The asymptomatic nature of chlamydial infection renders the differential diagnosis of acute and chronic infection difficult. An untreated Chlamydia trachomatis infection can become chronic, result in disease sequelae such as salpingitis and pelvic inflammatory disease (PID), and ultimately culminate in tubal occlusion and infertility. Diagnostic tests for C. trachomatis such as nucleic acid amplification testing (PCR), antigen detection and serological methods have variable performance capabilities with respect to sensitivity, specificity and stage of infection. The use of PCR as a diagnostic tool is somewhat limited, as specimen collection is routinely sampled from the lower genital tract; hence, infections in the fallopian tube where inflammatory damage is most significant, escape detection. Furthermore, PCR can only detect selected Chlamydia DNA sequences from readily accessible sites of the genital tract, and therefore cannot differentiate between acute and chronic infection. Other serological assays aim to discriminate the various stages of C. trachomatis infection through identification of key antigens. The efficacy of these assays however is impeded due to cross-reactivity between chlamydial species and the subsequent antibody response against the target antigen is not restricted to patients with a specific stage of infection. To identify antibody responses capable of differentiating various states of chlamydial infection, samples were collected from both men and women given the variability of immune responses between the two genders. Samples were assigned to a patient group according to infection status and then probed against protein extracts of HEp-2 cells infected with C. trachomatis serovar L2 and HEp-2 cells pre-treated with IFN-γ and infected with C. trachomatis serovar L2. (persistence cell culture) Serological analysis revealed the presence of five antigens (denoted bands A, B, C, D and M) which were shown to be differential between patient groups. Identification of bands B and C by N-terminal sequencing provided two possible candidates for each antigen, ie. CT727 and CT396 (band B) and CT157 and CT423 (band C). In contrast, band M which was unique to males was a PmpB (probable outer membrane protein B) fragment. The four target antigens (CT157, CT423, CT727 and CT396) were expressed as recombinant proteins using autoinduction media and were subsequently probed by both male and female sera to evaluate their diagnostic potential. Results showed that two chlamydial antigenic targets (CT157 and CT727) have the potential to discriminate between acute and chronic C. trachomatis infection. However, since only a small number of samples (n = 3) were used for this aspect of the study, the findings should simply be viewed as preliminary. In females, sensitivity and specificity values were derived using various combinations of the four target antigens into a panel format for the purpose of detecting chronic C. trachomatis infections. The preferred format was B + C with a sensitivity and specificity of 80% and 84% respectively. Using the IFN-γ-mediated persistence model, only two of the five antigenic targets were shown to be differentially expressed. PmpB in males and CT157 (the most likely band C candidate) in females were shown to be up-regulated to varying degrees in samples across the patient groups. We also demonstrated that no other chlamydial antigens are up-regulated during a persistent C. trachomatis infection. In conclusion, although combinations of bands A, B, C, D and M differentiate between male and female patient groups under normal chlamydial growth conditions, during IFN-γ-induced persistence, only bands C (CT157) and M (CT413 - PmpB) are up-regulated thus suggesting a potential role in chronic C. trachomatis infection.

