirus repeat ORF) genes that are found in AcMNPV, BmNPV, OpMNPV and LdMNPV. Gene parity analysis of baculovirus genomes suggests that SeMNPV and LdMNPV have a recent common ancestor and that they are more distantly related to the group I baculoviruses AcMNPV, BmNPV and OpMNPV. The orientation of the SeMNPV genome is reversed compared with the genomes of AcMNPV, BmNPV, OpMNPV and LdMNPV. However, the gene order in the ‘central’ part of baculovirus genomes is highly conserved and appears to be a key feature in the alignment of baculovirus genomes.

scholarly journals Partial Functional Rescue of Helicoverpa armigera Single Nucleocapsid Nucleopolyhedrovirus Infectivity by Replacement of F Protein with GP64 from Autographa californica Multicapsid Nucleopolyhedrovirus

2010 ◽  
Vol 84 (21) ◽  
pp. 11505-11514 ◽  
Author(s):  
Manli Wang ◽  
Feifei Yin ◽  
Shu Shen ◽  
Ying Tan ◽  
Fei Deng ◽  
...  
Keyword(s):  
Helicoverpa Armigera ◽  
Culture Supernatant ◽  
Selective Advantage ◽  
Autographa Californica ◽  
Cell Culture Supernatant ◽  
F Protein ◽  
Group I ◽  
Control Virus ◽  
Helicoverpa Armígera ◽  
Group Ii

ABSTRACT Two distinct envelope fusion proteins (EFPs) (GP64 and F) have been identified in members of the Baculoviridae family of viruses. F proteins are found in group II nucleopolyhedroviruses (NPVs) of alphabaculoviruses and in beta- and deltabaculoviruses, while GP64 occurs only in group I NPVs of alphabaculoviruses. It was proposed that an ancestral baculovirus acquired the gp64 gene that conferred a selective advantage and allowed it to evolve into group I NPVs. The F protein is a functional analogue of GP64, as evidenced from the rescue of gp64-null Autographa californica multicapsid nucleopolyhedrovirus (MNPV) (AcMNPV) by F proteins from group II NPVs or from betabaculoviruses. However, GP64 failed to rescue an F-null Spodoptera exigua MNPV (SeMNPV) (group II NPV). Here, we report the successful generation of an infectious gp64-rescued group II NPV of Helicoverpa armigera (vHaBacΔF-gp64). Viral growth curve assays and quantitative real-time PCR (Q-PCR), however, showed substantially decreased infectivity of vHaBacΔF-gp64 compared to the HaF rescue control virus vHaBacΔF-HaF. Electron microscopy further showed that most vHaBacΔF-gp64 budded viruses (BV) in the cell culture supernatant lacked envelope components and contained morphologically aberrant nucleocapsids, suggesting the improper BV envelopment or budding of vHaBacΔF-gp64. Bioassays using pseudotyped viruses with a reintroduced polyhedrin gene showed that GP64-pseudotyped Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) significantly delayed the mortality of infected H. armigera larvae.

scholarly journals Baculovirus envelope fusion proteins F and GP64 exploit distinct receptors to gain entry into cultured insect cells

2007 ◽  
Vol 88 (12) ◽  
pp. 3302-3306 ◽  
Author(s):  
Marcel Westenberg ◽  
Peter Uijtdewilligen ◽  
Just M. Vlak
Keyword(s):  
Fusion Proteins ◽  
Mammalian Cells ◽  
Structural Similarity ◽  
Autographa Californica ◽  
Viral Fusion ◽  
Fixed Amount ◽  
Group I ◽  
Protein Receptors ◽  
Viral Fusion Proteins ◽  
Budded Virus

Group II nucleopolyhedroviruses (NPVs), e.g. Helicoverpa armigera (Hear) NPV and Spodoptera exigua (Se) MNPV (multiple NPV), lack a GP64-like protein that is present in group I NPVs, e.g. Autographa californica (Ac)MNPV, but have an unrelated envelope fusion protein named F. Three AcMNPV viruses were constructed by introducing AcMNPV gp64, HearNPV f or SeMNPV f genes, respectively, into a gp64-negative AcMNPV bacmid. Sf21 cells were incubated with different amounts of inactivated budded virus to occupy receptors and were subsequently infected with a fixed amount of infectious virus to compete for attachment. The results suggest that GP64 and F act on their own and use different receptors, while the two different F proteins exploit the same receptor. Additionally, gp64-null AcMNPV pseudotyped with baculovirus F was, in contrast to GP64, unable to transduce mammalian cells, indicating that mammalian cells do not possess baculovirus F protein receptors despite the structural similarity of baculovirus F to vertebrate viral fusion proteins.

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