Publications (13)43.26 Total impact
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Article: Game-based assessment of first aid and resuscitation skills.
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ABSTRACT: Effective assessment of motor skills in large-size classes is a challenge in medical education. This case-study investigates whether a game can be considered a valid tool for the summative assessment of first aid and basic life support skills. Using a traditional exam as bench-mark, a board game format was experimentally trialed to assess students' competency after taking a first aid course. Fifty-five students were randomly assigned to two groups. Two assessments, a game-based assessment and a traditional test, consisting of a paper-and-pencil test in combination with a skill assessment, were applied to both groups in opposite order. In both formats students acted as judges of other students' efforts. In the game, the student's outcome was equal to the number of cards collected by answering questions correctly as deemed by peers. Similarities between both assessment types included individual testing, type of assessor (peers), content, type of questions and demonstrations, and the use of checklists for skill assessment. The assessment methods differed in format (written or oral test, both in combination with skill assessment) and feedback availability. Both groups performed equally in the game-based assessment as well as in the traditional test, in spite of the opposite order of the assessments. No significant difference was found between the mean scores on the game-based assessment and the traditional test. These data suggest that use of a game format for assessment purposes may provide an effective means of assessing students' competence at the end of a practical course.Resuscitation 01/2011; 82(4):442-6. · 3.60 Impact Factor -
Article: Replication of not-known-vector flaviviruses in mosquito cells is restricted by intracellular host factors rather than by the viral envelope proteins.
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ABSTRACT: Chimeric yellow fever virus 17D (YFV-17D) and dengue virus type 2 (DENV2) carrying the surface proteins of Modoc virus (MODV), a not-known-vector (NKV) flavivirus, replicated efficiently in mammalian (Vero-B) and mosquito (C6/36) cells, whereas MODV failed to replicate in mosquito cells. Transfection of C6/36 cells with MODV RNA did not result in virus replication; however, transfection of these mosquito cells with YFV-17D or DENV2 RNA did. The inability of NKV viruses (such as MODV) to infect and replicate in arthropod cells is thus not determined by the viral envelope, but by a post-entry event.Journal of General Virology 03/2010; 91(Pt 7):1693-7. · 3.36 Impact Factor -
Article: Conservation of the pentanucleotide motif at the top of the yellow fever virus 17D 3' stem-loop structure is not required for replication.
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ABSTRACT: The pentanucleotide (PN) sequence 5'-CACAG-3' at the top of the 3' stem-loop structure of the flavivirus genome is well conserved in the arthropod-borne viruses but is more variable in flaviviruses with no known vector. In this study, the sequence requirements of the PN motif for yellow fever virus 17D (YFV) replication were determined. In general, individual mutations at either the second, third or fourth positions were tolerated and resulted in replication-competent virus. Mutations at the fifth position were lethal. Base pairing of the nucleotide at the first position of the PN motif and a nucleotide four positions downstream of the PN (ninth position) was a major determinant for replication. Despite the fact that the majority of the PN mutants were able to replicate efficiently, they were outcompeted by parental YFV-17D virus following repeated passages in double-infected cell cultures. Surprisingly, some of the virus mutants at the first and/or the ninth position that maintained the possibility of forming a base pair were found to have a similar fitness to YFV-17D under these conditions. Overall, these experiments suggest that YFV is less dependent on sequence conservation of the PN motif for replication in animal cells than West Nile virus. However, in animal cell culture, YFV has a preference for the wt CACAG PN sequence. The molecular mechanisms behind this preference remain to be elucidated.Journal of General Virology 07/2007; 88(Pt 6):1738-47. · 3.36 Impact Factor -
Article: Mouse and hamster models for the study of therapy against flavivirus infections.
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ABSTRACT: Small animal models that are reminiscent of flaviviral disease in human will be instrumental in identifying therapeutic strategies against flavivirus infections. Here we review models in mice and hamsters for the most clinically important flaviviruses: dengue virus, yellow fever virus, West Nile virus, Japanese encephalitis virus and tick-borne encephalitis virus. In addition, models are discussed that employ no known vector viruses such as the Modoc virus. These viruses can be manipulated in BSL-2 laboratories and in infected mice and hamsters they mimic flaviviral disease in human.Novartis Foundation symposium 02/2006; 277:218-29; discussion 229-32, 251-3. -
Article: Rodent models for the study of therapy against flavivirus infections.
