Antimicrobial proteins (AMPs) are effector molecules and an important part of the innate immune system. AMPs have a broad antimicrobial spectrum and lyse microbial cells by interaction with biomembranes. Besides direct impact in host defence, AMPs are mediators of inflammation with impact on epithelial and inflammatory cells influencing diverse processes such as cytokine release, cell proliferation, angiogenesis, wound healing, chemotaxis, immune induction, and protease-antiprotease balance. AMPs could replace antibiotics which efficiency has decreased due to extensive clinical use. Therefore knowledge of mechanism of action of antimicrobial peptides, their properties and possible usage is essential for their further use as therapeutics. Ticks are blood-feeding ectoparisites that serve as extremely effective vectors of pathogens. Analysis of the ticks molecules that are involved in immune response to the pathogens invasion represent one of the strategies in searching for new compounds that might be used in future as theurapeutic agents. This study represents analysis of newly identified antimicrobial peptide form in the hard tick Ixodes ricinus (IRAMP). IRAMP revealed the high similarity to the recently described antimicrobial peptide isolated from hard tick Ixodes scapularis (protein ISAMP). Analysis and characterization of novel AMP, testing its antimicrobial potential and expression pattern are the main objectives of this study

Two cysteine and two serine protease inhibitors from a tick Ixodes ricinus saliva were overexpressed using a prokaryotic overexpression system and refolded to their native state. Both cysteine protease inhibitors were tested as potential antigens for an anti-tick vaccine showing no effect on tick feeding or reproduction. Various immunological methods were employed to test the potential immunomodulatory function of these proteins without success.

Four hand-reared, naïve roan antelope 6 months of age were exposed to naturally infected pasture on a game farm in Mpumalanga where roan are known to die from theileriosis. The predominant ticks parasitising these animals at this time (during the months of January and February) were Rhipicephalus appendiculatus and R. evertsi evertsi adults. After a period of 5 weeks the animals developed signs of clinical theileriosis, characterized by anorectal lymphadenomegaly, shortly followed by pyrexia and generalised peripheral lymphadenomegaly. Around the time of pyrexia, peripheral blood smears showed severe mononuclear leukocytosis, with some leukocytes containing cytoplasmic theilerial schizonts (Koch’s bodies). This was followed by erythrocytic piroplasmaemia. Animals were treated successfully using buparvaquone. Primary hyperplasia of the local draining lymph nodes (Lnn. anorectales) of adult R. e. evertsi feeding sites indicated vector status of theileriosis for this tick species. After recovery from theileriosis, these animals were confirmed carriers of Theileria sp. (sable) by PCR and DNA probe analysis. Laboratory-bred larvae and nymphae of R. e. evertsi and R. appendiculatus respectively were fed on the ears of these roan antelope, now known to be carriers. Engorged nymphae were recovered from the roan. A cryopreserved stabilate was produced from each species, using an adapted protocol for Theileria parva tick stabilate preparation. Both stabilates were tested for infectivity in T. sp. (sable) negative (PCR analysis) roan antelope calves that were intensively hand reared under tick-free conditions. The stabilate derived from R. e. evertsi induced clinical theileriosis at doses between 5 and 60 tick equivalents per calf. The R. appendiculatus stabilate did not induce clinical disease or infection; the calves remained PCR negative throughout the trial period. The calves that survived the R. e. evertsi stabilate trial showed no clinical reaction to field exposure, in contrast to the controls and R. appendiculatus stabilate inoculated calves which all exhibited clinical theileriosis The stabilate has the potential to be used as the infection source in an infection and treatment method of immunising roan antelope against theileriosis. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Paraclinical Sciences / unrestricted

In this study the structural characteristics and antibacterial activities of two peptides derived from the carboxy-terminal of a tick defensin were investigated. Two defensin isoforms (OsDef1 and OsDef2) were previously identified in the midgut of the tick, Ornithodoros savignyi. Both OsDef1 and OsDef2 were found to be active against Gram-positive bacteria but showed no antibacterial activity against Gram-negative bacteria. OsDef2 was found to be slightly more active than OsDef1 and was, therefore, used as the template for the design of smaller antimicrobial peptides. Two peptide analogues were synthesised using the carboxy-terminal sequence of OsDef2 and differed in that in the one peptide the cysteine residues were present (Os) and in the other the cysteine residues were omitted (Os-C). Structurally, Os contained more α-helical properties than Os-C, whereas Os-C was more β-sheeted when prepared in 25 mM SDS. Both Os and Os-C showed no antibacterial activity when tested in Luria-Bertani broth or Mueller-Hinton broth indicating that the activities of Os and Os-C were influenced by the presence of broth salts and proteins. When tested in sodium phosphate buffer, both Os and Os-C exhibited Gram-positive and Gram-negative antibacterial activity. Os was slightly more active than Os-C against 3 of the 4 tested strains, with minimum bactericidal concentrations (MBCs) ranging from 0.94 μg/ml to 3.75 μg/ml. Os retained bactericidal activity against both Staphylococcus aureus and Escherichia coli when tested in the presence of 100 mM NaCl or 30% human serum. Os-C retained activity against E. coli in the presence of NaCl but became inactive in 30% human serum against both bacterial strains. At the MBCs, Os exhibited faster killing kinetics than Os-C killing both Bacillus subtilis and E. coli within 5 min, whereas Os-C took up to 120 min and 60 min, respectively. SYTOX Green permeabilization assays showed that both Os and Os-C caused permeabilization of E. coli membranes after 30 min exposure. At high peptide concentrations, both Os and Os-C were shown to interact with plasmid DNA. Both Os and Os-C exhibited no cytotoxic effects against SC-1 and Caco-2 cell lines, even at peptide concentrations 32 times higher than the highest MBC. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Biochemistry / unrestricted

