Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Creation of a new genus in the family Secoviridae substantiated by sequence variation of newly identified strawberry latent ringspot
    Dullemans, A.M. ; Botermans, M. ; Kock, M.J.D. de; Krom, C.E. de; Lee, T.A.J. van der; Roenhorst, J.W. ; Stulemeijer, I.J.E. ; Verbeek, M. ; Westenberg, M. ; Vlugt, R.A.A. van der - \ 2020
    Archives of Virology 165 (2020)1. - ISSN 0304-8608 - p. 21 - 31.
    To obtain insight into the sequence diversity of strawberry latent ringspot virus (SLRSV), isolates from collections and diagnostic samples were sequenced by high-throughput sequencing. For five SLRSV isolates, the complete genome sequences were determined, and for 18 other isolates nearly complete genome sequences were determined. The sequence data were analysed in relation to sequences of SLRSV and related virus isolates available in the NCBI GenBank database. The genome sequences were annotated, and sequences of the protease-polymerase (Pro-Pol) region and coat proteins (CPs) (large and small CP together) were used for phylogenetic analysis. The amino acid sequences of the Pro-Pol region were very similar, whereas the nucleotide sequences of this region were more variable. The amino acid sequences of the CPs were less similar, which was corroborated by the results of a serological comparison performed using antisera raised against different isolates of SLRSV. Based on these results, we propose that SLRSV and related unassigned viruses be assigned to a new genus within the family Secoviridae, named “Stralarivirus”. Based on the phylogenetic analysis, this genus should include at least three viruses, i.e., SLRSV-A, SLRSV-B and lychnis mottle virus. The newly generated sequence data provide a basis for designing molecular tests to screen for SLRSV.
    High-throughput sequencing technologies for plant pest diagnosis: challenges and opportunities
    Olmos, A. ; Boonham, N. ; Candresse, T. ; Gentit, P. ; Giovani, B. ; Kutnjak, D. ; Liefting, L. ; Maree, H.J. ; Minafra, A. ; Moreira, A. ; Nakhla, M.K. ; Petter, F. ; Ravnikar, M. ; Rodoni, B.C. ; Roenhorst, J.W. ; Rott, M. ; Ruiz-Garcia, A.B. ; Santala, J. ; Stancanelli, G. ; Vlugt, R.A.A. van der; Varveri, C. ; Westenberg, M. ; Wetzel, T. ; Ziebell, H. ; Massart, S. - \ 2018
    EPPO Bulletin 48 (2018)2. - ISSN 0250-8052 - p. 219 - 224.
    High‐throughput sequencing (HTS) technologies have revolutionized plant pest research and are now raising interest for plant pest diagnostics, with plant virus diagnostics at the forefront of development. However, the application of HTS in plant pest diagnostics raises important challenges that plant health regulators will have to address. Adapted infrastructures, technical guidelines and training are pivotal for further use and adoption of the HTS technologies in the phytosanitary framework.
    Phytophtora terminalis sp. nov. and Phytophthora occultans sp. nov., two invasive pathogens of ornamental plants in Europe
    Man in 't Veld, W.A. ; Rosendahl, K.C.H.M. ; Rijswick, P.C.J. van; Meffert, J.P. ; Westenberg, M. ; Vossenberg, B.T.L.H. van de; Denton, G. ; Kuik, A.J. van - \ 2017
    Mycologia 107 (2017)1. - ISSN 0027-5514 - p. 54 - 65.
    To evaluate, among the elderly, the association of self-rated health (SRH) with mortality, and to identify determinants of self-rating health as “at-least-good”.

    Study Design
    Individual data on SRH and important covariates were obtained for 424,791 European and Unites States residents, ≥60 years at recruitment (1982-2008), in eight prospective studies in the Consortium on Health and Ageing: Network of Cohorts in Europe and the United States (CHANCES). In each study, adjusted mortality ratios (hazard ratios, HRs) in relation to SRH were calculated and subsequently combined with random-effect meta-analyses.

    Main outcome measures
    All-cause, cardiovascular and cancer mortality.