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ABSTRACT: Flaviviruses cause a variety of diseases including (meningo)encephalitis and hemorrhagic fevers. There is no specific antiviral therapy available for the treatment of infections with flaviviruses and such therapy should be urgently developed. Small animal models that are reminiscent of the disease in man will be instrumental to identify therapeutic strategies against flavivirus infections. Here we review models in mice and hamsters that may be used to assess the efficacy of novel antiviral strategies against flavivirus infections.Antiviral Research 09/2004; 63(2):67-77. · 4.30 Impact Factor -
Article: Exchanging the yellow fever virus envelope proteins with Modoc virus prM and E proteins results in a chimeric virus that is neuroinvasive in SCID mice.
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ABSTRACT: A chimeric flavivirus infectious cDNA was constructed by exchanging the premembrane (prM) and envelope (E) genes of the yellow fever virus vaccine strain 17D (YF17D) with the corresponding genes of Modoc virus (MOD). This latter virus belongs to the cluster of the "not-known vector" flaviviruses and is, unlike YF17D, neuroinvasive in SCID mice. Replication of in vitro-transcribed RNA from this chimeric flavivirus was shown by [(3)H]uridine labeling and RNA analysis. Expression of the MOD prM and E proteins was monitored by radioimmunoprecipitation and revealed that the MOD proteins were correctly and efficiently produced from the chimeric precursor protein. The MOD E protein was shown to be N-linked glycosylated, whereas prM, as predicted from the genome sequence, did not contain N-linked carbohydrates. In Vero cells, the chimeric virus replicated with a similar efficiency as the parental viruses, although it formed smaller plaques than YF17D and MOD. In SCID mice that had been infected intraperitoneally with the chimeric virus, the viral load increased steadily until death. The MOD/YF virus, like MOD from which it had acquired the prM and E structural proteins, but unlike YF, proved neuroinvasive in SCID mice. Animals developed neurological symptoms about 15 days after inoculation and died shortly thereafter. The distribution of MOD/YF RNA in the brain of infected mice was similar to that observed in MOD-infected mice. The observations provide compelling evidence that the determinants of neuroinvasiveness of flaviviruses are entirely located in the envelope proteins prM and E.Journal of Virology 08/2004; 78(14):7418-26. · 5.40 Impact Factor -
Article: Acute encephalitis, a poliomyelitis-like syndrome and neurological sequelae in a hamster model for flavivirus infections.
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ABSTRACT: Infection of hamsters with the murine flavivirus Modoc results in (meningo)encephalitis, which is, during the acute phase, frequently associated with flaccid paralysis, as also observed in patients with West Nile virus encephalitis. Twenty percent of the hamsters that recover from the acute encephalitis develop life-long neurological sequelae, reminiscent of those observed, for example, in survivors of Japanese encephalitis. Magnetic resonance imaging and histology revealed severe lesions predominantly located in the olfactory-limbic system, both in hamsters with acute encephalitis as in survivors. Prominent pathology was also detected in the spinal cord of hamsters with paralysis. Modoc virus infections in hamsters provide a unique model for the study of encephalitis, a poliomyelitis-like syndrome and neurological sequelae following flavivirus infection.Brain Pathology 08/2003; 13(3):279-90. · 3.99 Impact Factor -
Article: A rapid and convenient variant of fusion-PCR to construct chimeric flaviviruses.
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ABSTRACT: So far, full-length cDNAs of chimeric flaviviruses have been constructed by restriction-enzyme cleavage of the gene(s) to be exchanged or by fusion-PCR of two amplified PCR fragments. The construction of a chimeric flavivirus by a faster and more convenient variant of the standard fusion-PCR is reported. A Modoc/yellow fever chimeric virus was engineered in which the structural prM and E genes of yellow fever virus 17D were replaced by the homologous genes of Modoc virus. In two PCR steps, a fusion was made between the 3' end of the C gene of yellow fever virus and the 5' end of the prM gene of Modoc virus, and between the 3' end of the E gene of Modoc virus and the 5' end of the NS1 gene of yellow fever virus. For each of the two fusions between yellow fever and Modoc virus, a standard PCR was performed to amplify a short fragment with one overlapping end that could be used as one of the primers in the subsequent (fusion) PCR.Journal of Virological Methods 04/2003; 108(1):67-74. · 2.01 Impact Factor -
Article: Interferons, interferon inducers, and interferon-ribavirin in treatment of flavivirus-induced encephalitis in mice.