Human alteration of the landscape and environment is favoring the expansion of ticks and the pathogens they vector throughout the United States. The changes in these distributions are documented through literature and the deposition of specimens in scientific collections. In southern Illinois, tick species records are sporadic and inconsistent with what is actually found in the region. This information is necessary for public health officials to develop prevention strategies against tick-borne illnesses. I conducted research from 2018-2020 to accomplish the following: (1) conduct a ticks species and tick-borne disease survey of southern Illinois, (2) create habitat maps for Amblyomma americanum and Dermacentor variabilis in the region, and (3) attempt to identify microhabitat variables influencing tick abundance. To accomplish my first objective, I sampled 26 sites from 11 counties in southern Illinois utilizing the tick drag method. Ticks were then tested for their associated pathogens using quantitative PCR. Four species of tick, Amblyomma americanum (the lone star tick), Dermacentor variabilis (the American dog tick), Ixodes scapularis (the black-legged deer tick), and Amblyomma maculatum (the Gulf Coast tick) were identified. Rickettsia rickettsii and Rickettsia parkeri causative agents of human rickettsiosis, Ehrilichia ewingii and Ehrlichia chaffeensis, causative agents of human granulocytic ehrlichiosis, and Rickettsia amblyommii whose effects are not known, were all found in the study region. The second objective, lone star and American dog tick species distribution models (SDMs), was accomplished using the popular SDM program, Maxent. Maxent uses species presence data and their associated environmental characteristics to create predictions of habitat suitability. The resulting models indicate a correlation for both species with the Shawnee National Forest, likely due to the fragmented habitat structure as indicated by the strong impact of cultivated and managed vegetation on both species models. Lastly, I attempted to identify microhabitat characteristics that influence tick species abundance. Temperature, humidity, canopy closure, and wind speed were measured and recorded and vegetation density estimates and soil moisture were recorded categorically at each site, each visit. Using a chi-squared test I proved that tick abundance is not static, and varies throughout the summer months. I then used a principal component analysis (PCA) to assess correlation between habitat variables and tick abundance, but no signal was detected. This study established a baseline for tick species and tick-borne disease presence in southern Illinois. The information resulting from this study can be used to inform public health officials and inform future tick-borne disease prevention strategies. I recommend continued surveillance of the area to monitor species distributions and resulting pathogen risk to residents.

Neuromuscular paralysis caused by salivary proteins of ticks is a well-known complication after tick bites in Australia, North America, and South Africa. Symptoms may include general weakness, difficulty walking, ascending paralysis, and bulbar paralysis with diplopia, culminating in respiratory failure. In Europe, toxin-mediated paralysis has rarely been noted. We report a case of cranial nerve paralysis with delayed onset after a tick bite in northern Germany.

The occurrence of tick-borne pathogens in dogs on communal land in Botswana was studied using Reverse Line Blot (RLB). Eighty blood samples were collected from dogs that underwent a spay and neuter program in Maun, Botswana. These were sent to the Department of Veterinary Tropical Diseases, University of Pretoria, and were stored at the Molecular Laboratory. DNA was extracted from the samples followed by the Polymerase Chain Reaction (PCR) and the RLB. Six samples were found to be positive for Ehrlichia canis. Two of the samples were positive for a concurrent infection of E. canis and Ehrlichia ruminantium. There was one sample that was positive for the non-pathogenic Ehrlichia sp. Omatjenne. Although six samples were positive for the Babesia/Theileria catch-all probe, none hybridised with any of the species-specific probes. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Veterinary Tropical Diseases / unrestricted

No description available.

Two studies were conducted to evaluate the presence of tick-borne bacterial agents in Amblyomma americanum, lone star tick (LST), and various wildlife in Mississippi. Adult LSTs had DNA evidence of Ehrlichia chaffeensis (3.7%), E. ewingii (6.3%), and Borrelia lonestari (2.6%), while both larval (24.3%) and adult (43.5%) LSTs were positive for a Rickettsia spp. by polymerase chain reaction (PCR). White-tailed deer (WTD) were the only wildlife PCR positive for E. chaffeensis (18.8%), B. lonestari (3.1%), and Anaplasma phagocytophilum (3.1%). In addition, WTD had the highest seroprevalence to B. lonestari (19.3%) and E. chaffeensis (43.9%) antigens while raccoons had the highest seroprevalence to spotted fever group rickettsiae (R. parkeri antigen) (73.7%). These studies demonstrate evidence of potentially zoonotic tick-borne agents in LSTs and wildlife in Mississippi underscoring the importance of monitoring these agents for human and animal health.

No description available.