The main aim of the current study was to determine the prevalence and diversity of potentially zoonotic bacterial genera in accurately identified indigenous rodents from South Africa. Bacterial prevalence and diversity were determined by PCR amplification and sequence analyses. Rodents were molecularly identified by amplification and sequence analysis of the mitochondrial cytochrome b gene region. Three species (Aethomys ineptus, Mastomys coucha and Otomys angoniensis) belonging to murid species complexes were identified. Furthermore, phylogenetic analyses revealed that both the proposed subspecies (R. dilectus dilectus and R. d. chakae) within the recently erected Rhabdomys dilectus occur in Hammanskraal and at the University of Pretoria Experimental farm, both in the Gauteng Province of South Africa. An overall bacterial prevalence of 38.6 % was observed in kidney samples of commensal and natural indigenous rodents after molecular screening with broad range 16S rRNA gene primers. Nucleotide sequence analyses identified a diverse range of bacterial genera namely, Bartonella, Anaplasma, Helicobacter, Burkholderia, Streptococcus, Aerococcus and Lactobacillus. Some members of these genera have been identified as causative agents of human and animal diseases, being transmitted either through environmental contamination or through haematophagous arthropod vectors. Subsequent genus-specific bacterial screening focussed on vector-borne genera identified in the commensal and natural rodent populations sampled. Bartonella prevalence and genetic diversity was compared between a natural and commensal population of the southern multimammate mouse (M. coucha) using two gene regions (Citrate synthase gene and NADH dehydrogenase gamma subunit gene). A significantly higher infection prevalence was detected in the commensal population (92.9 %) as compared to the natural population (56.9 %). No differences however, were detected between infection status and the ectoparasite loads calculated for both rodent populations. Apart from several novel Bartonella strains identified in both M. coucha populations, phylogenetic analyses also identified a species of known zoonotic potential (B. elizabethae) in both populations. The present study represents one of the first to screen indigenous rodents for tick-borne members of the bacterial family Anaplasmataceae. Anaplasma bovis-like DNA was detected in five of the six rodent species sampled (A. ineptus, Lemniscomys rosalia, M. coucha, O. angoniensis and R. dilectus) at an overall prevalence of 39.2 %. The potentially zoonotic Ehrlichia ewingii was detected in M. coucha samples only at a prevalence of 5.3 %. The diverse bacterial genera detected in commensal and natural populations of indigenous rodents comprise members of zoonotic potential and agricultural significance, highlighting the importance of continuous disease surveillance of indigenous rodents. / Dissertation (MSc)--University of Pretoria, 2014. / National Research Foundation (NRF) / Zoology and Entomology / MSc / Unrestricted

No description available.

Glycosphingolipids (GSLs), composed of a polar saccharide head and a lipophilic ceramide tail, are ubiquitous components of the plasma membrane of eukaryotic cells. They serve in many regulatory capacities and have antigenic properties towards natural killer T (NKT) cells of the innate immune system. Critical to the recognition of glycosylceramides by NKT cells are antigen presenting cells (APC), such as dendritic cells, which are responsible for binding, processing, and delivery of ligands to these lymphocytes. This event is mediated by CD1d, a major histocompatibility complex-like protein expressed on the surface of APCs, which binds GSL antigens by the ceramide moiety and presents the polar group to the T cell receptors of CD1d-restricted cells. The subsequent immune response involves NKT cell proliferation and emission of numerous cytokines, such as interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), resulting in the stimulation of the innate and adaptive immune systems through maturation of APCs, activation of T cells, and secretion of antibodies by B cells. To understand the structure-activity relationship between GSLs and NKT cell activity and the requirements for intracellular processing of antigens, analogs of the model compound alphaGalCer (KRN-7000) have been synthesized. These include fluorophore-appended 6”-amino-α-galactosylceramides and N-alkenoyl GSLs, such as PBS-57, a potent alphaGalCer surrogate useful in NKT cell stimulation studies. A nonantigenic beta-C-galactosylceramide has also been prepared as an inhibitor of these innate lymphocytes. To probe the potential for using NKT cells to bias the immune system between the proinflammatory TH1 response or the immunomodulatory TH2 mode, versions of alphaGalCer with shortened ceramides have been created. One of these truncated analogs, PBS-25, has successfully been cocrystallized with CD1d and the binary complex structure solved by X-ray crystallography. Synthetic glycosphingolipids derived from Novosphingobium capsulatum and Sphingomonas paucimobilis have also been made. In assays with classical Valpha14i/Valpha24i NKT cell lines, these Gram-negative bacterial antigens were recognized directly and specifically by host immune systems through CD1d-restriction, unlike GSL-deficient microbes (e.g., Salmonella typhimurium). A search for other GSL-bearing alpha-proteobacteria led to the discovery of another natural glycosphingolipid, an N-alkenoylphytosphingoid-alpha-galactoside, isolated from the outer membrane of Ehrlichia muris.

No description available.

