Search Results (262)

The recent discovery of Orthonairovirus songlingense (SGLV) and Norwavirus beijiense (BJNV) in China has raised significant concern due to their potential to cause severe human disease. However, little is known about the structural features and function of their nucleoproteins, which play a key role in the viral life cycle. By combining small-angle X-ray scattering (SAXS) data and AlphaFold 3 simulations, we reconstructed the BJNV and SGLV nucleoprotein structures for the first time. The SGLV and BJNV nucleoproteins have structures that are broadly similar to those of Orthonairovirus haemorrhagiae (CCHFV) nucleoproteins despite low sequence similarity. Based on structural analysis, several residues located in the positively charged region of BJNV and SGLV nucleoproteins have been indicated to be important for viral RNA binding. A positively charged RNA-binding crevice runs along the interior of the SGLV and BJNV ribonucleoprotein complex (RNP), shielding the viral RNA. Despite the high structural similarity between SGLV and BJNV nucleoprotein monomers, their RNPs adopt distinct conformations. These findings provide important insights into the molecular mechanisms of viral genome packaging and replication in these emerging pathogens. Also, our work demonstrates that experimental SAXS data can validate and improve predicted AlphaFold 3 structures to reflect their solution structure and also provides the first low-resolution structures of the BJNV and SGLV nucleoproteins for the future development of POC tests, vaccines, and antiviral drugs. Full article

Background: Bovine babesiosis, caused by the tick-borne apicomplexan parasite Babesia spp., is an economically significant disease that threatens the cattle industry worldwide. Babesia bovis is the most pathogenic species, leading to high morbidity and mortality in infected animals. One promising approach to vaccination against bovine babesiosis involves the use of multiple protective antigens, offering advantages over traditional live-attenuated vaccines. Tools such as immunobioinformatics and reverse vaccinology have facilitated the identification of novel antigens. Enolase, a “moonlighting” enzyme of the glycolytic pathway with demonstrated vaccine potential in other pathogens, has not yet been studied in B. bovis. Methods: In this study, the enolase gene from two B. bovis isolates was successfully identified and sequenced. The gene, consisting of 1366 base pairs, encodes a predicted protein of 438 amino acids. Its expression in intraerythrocytic parasites was confirmed by RT-PCR. Two peptides containing predicted B-cell epitopes were synthesized and used to immunize rabbits. Hyperimmune sera were then analyzed by ELISA, confocal microscopy, Western blot, and an in vitro neutralization assay. Results: The hyperimmune sera showed high antibody titers, reaching up to 1:256,000. Specific antibodies recognized intraerythrocytic merozoites by confocal microscopy and bound to a ~47 kDa protein in erythrocytic cultures of B. bovis as detected by Western blot. In the neutralization assay, antibodies raised against peptide 1 had no observable effect, whereas those targeting peptide 2 significantly reduced parasitemia by 71.99%. Conclusions: These results suggest that B. bovis enolase contains B-cell epitopes capable of inducing neutralizing antibodies and may play a role in parasite–host interactions. Enolase is therefore a promising candidate for further exploration as a vaccine antigen. Nonetheless, additional experimental studies are needed to fully elucidate its biological function and validate its vaccine potential. Full article

Rhipicephalus microplus is an important biological vector as it transmits several pathogens, including Babesia bovis, the causative agent of bovine babesiosis. The available strategies for controlling B. bovis are limited, resulting in substantial challenges for both animal health and livestock management. Infection of the tick midgut is the essential first step for the transmission cycle of B. bovis, yet this process remains largely unexamined. To better understand the first step of tick infection, this study employed a proteomic approach to identify a midgut protein that responds to B. bovis infection. We then used RNA interference for gene silencing to determine if the protein is essential for R. microplus infection. The protein we identified, Rm24, is twofold upregulated in the tick midgut during B. bovis infection. We silenced the gene encoding Rm24 and examined the effect of reduced expression on both tick fitness and B. bovis infection. Our results indicated that silencing the Rm24 gene impacted the survivability of adult female ticks, which exhibited a significant reduction in viability as compared to the control and non-injected groups. Importantly, we found that suppressing the gene encoding Rm24 led to a significant decrease in the number of engorged female ticks infected, with only 15% of female ticks testing positive for B. bovis kinetes as compared to over 50% in the control groups. We also detected a significant reduction in vertical transmission of B. bovis to larval progenies. These findings suggest that the Rm24 protein is critical for infection by B. bovis and could serve as a promising target for future transmission-blocking strategies. Full article