    Within the median 12.5 years of follow-up, 93,014 (22%) deaths occurred. SRH “fair” or “poor” vs. “at-least-good” was associated with increased mortality: HRs 1.46 (95% CI 1·23-1.74) and 2.31 (1.79-2.99), respectively. These associations were evident: for cardiovascular and, to a lesser extent, cancer mortality, and within-study, within-subgroup analyses. Accounting for lifestyle, sociodemographic, somatometric factors and, subsequently, for medical history explained only a modest amount of the unadjusted associations. Factors favourably associated with SRH were: sex (males), age (younger-old), education (high), marital status (married/cohabiting), physical activity (active), body mass index (non-obese), alcohol consumption (low to moderate) and previous morbidity (absence).

    SRH provides a quick and simple tool for assessing health and identifying groups of elders at risk of early mortality that may be useful also in clinical settings. Modifying determinants of favourably rating health, e.g. by increasing physical activity and/or by eliminating obesity, may be important for older adults to “feel healthy” and “be healthy”.
    Generic RT-PCR tests for detection and identification of tospoviruses
    Hassani-Mehraban, A. ; Westenberg, M. ; Verhoeven, J.T.J. ; Vossenberg, B.T.L.H. van de; Kormelink, R. ; Roenhorst, J.W. - \ 2016
    Journal of Virological Methods 233 (2016). - ISSN 0166-0934 - p. 89 - 96.
    Bunyaviridae - Clade-specific primers - Diagnostics - Nucleocapsid gene - Plant virus

    A set of tests for generic detection and identification of tospoviruses has been developed. Based on a multiple sequence alignment of the nucleocapsid gene and its 5' upstream untranslated region sequence from 28 different species, primers were designed for RT-PCR detection of tospoviruses from all recognized clades, i.e. the American, Asian and Eurasian clades, and from the small group of distinct and floating species. Pilot experiments on isolates from twenty different species showed that the designed primer sets successfully detected all species by RT-PCR, as confirmed by nucleotide sequence analysis of the amplicons. In a final optimized design, the primers were applied in a setting of five RT-PCR tests. Seven different tospoviruses were successfully identified from diagnostic samples and in addition a non-described tospovirus species from alstroemeria plants. The results demonstrate that the newly developed generic RT-PCR tests provide a relevant tool for broad detection and identification of tospoviruses in plant quarantine and diagnostic laboratories.

    Winter Activity and Aboveground Hybridization Between the Two Biotypes of the West Nile Virus Vector Culex pipiens
    Vogels, C.B.F. ; Peppel, L.J.J. van de; Vliet, A.J.H. van; Westenberg, M. ; Ibanez-Justicia, A. ; Stroo, A. ; Buijs, J.A. ; Visser, T.M. ; Koenraadt, C.J.M. - \ 2015
    Vector-Borne and Zoonotic Diseases 15 (2015)10. - ISSN 1530-3667 - p. 619 - 626.
    Culex (Cx.) pipiens mosquitoes are important vectors of West Nile virus (WNV). In Europe, the species Cx. pipiens consists of two biotypes, pipiens and molestus, which are morphologically identical, but differ in behavior. Typical behavior of the molestus biotype is the ability to remain active during winter, whereas the pipiens biotype enters diapause. The current paradigm is that the two biotypes occur sympatrically in southern Europe, but occur in isolated above- and belowground populations in northern Europe. In northern Europe, hybridization between biotypes is considered to be low because of the barrier that exists between typical habitats. Data on the occurrence of the biotypes and hybrids in northern Europe, however, are scarce, because identification to the level of biotype is often not performed. Our objective was to clarify the distribution of the Cx. pipiens biotypes and to determine hybridization rates in The Netherlands. Cx. pipiens mosquitoes were collected using three different approaches. First, traps were deployed randomly throughout The Netherlands during the summers of 2011 and 2012 (active surveillance). Second, using a web-based reporting platform and media campaign, Dutch citizens were asked to send dead mosquitoes to our laboratory during the winter and summer of 2014 (passive surveillance). Third, larvae and adults were collected during the summer of 2014 from aboveground locations in Amsterdam to identify molestus larval habitats. Real-time PCR was used for identification to the level of biotype. We found that biotype molestus and hybrids were feeding indoors during winter and summer in The Netherlands and that hybridization rates ranged between 6% and 15%. Larval habitats of biotype molestus were found to occur aboveground. The high percentage of hybridization has implications for assessing the risk of WNV transmission, because hybrids are thought to have ideal characteristics for bridging WNV between birds and humans.
