Monique M van Oers

Publications (80) View all

• Source

  Available from: Margaret Saimo-Kahwa

  Dataset: Ikwap v2-97-103

  Margaret Saimo, David O Odongo, Stephen Mwaura, Just M Vlak, Anthony J Musoke, George W Lubega, Richard P Bishop, Monique M Van Oers
• Article: Correlation between structure, protein composition, morphogenesis and cytopathology of Glossina pallidipes salivary gland hypertrophy virus

  Henry M. Kariithi, Jan W. M. van Lent, Sjef Boeren, Adly M. M. Abd-Alla, I. Agah Ince, Monique M. van Oers, Just M. Vlak
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  ABSTRACT: The Glossina pallidipes salivary gland hypertrophy virus (GpSGHV) is a dsDNA virus with rod-shaped, enveloped virions. Its 190-kb genome contains 160 putative protein-coding open reading frames (ORFs). Here, structural components, protein composition and associated aspects of GpSGHV morphogenesis and cytopathology were investigated. Four morphologically distinct structures: nucleocapsid, tegument, envelope, and helical surface projections, were observed in purified GpSGHV virions by electron microscopy. Nucleocapsids were present in virogenic stroma within the nuclei of infected salivary gland cells, whereas enveloped virions were located in the cytoplasm. The cytoplasm of infected cells appeared disordered and the plasma membranes disintegrated. Treatment of virions with 1% Nonidet P-40 efficiently partitioned the virions into envelope and nucleocapsid fractions. The fractions were separated by 12% SDS-PAGE followed by in-gel trypsin digestion and analysis of the tryptic peptides by LC-MS/MS. Using the MaxQuant program with Andromeda as a database search engine, a total of forty-five viral proteins were identified. Of these, ten and fifteen were associated with the envelope and the nucleocapsid fractions respectively, while twenty were detected in both fractions, most likely representing tegument proteins. In addition, fifty-one host-derived proteins were identified in the proteome of the virus particle, thirteen of which were verified to be incorporated into the mature virion using a proteinase K protection assay. This study provides important information about GpSGHV biology and suggests options for development of future anti-GpSGHV strategies by interfering with virus-host interactions.
  Journal of General Virology 10/2012; · 3.36 Impact Factor
• Article: Temporal classification and mapping of non-polyadenylated transcripts of an invertebrate iridovirus.

  I Agah Ince, Kadriye Ozkan, Just M Vlak, Monique M van Oers
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  ABSTRACT: The genome of Chilo iridescent virus (CIV) is known for some time, but knowledge on the transcriptional regulation of viral gene expression is limited. In the current study the temporal expression of fifty-four CIV virion protein genes was investigated by combining drug treatments that inhibit protein or DNA synthesis with an RT-PCR strategy, especially designed for non-polyadenylated mRNAs. The latter method is based on the ligation of an oligonucleotide to the 3' end of a capped mRNA to generate a uniform 3' terminus, which can be recognized by a complementary oligonucleotide primer for RT-PCR amplification. By combining this second primer with gene-specific forward primers cDNAs for individual genes can be obtained. This method was named Ligation-based Amplification of cDNA Ends (LACE). Contrary to the assumption that virion proteins would belong predominantly to the late gene class, i.e. genes requiring DNA replication for their expression, CIV virion protein genes fall into all three predetermined temporal classes (i.e. immediate-early, delayed-early and late). Early transcription for many virion protein genes supports the notion that CIV virion proteins may not only have crucial roles in virion structure formation, but also may play essential roles in the initial stages of infection. Alternatively, some of these proteins may reflect the intracellular path that the virus followed during infection.
  Journal of General Virology 10/2012; · 3.36 Impact Factor
• Article: Proteomic footprints of a member of Glossinavirus (Hytrosaviridae): An expeditious approach to virus control strategies in tsetse factories.

  Henry M Kariithi, Jan van Lent, Monique M van Oers, Adly M M Abd-Alla, Just M Vlak
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  ABSTRACT: The Glossinavirus (Glossina pallidipes salivary gland hypertrophy virus (GpSGHV)) is a rod-shaped enveloped insect virus containing a 190,032bp-long, circular dsDNA genome. The virus is pathogenic for the tsetse fly Glossina pallidipes and has been associated with the collapse of selected mass-reared colonies. Maintenance of productive fly colonies is critical to tsetse and trypanosomiasis eradication in sub-Saharan Africa using the Sterile Insect Technique. Proteomics, an approach to define the expressed protein complement of a genome, was used to further our understanding of the protein composition, morphology, morphogenesis and pathology of GpSGHV. Additionally, this approach provides potential targets for novel and sustainable molecular-based antiviral strategies to control viral infections in tsetse colonies. To achieve this goal, identification of key protein partners involved in virus transmission is required. In this review, we integrate the available data on GpSGHV proteomics to assess the impact of viral infections on host metabolism and to understand the contributions of such perturbations to viral pathogenesis. The relevance of the proteome findings to tsetse and trypanosomiasis management in sub-Sahara Africa is also considered.
  Journal of Invertebrate Pathology 07/2012; · 2.06 Impact Factor
• Article: Enhanced Protein Secretion From Insect Cells by Co-Expression of the Chaperone Calreticulin and Translation Initiation Factor eIF4E.

  Chao-Yi Teng, Shou-Lin Chang, Monique M van Oers, Tzong-Yuan Wu
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  ABSTRACT: Host protein synthesis is shut down in the lytic baculovirus expression vector system (BEVS). This also affects host proteins involved in routing secretory proteins through the endoplasmic reticulum (ER)-Golgi system. It has been demonstrated that a secretory alkaline phosphatase-EGFP fusion protein (SEFP) can act as a traceable and sensitive secretory reporter protein in BEVS. In this study, a chaperone, calreticulin (CALR), and the translation initiation factor eIF4E were co-expressed with SEFP using a bicistronic baculovirus expression vector. We observed that the intracellular distribution of SEFP in cells co-expressing CALR was different from co-expressing eIF4E. The increased green fluorescence emitted by cells co-expressing CALR had a good correlation with the abundance of intracellular SEFP protein and an unconventional ER expansion. Cells co-expressing eIF4E, on the other hand, showed an increase in extracellular SEAP activity compared to the control. Utilization of these baculovirus expression constructs containing either eIF4E or CALR offers a significant advantage for producing secreted proteins for various biotechnological and therapeutic applications.
  Molecular Biotechnology 05/2012; · 2.17 Impact Factor