The genus Ceratomyxa Thélohan, 1892 is one of the largest myxozoan genera, the species of which almost always infect the gall bladder of marine teleosts. Although there are over 180 species known globally, prior to this study only three had been described from Australia. This study explores the systematics, host specificity and species richness of Ceratomyxa species from a diverse range of Queensland marine fishes. The first part of this thesis deals with the issues associated with spore based taxonomy and incorporates the first molecular studies to investigate host specificity and radiation in three common families of Great Barrier Reef (GBR) fishes. Twenty-two new species were described in these chapters, and although they were superficially similar in morphology all were genetically distinct. A focus on Ceratomyxa spp. infecting labrid, pomacentrid and serranid fish revealed tight host specificity of parasite species, confirmed the presence of multiple parasite species in a single host and revealed that no parasite radiation had occurred that could be associated with co-evolution with host families. Exploration of intra- and inter-specific variation by sequencing of multiple replicates from host/parasite combinations allowed interpretation of species boundaries within the system. Ten additional species described in Chapter 5 supported the findings from the labrid, pomacentrid and serranid studies but broadened the host range studied. In total 32 Ceratomyxa species were described from Queensland fishes increasing the number of described species in the genus by 15%. This study also reports on undescribed species collected from a further 70 host species and broadens the known host range to seven families of fishes. A checklist of bivalvulidans from marine teleosts in Australia is compiled of described and undescribed species and highlights the abundance of Ceratomyxa relative to other gall bladder dwelling myxosporeans. A phylogeny of the Ceratomyxa based on SSU rDNA analyses explored the taxonomic integrity of the genus. In general, the morphological diagnostic characters that divide the Myxozoa into genera are not well supported by molecular phylogenetic analyses. The relationship between 42 Ceratomyxa spp. and 36 other marine myxosporeans was examined using Bayesian inference, maximum likelihood and maximum parsimony. Results indicate Ceratomyxa is one of the most cohesive lineages within the Myxozoa and that the freshwater fish parasite, C. shasta, does not represent an independent lineage as suggested in previous studies. The strict host specificity of Ceratomyxa species prompted the investigation of species richness on the GBR. Species accumulation curves were used to explore species richness by using Choa2 and Jackknife1 estimators. The estimates suggested Ceratomyxa is almost as rich as their teleost hosts and that 1,600 species could be present on the GBR and as many as 15,000 species may exist globally. As an unexpected result, Ceratomyxa may be the richest metazoan genus in the sea. In light of what the study revealed, a revision of a second genus within the family Ceratomyxidae, Leptotheca, is presented. The boundaries between Ceratomyxa and Leptotheca were unclear. The diagnostic characters that separate these genera (length to thickness ratios) were found to be plastic and the type species of Leptotheca ultimately fitted the diagnosis for Ceratomyxa. To eliminate confusion between these genera and also between Sphaerospora and Leptotheca, the genus Leptotheca was considered invalid, with all species appropriately assigned to other genera based on morphological and biological characters and supported by genetic evidence.

The genus Ceratomyxa Thélohan, 1892 is one of the largest myxozoan genera, the species of which almost always infect the gall bladder of marine teleosts. Although there are over 180 species known globally, prior to this study only three had been described from Australia. This study explores the systematics, host specificity and species richness of Ceratomyxa species from a diverse range of Queensland marine fishes. The first part of this thesis deals with the issues associated with spore based taxonomy and incorporates the first molecular studies to investigate host specificity and radiation in three common families of Great Barrier Reef (GBR) fishes. Twenty-two new species were described in these chapters, and although they were superficially similar in morphology all were genetically distinct. A focus on Ceratomyxa spp. infecting labrid, pomacentrid and serranid fish revealed tight host specificity of parasite species, confirmed the presence of multiple parasite species in a single host and revealed that no parasite radiation had occurred that could be associated with co-evolution with host families. Exploration of intra- and inter-specific variation by sequencing of multiple replicates from host/parasite combinations allowed interpretation of species boundaries within the system. Ten additional species described in Chapter 5 supported the findings from the labrid, pomacentrid and serranid studies but broadened the host range studied. In total 32 Ceratomyxa species were described from Queensland fishes increasing the number of described species in the genus by 15%. This study also reports on undescribed species collected from a further 70 host species and broadens the known host range to seven families of fishes. A checklist of bivalvulidans from marine teleosts in Australia is compiled of described and undescribed species and highlights the abundance of Ceratomyxa relative to other gall bladder dwelling myxosporeans. A phylogeny of the Ceratomyxa based on SSU rDNA analyses explored the taxonomic integrity of the genus. In general, the morphological diagnostic characters that divide the Myxozoa into genera are not well supported by molecular phylogenetic analyses. The relationship between 42 Ceratomyxa spp. and 36 other marine myxosporeans was examined using Bayesian inference, maximum likelihood and maximum parsimony. Results indicate Ceratomyxa is one of the most cohesive lineages within the Myxozoa and that the freshwater fish parasite, C. shasta, does not represent an independent lineage as suggested in previous studies. The strict host specificity of Ceratomyxa species prompted the investigation of species richness on the GBR. Species accumulation curves were used to explore species richness by using Choa2 and Jackknife1 estimators. The estimates suggested Ceratomyxa is almost as rich as their teleost hosts and that 1,600 species could be present on the GBR and as many as 15,000 species may exist globally. As an unexpected result, Ceratomyxa may be the richest metazoan genus in the sea. In light of what the study revealed, a revision of a second genus within the family Ceratomyxidae, Leptotheca, is presented. The boundaries between Ceratomyxa and Leptotheca were unclear. The diagnostic characters that separate these genera (length to thickness ratios) were found to be plastic and the type species of Leptotheca ultimately fitted the diagnosis for Ceratomyxa. To eliminate confusion between these genera and also between Sphaerospora and Leptotheca, the genus Leptotheca was considered invalid, with all species appropriately assigned to other genera based on morphological and biological characters and supported by genetic evidence.

