Publications by authors named "Talactac Melbourne Rio"

Ticks, being obligate hematophagous arthropods, are exposed to various blood-borne pathogens, including arboviruses. Consequently, their feeding behavior can readily transmit economically important viral pathogens to humans and animals. With this tightly knit vector and pathogen interaction, the replication and transmission of tick-borne viruses (TBVs) must be highly regulated by their respective tick vectors to avoid any adverse effect on the ticks' biological development and viability.

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Ticks are important vectors of diseases affecting both humans and animals. To be an efficient vector, ticks have to survive infection by pathogens such as the Langat virus (LGTV). One method utilized by ticks is their complex antioxidant mechanism.

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Ticks are hematophagous arthropods, and their blood feeding on vertebrate hosts is essential for their development. The vertebrate blood contains high levels of free iron that can react with oxygen in ticks, resulting in the production of hydrogen peroxide (HO), one of the reactive oxygen species. Peroxiredoxins (Prxs), HO-scavenging enzymes, take on an important role in the ticks' oxidative stress coping mechanism.

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The blood-feeding behavior of ticks has resulted in them becoming one of the most important vectors of disease-causing pathogens. Ticks possess a well-developed innate immune system to counter invading pathogens. However, the coevolution of ticks with tick-borne pathogens has adapted these pathogens to the tick's physiology and immune response through several mechanisms including transcriptional regulation.

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To fully unravel the ixodid ticks' role as vectors of viral pathogens, their susceptibility to new control measures, and their ability to develop acaricide resistance, acclimatization of ticks under laboratory conditions is greatly needed. However, the unique and complicated feeding behavior of these ticks compared to that of other hematophagous arthropods requires efficient and effective techniques to infect them with tick-borne viruses (TBVs). In addition, relatively expensive maintenance of animals for blood feeding and associated concerns about animal welfare critically limit our understanding of TBVs.

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Iron is a very important nutrient for cells; however, it could also cause fatal effects because of its capability to trigger oxidative stress. Due to high exposure to iron from their blood diet, ticks make use of several mechanisms to cope up with oxidative stress. One mechanism is iron sequestration by ferritin and its control protein (IRP).

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  • Haemaphysalis longicornis ticks are significant health threats as they spread various pathogens; current control mainly relies on chemical acaricides.
  • Studies showed that the tick's GST enzymes can metabolize these acaricides, with specific GSTs (HlGST and HlGST2) responding differently to various chemicals.
  • Knockdown of these GST genes increased tick susceptibility to specific acaricides, highlighting their critical role in detoxification and suggesting potential targets for improving control methods.
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Ticks are key vectors of some important diseases of humans and animals. Although they are carriers of disease agents, the viability and development of ticks are not harmed by the infectious agents due to their innate immunity. Antimicrobial peptides directly protect hosts against pathogenic agents such as viruses, bacteria, and parasites.

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  • Thogoto virus (THOV) was recently found in East Asia for the first time, isolated from a tick species in Kyoto, Japan.
  • Researchers tested how well the tick species Haemaphysalis longicornis can carry and transmit THOV, finding that ticks could be infected through a specific microinjection method.
  • The study concluded that H. longicornis can effectively transmit THOV to mice, indicating it may be the main tick vector for this virus in Japan.
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  • Ticks rely on blood from vertebrates to thrive, which leads to high levels of harmful reactive oxygen species (ROS), like hydrogen peroxide (HO), in their tissues.
  • A new method combining a fluorescent probe and a clearing technique was developed to visualize HO in unfed tick tissues, revealing that HO and paraquat increase oxidative stress in specific tissues.
  • The study also demonstrated that peroxiredoxins (PRXs) help regulate HO levels in tick cell cultures, with evidence showing that knocking down PRX genes increases HO levels, enhancing our understanding of tick biology and oxidative stress mechanisms.
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Background: Ticks are obligate hematophagous parasites important economically and to health. Ticks consume large amounts of blood for their survival and reproduction; however, large amounts of iron in blood could lead to oxidative stress. Ticks use several molecules such as glutathione S-transferases (GSTs), ferritins, and peroxiredoxins to cope with oxidative stress.

