The In Silico Prediction of hotspot residues that contribute to the structural stability of subunit interfaces of a Picornavirus Capsid:
- Authors: Upfold, Nicole , Ross, Caroline J , Tastan Bishop, Özlem , Knox, Caroline M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149970 , vital:38919 , https://doi.org/10.3390/v12040387
- Description: The assembly of picornavirus capsids proceeds through the stepwise oligomerization of capsid protein subunits and depends on interactions between critical residues known as hotspots. Few studies have described the identification of hotspot residues at the protein subunit interfaces of the picornavirus capsid, some of which could represent novel drug targets. Using a combination of accessible web servers for hotspot prediction, we performed a comprehensive bioinformatic analysis of the hotspot residues at the intraprotomer, interprotomer and interpentamer interfaces of the Theiler’s murine encephalomyelitis virus (TMEV) capsid.
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- Date Issued: 2020
Morphological, genetic and biological characterisation of a novel alphabaculovirus isolated from Cryptophlebia peltastica (Lepidoptera: Tortricidae)
- Authors: Marsberg, Tamryn , Jukes, Michael , Krejmer-Rabalska, Martyna , Rabalski, Lukasz , Knox, Caroline M , Moore, Sean D , Hill, Martin P , Szewczyk, Boguslaw
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419330 , vital:71635 , xlink:href="https://doi.org/10.1016/j.jip.2018.08.006"
- Description: Cryptophlebia peltastica is an agricultural pest of litchis and macadamias in South Africa with phytosanitary status for certain markets. Current control methods rely on chemical, cultural and classical biological control. However, a microbial control option has not been developed. An Alphabaculovirus from C. peltastica was recovered from a laboratory reared colony and morphologically characterised by transmission electron microscopy (TEM). Analysis of occlusion bodies indicated a single NPV (SNPV) varying in size from 421 to 1263 nm. PCR amplification and sequencing of the polh gene region using universal primers followed by BLAST analysis revealed a 93% similarity to a partial polh gene sequence from Epinotia granitalis NPV. Further genetic characterisation involving single restriction endonuclease (REN) digestion of genomic DNA was carried out to generate profiles for comparison against other baculovirus species and potential new isolates of the same virus. The complete genome of the virus was sequenced, assembled and analysed for a more comprehensive genetic analysis. The genome was 115 728 base pairs (bp) in length with a GC content of 37.2%. A total of 126 open reading frames (ORFs) were identified with minimal overlap and no preference in orientation. Bioassays were used to determine the virulence of the NPV against C. peltastica. The NPV was virulent against C. peltastica with an LC50 value of 6.46 × 103 OBs/ml and an LC90 value of 2.46 × 105 OBs/ml, and time mortality ranging between 76.32 h and 93.49 h. This is the first study to describe the isolation and genetic characterisation of a novel SNPV from C. peltastica, which has potential for development into a biopesticide for the control of this pest in South Africa.
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- Date Issued: 2018
The generation and characterisation of neutralising antibodies against the Theiler’s murine encephalomyelitis virus (TMEV) GDVII capsid reveals the potential binding site of the host cell co-receptor, heparan sulfate:
- Authors: Upfold, Nicole , Ross, Caroline J , Tastan Bishop, Özlem , Luke, Garry A , Knox, Caroline M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148181 , vital:38717 , DOI: 10.1016/j.virusres.2017.11.017
- Description: The early stages of picornavirus capsid assembly and the host factors involved are poorly understood. Since the localisation of viral proteins in infected cells can provide information on their function, antibodies against purified Theiler's murine encephalomyelitis virus (TMEV) GDVII capsids were generated by immunisation of rabbits. The resultant anti-TMEV capsid antibodies recognised a C-terminal region of VP1 but not VP2 or VP3 by Western analysis. Examination of the sites of TMEV capsid assembly by indirect immunofluorescence and confocal microscopy showed that at 5 h post infection, capsid signal was diffusely cytoplasmic with strong perinuclear staining and moved into large punctate structures from 6 to 8 h post infection.
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- Date Issued: 2018
Interacting motif networks located in hotspots associated with RNA release are conserved in Enterovirus capsids
- Authors: Ross, Caroline J , Knox, Caroline M , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124855 , vital:35704 , https://doi.10.1002/1873-3468.12663
- Description: Enteroviruses are responsible for a multitude of human diseases. Expansion of the virus capsid is associated with a cascade of conformational changes that allow the subsequent release of RNA. For the first time, this study presents a comprehensive bioinformatic screen for the prediction of interacting motifs within intraprotomer interfaces and across respective interfaces surrounding the fivefold and twofold axes. The results identify a network of conserved motif residues involved in interactions in enteroviruses that may be critical to capsid stabilisation, providing guidelines towards developing antivirals that interfere with viral expansion during RNA release.
