Marburg, Universiẗat, Diss., 2002.

No description available.

The Mononegavirales order unifies the non-segmented negative sense viruses (nsNSVs), including Marburgvirus (MARV) of the Filoviridae family and respiratory syncytial virus (RSV) of the Pneumoviridae. The mechanism of action of these viruses and how they infect cells are very similar, especially when focusing on their polymerases, which are distinct from those of eukaryotes and therefore possible targets for antiviral drugs. nsNSVs utilize a RNA-dependent RNA polymerase to either replicate the viral RNA genome or transcribe it into positive sense mRNA. Despite this, these two viruses result in very different, but equally devastating, effects in humans. Whereas MARV virus often results in rare but fatal hemorrhagic fevers, RSV is a common seasonal virus that can result in long term negative effects to respiratory health. These negative effects on public health demand extensive research in these two fields and a need to develop new technology and methods in order to uncover the missing pieces of viral gene expression. Specifically, the development of a MARV minigenome system would allow for increased testing of this virus outside of the confines of the biosafety level 4 (BSL-4) setting. By replacing MARV genes with reporter genes, but retaining the characteristic leader, intergenic, and trailer regions of the genome, tests involving site directed mutagenesis would reveal new insights into the crucial genomic elements needed for successful gene expression. Coupled with the transfection of the minigenome with plasmids coding for the crucial MARV proteins, artificial changes to the genome would lead to the presence of absence of translated bioluminescent reporter proteins. Using these two viruses, this study attempted to find commonalities across families. Specifically, the goals of this research were twofold, to find the optimal ratio of MARV plasmids in the minigenome system to understand the effects of the stem-loop secondary structure of MARV mRNA transcripts as well as determine the tail length of the poly(A) tail of RSV mRNA transcripts using digestion and probing primers. Calculating the RSV poly(A) tail length would allow for further research into determining whether the MARV and RSV polymerase polyadenylates before or after it releases the transcript. Despite multiple failed attempts, transfections using pCAGGS plasmids and the eGFP monocistronic minigenome in a 6-well plate qualitatively demonstrated the need for pCAGGS-L plasmid concentration of 1000 ng/µl. Due to time constraints, the poly(A) tail length of the RSV NS-1 mRNA transcript could not be determined. Overall, this study focused on gaining new insights on the techniques and procedures necessary for conducting virus research in a biosafety level 2 (BSL-2) setting, as well as developing troubleshooting skills in approaching fail experiments.

Bats asymptomatically host a number of viruses that are the cause of recently emergent infectious diseases in humans. While the mechanisms underlying this asymptomatic infection are currently not known, studies of sequenced bat genomes help uncover genetic adaptations in bats that may have functional importance in the antiviral response of these animals. To identify differences between antiviral mechanisms in humans and bats, we sequenced, assembled, and analyzed the genome of the Egyptian rousette bat (ERB; Rousettus aegyptiacus), a natural reservoir of Marburg virus and the only known reservoir for any filovirus. We used this genome to understand the evolution of immune genes and gene families in bats, and describe several observations relevant to defense against viruses. We observed an unusual expansion of the NKG2/CD94 natural killer (NK) cell receptor gene families in Egyptian rousette bats relative to other species, and found genomic evidence of unique features and expression of these receptors that may result in a net inhibitory balance within bat NK cells. The expansion of NK cell receptors is matched by an expansion of potential major histocompatibility complex (MHC) class I ligands, which are distributed both within and, surprisingly, outside the canonical MHC loci. We also observed that the type I interferon (IFN) locus is considerably expanded and diversified in the ERB, and that the IFN-ω subfamily contributes most to this expansion. To understand the functional implications of this expansion, we synthesized multiple IFN-ω proteins and examined their antiviral effects. Members of this subfamily are not constitutively expressed but are induced after viral infection, and show antiviral activity in vitro, with different antiviral potencies observed for different IFN-ω proteins. Taken together, these results show that multiple bats, including the ERB, have expanded and diversified numerous antiviral loci, and potentially developed unique adaptations in NK cell receptor signaling, and type I IFN responses. The concerted evolution of so many key components of immunity in the ERB is strongly suggestive of novel modes of antiviral defense that may contribute to the ability of bats to asymptomatically host viruses that are pathogenic in humans.

Universiẗat, Diss., 2008--Marburg.

MSc (Med) (Bioethics and Health Law), Faculty of Health Sciences, University of the Witwatersrand

Zugl.: Marburg, Univ., Magisterarbeit, 1999

Zugl.: Marburg, Universiẗat, Diss., 2005.

No description available.

Teilveröffentlichung aus: RISM, Serie A/II Musikhandschriften nach 1600