Orthoflavivirus omskense (Omsk hemorrhagic fever virus, OHFV) is a tick-borne flavivirus that causes Omsk hemorrhagic fever (OHF), a severe zoonotic disease endemic to Western Siberia. Despite the fact that the role of NS1 proteins of various mosquito-borne flaviviruses in pathogenesis was investigated and their ability to affect human endothelial permeability was shown, the role of the NS1 protein of OHFV in pathogenesis is unstudied. In this work, the ability of OHFV NS1 to induce human endothelial permeability was investigated for the first time. It was shown that recombinant OHFV NS1 produced in eucaryotic cells directly affects both human lung microvascular endothelial cells (HLMVEC) and human umbilical vein endothelial cells (HUVEC) in vitro. RNAseq of endothelial cells treated with OHFV NS1 indicated that OHFV NS1 enhances the expression of genes associated with cellular stress responses, vascular signaling, and cell–cell junction regulation, resulting in a nonspecific increase in the endothelial permeability of various vessels. These results suggest that the NS1 protein may contribute to OHFV pathogenesis by disrupting endothelial barrier function and promoting vascular leakage, potentially playing a role in the hemorrhagic manifestations of Omsk hemorrhagic fever. Full article

Orthoflavivirus encephalitidis (tick-borne encephalitis virus, TBEV) is of high concern due to its ability to cause severe neurological manifestations. Despite the fact that the role of NS1 proteins from various mosquito-borne flaviviruses in pathogenesis and their ability to affect human endothelial permeability have been investigated, TBEV NS1 has thus far been insufficiently studied. In this study, human endothelial permeability was assessed using TEER and transwell permeability assays. Signaling pathways were determined by RNAseq. The ability of the NS1 protein of TBEV to affect human endothelial permeability was investigated for the first time. It was shown that recombinant TBEV NS1 produced in eucaryotic cells directly affected human lung microvascular endothelial cells (HLMVECs) in vitro but not human umbilical vein endothelial cells (HUVECs). It was indicated that TBEV NS1 induced endothelial hyperpermeability of HLMVECs through activating TNF-α and other inflammatory signaling pathways. Full article

Bovine anaplasmosis, caused by Anaplasma marginale, is a major tick-borne disease in tropical and subtropical regions of the world, leading to significant production losses. Prolonged convalescence periods are common and surviving animals often become subclinical carriers. This study aimed to detect and characterise A. marginale in bovines in smallholder dairy farms across diverse climatic zones of Pakistan using molecular methods. In total, 321 blood DNA samples from apparently healthy cattle (n = 174) and buffaloes (n = 147) from six districts in Pakistan were tested for A. marginale using a nested PCR assay, targeting part of the major surface protein B gene (msp1β) as a genetic marker, followed by agarose gel electrophoresis and selective sequencing of amplicons from test-positive samples. Of the 321 DNA samples tested, 135 (42.1%) were test-positive for A. marginale. Prevalence was significantly higher in cattle (64.4%; 112/174) than in buffaloes (15.6%; 23/147), and female bovines (43.5%; 108/248) were more frequently infected than males (37%; 27/73). Phylogenetic analysis of the msp1β sequence data (n = 42) revealed that A. marginale from Pakistan clustered with those from Brazil, Thailand, South Africa, and the USA. This study represents the first comprehensive investigation of A. marginale from bovines from diverse agroecological zones of Pakistan and will further stimulate population genetic studies of A. marginale and investigations into the economic impact of subclinical infections in bovines in smallholder farming systems. Full article

