New affinity molecules such as nucleic acid aptamers are in demand in the science and medical fields. Current aptamer selection technologies can generate unique aptamers with desired properties to targets of interest. My thesis describes a series of investigations on the protection of an oncolytic virus, the isolation of target cells from biological fluids, and aptamer-facilitated biomarker discovery. We tested individual aptamers and constructed a tetramer aptamer structure (quadramer) to increase virus infectivity. The quadramer protects vesicular stomatitis virus (VSV) during freeze–thaw cycles, shields the virus from neutralizing antibodies and increases viral active units. In addition to aptamers, we screened carbohydrate-based ice recrystallization inhibitors for the possible elimination of the cold chain of Vaccinia virus, VSV, and Herpes virus-1. N-octyl-gluconamide provides the longest shelf life for Vaccinia virus and Herpes virus-1 as tested according to the World Health Organization’s requirements for viral vaccines efficiency during transportation and distribution. We generated switchable aptamers capable of isolating cells expressing LIFR, NRP1, DLL4, uPAR, or PTCH1. These aptamers bind to the receptor positive cells in the presence of Mg2+ and Ca2+, and release the pure cells upon addition of EDTA. The aptamers were applied for a sequential positive immunomagnetic isolation of cells from mice bone marrow. We also utilized fluorescence-activated cell sorting (FACS) in our aptamer selections to develop switchable aptamers to positive isolation of monocytes from human blood. Moreover, we have selected non-switchable aptamers as an affinity probe to the cells expressing Axl receptor for immunofluorescent analysis and cell sorting. We determined aptamers to CD107a and applied them for biomarker discovery with mass spectrometry and found that CD107a was co-expressing with PD-1. Furthermore, we identified CD91 as binding partners to our aptamers in human monocytes using FACS and orbitrap mass spectrometry.

Thesis (MBA (Business Management))--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Soon after the development of the internet as a network structure connecting computers on a global scale, was the introduction of malicious computer code, which was disseminated through this network. Initially this code was the relegation of pranksters, but evolved quickly to be code causing destruction, intrusion and loss of privacy while on the internet. This code became known as the computer virus and was soon used by fraudsters to infiltrate networks to create deception and fraud for financial gain. It has become of paramount importance for users of the internet to protect themselves and their networks from these attacks, through various ingenious mechanisms of protection. The traditional mainstay for computer virus protection has been the software approach using counter code to protect against any malicious computer code. This protection has had limited success as the very nature of malicious code is constantly changing and evolving, making it sometimes an impossible task for internet users to be protected with the latest anti-virus software for protection. The author of this study introduces a managed anti-virus protection alternative which is delivered by a computer hardware device. This is a new technology and a full description is made of the role of this product as a new product development. The empirical research of this paper focuses around the test for a need for the product described to the point, but excluding commercialization. / AFRIKAANSE OPSOMMING: Kort na die ontwikkeling van die internet as 'n netwerkstruktuur wat rekenaars op 'n globale skaal verbind, was daar die bekendstelling van kwaadwillige rekenaarkodes wat reg deur die netwerk versprei het. Aanvanklik was die kode gemik op die verdrywing van poetsbakkers, maar het spoedig ontwikkel in kodeverdrywing, inmenging en verlies aan privaatheid op die internet. Hierdie kode het bekend geword as die rekenaarvirus, en is spoedig deur bedrieërs gebruik om netwerke te infiltreer om gebruikers te mislei en te bedrieg vir eie finansiële gewin. Dit het vir gebruikers van die internet van uiterste belang geword om hulle en hulle netwerkte teen hierdie aanvalle te beskerm, en wel deur middel van verskeie meganismes. Die bekendste bekermingsmatreël teen die virus is die aanwending van sagteware as teenkode. Hierdie bekermingsmetode het egter tot dusver beperkte sukses behaal, aangesien die aard van kwaadwilligheid voortdurend verander en ontwikkel, sodat dit soms onmoontlik is dat gebruikers deur die nuutste anti-virussagteware beskerm kan word. Die skrywer van hierdie verhandeling stel 'n werkbare, alternatiewe anti-virusbeskermer bekend wat deur rekenaar-hardewareplan daargestel is. Dit het nuwe tegnologie, en 'n volledige beskrywing word gegee van die rol van hierdie produk as 'n nuwe ontwikkeling. Die empiriese navorsing van die verhandeling fokus op die toets vir die noodsaaklikheid van so 'n produk, met die uisluiting van kommersialisering.