Avibacterium paragallinarum is an avian pathogen and has the ability to
cause vast economical losses. This bacterium forms part of the
Pasteurellaceae family and factors contributing to pathogenicity,
immunogenicity and serotyping are not clearly understood.
One of the main questions that were addressed in this study was the
identification of genetic tools are that is responsible for the NAD+-
independence ability of this organism. NAD+ recycling genes were implicated
for this bacterium and Av. paragallinarum seem to follow the recycling pathway
as set out for the Pasteurellaceae family. Still the question regarding NAD+-
independence remains unanswered as no complete pathway could be
implicated for this trait. Furthermore, no plasmid(s) could be isolated that
conferred this trait and no complete NAD+ synthesis pathway could be
implicated. Only two genes were identified to form part of a NAD+-independent
pathway which indicated that Av. paragallinarum may use genetic tools for
NAD+-independence as set out for bacteria in general and not as the rest of the
Pasteurellaceae family members.
Plasmid isolation studies revealed only the plasmid p250 identical to the
established plasmid p250 for Av. paragallinarum. Literature reports on two
other native plasmids namely pYMH5 and pA14, however, these two plasmids
could not be detected in any of the strains used in this study during plasmid
screens. This study confirms and illustrates the integration of plasmid p250
within the genome of Av. paragallinarum by different serovars.
In order to study this bacterium on a genomic level a whole genome
sequencing project was launched. This project experienced vast amount of difficulties regarding the assembly of a complete genome for Av.
paragallinarum. This bacterium contains numerous repeated regions within
its genome which, with current sequencing technology, prevent the genome
assembly into a single chromosome. A complete assembled genome can only
be achieved when longer read lengths are available in high-throughput
sequencing technologies and will thus enable clarification regarding the
repeated regions.
A pseudo-assembled molecule was sent to the JCVI for genome annotation.
Annotated data revealed that Av. paragallinarum contains a high degree of
complexity regarding its cell envelope which may shed light on pathogenicity
and immunogenicity problems endured. This bacterium contains numerous
mobile and extrachromosomal elements which contribute to the inability to
close the genome of Av. paragallinarum. Nine site-specific integrases and 10
transposases were identified. These tools could allow for a high degree of
genetic diversity within the Av. paragallinarum specie. Alongside these tools
two putative prophages was identified for Av. paragallinarum. One prophage
resembles the Mu-like prophages and was termed ФAvpmuC-2M, the other
resembles the HP2-like prophages and was termed ФAvpC-2M-HP2.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-11222010-124046 |
| Date | 22 November 2010 |
| Creators | Roodt, Yolandi |
| Contributors | Prof RR Bragg, Prof J Albertyn |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-11222010-124046/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.014 seconds