450 research outputs found
Transmission of Digitaria Streak Virus by the Maize Streak Virus Leafhopper Vector Cicadulina Mbila Naude
No full textAn unpublished account of possible trans-encapsidation of one mastrevirus by another, allowing transmission of both by a vector that normally only transmits one
Manual of SDS-PAGE and Immunoblotting Techniques
No full textA collection of methods and examples illustrating how to do sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoelectroblotting, or western blotting
Experimental investigations of mastrevirus molecular biology and evolution
No full textIncludes abstract.Includes bibliographical references (leaves 138-161).This dissertation describes three major sets of experiments, all of which involved the construction and use of various reciprocal chimaeric MSV constructs. First, chimaeric viruses were used in genetic complementation-type experiments to investigate the biological significance of interactions between the two virion-sense open reading frames (ORFs) of MSV, their products, and the rest of the genome. Six chimaeric MSV constructs were made by reciprocally exchanging the ORFs encoding movement protein (MP) and coat protein (CP) individually, and in pairs, between MSV-Kom and MSV-Set, which share just 78% overall nucleotide identity. Analysis of symptomatology and infection efficiency of chimaeras and wild-type parental viruses revealed evidence of functionally relevant specific interactions between MSV MP and CP
Maize Streak Virus: diversity and virulence
No full textZea mays was first introduced to Africa in Ghana by Portuguese traders in the 16th century. The steady spread of maize cultivation since then has made it the most important cereal crop in Africa today. Whereas improved maize genotypes and agricultural techniques enable yearly yields above 10 tons hectare-1 in the developed world, yearly yields across Africa have remained low at about 1 ton hectare-1 in most countries. Although outmoded agricultural practices are the main reason for poor yields, maize pathogens inflict substantial additional losses. Of the many pathogens currently confronting maize farmers in Africa, Maize streak virus (MSV) is the most significant
Magnetoresistance in triphenyl-diamine derivative blue organic light emitting devices
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 103, 043706 (2008) and may be found at
Investigations of the molecular determinants of maize streak virus replication
No full textIncludes bibliographical references.Geminiviruses replicate via a rolling circle mechanism, which initiates at the origin of replication located within the long intergenic region (LIR). The viral replication associated-protein (Rep) in conjunction with the host's DNA replication machinery is responsible for the initiation and termination of the replication cycle from a stem-loop structure, located within the LIR and conserved throughout the three genera of Geminiviridae. The specific interaction between the Rep protein with sequences within the intergenic region has been well characterised for the begomoviruses and to some extent the curtoviruses; however, this interaction in the mastreviruses, and in particular maize streak virus (MSV), has yet to be fully explored. A theoretical model has been proposed based on sequence data and informed by the current understanding of replication specificity in begomoviruses. Due to the lack of conservation of the stem sequence of the stem-loop structure amongst mastreviruses, the model implicates a pair of nucleotide sequence repeats called iterons. These are located within the stem structure, and on the complementary sense side of the LIR. The former is the putative site of Rep interaction with the LIR. These iterons would therefore potentially act as the determinants of replication specificity amongst mastreviruses
Optimization of chimaeric HIV-1 virus-like particle (VLP) production and immunogenicity testing of VLPs in mice
No full textIncludes abstract.Includes bibliographical references (leaves 139-148).The devastating effect the HIV pandemic has had on the human population in the last twenty five years has highlighted the great need to develop a prophylactic HIV vaccine. The manufacture of a vaccine has proven difficult though, with a number of successful designs in animal models having little success in humans. In view of this, there has been a need for novel vaccine approaches that are able to elicit effective cellular and humoral immune responses, both of which are believed to be important in the eradication of the virus. One such approach is the use of HIV-1 Gag VLPs as vaccine candidates. In this study, the production of two chimaeric (Gag VLP vaccine candidates (GagRT and GagTN) was optimized in insect cells, and their ability to enhance a murine immune response in a DNA prime-VLP boost vaccine strategy was evaluated
Plant production and immunogenic characterisation of Human papillomavirus chimaeric vaccines
No full textIncludes abstract.Includes bibliographical references (leaves 153-175).Cervical cancer is primarily caused by infection with Human papillomavirus (HPV) and is a global concern, particularly in developing countries which contain ~80% of the cervical cancer burden. Current HPV L1 major capsid protein virus-like particle (VLP)-based vaccines are effective in the type-specific prevention of infection and associated disease. However, the high cost of the vaccines has limited their widespread application, and cytological screening programmes are still required to detect malignant lesions associated with the non-vaccine types, particularly in HIV-infected populations
Targeted expression of the anti-HIV microbicide lectin griffithsin in maize and tobacco
No full textIncludes abstract.Includes bibliographical references.Plants are emerging as cost friendly alternative production systems for a variety of pharmaceuticals. Numerous therapeutic proteins have been produced in plant systems (Giddings et al., 2000; Ma et al., 2003). Protein based microbicides,-namely, neutralising antibodies and peptide lectins- lend themselves to production in plants (De Muynck et al., 2010; Matoba et al., 2010; Sexton et al. 2006; O’Keefe et al., 2009). One of these lectins, namely Griffithsin (GRFT) was isolated from the blue green algae Griffithsia and is being developed as a leading anti-HIV microbicide peptide (Mori et al., 2005). As literature indicates, the optimal production of any protein is an empirical experimentation with different host systems, vector systems, codon optimisations and subcellular targeting. (Maclean et al., 2007; Yang et al., 2005). The latter sometimes results in unexpected locations which might reflect on an inherent property of the protein itself or specifically be associated with the plant organ involved (Chikwamba et al., 2003). This again can influence protein yield- and activity, and impact downstream purification. In this study we aimed to compare expression levels using both Zea mays (maize) and Nicotiana benthamiana (tobacco) with relevant vector technologies. We expressed GRFT in maize using an endosperm specific maize expression vector with and without a signal peptide. In tobacco we utilised both the pTRA binary vector and magnICON deconstructed viral vector system to express GRFT with different subcellular targeting signals
An in depth study of human papillomavirus diversity in South African women infected with HIV
No full textIncludes abstract. Includes bibliographical references (leaves 109-129).Cervical cancer is the second most common cancer affecting women and in most developing countries it remains the leading cause of cancer deaths. In South Africa, more than 3 400 women succumb to the disease every year and 1 in 31 women develop cervical cancer. The causative agent for cervical cancer is the Human papillomavirus (HPV). High-risk (carcinogenic) HPV types have been linked with 99% of the incidences of cervical cancer. The most common types identified in almost 70% of cervical cancer cases worldwide are HPV 16 and 18. HPV infection is very common in young healthy women and most immunocompetent individuals can clear HPV infection. However, in immunosuppresed women, clearance by host immune system is impaired. In addition, multiple HPV infections are quite common in women with Human immunodeficiency virus (HIV) infections. The objectives of this study were to identify HPV types in South African women who also had HIV infection, and secondarily, to determine if recombination of HPV genomes occurs. Determining the HPV types circulating in this country is important to enable identification of most common HPV types, in order to guide the development of vaccines against HPV infection. HPV genotyping was performed by the commercial Roche Linear Array HPV Genotyping Test
- …