The saliva of hematophagous arthropods, such as ticks and triatomines, contains bioactive ligands capable of modulating immune molecules, including cytokines. Cytokines play a critical role in immune regulation and have therapeutic relevance in inflammatory and immune-mediated diseases. Despite recent advances, identifying cytokine-binding molecules remains a significant challenge. Interferon-gamma (IFN-γ), interleukin-4 (IL-4), and interleukin-17 (IL-17) are key cytokines involved in inflammation, adaptive immunity, and host defense. This study evaluated the ability of salivary components from Amblyomma sculptum and compared the results to the triatomine Rhodnius neglectus (used as control) to bind to IL-2, IL-4, IL-6, IL-10, IL-17, IFN-γ, and TNF-α using ELISA assays with human cytokines. Saliva samples were tested at dilutions of 1:25, 1:50, and 1:100. Saliva from A. sculptum, which demonstrated significant anti-cytokine activity, was fractionated via HPLC to identify the active components. The results confirmed the inhibitory capacity of A. sculptum saliva on IFN-γ, IL-4, and IL-17, with inhibition rates ranging from 30% to 70%, depending on the cytokine and dilution. No inhibitory activity was observed against IL-2, IL-6, IL-10, or TNF-α. These findings underscore the immunomodulatory role of A. sculptum saliva during tick feeding and suggest its potential for the development of novel immunobiologics to treat inflammatory and immune-mediated diseases. Full article

Rickettsiae are Gram-negative and obligate intracellular bacteria that cause rickettsioses. These pathogens are typically transmitted by arthropod vectors, such as ticks, mesostigmatid mites, and fleas. Rickettsiae are responsible for many emerging infectious diseases worldwide and are the second most frequently reported cause of non-malarial febrile illnesses in Southeast Asia. However, in Malaysia, studies on the prevalence and distribution of rickettsiae have primarily focused on humans, with limited data on these bacteria in vectors and small mammal hosts. Thus, this study aims to investigate the presence of Rickettsia spp. in small mammals and their associated mesostigmatid mites collected from potential rickettsioses areas in Selangor. Animal trapping was conducted across three different ecological study sites comprising a recreational area, agricultural land, and coastal area. A total of 41 small mammals and 363 mesostigmatid mites were collected and identified. Ten percent of the total individual mites were processed for morphological examination, and the remaining mites were then pooled by hosts, with five individual mites per tube, for DNA extraction. The collected samples, comprising blood, animal tissue, and pooled mites, were subjected to DNA extraction and were screened for Rickettsia spp. via nested polymerase chain reaction (PCR), targeting the citrate synthase-encoding gene (gltA) and outer membrane protein B gene (ompB). Interestingly, two pools (3.33%) of Laelaps spp. recovered from Maxomys whiteheadi and Bandicota indica, collected from a recreational area, tested positive for Rickettsia spp. Sequence analysis and phylogenetic tree of the ompB gene revealed the presence of Rickettsia felis in both laelapid mite pools. To our knowledge, this study provides the first molecular detection of R. felis in Laelaps spp. in Malaysia. Full article

Flaviviruses are usually transmitted to humans via mosquito or tick bites, whose infections may lead to severe diseases and fatality. During intracellular infection, they remodel the endoplasmic reticulum (ER) membrane to generate compartments scaffolding the replication complex (RC) where replication of the viral genome takes place. In this study, we purified the ER membrane fraction of virus infected cells to identify the proteins that were enriched during flavivirus infection. We found that tripartite motif-containing proteins (TRIMs) including TRIM38, TRIM21, and TRIM14 were significantly enriched during infection with mosquito-borne (West Nile virus strain Kunjin and Zika virus (ZIKV)) and tick-borne (Langat virus (LGTV)) flaviviruses. Further characterizations showed that TRIM21 and TRIM14 act as restriction factors against ZIKV and LGTV, while TRIM38 hinders ZIKV infection. These TRIMs worked as interferon-stimulated genes to mediate IFN-I response against LGTV and ZIKV infections. Restriction of ZIKV by TRIM14 and TRIM38 coincides with their colocalization with ZIKV NS3. TRIM14-mediated LGTV restriction coincides with its colocalization with LGTV NS3 and NS5 proteins. However, TRIM21 did not colocalize with ZIKV and LGTV NS3 or NS5 protein suggesting its antiviral activity is not dependent on direct targeting the viral enzyme. Finally, we demonstrated that overexpression of TRIM21 and TRIM14 restricted LGTV replication. Full article