    DNA barcoding as an identification tool for selected EU-regulated plant pests: an international collaborative test performance study among 14 laboratories
    Bonants, P.J.M. ; Vossenberg, B.T.L.H. van de; Westenberg, M. - \ 2013
    EPPO Bulletin 43 (2013)2. - ISSN 0250-8052 - p. 216 - 228.
    This paper describes the database Q-bank ( This freely accessible database contains data on plant pathogenic quarantine organisms to allow fast and reliable identification. Development of accurate identification tools for plant pests is vital to support European Plant Health Policies. Council Directive 2000 / 29 /EC lists approximately 300 entries representing a large number of species (e.g. non-European Tephritids contains approximately 3500 species) for which protective measures, against introduction and their spread within the European Community, need to be taken. The risk of introduction of pests into the European Union is increasing because of the increase in the volumes, commodity types and origins of trade, the introduction of new crops, the continued expansion of the EU, the numbers of international travellers and the impact of climate change. Identifying pests (in particular new emerging pests) requires staff with specialised skills in all disciplines (mycology, bacteriology etc.), which is only possible within large centralised laboratory facilities. Expertise in taxonomy, phytopathology and other fields in plant health, which are vital for sustaining sound public policy on phytosanitary issues, are under threat. Sharing knowledge on regulated and non-regulated pests is necessary to manage a cost-effective and efficient plant health system in the context of expanding globalisation of trade in plant material
    Functional analysis of two inhibitor of apoptosis (iap) orthologs from Helicoverpa armigera nucleopolyhedrovirus
    Liang, Ch.Y. ; Lange, J. de; Chen, X.W. ; Oers, M.M. van; Vlak, J.M. ; Westenberg, M. - \ 2012
    Virus Research 165 (2012)1. - ISSN 0168-1702 - p. 107 - 111.
    programmed cell-death - baculovirus gene - insect cells - p35 gene - proteins - lines - identification - establishment - expression - tolerance
    Baculoviruses induce apoptotic responses in cultured insect cells, which can severely limit viral replication. To overcome this host response baculoviruses carry anti-apoptotic genes, including members of the p35 and inhibitor of apoptosis (iap) gene families. The baculovirus Helicoverpa armigera nucleopolyhedrovirus (HearNPV) carries two putative apoptosis suppressor genes (iap2 and iap3), which we studied in more detail. IAPs are believed to be functional in the cytoplasm, but surprisingly, when transiently expressed as EGFP fusions, IAP2 was evenly distributed throughout the cell, while IAP3 was mainly found in the nucleus. The latter became evenly distributed in both compartments in HearNPV infected cells. When iap2 was deleted, HearNPV could be propagated in Hz2e5 cells, while an iap3 deletion was lethal. The HearNPV ¿iap3 mutant could be rescued by reinsertion of the HearNPV iap3 gene and by the well-studied anti-apoptotic genes Autographa californica (Ac)MNPV p35 or Orgyia pseudotsugata (Op)MNPV iap3. RNAi analysis showed that HearNPV induced apoptosis in Hz2e5 cells transfected with iap3 dsRNA, while silencing of iap2 did not lead to apoptosis. Finally, IAP3 was able to inhibit actinomycin-D induced apoptosis when transiently expressed in Sf21 cells. These results together indicate that HearNPV IAP3 is a functional apoptosis suppressor, while the function of IAP2 remains elusive.
    Helicoverpa armigera nucleopolyhedrovirus occlusion-derived virus-associated protein, HA100, affects oral infectivity in vivo but not virus replication in vitro
    Luo, S. ; Zhang, Y. ; Xu, X. ; Westenberg, M. ; Vlak, J.M. ; Wang, H. ; Hu, Z. ; Deng, F. - \ 2011
    Journal of General Virology 92 (2011)6. - ISSN 0022-1317 - p. 1324 - 1331.