The genus Ceratomyxa Thélohan, 1892 is one of the largest myxozoan genera, the species of which almost always infect the gall bladder of marine teleosts. Although there are over 180 species known globally, prior to this study only three had been described from Australia. This study explores the systematics, host specificity and species richness of Ceratomyxa species from a diverse range of Queensland marine fishes. The first part of this thesis deals with the issues associated with spore based taxonomy and incorporates the first molecular studies to investigate host specificity and radiation in three common families of Great Barrier Reef (GBR) fishes. Twenty-two new species were described in these chapters, and although they were superficially similar in morphology all were genetically distinct. A focus on Ceratomyxa spp. infecting labrid, pomacentrid and serranid fish revealed tight host specificity of parasite species, confirmed the presence of multiple parasite species in a single host and revealed that no parasite radiation had occurred that could be associated with co-evolution with host families. Exploration of intra- and inter-specific variation by sequencing of multiple replicates from host/parasite combinations allowed interpretation of species boundaries within the system. Ten additional species described in Chapter 5 supported the findings from the labrid, pomacentrid and serranid studies but broadened the host range studied. In total 32 Ceratomyxa species were described from Queensland fishes increasing the number of described species in the genus by 15%. This study also reports on undescribed species collected from a further 70 host species and broadens the known host range to seven families of fishes. A checklist of bivalvulidans from marine teleosts in Australia is compiled of described and undescribed species and highlights the abundance of Ceratomyxa relative to other gall bladder dwelling myxosporeans. A phylogeny of the Ceratomyxa based on SSU rDNA analyses explored the taxonomic integrity of the genus. In general, the morphological diagnostic characters that divide the Myxozoa into genera are not well supported by molecular phylogenetic analyses. The relationship between 42 Ceratomyxa spp. and 36 other marine myxosporeans was examined using Bayesian inference, maximum likelihood and maximum parsimony. Results indicate Ceratomyxa is one of the most cohesive lineages within the Myxozoa and that the freshwater fish parasite, C. shasta, does not represent an independent lineage as suggested in previous studies. The strict host specificity of Ceratomyxa species prompted the investigation of species richness on the GBR. Species accumulation curves were used to explore species richness by using Choa2 and Jackknife1 estimators. The estimates suggested Ceratomyxa is almost as rich as their teleost hosts and that 1,600 species could be present on the GBR and as many as 15,000 species may exist globally. As an unexpected result, Ceratomyxa may be the richest metazoan genus in the sea. In light of what the study revealed, a revision of a second genus within the family Ceratomyxidae, Leptotheca, is presented. The boundaries between Ceratomyxa and Leptotheca were unclear. The diagnostic characters that separate these genera (length to thickness ratios) were found to be plastic and the type species of Leptotheca ultimately fitted the diagnosis for Ceratomyxa. To eliminate confusion between these genera and also between Sphaerospora and Leptotheca, the genus Leptotheca was considered invalid, with all species appropriately assigned to other genera based on morphological and biological characters and supported by genetic evidence.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 10 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 6 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.