Crimean–Congo hemorrhagic fever (CCHF) is a tick-borne zoonotic disease, causing clinical presentations ranging from asymptomatic infection to fatal viral hemorrhagic fever. Throughout the course of CCHF, the levels of certain biomarkers, such as platelets (PLTs), white blood cells (WBCs), C-reactive protein (CRP), and interleukin-6 (IL-6), may vary, decreasing below or rising above normal limits. This study aimed to investigate the role of parameters such as WBC/PLT, WBC/IL-6, WBC/CRP, and WBC/D-dimer ratios in predicting disease prognosis in patients diagnosed with CCHF. The study population consisted of 60 CCHF patients and 30 controls. Statistically significant differences were observed in hemoglobin (HGB), PLT, WBC, activated partial thromboplastin time (aPTT), international normalized ratio (INR), fibrinogen, and d-dimer values between the patients and controls. Statistically significant differences were observed in WBC/aPTT, WBC/fibrinogen, WBC/D-dimer, and WBC/IL-6 values between the patient and control groups. WBC/INR and WBC/fibrinogen values were lower in fatal cases compared to survivors. WBC/D-dimer and WBC/IL-6 values, on the other hand, were higher in fatal cases compared to survivors. In patients requiring intensive care unit (ICU), WBC/PLT, WBC/INR, WBC/aPTT, and WBC/fibrinogen values were higher compared to those who did not. However, WBC/D-dimer and WBC/IL-6 values were lower in patients requiring ICU compared to those who did not. Full article

The advancement of multi-omics technologies is crucial to deepen knowledge on tick biology. These approaches, used to study diverse phenomena, are applied to experiments that aim to understand changes in gene transcription, protein function, cellular processes, and prediction of systems at global biological levels. This review addressed the application of omics data to investigate and elucidate tick physiological processes, such as feeding, digestion, reproduction, neuronal, endocrine systems, understanding population dynamics, transmitted pathogens, control, and identifying new vaccine targets. Furthermore, new therapeutic perspectives using tick bioactive molecules, such as anti-inflammatory, analgesic, and antitumor, were summarized. Taken together, the application of omics technologies can help to understand the protein functions and biological behavior of ticks, as well as the identification of potential new antigens influencing the development of alternative control strategies and, consequently, the tick-borne disease prevention in veterinary and public health contexts. Finally, tick population dynamics have been determined through a combination of environmental factors, host availability, and genetic adaptations, and recent advances in omics technologies have improved our understanding of their ecological resilience and resistance mechanisms. Future directions point to the integration of spatial omics and artificial intelligence to further unravel tick biology and improve control strategies. Full article

Babesia bigemina is one of the most important etiological agents of bovine babesiosis, a tick-borne disease posing a major threat in the livestock industry globally, including South Africa. Despite the huge economic impact of cattle babesiosis in South Africa, antigenic variation observed among B. bigemina strains worldwide has impeded the successful development of a single vaccine with the potential to eliminate the disease. As such, there is still a dearth of information regarding the conservation of B. bigemina genes encoding functionally important proteins that play a crucial role during the invasion of bovine erythrocytes by merozoites. Fifty blood samples previously collected from cattle in eight provinces of South Africa were genetically tested for the presence of B. bigemina DNA fragments using four nested PCR-based assays. The genes targeted coded for SpeI-AvaI restriction fragment, rhoptry-associated protein 1 (BgRAP-1), apical membrane antigen 1 (BgAMA-1) and β-tubulin (BgβTUB). PCR-generated fragments of randomly selected samples were sequenced. BLAST searches in GenBank were performed with newly determined sequences to search for homologous sequences. Neighbor-joining phylogenies were inferred from aligned, contiguous sequences of BgRAP-1, BgAMA-1 and BgβTUB genes. Nested PCR assays generated single fragments of 170 bp, 472 bp, 765 bp and 302 bp for SpeI-AvaI, BgRAP-1, BgAMA-1 and BgβTUB fragments, respectively. Of the 50 bovine samples tested by nested PCR, 82% (42/50; 95% CI = 69.2–90.2%), 68% (34/50; 95% CI = 54.2–79.2%), 50% (25/50; 95% CI = 36.6–63.4%) and 46% (23/50; 95% CI = 33.0–59.6%) possessed B. bigemina-specific SpeI-AvaI, BgRAP-1, BgAMA-1 and BgβTUB DNA fragments, respectively. The BgRAP-1, BgAMA-1 and BgβTUB sequences of South African B. bigemina isolates shared 98–100% similarity with previously reported sequences of strains originating from cattle in countries other than South Africa. The high genetic conservation observed among geographical isolates of B. bigemina suggests the conserved functional role of BgRAP-1 and BgAMA-1 proteins as potential candidates that could be incorporated in recombinant subunit vaccines. Full article

