Leucocin A is a class 11a bacteriocin produced by Leuconostoc mesenteroides TA33a that was previously shown to inhibit Listeria monocytogenes. A spontaneous resistant mutant of L. monocytogenes was isolated, and found to be resistant to leucocin A at levels in excess of 2 mg/ml. The resistant mutant had an eight-fold increased binding capacity for leucocin A in comparison to the parental strain. The mutant showed no significant cross resistance to nisaplin or ESFI-7GR. The resistant phenotype had a similar growth rate in monoculture, to the sensitive phenotype. DNA and protein analysis of the resistant and susceptible strains were carried out using silver stained amplified fragment length polymorphism (ssAFLP) and one and two dimensional (2D) SDS polyacrylamide gel electrophoresis (PAGE). Two-dimensional SDS PAGE revealed two differences. The first was a 35 kDa protein which was present in the sensitive but absent from the resistant phenotype and, secondly there was a higher level of expression of a 18 kDa protein in the resistant phenotype compared with the sensitive phenotype. The 35 kDa protein was found to have a 83% homology to the mannose-specific phosphotransferase system IIAB of Streptococcus salivarius. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

In this study, we determined the immunogenicity of CWP2 and its potential as a vaccine candidate against giardiasis. CWP2 was expressed as a recombinant protein with an hexa-histidine affinity tag and was isolated from inclusion bodies. When BALB/c mice were immunized with CWP2, a specific IgA was detected in the feces. When mice were immunized with CWP2 + cholera toxin, as an adjuvant, IgA in the feces, and IgA, IgG1, and IgG2a in the serum, all specific to CWP2, were detected. Also, CD-1 mice were infected with G. muris and presence of specific IgA antibodies to CWP2 were detected in the feces. This result indicated that CWP2 was recognized by the immune system in a natural infection. IL-4 and IL-5 were released from Peyer's patches (PP) and mesenteric lymph nodes (MLN) cells when stimulated with concanavalin A. In spleen cells, IFN-gamma, IL-4, and IL-5 were released when stimulated with concanavalin A. However, in PP, MLN and spleen cells, the levels of cytokines were barely detectable when stimulated with CWP2. The presence of IgG2a (Th1), IgA and IgG1 (Th2) as the production of IFN-gamma (Th1), IL-4 and IL-5 (Th2) confirmed that CWP2, when presented orally to mice, stimulates both a Th1 and Th2 type immune response, locally and systemically.

1. The DNA sequence of the human complement C4A gene from a cosmid clone Cos 3A3 was determined and the complete exon-intron structure elucidated. The 5' flanking region of the C4 gene contains three TATA sequences and a transcriptional enhancer core sequence, which are >200 nucleotides (nt) and 60-70 nt upstream from the CAP site, respectively. The gene consists of 42 exons coding for a precursor protein of 1745 residues. The first exon codes for a 51 nt 5' untranslated sequence, a leader peptide of 19 residues, and the N-terminus of the β chain. The β-α and the α-γ chain junctions are encoded by exons 17 and 34, respectively. The anaphylatoxin C4a and the thiolester site are encoded by phase 1-1 symmetrical exons. Most of the amino acids encoded at the splice junctions are polar or charged. Between exons 10 and 11 is a 6-7 kb intron that is flanked by direct long terminal repeats and may be absent in some C4 genes located at the second C4 locus. The last exon codes for the C-terminus of the γ chain and a 140 bp 3' untranslated sequence. The intergenic region between the C4 gene and its neighbouring 21-hydroxylase (210Hase) gene is ~3028 bp. 2. Eighteen polymorphic amino acids on C4 have been identified through genomic DNA, cDNA and protein sequencing. Fourteen of them are located on the* chain (C4a: 2 changes; C4d: 12 changes). The rest are scattered on the β and the γ chains. There are potential size variations by one residue on the β chain, and by a tripeptide that contains a sulphation site on the α chain. 3. Four common and rare C4 alleles have been cloned from individuals whose C4 proteins were chemically and serologically characterised. Analysis of the sequences at the C4d regions has allowed the identification of the C4A/C4B isotypic residues at positions 1101-6: C4A has the sequence PCPVLD, while C4B has the sequence LSPVIH. Presumably these isotypic residues are the cause of the class-specific, differential chemical reactivates. Moreover, the probable locations for the two Eodgers (Kg) and the six Chido (Ch) antigenic determinants were deduced. The C4B isotypic residues may be involved in the expression of the Ch2 and the Ch4 epitopes, while the C4A isotypic residues may not be related to either of the Eg determinants. 4. Definitive restriction fragment length polymorphisms (RFLPs) representing the exact locations responsible for the isotypicity between C4A and C4B, and for their generally associated Rg1 and Ch1 antigenic determinants, have been designed. In combination with the Taq I polymorphic patterns specific for the C4 and for the 210Hase gene loci, it has been shown that the null allele of the HLA haplotype B44 DR6 C4A 3 C4B QO is not a C4B allele, but probably encodes another C4A 3 allotype at the second C4 locus.

There is growing evidence that susceptibility to many inflammatory and infectious diseases may be influenced by our genetic make up. Genetic variants in important immune genes may partially explain variation in susceptibility to common diseases. Interferon-γ (IFNγ) is one of the central mediators of the innate and adaptive immunity and has been implicated in a wide range of infectious and inflammatory disease processes. Severe disruptive mutations in coding regions of the IFN-γ receptor 1 gene (IFNGR1) have been found to be associated with fatal but very rare mycobacterial infections. This study looked at common polymorphisms in potentially regulatory non-coding regions of the IFNγ gene and the IFNGR1 gene and investigated their association with susceptibility to severe malaria, a disease for which there have been indications of a genetic component to susceptibility. Malaria is one of the major causes of childhood deaths in Africa. IFNγ and its receptor have been shown to be critically involved in the host response to the malaria parasites. The promoter regions of IFNGR1 and its neighbouring genes, located on chromosome 6q23, and IFNγ and its neighbours, on chromosome 12ql4, were screened for polymorphisms. Haplotypes and linkage disequilibrium maps were constructed, signatures of natural selection were investigated, haplotype tagging SNPs were dentified, and association with disease was analysed. One of these preliminary results was a putative association between the IFNGRl-470ddel allele and susceptibility to severe malaria in the Mandinka ethnic group. This allele was in strong linkage disequilibrium (LD) with markers which are a considerable distance away which might represent a signature of natural selection. To assess the potential functional significance of the IFNGR1-47Q polymorphism, its effects on DNA-protein interactions and gene expression was investigated further in various cell lines. Evidence of tissue-specific nuclear protein binding to this site which seems to be involved in transcriptional regulation was observed.

Typescript (photocopy) / xiii, 209 leaves : ill., (1 col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Genetics, 1983

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (M.S.)--Georgia State University, 2006. / Title from title screen. Susanna Greer, committee chair; Delon Barfus,Yuan Liu, committee members. Electronic text (72 p. : ill.) : digital, PDF file. Description based on contents viewed Aug. 20, 2007. Includes bibliographical references (p. 69-72).

Thesis (M.S.)--University of Delaware, 2009. / Principal faculty advisor: Calvin L. Keeler, Jr., Dept. of Animal & Food Sciences. Includes bibliographical references.