    single-nucleocapsid nucleopolyhedrovirus - nuclear polyhedrosis-virus - spodoptera-frugiperda - multiple nucleopolyhedrovirus - identification - heliothis - sequence - deletion - genomes - gene
    ORF100 (ha100) of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) has been reported as one of the unique genes of group II alphabaculoviruses encoding a protein located in the occlusion-derived virus (ODV) envelope and nucleocapsid. The protein consists of 510 aa with a predicted mass of 58.1 kDa and is a homologue of poly(ADP–ribose) glycohydrolase in eukaryotes. Western blot analysis detected a 60 kDa band in HearNPV-infected HzAM1 cells starting at 18 h post-infection. Transient expression of GFP-fused HA100 in HzAM1 cells resulted in cytoplasmic localization of the protein, but after superinfection with HearNPV, GFPfused HA100 was localized in the nucleus. To study the function of HA100 further, an ha100-null virus was constructed using bacmid technology. Viral one-step growth curve analyses showed that the ha100-null virus had similar budded virus production kinetics to that of the parental virus. Electron microscopy revealed that deletion of HA100 did not alter the morphology of ODVs or occlusion bodies (OBs). However, bioassays in larvae showed that the 50% lethal concentration (LC50) value of HA100-null OBs was significantly higher than that of parental OBs; the median lethal time (LT50) of ha100-null OBs was about 24 h later than control virus. These results indicate that HA100 is not essential for virus replication in vitro. However, it significantly affects the oral infectivity of OBs in host insects, suggesting that the association HA100 with the ODV contributes to the infectivity of OBs in vivo.
    Specificity of Baculorivus P6.9 Basic DNA-Binding Proteins and Critical Role of the C Terminus in Virion Formation
    Wang, M. ; Tuladhar, E. ; Shen, S. ; Wang, H. ; Oers, M.M. van; Vlak, J.M. ; Westenberg, M. - \ 2010
    Journal of Virology 84 (2010)17. - ISSN 0022-538X - p. 8821 - 8828.
    nuclear polyhedrosis-virus - envelope fusion protein - infecting plodia-interpunctella - spot syndrome virus - granulosis-virus - genome sequence - nucleocapsid protein - escherichia-coli - purified capsids - nucleopolyhedrovirus
    The majority of double-stranded DNA (dsDNA) viruses infecting eukaryotic organisms use host- or virus-expressed histones or protamine-like proteins to condense their genomes. In contrast, members of the Baculoviridae family use a protamine-like protein named P6.9. The dephosphorylated form of P6.9 binds to DNA in a non-sequence-specific manner. By using a p6.9-null mutant of Autographa californica multiple nucleopolyhedrovirus (AcMNPV), we demonstrate that P6.9 is not required for viral DNA replication but is essential for the production of infectious virus. Virion production was rescued by P6.9 homologs from a number of Alphabaculovirus species and one Gammabaculovirus species but not from the genus Betabaculovirus, comprising the granuloviruses, or by the P6.9 homolog VP15 from the unrelated white spot syndrome virus of shrimp. Mutational analyses demonstrated that AcMNPV P6.9 with a conserved 11-residue deletion of the C terminus was not capable of rescuing p6.9-null AcMNPV, while a chimeric Betabaculovirus P6.9 containing the P6.9 C-terminal region of an Alphabaculovirus strain was able to do so. This implies that the C terminus of baculovirus P6.9 contains sequence elements essential for virion formation. Such elements may possibly interact with species- or genus-specific domains of other nucleocapsid proteins during virus assembly.
    On the function and specificity of baculovirus envelope fusion proteins
    Vlak, J.M. ; Long, G. ; Westenberg, M. ; Wang, M. ; Hu, Z.H. ; Wang, H. - \ 2008
    In: Book of the 14th International Congress of Virology, Istanbul, Turkey, 10 - 15 August, 2008. - Istanbul : - p. 29 - 29.
    Open reading frame 193R of Chilo iridescent virus encodes a functional inhibitor of apoptosis (IAP)
    Ince, I.A. ; Westenberg, M. ; Vlak, J.M. ; Demirbag, Z. ; Nalcacioglu, R. ; Oers, M.M. van - \ 2008
    Virology 376 (2008)1. - ISSN 0042-6822 - p. 124 - 131.
