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The Ornithodoros moubata (Om) soft tick, a vector for diseases like tick‐borne human relapsing fever and African swine fever, poses challenges to conventional control methods. With diminishing insecticide efficacy, harnessing the tick's microbiota through innovative approaches like microbiota‐driven vaccination emerges as a promising strategy for sustainable and targeted disease control. This study investigated the intricate relationship between Pseudomonas, a keystone taxon in the Om microbiome, and its impact on tick fitness, microbiome structure and network dynamics. Utilizing in silico analyses and empirical vaccination experiments, the role of Pseudomonas within microbial networks in the tick midguts (MG) and salivary glands (SG) of Om was studied. Additionally, the consequences of anti‐microbiota vaccines targeting Pseudomonas and Lactobacillus on tick fitness, microbiome diversity and community assembly were explored. The result of the study shows that in Om, Pseudomonas plays a central role in microbial networks, influencing keystone species despite being categorized as peripheral (interacting with 47 different taxa, 13 of which are keystone species). Anti‐microbiota vaccination targeting Pseudomonas and Lactobacillus yields distinct effects on tick fitness, with Pseudomonas vaccination significantly impacting female tick survival, while Lactobacillus significantly reduced oviposition and fertility. Microbiome changes post‐vaccination reveal diversity alterations, emphasizing the impact of vaccine choice. Community assembly dynamics and network robustness analyses highlight Pseudomonas' pivotal role, in influencing topological features and network resilience. The findings of the study provide comprehensive insights into the intricate dynamics of Om microbial networks and the potential of targeted microbiota‐driven vaccines for tick control. [ABSTRACT FROM AUTHOR]

Initiation of vitellogenesis by blood feeding is essential for egg maturation in ticks. Nutrients derived from the blood meal are utilized by female ticks to synthesize the yolk protein precursor vitellogenin (Vg). Engorged Ornithodoros moubata ticks can synthesize Vg whether mated or virgin, thus O. moubata is an excellent model for studying the relative roles of blood feeding and mating in tick vitellogenesis. Injection of rapamycin into engorged O. moubata resulted in a reduction of ovarian growth and yolk accumulation in the oocytes of mated females. OmVg expression in the midgut and fat body and protein concentrations in the hemolymph significantly decreased in mated ticks after injection with rapamycin, indicating that inhibition of the nutrient‐sensing target of rapamycin (TOR) pathway disrupts egg maturation at the levels of Vg expression and synthesis. These results suggest that the TOR‐signaling pathway induces vitellogenesis in response to nutritional stimulation after a blood meal in O. moubata and is functionally independent of the mating‐induced pathway. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) causes persistent outbreaks in endemic and non‐endemic regions in Zambia. However, the epidemiology of the disease is poorly understood, particularly during the inter‐epidemic periods. We conducted surveillance for ASF in asymptomatic domestic pigs and soft ticks in selected Zambian provinces. While serum samples (n = 1,134) were collected from crossbred pigs from all study sites between 2014 and 2017, whole blood (n = 300) was collected from both crossbred and indigenous pigs in Eastern Province (EP) in 2017. Soft ticks were collected from Mosi‐oa‐Tunya National Park in Southern Province (SP) in 2019. Sera were screened for antibodies against ASF by ELISA while genome detection in whole blood and soft ticks was conducted by PCR. Ticks were identified morphologically and by phylogenetic analysis of the 16S rRNA gene. Seroprevalence was highest in EP (50.9%, 95% CI [47.0–54.9]) compared to significantly lower rates in SP (2.9%, 95% CI [1.6–5.1]). No antibodies to ASFV were detected in Lusaka Province. In EP, the prevalence of ASFV genome was 11.7% (35/300), significantly higher (OR = 6.2, 95% CI [2.4–16.6]) in indigenous pigs compared to crossbred pigs. The pooled prevalence of ASFV genome in ticks was 11.0%, 95% CI [8.5–13.9]. Free‐range husbandry system was the only factor that was significantly associated with seropositive (p <.0001, OR = 39.3) and PCR‐positive results (p <.001, OR = 5.7). Phylogenetically, based on the p72 gene, ASFV from Ornithodoros moubata ticks detected in this study belonged to genotype I, but they separated into two distinct clusters. Besides confirming ASF endemicity in EP and the presence of ASFV‐infected ticks in SP, these results provide evidence for exposure of domestic pigs to ASFV in non‐endemic regions during the inter‐epidemic period. [ABSTRACT FROM AUTHOR]

Tolypocladium cylindrosporum is a fungus which has been isolated from soil, from asymptomatic plants as an endophyte and has been shown to be pathogenic to several species of arthropods. The objective of the present work was to study a collection of T. cylindrosporum strains to evaluate the characteristics of this fungus as a bioacaricide. The pathogenicity of five different strains of T. cylindrosporum was tested against two tick species, Ornithodoros erraticus and Ornithodoros moubata. Both tick species were susceptible to all the fungal strains. Mortality was greater for O. erraticus and differed among the five developmental stages of the ticks tested and among the fungal treatments. Mean mortality rates were close to 60% for O. erraticus, similar to those reported for other entomopathogenic fungi used for this purpose. The responses of 11 different strains of the fungus to 22°C and 30°C were also studied. Significant differences in temperature tolerance occurred among the strains and growth inhibition was observed at 30°C. Several mycoviruses were found infecting 5 of the 11 strains. However, no clear relationship was found between the presence of viruses and fungal growth or pathogenicity. [ABSTRACT FROM AUTHOR]