In impoverished and resource limited communities such as townships, and welfare organizations, areas such as living and sleeping spaces are sometimes shared with animals, and occasionally humans. Dogs play an integral role in our lives and have become part of the family. Therefore, it is probable that ectoparasites, such as ticks, that feed on dogs also feed on other vertebrates, thereby, transmitting pathogens. The primary aim of this study was to screen for the presence of tick-borne pathogens in dogs from welfare organisations and townships in Cape Town, with special focus on Ehrlichia and Babesia spp. The reason for this choice of subject is due to the fact that very few tick-borne infection studies have focused on resource limited communities. Furthermore, welfare organisations have continuously attracted awareness due to the amount of unrestricted work performed by veterinarians in communities with limited resources. Consequently, the topic was borne. A total of 126 blood samples and 509 ticks (adults and nymphs) were collected directly from dogs from four welfare organisations and two townships in Cape Town. Samples were collected from April to July 2014. The four welfare organisations where samples were collected included the Animal Anti Cruelty League welfare organisations in Epping and Bellville, the Lucky Lucy Foundation in Joostenberg Vlakte and The Emma Animal Rescue Society (TEARS), located in the Sunnydale area. Samples were also collected from the Asanda village and Nomzamo, two townships located just outside the Cape Town suburb, the Strand. DNA was extracted from blood and ectoparasites and screened for the presence of Ehrlichia, Anaplasma, Theileria and Babesia species infections using touchdown PCR and RLB hybridization assays. Genus and species-specific probes were used during hybridization in order to identify specific parasite infections in the blood samples and the tick samples pooled according to geographical origin and species. Forty six (36.5%) of the blood samples tested positive for tick-borne pathogen DNA. Of the positive blood samples, 17 (13.5%) were infected with Ehrlichia canis; 16 (12.7%) with Babesia rossi and four (3.2%) samples were infected with Babesia vogeli. Incidental infections were also detected, these included Ehrlichia ruminantium (n=6, [4.7%]), Theileria taurotragi (n=2, [1.6%]) and Anaplasma sp. Omatjenne (n=1, [0.8%]) infections. DNA detected from 10 samples (7.94%) hybridized only to the Ehrlichia/Anaplasma genus-specific probes and four samples (3.17%) hybridized only to the Theileria/Babesia genus-specific probes. None of these 14 samples hybridized to any of the species-specific probes. Collected Rhipicephalus sanguineus (n=457) and Haemaphysalis elliptica (n=52) ticks were grouped into 15 pools, representing both tick species according to specific collection locations. Since only two H. elliptica from Asanda and one R. sanguineus from TEARS were collected, these ticks were mixed in pools of the dominant species as they were too few for DNA extraction. Ticks were collected from the Nomzamo Township (R. sanguineus n=400), Asanda village (H. elliptica n=2; R. sanguineus n=42), TEARS (H. elliptica n=21; R. sanguineus n=1), and the Animal Anti Cruelty League in both Epping (R. sanguineus n=14), and Bellville (H. elliptica n=29), in Cape Town. Analysis by the RLB assay showed that 11 (73.3%) of the 15 tick pools representing both tick species were positive for at least one parasite species. All positive samples hybridized with the Ehrlichia/Anaplasma genus-specific probe. Three (20%) tick pools containing both tick species tested positive for Ehrlichia canis infection, two (13.3%) tested positive for Babesia rossi and Babesia vogeli DNA was identified in one (6.6%) tick pool. The Theileria/Babesia genus-specific probe hybridised in three (20%) tick pools. These three pools were comprised of both R. sanguineus and H. elliptica tick species. These tick pools also tested positive for a specific Babesia tick-borne pathogen. Tick-borne pathogen DNA could not be detected in four (26.6%) tick pools. The fore-mentioned tick-borne pathogen DNA detected in the dog blood samples, and the ectoparasites collected from the same dogs during this study, suggests that dogs play a large role in the endemicity of these pathogens / Environmental Sciences / M. Sc. (Life Science)

Little is understood about off-host behavior and ecology of immature Amblyomma maculatum Koch (Gulf Coast tick). A more complete understanding of this tick is essential to protect human and animal health. My research focused on seasonality and distribution of immatures in Mississippi, potential suitability of some insect and human hosts to larvae, and aspects of nymphal questing behavior. A single larva was collected (third off-host collection reported) when sampling A. maculatum habitat using a novel device. Collection of this larva in November expands the stage’s known seasonality and confirmed a prediction concerning seasonality of larval A. maculatum. Low frequency of immatures (8.3%) confirmed that they’re incredibly difficult to collect off-host. Nymphal collections peaked in March, and known seasonality was extended for both nymphs and adults. I examined known records, elucidating seasonality and distribution of A. maculatum in Mississippi. Either multiple generations per year or diapause are responsible for observed bi-modal distribution of immature collections. Additionally, I compiled the most extensive host record of immature A. maculatum in Mississippi and investigated seasonality patterns using USDA plant hardiness zones. I compiled the most complete record of ticks found on arthropods. Amblyomma americanum and A. maculatum were both confirmed to crawl onto arthropods, giving support to occasional, unintentional dispersal by phoresy. There was no conclusive evidence that larval A. maculatum feed on arthropods, however data supported feeding by larval A. americanum. These results have interesting implications regarding evolution of pathogens/endosymbionts. I provided the first evidence that larval A. maculatum can attach to humans. Rickettsia parkeri, a human pathogen transmitted by this species has recently been shown to be capable of transovarial transmission. Therefore, larval A. maculatum may provide another avenue of transmission. I have demonstrated that A. maculatum are difficult to collect off-host in part because they prefer to quest low to the ground. In choice studies, 5-cm-tall stems were most likely to be occupied by nymphs released into an array of stems. Low vapor pressure deficit encouraged questing, while higher VPD and warmer temperature increased questing height. These results may have implications in understanding host-seeking behavior in other tick species as well.