Background: Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel tick-borne bunyavirus, causing the hemorrhagic infectious disease of SFTS, with a case fatality rate up to 30% due to the absence of effective therapeutic interventions. Therefore, it is urgent to develop safe and effective therapeutic drugs to control this viral hemorrhagic fever. Methods: The activity of verteporfin (VP), screened from an FDA-approved drugs library, against SFTSV, was systematically evaluated in Huh7 cells in a wide range of concentrations. We performed time-of-addition experiments with VP, along with binding, endocytosis, and membrane fusion assays, to determine which part of the SFTSV life cycle VP has its effect on. The potential targets of VP were detected by a drug affinity responsive target stability (DARTS) assay. Results: VP exhibited a potent anti-SFTSV activity by blocking the initial viral binding to the target cells during viral entry via significantly inducing the degradation of the viral Gn protein. Conclusions: The VP-induced inhibition of SFTSV binding, the first step of viral invasion, suggested that VP might be an ideal and potent anti-SFTSV agent due to its prophylaxis and therapeutic effects on viral infection. Full article

Despite its ecological and economic importance, many aspects of Varroa destructor’s biology remain poorly understood, particularly its defense mechanisms against pathogens. The limited knowledge of Varroa’s immunity has hindered the development of RNA interference (RNAi)-based strategies targeting immune-related genes. In this study, we investigated the immune gene repertoire of V. destructor by querying its NCBI nr protein database and comparing it to model species of ticks (Ixodes scapularis) and mites (Galendromus occidentalis and Tetranychus urticae). Transcription of candidate immune genes was confirmed by analyzing a de novo assembled transcriptome of V. destructor. Our findings reveal that V. destructor shares key immunological traits with ticks, including lysozymes, chitinases, and thioester-containing proteins (TEPs), but also shares the absence of transmembrane peptidoglycan recognition proteins (PGRPs), Gram-negative binding proteins, and several lectin families involved in pathogen recognition. Additionally, Varroa mites, like ticks, lack homologs of crucial immune signaling components, such as the unpaired ligand (JAK/STAT), Eiger (JNK), and multiple elements of the IMD pathway. They also do not encode canonical antimicrobial peptides (AMPs) like defensins but possess putative homologs of ctenidins, AMPs previously identified in spiders and ticks, which may be adopted as a novel genetic readout for immune response in mites. Our findings lay the groundwork for future functional studies on mite immunity and open new avenues for RNAi-based biocontrol strategies targeting immune pathways to enhance Varroa management. Full article

Background/Objective: Anti-tick vaccines represent a promising alternative to chemical acaricides for the management of ticks on wildlife; however, little progress has been made to produce a vaccine effective in wild hosts that are critical for tick reproduction, such as the white-tailed deer (Odocoileus virginianus). We recently tested Amblyomma americanum salivary and midgut extracellular vesicles as vaccine candidates in white-tailed deer, which resulted in on-host female tick mortality. The objective of this study was to identify the proteins recognized by the antibodies regenerated during these vaccinations to determine potential antigens for vaccine development for white-tailed deer. Methods: Using a proteomic approach, we characterized the cargo within salivary and midgut vesicles. Label-free quantitative proteomics were used to investigate significant changes in protein loading within extracellular vesicles in these two organs. The pre-vaccination and post-vaccination serum from three animals vaccinated with salivary and midgut vesicles and one control animal were used to identify proteins recognized by circulating antibodies. Results: We show that these salivary and midgut vesicles contain a “core-cargo” enriched in chaperones, small GTPases, and other proteins previously reported in small EVs. Label-free quantitative proteomics show significant differences in protein cargo between salivary and midgut vesicles (333 proteins out of 516). Proteomic analysis of immunoprecipitated proteins identified thirty antigens with potential for use in anti-tick vaccines, seven of which we have categorized as high priority. Conclusions: Proteins within tick salivary and midgut vesicles are recognized by antibodies from vaccinated white-tailed deer. These proteins can be further evaluated for their function and potential as vaccine candidates against ticks. Full article