Prediction of Novel Drug Targets and Vaccine Candidates against Human Lice (Insecta), Acari (Arachnida), and Their Associated Pathogens

The emergence of drug-resistant lice, acari, and their associated pathogens (APs) is associated with economic losses; thus, it is essential to find new appropriate therapeutic approaches. In the present study, a subtractive proteomics approach was used to predict suitable therapeutics against these vectors and their infectious agents. We found 9701 proteins in the lice (Pediculus humanus var. corporis) and acari (Ixodes scapularis, Leptotrombidium deliense), and 4822 proteins in the proteomes of their APs (Babesia microti, Borreliella mayonii, Borrelia miyamotoi, Borrelia recurrentis, Rickettsia prowazekii, Orientia tsutsugamushi str. Boryong) that were non-homologous to host proteins. Among these non-homologous proteins, 365 proteins of lice and acari, and 630 proteins of APs, were predicted as essential proteins. Twelve unique essential proteins were predicted to be involved in four unique metabolic pathways of lice and acari, and 103 unique proteins were found to be involved in 75 unique metabolic pathways of APs. The sub cellular localization analysis of 115 unique essential proteins of lice and acari and their APs revealed that 61 proteins were cytoplasmic, 42 as membrane-bound proteins and 12 proteins with multiple localization. The druggability analysis of the identified 73 cytoplasmic and multiple localization essential proteins revealed 22 druggable targets and 51 novel drug targets that participate in unique pathways of lice and acari and their APs. Further, the predicted 42 membrane bound proteins could be potential vaccine candidates. Screening of useful inhibitors against these novel targets may result in finding novel compounds efficient for the control of these parasites.

Real time micro-organisms PCR in 104 patients with polymorphic signs and symptoms that may be related to a tick bite

Introduction Ticks are frequently polyinfected and can thus transmit numerous microorganisms. A large number of bacteria, parasites and viruses are transmitted by tick bites and could cause different signs and symptoms in patients. The main goal of this study was to search for these numerous microorganisms in patients presenting with persistent polymorphic syndrome possibly due to a tick bite (SPPT). Patients and methods The following microorganisms were searched for in saliva, urine, venous and capillary blood by using real time PCR: Borrelia burgdorferi sensu lato, Borrelia miyamotoi, Borrelia hermsii, Bartonella spp., Bartonella quintana, Bartonella henselae, Ehrlichia spp., Anaplasma spp., Rickettsia spp., Coxiella burnetii, Brucella spp., Francisella tularensis, Mycoplasma spp., Chlamydia spp., Babesia spp., Theileria spp. Results 104 patients were included. 48% of the patients were poly-infected, and 25% harboured at least three different microorganisms. Borrelia spp. were not the most frequent bacteria observed, observed far behind Mycoplasma spp., Rickettsia spp. and Ehrlichia spp. which were the most frequent microorganisms observed. Piroplasms were found in a significant number of patients. The most sensitive matrix was saliva, followed by urine, capillary blood and venous blood. Conclusion Our prospective study has shown that patients with SPPT, a syndrome close to fibromyalgia, could harbour several tick borne microorganisms.

Detection of Borrelia miyamotoi in Ixodidae Ticks Collected in the South of Western Siberia

Objective of the study was to assess the level of infection with Borrelia miyamotoi in ticks Ixodes persulcatus and Ixodes pavlovskyi collected in the south of Western Siberia.Materials and methods. 688 ticks I. persulcatus and I. pavlovskyi collected on the territory of Novosibirsk, Tomsk and Kemerovo Regions were examined. Borrelia DNA was detected by a two-round polymerase chain reaction with specifc primers to the omp66 gene region, followed by sequencing of the isolated fragments and phylogenetic analysis, including the sequences of prototype isolates published in the international GenBank database. Comparison and analysis of nucleotide sequences was carried out using the MEGA 7 software package. In parallel, the samples were examined for the presence of the agents of transmissible infections – West Nile fever and tick-borne encephalitis, anaplasmosis, ehrlichiosis, babesiosis, bartonellosis and candidate pathogens of tick-borne rickettsiosis through RT-PCR and PCR with species-specifc and genus-specifc primers.Results and discussion. The genetic material of B. miyamotoi was found in 2.2 % of I. persulcatus and I. pavlovskyi ticks in the Tomsk, Novosibirsk, and Kemerovo Regions and their appurtenance to the Asian genotype was determined. It was revealed that the degree of similarity of the omp66 gene fragments within the group of isolates of the Asian genotype was 100 %. No relation between B. miyamotoi and a specifc vector species was identifed.