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  • Ticks need blood from vertebrates for survival, which increases hydrogen peroxide levels that can be damaging, so they use antioxidant enzymes like peroxiredoxins to manage this.
  • This study evaluated the potential of a tick peroxiredoxin (HlPrx2) as a vaccine candidate by expressing it in E. coli, confirming its purity and safety, and testing its ability to stimulate an immune response in mice.
  • The results showed that rHlPrx2 could provoke an immune response in mice, though it did not significantly impact the nymphal ticks, suggesting that it still holds potential as a vaccine candidate against ticks due to its immunogenic properties.
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Due to the continuous threat of ticks and tick-borne diseases to human and animal health worldwide, and the drawbacks of chemical acaricide application, many researchers are exploring vaccination as an alternative tick control method. Earlier studies have shown that host antibodies can circulate in the ticks, but it has not been confirmed whether these antibodies can be passed on to the eggs. We previously reported that ticks infesting rabbits immunized with a recombinant secretory ferritin of Haemaphysalis longicornis (HlFER2) had reduced egg production and hatching.

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The tick-borne encephalitis virus (TBEV) serocomplex of flaviviruses consists of arboviruses that cause important diseases in animals and humans. The transmission of this group of viruses is commonly associated with tick species such as Ixodes spp., Dermacentor spp.

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  • Tick defensins, like HEdefensin identified in Haemaphysalis longicornis, are antimicrobial peptides crucial for tick immunity, showing increased expression during blood feeding.
  • HEdefensin exhibits significant virucidal activity against Langat virus (LGTV) in lab tests, while it does not affect adenovirus and gene silencing did not impact virus levels significantly.
  • This research emphasizes the need for further exploration into HEdefensin's role in tick immunity and its potential to combat various pathogens like bacteria, fungi, and parasites.
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  • Ticks are blood-feeding parasites that accumulate high levels of iron, leading to oxidative stress due to reactive oxygen species like hydrogen peroxide (H2O2).
  • The study focused on peroxiredoxin (Prx), an enzyme that helps manage H2O2 levels in the hard tick Haemaphysalis longicornis by looking at its expression during blood feeding and its impact on tick health.
  • Results showed that blood-feeding significantly upregulated the HlPrx2 gene, and knocking it down led to increased H2O2 levels along with reduced body and egg weights, suggesting HlPrx2 is crucial for tick survival and reproduction, highlighting its potential as a target for tick control.
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The continuous emergence of tick-borne diseases and chemical acaricide-resistant tick strains necessitates the development of new and more effective control strategies. RNA interference through the injection of double-stranded RNA (dsRNA) has been a very useful tool in tick research for evaluating gene function. However, this technique can be sophisticated due to the required equipment and technique.

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  • In vitro cultivation and cryopreservation of Babesia bovis and Babesia bigemina are well-established, while Babesia gibsoni's cryopreservation methods are not fully developed.
  • This study compared various freezing media for B. gibsoni cryopreservation, including commercial options like CELLBANKER® and STEM-CELLBANKER®, as well as conventional methods using different cryoprotectants.
  • The findings suggest that the CELLBANKER® series and other commercial media are more effective for B. gibsoni cryopreservation than existing methods for bovine Babesia and Plasmodium parasites, potentially enhancing the stability of B. gibsoni cultivation.
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Background: Longicin is a defensin-like peptide, identified from the midgut epithelium of hard tick Haemaphysalis longicornis. Several studies have already shown the antimicrobial and parasiticidal activities of longicin peptide and one of its synthetic partial analogs, longicin P4. In this study, longicin peptides were tested for potential antiviral activity against Langat virus (LGTV), a tick-borne flavivirus.

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Iron is an indispensable element for most microorganisms, including many pathogenic bacteria. Iron-withholding is a known component of the innate immunity, particularly of vertebrate hosts. Ticks are vectors of multiple pathogens and reports have shown that they naturally harbor several bacterial species.

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C-type lectins (CLecs) play an important role in innate immunity against invaders. In this study, a novel CLec was identified from Haemaphysalis longicornis ticks (HlCLec). HlCLec contains a signal peptide and a transmembrane region.

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A tumor necrosis factor receptor-associated factor-type zinc finger domain containing protein 1 (TRAFD1) is a negative feedback regulator that controls excessive immune responses in vertebrates. The sequence of tick hemolymph TRAFD1 from the hard tick Haemaphysalis longicornis (HlTRAFD1) was analyzed after identification and cloning from the expressed sequence tag database. RT-PCR and Western blot analyses showed that HlTRAFD1 transcript and protein levels after blood feeding were present in all developmental stages, and the transcript level was consistently high in all organs examined from adult female ticks upon engorgement.

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Haemaphysalis longicornis is a tick known for transmitting Babesia parasites, including Babesia gibsoni, in East Asian countries. The vector tick must have strategies to control Babesia parasites, while Babesia parasites are also considered to establish an evasive mechanism from the tick's innate immunity. Due to this mutual tolerance, H.

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