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ABSTRACT: We evaluated the prophylactic and therapeutic efficacy of interferon alpha-2b, pegylated interferon alpha-2b, poly(I. C), and Ampligen against Modoc virus encephalitis in an animal model for flavivirus infections. All compounds significantly delayed virus-induced morbidity (paralysis) and mortality (due to progressive encephalitis). Viral load (as measured on day 7 postinfection) was significantly reduced by 80 to 100% in the serum, brain, and spleen in mice that had been treated with either interferon alpha-2b, pegylated interferon alpha-2b, poly(I. C), or Ampligen. We also studied whether a combination of interferon alpha-2b and ribavirin (presently the standard therapy for the treatment of infections with hepatitis C virus) would be more effective than treatment with interferon alone. However, ribavirin did not enhance the inhibitory effect of interferon therapy in this animal model for flavivirus infections.Antimicrobial Agents and Chemotherapy 03/2003; 47(2):777-82. · 4.84 Impact Factor -
Article: Impact of direct virus-induced neuronal dysfunction and immunological damage on the progression of flavivirus (Modoc) encephalitis in a murine model.
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ABSTRACT: Flavivirus encephalitis is believed to be the result of two main mechanisms: (i) direct damage to and dysfunction of neurons as a result of viral replication and (ii) destruction of the brain tissue by an inflammatory response. The differential impact of both mechanisms on the progression of flavivirus encephalitis has not been clearly determined. We have now studied the encephalitis caused by Modoc virus (MODV) infection in (i) severe combined immunodeficiency (SCID) mice, (ii) immunocompetent NMRI mice, and (iii) NMRI mice under varying immunosuppressive treatment regimens. In SCID mice, Modoc virus infection proved to be uniformly lethal (100%). The virus replicated extensively in neurons and no signs of inflammation of the brain were observed. In immunocompetent NMRI mice, intranasal (but not intraperitoneal) inoculation with MODV caused severe encephalitis accompanied by a fulminate inflammatory response. When NMRI mice, infected with MODV via the intraperitoneal route, were submitted to a brief immunosuppressive treatment, they also developed encephalitis with an obvious inflammatory component. These animals died significantly earlier than NMRI mice, which received immunosuppressive treatment for a longer period of time. In the latter group, no signs of inflammation of the brain were noted. These models thus allow us to distinguish between the impact of direct viral replication and that of immunological factors in the development of MODV encephalitis, and let us to conclude that (i) replication of the virus in neurons is sufficient to cause fatal encephalitis and (ii) immunological factors contribute significantly to disease progression.Journal of NeuroVirology 03/2003; 9(1):69-78. · 2.31 Impact Factor -
Article: Infection of SCID mice with Montana Myotis leukoencephalitis virus as a model for flavivirus encephalitis.
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ABSTRACT: We have established a convenient animal model for flavivirus encephalitis using Montana Myotis leukoencephalitis virus (MMLV), a bat flavivirus. This virus has the same genomic organization, and contains the same conserved motifs in genes that encode potential antiviral targets, as flaviviruses that cause disease in man (N. Charlier et al., accompanying paper), and has a similar particle size (approximately 40 nm). MMLV replicates well in Vero cells and appears to be equally as sensitive as yellow fever virus and dengue fever virus to a selection of experimental antiviral agents. Cells infected with MMLV show dilation of the endoplasmic reticulum, a characteristic of flavivirus infection. Intraperitoneal, intranasal or direct intracerebral inoculation of SCID mice with MMLV resulted in encephalitis ultimately leading to death, whereas immunocompetent mice were refractory to either intranasal or intraperitoneal infection with MMLV. Viral RNA and/or antigens were detected in the brain and serum of MMLV-infected SCID mice, but not in any other organ examined: MMLV was detected in the olfactory lobes, the cerebral cortex, the limbic structures, the midbrain, cerebellum and medulla oblongata. Infection was confined to neurons. Treatment with the interferon-alpha/beta inducer poly(I).poly(C) protected SCID mice against MMLV-induced morbidity and mortality, and this protection correlated with a reduction in infectious virus titre and viral RNA load. This validates the MMLV model for use in antiviral drug studies. The MMLV SCID model may, therefore, be attractive for the study of chemoprophylactic or chemotherapeutic strategies against flavivirus infections causing encephalitis.Journal of General Virology 09/2002; 83(Pt 8):1887-96. · 3.36 Impact Factor -
Article: Complete genome sequence of Montana Myotis leukoencephalitis virus, phylogenetic analysis and comparative study of the 3' untranslated region of flaviviruses with no known vector.