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- Date Issued: 2017
Isolation, identification and genetic characterisation of a microsporidium isolated from carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)
- Authors: Lloyd, Melissa , Knox, Caroline M , Hill, Martin P , Moore, Sean D , Thackeray, Sean R
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59874 , vital:27674 , https://doi.org/10.4001/003.025.0529
- Description: 'Microsporidia' is a term used for organisms belonging to the phylum Microspora, which contains approximately 187 genera and 1500 species (Corradi 2015). They are obligate intracellular parasites with no active metabolic stages of the life cycle occurring outside of the host cells (Franzen & Muller 1999; Garcia 2002; Tsai et al. 2003; Huang et al. 2004). They exhibit eukaryotic characteristics such as a membrane-bound nucleus, an intracytoplasmic membrane system, and chromosome separation occurs on mitotic spindles. However, they also exhibit prokaryotic characteristics such as possession of a 70S ribosome, lack of true mitochondria and peroxisomes, a simple version of the Golgi apparatus, and a small genome which is much less complex than those of most eukaryotes (Franzen & Muller 1999; Garcia 2002). Microspo- ridia are parasitic in all major groups of animals, both vertebrates and invertebrates (Sprague 1977; Franzen & Muller 1999). Microsporidia were first recognised as pathogens in silkworms by Nageli (1857), and now have been found to infect many hosts such as humans, insects, fish and mammals (Stentiford et al. 2016).
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- Date Issued: 2017
Heterogeneity in virulence relationships between Cryptophlebia leucotreta granulovirus isolates and geographically distinct host populations: Lessons from codling moth resistance to CpGV-M
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
- Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
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- Date Issued: 2016
Subcellular localisation of Theiler's murine encephalomyelitis virus (TMEV) capsid subunit VP1 vis-á-vis host protein Hsp90:
- Authors: Ross, Caroline J , Upfold, Nicole , Luke, Garry A , Tastan Bishop, Özlem , Knox, Caroline M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148016 , vital:38702 , DOI: 10.1016/j.virusres.2016.06.003
- Description: The VP1 subunit of the picornavirus capsid is the major antigenic determinant and mediates host cell attachment and virus entry. To investigate the localisation of Theiler's murine encephalomyelitis virus (TMEV) VP1 during infection, a bioinformatics approach was used to predict a surface-exposed, linear epitope region of the protein for subsequent expression and purification. This region, comprising the N-terminal 112 amino acids of the protein, was then used for rabbit immunisation, and the resultant polyclonal antibodies were able to recognise full length VP1 in infected cell lysates by Western blot. Following optimisation, the antibodies were used to investigate the localisation of VP1 in relation to Hsp90 in infected cells by indirect immunofluorescence and confocal microscopy.
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- Date Issued: 2016
Baculovirus-based strategies for the management of insect pests: a focus on development and application in South Africa
- Authors: Knox, Caroline M , Moore, Sean D , Luke, Garry , Hill, Martin P
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416829 , vital:71389 , xlink:href="https://doi.org/10.1080/09583157.2014.949222"
- Description: There is growing concern among governments, scientists, agricultural practitioners and the general public regarding the negative implications of widespread synthetic chemical pesticide application for the control of crop pests. As a result, baculovirus biopesticides are gaining popularity as components of integrated pest management (IPM) programmes in many countries despite several disadvantages related to slow speed of kill, limited host range and complex large scale production. In South Africa, baculoviruses are incorporated into IPM programmes for the control of crop pests in the field, and recent bioprospecting has led to the characterisation of several novel isolates with the potential to be formulated as commercial products. This contribution will provide an overview of the use of baculoviruses against insect pests in South Africa, as well as research and development efforts aimed at broadening their application as biocontrol agents. Challenges faced by researchers in developmental projects as well as potential users of baculoviruses as biopesticides in the field are also discussed.