    programmed cell-death - multicapsid nucleopolyhedrovirus - caspase activation - amsacta-moorei - dna polymerase - insect cells - gene - iridovirus - genome - identification
    Programmed cell death or apoptosis is a major defense mechanism in insects in response to viral infections. The genome of Chilo iridescent virus (CIV) has three ORFs with homology to baculovirus inhibitor of apoptosis (iap) genes. The proteins encoded by the 157L, 193R, and 332L ORFs contain 152, 208 and 234 amino acids, respectively. While all three proteins contain C-terminal RING domains, only the protein encoded by ORF 193R contains a baculoviral iap repeat (BIR) domain, indicative of a putative IAP protein. The 193R protein has 28 and 27% similarity in amino acid sequence to the Orgyia pseudotsugata MNPV and Cydia pomonella granulovirus IAP-3 proteins, respectively. ORF 193R from CIV is the only gene known to exist among the Iridoviridae that encodes a BIR domain. 193R is transcribed early during CIV infection, and its transcription is not dependent on the synthesis of early viral proteins. When this putative CIV IAP was transiently expressed in SPC-BM-36 and Sf21 cells under the control of an immediate early baculovirus promoter it significantly reduced apoptosis induced by actinomycin-D. Silencing of the CIV iap gene (193R) in CIV infected SPC-BM-36 cells with 193R-specific dsRNA resulted in apoptosis. Thus, CIV ORF 193R is the first iap gene identified in an iridovirus, which encodes a functional IAP protein.
    Chilo iridescent virus encodes an active anti-apoptopic gene
    Ince, I.A. ; Westenberg, M. ; Demirbag, Z. ; Vlak, J.M. ; Nalcacioglu, R. ; Oers, M.M. van - \ 2008
    In: XIV International Congress of Virology, Istanbul, Turkey, 10 - 15 August, 2008. - Istanbul : IUMS Instanbul - p. 343 - 343.
    GP64 of group I nucleopolyhedroviruses cannot readily rescue infectivity of group II f-null nucleopolyhedroviruses
    Westenberg, M. ; Vlak, J.M. - \ 2008
    Journal of General Virology 89 (2008)2. - ISSN 0022-1317 - p. 424 - 431.
    envelope fusion protein - nuclear polyhedrosis-virus - californica multicapsid nucleopolyhedrovirus - spodoptera-exigua - cytoplasmic domain - baculovirus gp64 - nucleotide-sequence - glycoprotein gp64 - escherichia-coli - dna-replication
    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.
    Functional analysis of the putative inhibitor of apoptosis (IAP) encoded by Chilo iridescent virus
    Ince, I.A. ; Westenberg, M. ; Demirbag, Z. ; Vlak, J.M. ; Nalcacioglu, R. ; Oers, M.M. van - \ 2007
    In: Proceedings of the 40th Annual Meeting of the Society for Invertebrate Pathology, Quebec City, Canada, 12 - 15 August, 2007. - Quebec : - p. 73 - 73.
    Functional analysis of HearNPV putative anti-apoptosis genes
    Liang, C. ; Chen, X. ; Oers, M.M. van; Vlak, J.M. ; Westenberg, M. - \ 2007
    In: Proceedings of the 40th Annual Meeting of the Society for Invertebrate Pathology, Quebec City, Canada, 12 - 15 August, 2007. - - p. 73 - 73.
    Deletion of a Helicoverpa armigera nucleopolyhedrovirus gene encoding a virion structural protein (OR1 07) increases the budded virion titre and reduces in vivo infectivity
    Pan, X. ; Long, G. ; Wang, R.R. ; Hou, S. ; Wang, H. ; Zheng, Y. ; Sun, X. ; Westenberg, M. ; Deng, F. ; Vlak, J.M. ; Hu, Z. - \ 2007
    Journal of General Virology 88 (2007). - ISSN 0022-1317 - p. 3307 - 3316.
    single-nucleocapsid nucleopolyhedrovirus - escherichia-coli - genome sequence - baculoviruses - cloning - virus - dna
    The open reading frame Ha107 of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) encodes a putative protein of 51 kDa with homologues in a few group II NPVs and a granulovirus. Ha107 was transcribed as polyadenylated transcripts in infected HzAM1 insect cells. The transcripts were initiated at two distinct locations, one upstream of Ha106 (superoxide dismutase gene, sod) and the second upstream of Ha107. By Western blot analysis, two forms of the HA107 protein were detected in infected cells, a major polypeptide of 48 kDa and a minor one of 51 kDa. Western blot and immunoelectron microscopy analyses further showed that the HA107 protein was associated with the nucleocapsids of both budded virions (BVs) and occlusion-derived virions. A Ha107 knockout virus expressing enhanced green fluorescent protein and polyhedrin was constructed using bacmid technology. A one-step virus growth curve indicated that the BV titre of the knockout virus was significantly higher than that of the parental virus and a Ha107 repair virus. Bioassays indicated that the knockout virus was able to infect third-instar H. armigera larvae; however, its median lethal dose (LD50) was significantly higher than those of the parental virus and Ha107 repair virus. These data indicate that Ha107 encodes a non-essential structural protein of HearNPV virions and that deletion of this gene increases the BV titre and LD50 of the occluded virus.