Surveillance and Molecular Identification of Borrelia Species in Ticks Collected at U.S. Army Garrison Humphreys, Republic of Korea, 2018–2019

Tick-borne pathogens are contributing factors for the increased incidence of vector-borne diseases throughout the world, including Lyme borreliosis, one of the most prevalent spirochetes belonging to the Borrelia burgdorferi sensu lato group. The present study focused on the detection of Borrelia species from hard ticks collected at U.S. Army Garrison Humphreys, Republic of Korea (ROK), using molecular and genotypic analyses. Tick-borne disease surveillance was conducted from January to December, 2018–2019. A total of 24,281 ticks (2 genera and 5 species) were collected from road-killed Korean Water deer (KWD) and by tick drag. Haemaphysalis longicornis (92.0%) was the most commonly collected species, followed by Haemaphysalis flava (4.9%), Ixodes nipponensis (3.1%), Haemaphysalis phasiana (0.07%), and Haemaphysalis japonica (<0.01%). The ospA gene sequences of Borrelia afzelii were detected in 12/529 pools of I. nipponensis. Three and one pools were positive for B. afzelii and Borrelia miyamotoi, respectively, using the 16s rRNA gene. None of the pools of Haemaphysalis ticks collected from KWD or by tick drag were positive for Borrelia species. I. nipponensis was collected throughout the year from KWD and from February to November by tick drag, suggesting that they were active throughout the year, and expanding the risk period for acquiring Lyme borreliosis and Borrelia relapsing fever in the ROK. This study assessed disease risk factors associated with the prevalence of Lyme disease in ticks collected from KWD and by tick drag using molecular analysis. These results provide an understanding and awareness into the prevalence and molecular characteristics of Borrelia species in the ROK.

The Genetic Diversity of Rickettsiella Symbionts in Ixodes ricinus Throughout Europe

Rickettsiella species are bacterial symbionts that are present in a great variety of arthropod species, including ixodid ticks. However, little is known about their genetic diversity and distribution in Ixodes ricinus, as well as their relationship with other tick-associated bacteria. In this study, we investigated the occurrence and the genetic diversity of Rickettsiella spp. in I. ricinus throughout Europe and evaluated any preferential and antagonistic associations with Candidatus Midichloria mitochondrii and the pathogens Borrelia burgdorferi sensu lato and Borrelia miyamotoi. Rickettsiella spp. were detected in most I. ricinus populations investigated, encompassing a wide array of climate types and environments. The infection prevalence significantly differed between geographic locations and was significantly higher in adults than in immature life stages. Phylogenetic investigations and protein characterization disclosed four Rickettsiella clades (I–IV). Close phylogenetic relations were observed between Rickettsiella strains of I. ricinus and other arthropod species. Isolation patterns were detected for Clades II and IV, which were restricted to specific geographic areas. Lastly, although coinfections occurred, we did not detect significant associations between Rickettsiella spp. and the other tick-associated bacteria investigated. Our results suggest that Rickettsiella spp. are a genetically and biologically diverse facultative symbiont of I. ricinus and that their distribution among tick populations could be influenced by environmental components.