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- Date Issued: 2015
Genetic and biological characterisation of a novel Plutella xylostella granulovirus, PlxyGV-SA
- Authors: Abdulkadir, Fatima , Knox, Caroline M , Marsberg, Tamryn , Hill, Martin P , Moore, Sean D
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417971 , vital:71498 , xlink:href="https://doi.org/10.1007/s10526-015-9666-3"
- Description: Plutella xylostella granulovirus (PlxyGV) has been isolated from insect populations in many countries and is considered a potential biopesticide for sustainable control of P. xylostella (L.) (Lepidoptera: Plutellidae). Several PlxyGV isolates have been genetically characterised, and the full genome sequence of PlxyGV-Japan is available for comparison with novel isolates. A South African PlxyGV was recently recovered from an overcrowded laboratory P. xylostella colony and identified as a genetically distinct isolate by sequencing of the granulin gene and restriction endonuclease (REN) analysis of genomic DNA. In this report, PlxyGV-SA was further characterised by PCR amplification and sequencing of egt, lef-8 and lef-9 genes, and several amino acid substitutions were observed. The PstI REN profile of PlxyGV-SA was different from that of PlxyGV-Japan in terms of band size and number, thereby confirming its novel genetic identity. Surface dose bioassays showed that PlxyGV-SA is pathogenic to neonate but not late instar larvae at the same and higher virus doses, indicating that a biopesticide should be targeted at early larval stages in the field.
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- Date Issued: 2015
Comparison of the biology of geographically distinct populations of the citrus pest, Thaumatotibia leucotreta (Meyrick)(Lepidoptera: Tortricidae)
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/405769 , vital:70204 , xlink:href="https://hdl.handle.net/10520/EJC160246"
- Description: Baculovirus biopesticides are an important component of integrated pest management programmes worldwide. One such example is the Cryptophlebia leucotreta granulovirus (CrleGV) which is used for the control of false codling moth, Thaumatotibia (= Cryptophlebia) leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus and other crops in South Africa. A potential problem associated with constant application of viral biopesticides is the differing susceptibility to the virus observed between different geographic populations of the insect host. This could be related to a number of factors, including biological performance and fitness of the target insect population. This study compared a variety of phenotypic traits between geographically distinct T. leucotreta populations collected from the Addo, Marble Hall, Citrusdal and Nelspruit regions of South Africa, and reared under laboratory conditions for several generations. Traits including pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and developmental time were used as parameters to measure biological performance and fitness. Insects from the Citrusdal region of the Western Cape exhibited significantly lower pupal mass, female fecundity, egg hatch, pupal survival, adult eclosion and the longest duration in larval and pupal development compared to the other colonies investigated. This is the first study to report differences in the performance of laboratory reared T. leucotreta from different geographic locations, and the findings may have important implications for the application of viral biopesticides for the control of this pest in South Africa.
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- Date Issued: 2014
Characterisation of novel CrleGV isolates for false codling moth control-lessons learnt from codling moth resistance to CpGV. Characterisation of novel CrleGV isolates for false codling moth control-lessons learnt from codling moth resistance to CpGV
- Authors: Opoku-Debrah, John K , Moore, Sean D , Hill, Martin P , Knox, Caroline M
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425414 , vital:72237 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20133257674"
- Description: Recently some codling moth, Cydia pomonella, populations in Europe developed resistance to CpGV. In order to prepare for the possibility of a similar occurrence with the false codling moth, Thaumatotibia leucotreta, in South Africa, a search was conducted for novel CrleGV isolates. Through overcrowding, outbreaks of novel isolates were recorded from laboratory populations of five geographically distinct host populations. The genetic novelty of these and two commercially available isolates was confirmed through restriction enzyme analysis and sequence analysis of the granulin and egt genes. Phylogenetic analysis showed the existence of two CrleGV-SA genome types. Significant differences in virulence were also shown between certain isolates against certain host populations.
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- Date Issued: 2013
Morphological and genetic characterization of a South African Plutella xylostella granulovirus (plxy GV) isolate
- Authors: Abdulkadir, Fatima , Marsberg, Tamryn , Knox, Caroline M , Hill, Martin P , Moore, Sean D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406117 , vital:70240 , xlink:href="https://hdl.handle.net/10520/EJC132828"
- Description: Plutella xylostella (L.) (Lepidoptera: Plutellidae), also known as diamondback moth, is a destructive insect pest of cruciferous crops (Talekar and Shelton 1993; Shelton 2004). The pest occurs wherever its host plants are cultivated and the global annual cost of damage and control is estimated to be US$4-5 billion (Zalucki et al. 2012). The extensive use of synthetic pesticides for control combined with the high fecundity of P. xylostella has resulted in the pest developing resistance to nearly all classes of insecticides (Grzywacz et al. 2009). Moreover, these chemicals have negative environmental implications and may affect non-target species, some of which are natural enemies of the pest.