Synthesis of the precursor yolk protein vitellogenin (Vg) occurs after engorgement in haematophagous arthropods. We identified the Vg cDNA of the soft tick Ornithodoros moubata ( OmVg) and compared its expression in mated and virgin females. Both mated and virgin females showed increases in OmVg expression after engorgement but expression was higher in mated females than virgin females particularly as time advanced. Delayed mating in virgin females induced an increase in OmVg expression. OmVg expression was observed in the midgut and fat body by whole mount in situ hybridization, but enlarged fat body with high expression occurred in only mated females during the late phase of vitellogenesis. Therefore, engorgement initially induces OmVg expression but mating is necessary for continued Vg expression to produce mature eggs. [ABSTRACT FROM AUTHOR]

Molecular mechanisms of ecdysteroid regulation in development and reproduction have been thoroughly investigated in Diptera and Lepidoptera, but few studies report the molecular actions of ecdysteroids in hemimetabolous insects and more primitive arthropods. Ecdysteroids appear to be the main hormones regulating development and vitellogenesis in ticks. An ecdysteroid receptor that showed high homology with EcRs of other arthropods was isolated from Ornithodoros moubata (OmEcRA). OmEcR expression patterns coincided with ecdysteroid titres in the haemolymph during moulting and vitellogenesis and differed between mated and virgin females. Therefore, OmEcR appears to mediate the regulation of moulting and vitellogenesis by ecdysteroids in O. moubata females as seen in other arthropods. [ABSTRACT FROM AUTHOR]

Omithodoros moubata complex (Argasidae) ticks collected from human dwellings in central Tanzania were found to carry a novel rickettsial species that clustered among the spotted fever group. Atlhough no evidence of human infection was evident, these ticks feed primarily on man, thus providing opportunity for zoonotic infection. [ABSTRACT FROM AUTHOR]

Abstract Two defensin genes A and B were previously demonstrated to be up-regulated by blood feeding in the soft tick, Ornithodoros moubata [Nakajima et al . (2001) Two isoforms of a member of the arthropod defensin family from the soft tick, Ornithodoros moubata (Acari: Argasidae). Insect Biochem Mol Biol 31: 747–751]. In this study, two defensin isoforms C and D similar to defensins A and B were newly cloned. A total of four defensins have been identified in O. moubata . All four Ornithodoros defensins are coded as prepro-defensins. Ornithodoros defensin genes consist of four exons and three introns, an organization reported in mussel defensins but not insect defensins. Ornithodoros defensin C and D genes are predominantly expressed in the midgut and up-regulated in response to blood feeding. The mature peptide of the previously cloned Ornithodoros defensin A was purified from the midgut lumen, indicating defensin is secreted into the midgut. These findings confirm the involvement of Ornithodoros defensin in midgut immunity. [ABSTRACT FROM AUTHOR]

Summary The aim of this study was to determine filial infection prevalence of experimentally infected colony Ornithodoros moubata Walton (Ixodoidea: Argasidae) ticks for African swine fever virus (ASFV). Three groups of ticks were used: an uninfected control group, one group orally infected with the VIC T90/1 isolate and another group orally infected with the LIV 13/33 isolate of ASFV. The results show that filial infection prevalences were not constant but were highly variable between egg batches from different ticks and between successive egg batches from the same tick. Filial infection prevalences ranged from 1.8% to 31.8% for ticks infected with the VICT90/1 isolate and from 1.2% to 35.5% for ticks infected with the LIV 13/33 isolate. A similar pattern was noted after the third feed. Immunohistochemisty showed that virus replicates in the developing larval cells and not in the yolk sac cells or within the outer layers of the eggs. The results show that ASFV can replicate to a high titre (105.1log10HAD50) within the larval cells of the developing egg. [ABSTRACT FROM AUTHOR]

Summary The effects of infection with African swine fever virus (ASFV) on adult and nymphal Ornithodoros moubata Murray (Ixodoidea, Argasidae) ticks were examined. Three groups of ticks were used, an uninfected control group, one group infected with the VIC T90/1 isolate of ASFV and another group infected with the LIV 13/33 isolate of ASFV. Infection with ASFV did not affect the oviposition rates of infected ticks when compared with uninfected ticks. There was no difference between infected and uninfected ticks in progeny hatching rates and first nymphal stage feeding rates. Feeding rates of infected adult ticks were also unaffected. However, a significant increase in mortality rates was observed amongst the adult ticks that fed on an infective bloodmeal compared to ticks fed on an unifected bloodmeal. [ABSTRACT FROM AUTHOR]

Studies the characterization of an alpha-macroglobulin-like glycoprotein isolated from the plasma of the soft tick Ornithodoros moubata. Representative of the alpha-2-macroglobulin family in terrestrial invertebrates; Subunits generated from a precursor polypeptide by post-translational processing; Theoretical significance of the study.