Transmissible tick-borne infections in the south of the Far East

Natural foci of tick-borne infections associated with tick-borne encephalitis virus (TBEV), borrelia (Borrelia burgdorferi sensu lato), including Borrelia miyamotoi, anaplasma, ehrlichia and rickettsia are widespread in the Primorsky Krai. The carriers of these pathogens are ixodid ticks. The population of Primorsky Krai meets with ticks in natural biotopes, as well as in anthropurgic foci. The aim of the study is to give a comparative assessment of the epizootic activity in the natural foci of transmissible tick-borne infections in the south of Primorsky Krai in the epidemic seasons of 2017–2020. In this periodixodid ticks (3778 samples), taken from humans in natural foci in the Primorsky Territory, were studied. The TBEV antigen was determined by enzyme-linked immunosorbent assay (ELISA), genetic markers of pathogens were detected by real-time polymerase chain reaction (RT-PCR). The incidence of tick-borne infections has been analyzed. Based on the results of monitoring the infection of ixodid ticks, we found that 26.9 % of the studied samples were infected with various pathogens of tick-borne infections. Low infection rate of TBEV in ixodid ticks and high infection with pathogens of a bacterial nature were established. TBEV antigen was detected in 30 cases (1.4 %), TBEV RNA was detected in 20 cases (0.7 %), Borrelia burgdorferis. l. DNA — in 820 cases (30.7 %), ehrlichia — in 64 (2.4 %), anaplasma — in 55 (2.1 %).Genetic marker of Rickettsia spp. was detected in 3 cases (0.9 %) out of 322 examined ixodid ticks, B. miyamotoi — in 26 cases (6.9 %) out of 373 examined samples. A positive correlation was noted between the incidence rates and the cases of detection of TBEV and Lyme borreliosis in ticks. The results obtained indicate the need for annual epidemiological monitoring of infections transmitted by ixodid ticks, to determine the real epidemic situation and the activity of the functioning natural foci transmissible tick-borne infections on the territory of Primorsky Krai.

Occurrence of tick-borne pathogens in questing Ixodes ricinus ticks from Wester Ross, Northwest Scotland

Background Lyme borreliosis and other tick-borne diseases emerge from increased interactions between humans, other animals, and infected ticks. The risk of acquiring a tick-borne infection varies across space and time, so knowledge of the occurrence and prevalence of pathogens in ticks can facilitate disease diagnosis in a specific area and the implementation of mitigation measures and awareness campaigns. Here we identify the occurrence and prevalence of several pathogens in Ixodes ricinus ticks in Wester Ross, Northwest Scotland, a region of high tourism and tick exposure, yet data-poor in terms of tick-borne pathogens. Methods Questing I. ricinus nymphs (n = 2828) were collected from 26 sites in 2018 and 2019 and tested for the presence of tick-borne pathogens using PCR-based methods. Prevalence was compared with other regions of Scotland, England, Wales, and the Netherlands. Results Anaplasma phagocytophilum (4.7% prevalence), Borrelia burgdorferi sensu lato (s.l.) (2.2%), Babesia from clade X (0.2%), Rickettsia helvetica (0.04%), and Spiroplasma ixodetis (0.4%) were detected, but no Neoehrlichia mikurensis, Borrelia miyamotoi, or Babesia microti. Typing of A. phagocytophilum using a fragment of the GroEL gene identified the presence of both ecotype I and ecotype II. Genospecies identification of Borrelia burgdorferi s.l. revealed B. afzelii (53% of infected nymphs), B. garinii (9%), B. burgdorferi sensu stricto (7%), and B. valaisiana (31%). We found similar prevalence of A. phagocytophilum in Wester Ross as in the Netherlands, but higher than in other parts of Great Britain. We found lower B. burgdorferi s.l. prevalence than in England or the Netherlands, and similar to some other Scottish studies. We found higher prevalence of B. valaisiana and lower prevalence of B. garinii than in other Scottish studies. We found S. ixodetis at much lower prevalence than in the Netherlands, and R. helvetica at much lower prevalence than in England and the Netherlands. Conclusions As far as we know, this is the first description of S. ixodetis in Great Britain. The results are relevant for disease surveillance and management for public and veterinary health. The findings can also aid in designing targeted public health campaigns and in raising awareness among outdoor recreationists and professionals. Graphical abstract