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ABSTRACT: Montana Myotis leukoencephalitis virus (MMLV), a virus isolated from bats, causes an encephalitis in small rodents reminiscent of flavivirus encephalitis in humans. The complete MMLV genome is 10690 nucleotides long and encodes a putative polyprotein of 3374 amino acids. The virus contains the same conserved motifs in genes that are believed to be interesting antiviral targets (NTPase/helicase, serine protease and RNA-dependent RNA polymerase) as flaviviruses of clinical importance. Phylogenetic analysis of the entire coding region has confirmed the classification of MMLV in the clade of the flaviviruses with no known vector (NKV) and within this clade to the Rio Bravo branch (both viruses have the bat as their vertebrate host). We have provided for the first time a comparative analysis of the RNA folding of the 3' UTR of the NKV flaviviruses (Modoc, Rio Bravo and Apoi viruses, in addition to MMLV). Structural elements in the 3' UTR that are preserved among other flaviviruses have been revealed, as well as elements that distinguish the NKV from the mosquito- and tick-borne flaviviruses. In particular, the pentanucleotide sequence 5' CACAG 3', which is conserved in all mosquito- and tick-borne flaviviruses, is replaced by the sequence 5' C(C/U)(C/U)AG 3' in the loop of the 3' long stable hairpin structure of all four NKV flaviviruses. The availability of this latter sequence motif allows us to designate a virus as either an NKV or a vector-borne flavivirus.Journal of General Virology 09/2002; 83(Pt 8):1875-85. · 3.36 Impact Factor -
Article: Complete genome sequence, taxonomic assignment, and comparative analysis of the untranslated regions of the Modoc virus, a flavivirus with no known vector.
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ABSTRACT: We recently developed a model for flavivirus infection in mice and hamsters using the Modoc virus (MODV), a flavivirus with no known vector (P. Leyssen, A. Van Lommel, C. Drosten, H. Schmitz, E. De Clercq, and J. Neyts, 2001, Virology 279, 27-37). We now present the coding and noncoding sequence of MODV. The Modoc virus genome was determined to be 10,600 nucleotides in length with a single open reading frame extending from nucleotides 110 to 10,234, encoding 3374 amino acids. The deduced gene order of the single open reading frame is C-prM-E-NS1-NS2A-NS2B-NS3-NS4A-NS4B-NS5, which is exactly the same as that of the mosquito- and tick-borne flaviviruses. It is flanked by a 5'- and 3'-untranslated region (UTR) of 109 and 366 nucleotides, respectively. Alignment of the MODV amino acid sequence with that of 20 other flaviviruses revealed several regions with high sequence similarity corresponding to functionally important domains (e.g., the serine protease/helicase/NTPase of NS3 and the methyltransferase/RNA-dependent RNA polymerase of NS5) and conserved sites for proteolytic cleavage by viral and cellular proteases. Phylogenetic analysis of the entire coding region confirmed the classification of MODV within the flaviviruses with no known vector, which is in agreement with previous findings based on partial NS5 sequences. A detailed comparative analysis of the putative folding patterns of the 5'- and 3'-UTR of MODV and of the tick- and mosquito-borne viruses was carried out. Structural elements in the 5'- and 3' UTR of MODV that are preserved among vector-borne flaviviruses were noted and so were structural elements distinguishing the MODV UTRs from mosquito-borne and tick-borne flaviviruses. Also the putative secondary structure of circularized MODV RNA is presented.Virology 03/2002; 293(1):125-40. · 3.35 Impact Factor
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2011
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KU Leuven
- Faculty of Pharmaceutical Sciences
Leuven, VLG, Belgium
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