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- Date Issued: 2013
Overcrowding of false codling moth, Thaumatotibia leucotreta (Meyrick) leads to the isolation of five new Cryptophlebia leucotreta granulovirus (CrleGV-SA) isolates
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419360 , vital:71637 , xlink:href="https://doi.org/10.1016/j.jip.2012.12.008"
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) is a serious pest of economic importance to the South African fruit industry. As part of sustainable efforts to control this pest, biological control options that involve the application of baculovirus-based biopesticides such as Cryptogran and Cryptex (both formulated with a South African isolate of Cryptophlebia leucotreta granulovirus, CrleGV-SA) are popularly used by farmers. In order to safeguard the integrity of these biopesticides as well as protect against any future development of resistance in the host, we conducted a study to bioprospect for additional CrleGV isolates as alternatives to existing ones. Using overcrowding as an induction method for latent infection, we recovered five new CrleGV isolates (CrleGV-SA Ado, CrleGV-SA Mbl, CrleGV-SA Cit, CrleGV-SA MixC and CrleGV-SA Nels). Single restriction endonuclease (REN) analysis of viral genomic DNA extracted from purified occlusion bodies showed that isolates differed in their DNA profiles. Partial sequencing of granulin and egt genes from the different isolates and multiple alignments of nucleotide sequences revealed the presence of single nucleotide polymorphisms (SNPs), some of which resulted in amino acid substitutions in the protein sequence. Based on these findings as well as comparisons with other documented CrleGV isolates, we propose two phylogenetic groups for CrleGV-SA isolates recovered in this study.
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- Date Issued: 2013
Emerging pests and Vector-borne diseases in Europe, Volume 1, W. Takken and B.G.J. Knols (Eds.): book review
- Authors: Knox, Caroline M
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452322 , vital:75120 , https://hdl.handle.net/10520/EJC32875
- Description: Emerging and re-emerging vector-borne diseases caused by viruses, bacteria, protozoa and other pathogens have increased dramatically throughout the world in recent years. Among the factors that have undoubtedly contributed to this scenario are environmental change, increased international trade and travel, human-induced changes in land use, technical innovations in food processing, microbial adaptation and insecticide resistance. Such diseases pose a serious threat to both human and animal health, and measures for their surveillance and control urgently need to be implemented. In view of the fact that infectious diseases are currently appearing in countries where they did not previously exist or are reappearing after a period of decline, this book is both timely and crucial to our understanding and awareness of this serious problem.
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- Date Issued: 2011
Theiler’s murine encephalomyelitis virus infection induces a redistribution of heat shock proteins 70 and 90 in BHK-21 cells, and is inhibited by novobiocin and geldanamycin:
- Authors: Mutsvunguma, Lorraine Z , Moetlhoa, Boitumelo , Edkins, Adrienne L , Luke, Garry A , Blatch, Gregory L , Knox, Caroline M
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165085 , vital:41207 , DOI: 10.1007/s12192-011-0262-x
- Description: Theiler’s murine encephalomyelitis virus (TMEV) is a positive-sense RNA virus belonging to the Cardiovirus genus in the family Picornaviridae. In addition to other host cellular factors and pathways, picornaviruses utilise heat shock proteins (Hsps) to facilitate their propagation in cells. This study investigated the localisation of Hsps 70 and 90 in TMEV-infected BHK-21 cells by indirect immunofluorescence and confocal microscopy. The effect of Hsp90 inhibitors novobiocin (Nov) and geldanamycin (GA) on the development of cytopathic effect (CPE) induced by infection was also examined. Hsp90 staining was uniformly distributed in the cytoplasm of uninfected cells but was found concentrated in the perinuclear region during late infection where it overlapped with the signal for non-structural protein 2C within the viral replication complex.
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- Date Issued: 2011
Localisation of Theiler's murine encephalomyelitis virus protein 2C to the golgi apparatus using antibodies generated against a peptide region:
- Authors: Jauka, Tembisa , Mutsvunguma, Lorraine Z , Boshoff, Aileen , Edkins, Adrienne L , Knox, Caroline M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165074 , vital:41206 , DOI: 10.1016/j.jviromet.2010.05.009
- Description: The picornavirus 2C protein is highly conserved and indispensible for virus replication. Polyclonal antibodies against Theiler's murine encephalomyelitis virus (TMEV) 2C protein were generated by immunisation of rabbits with a peptide comprising amino acids 31–210 of the protein. Antibodies were used to investigate the localisation of 2C in infected cells by indirect immunofluorescence and confocal microscopy. Analysis of infected cells revealed that the distribution of 2C changed during infection.
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- Date Issued: 2010