    Baculovirus envelope fusion proteins F and GP64 exploit distinct receptors to gain entry into cultured insect cells
    Westenberg, M. ; Uijtdewilligen, P. ; Vlak, J.M. - \ 2007
    Journal of General Virology 88 (2007). - ISSN 0022-1317 - p. 3302 - 3306.
    nuclear polyhedrosis-virus - californica multicapsid nucleopolyhedrovirus - membrane-fusion - recombinant baculovirus - lymantria-dispar - mammalian-cells - genome sequence - lines - glycoprotein - mechanism
    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.
    Absence of N-linked glycans from the F2 subunit of the major baculovirus envelope fusion protein F enhances fusogenicity
    Long, G. ; Pan, X. ; Vlak, J.M. - \ 2007
    Journal of General Virology 88 (2007)2. - ISSN 0022-1317 - p. 441 - 449.
    newcastle-disease-virus - membrane-fusion - oligosaccharide chains - influenza-virus - intracellular-transport - endoplasmic-reticulum - cell-surface - glycosylation - hemagglutinin - neuraminidase
    The F protein is the major glycoprotein present in the envelopes of budded virus (BV) of members of the family Baculoviridae. The F protein mediates low-pH-activated fusion with insect cell membranes. Baculovirus F proteins are synthesized as a precursor (F0) and cleaved post-translationally into two disulfide-bonded subunits, F1 (C-terminal, large subunit) and F2 (N-terminal, small subunit). Recently, N-linked glycosylation of the F1 and F2 subunits of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) was demonstrated [Long, G., Westenberg, M., Wang, H., Vlak, J. M. & Hu, Z. (2006). J Gen Virol 87, 839¿846]. Sequence analysis frequently predicts that one or more N-linked glycosylation sites are present in the F2 subunit of baculovirus F proteins. N-glycans on envelope fusion proteins are usually required for proper conformational integrity and biological function, such as infectivity. This study examined the importance of N-linked glycosylation of the F2 subunit of HearNPV by site-directed mutagenesis. The only putative N-linked glycosylation site in F2 was eliminated by mutating asparagine (N104) to glutamine (Q), resulting in the mutant HearNPVfN104Q. When inserted into an f-null HearNPV and a gp64-null bacmid of Autographa californica multiple nucleopolyhedrovirus, infectious BV could be retrieved that contained unglycosylated F2. The virulence of HearNPVfN104Q was enhanced, as BV was produced earlier after infection and yielded larger plaques than f-null HearNPV repaired with the wild-type f gene. HearNPVfN104Q BV also induced much more efficient low-pH-activated syncytium formation. These results indicate that N-linked glycosylation of the HearNPV baculovirus F2 subunit is not essential for viral infectivity and suggest that it is involved in BV production and fusogenicity
    siRNA injection induce sequence-independent protection in Penaeus monodon against White Spot Syndrome Virus
    Westenberg, M. ; Heinhuis, B. ; Vlak, J.M. - \ 2006
    In: 9th International Colloquium on Invertebrate Pathology and Microbial Control (ICIPMC) & 39th Annual Meeting of the Society of Invertebrate Pathology (SIP) and the 8th International Conference on Bacillus thuringiensis (ICBt), Wuhan, China, 27 August-1 September 2006 - p. 179 - 179.
    Ha 1 35, a unique nonstructural protein of HearNPV, is not essential for viral propagation
    Pan, X. ; Long, G. ; Westenberg, M. ; Hou, S. ; Deng, F. ; Wang, H. ; Vlak, J.M. ; Hu, Z. - \ 2006
    In: Book of Abstracts of the 9th International Colloquium on Invertebrate Pathology and Microbial Control (ICIPMC), 39th Annual Meeting of the Society for Invertebrate Pathology (SIP) and the 8th International Conference on Bacillus thuringiensis (ICBt), Wuhan, China, 27 August-1 September 2006. - Wuhan : - p. 83 - 83.
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