Comparative Proteomic Analysis of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) Tropical and Temperate Lineages: Uncovering Differences During Ehrlichia canis Infection

Optimization of reversed-phase solid-phase extraction for shotgun proteomics analysis

Reversed-phase solid-phase extraction (SPE) is the method of choice for the purification of proteomics samples. Even though the efficacy of SPE methods is sample type-dependent, the manufacturers' protocols are used in most studies. Using an optimized SPE method can lead to a substantial gain in identification and recovery. In this tutorial, we give a brief introduction to the most important parameters influencing SPE performance, and we present a short workflow (16 measurements) for optimizing the SPE procedure. This is complemented by method performance assessment instructions and a short troubleshooting guide to help users further understand and investigate their SPE methods.

Molecular detection of tick-borne pathogens in Rhipicephalus sanguineus sensu stricto collected from dogs in the steppe and high plateau regions of Algeria

Epidemiology and distributions of canine tick-borne diseases as well as their veterinary and zoonotic significance are poorly understood in Algeria. The present study describes a molecular investigation of important tick-borne pathogens in Rhipicephalus sanguineus sensu stricto collected from domestic dogs in steppe and high plateau areas of central and eastern Algeria. In total, 1,043 ticks were collected from 147 domestic dogs, including 756 ticks from 124 dogs in the steppe region of Djelfa, and 287 ticks from 23 dogs in the high plateau area of Bordj Bou Arreridj. Ticks were divided into 384 pools (309 pools from Djelfa and 75 pools from Bordj Bou Arreridj) and tested for genomic materials of Crimean-Congo hemorrhagic fever virus (CCHFV) as well as DNA for Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis, Rickettsia spp., Babesia spp., and Hepatozoon spp. using PCR, sequencing and phylogenetic analysis. Hepatozoon spp. was most prevalent, with 160 positive pools (41.70%), and 12 of these were sequenced and identified as Hepatozoon canis. Babesia spp. was detected in 50 samples (13.0%), of which 11 were sequenced and identified as Babesia vogeli. A. platys and E. canis were detected in 92 (24.0%) and 15 (3.9%) of tested samples, respectively. Rickettsia spp. were detected in 24 (6.3%) samples, including 11 samples identified as R. massiliae, 6 samples identified as R. conorii conorii, and 7 samples could not be identified to species level. All 384 pools tested negative for CCHFV and A. phagocytophilum. In addition to detection of R. conorii conorii, R. massiliae, and E. canis, the present study provides the first molecular data for occurrence of A. platys, B. vogeli, and H. canis in Rh. sanguineus s.s. infesting dogs in Algeria. Further large scale studies should be conducted to better understand the epidemiology, distributions and importance of canine tick-borne pathogens in Algeria.

Characterization of tick salivary gland and saliva alphagalactome reveals candidate alpha-gal syndrome disease biomarkers

BACKGROUND

Ticks are obligate hematophagous arthropods that synthesize the glycan Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal) associated with the alpha-gal syndrome (AGS) or allergy to mammalian meat consumption.

RESEARCH DESIGN AND METHODS

In this study, we used a proteomics approach to characterize tick proteins in salivary glands (sialome SG), secreted saliva (sialome SA) and with α-Gal modification (alphagalactome SG and SA) in model tick species associated with the AGS in the United States (Amblyomma americanum) and Australia (Ixodes holocyclus). Selected proteins reactive to sera (IgE) from patients with AGS were identified to advance in the identification of possible proteins associated with the AGS. For comparative analysis, the α-Gal content was measured in various tick species.

RESULTS

The results confirmed that ticks produce proteins with α-Gal modifications and secreted into saliva during feeding. Proteins identified in tick alphagalactome SA by sera from patients with severe AGS symptomatology may constitute candidate disease biomarkers.

CONCLUSIONS

The results support the presence tick-derived proteins with α-Gal modifications in the saliva with potential implications in AGS and other disorders and protective capacity against tick infestations and pathogen infection. Future research should focus on the characterization of the function of tick glycoproteins with α-Gal in tick biology and AGS.

Current status of resistance to ivermectin in Rhipicephalus sanguineus sensu stricto infesting dogs in three provinces in Argentina

Intensive use of macrocyclic lactones for parasite control exerts strong selective pressure for arthropods such as ticks to become resistant to them. Rhipicephalus sanguineus sensu stricto is a tick and disease vector of significant public health and veterinary importance worldwide. We assessed the toxicological response to the macrocyclic lactone ivermectin (IVM) in R. sanguineus s.s. infesting dogs in Argentina. Samples of nine tick populations were obtained by inspecting dogs at veterinary clinics, hospitals, or rural areas in the provinces of San Luis, Rio Negro, and Buenos Aires. Pet owners were interviewed to gather data on the history of dog treatment with ectoparasiticides. The larval immersion test was used to assess the toxicological response of R. sanguineus s.s. to IVM. Dose-response mortality regressions, lethal concentrations (LC), and slope were calculated by probit analysis. The lowest LC concentrations were used to designate the reference susceptible population because a laboratory reference strain of R. sanguineus s.s. does not exist in Argentina. Compared with the most susceptible tick population in this study, six populations (66.66%) were classified as resistant to IVM. A clear interpopulation variation in the level of IVM resistance was present (resistance ratios at LC_50% ranged from 1.0 to 18.33 and at LC_99% ranged from 1.0 to 8.96). In San Luis Province, all tick populations were classified as resistant. The highest level of IVM resistance (resistance ratio at LC_50%:18.83 and LC_99%:8.96) was found in a population of R. sanguineus s.s. from a rural area in the province of Buenos Aires. It is concluded that populations of R. sanguineus s.s. from dogs in three provinces of Argentina were resistant to IVM. Clear interpopulation variation in the level of IVM resistance was present.

Analysis on the prokaryotic microbiome in females and embryonic cell cultures of Rhipicephalus sanguineus tropical and temperate lineages from two specific localities in Brazil

Two lineages of Rhipicephalus sanguineus are known in Brazil: the temperate or southern and the tropical or northern populations. The distribution patterns of both lineages of R. sanguineus have epidemiological implications that can affect vectorial competence concerning Ehrlichia canis, the agent of canine monocytic ehrlichiosis. Intending to identify the microbiomes of both lineages and compare microorganisms in R. sanguineus, we used the 16S rRNA (V4-V5 region) gene-based metataxonomic approach, through NGS sequencing on the MiSeq Illumina platform. We selected specimens of females from the environment and samples of primary embryonic cell cultures, from both lineages, and this was the first study to investigate the prokaryotic microbiome in tick cell cultures. The results showed that many bacterial taxa detected in the samples were typical members of the host environment. A significant diversity of microorganisms in R. sanguineus females and in embryonic cell cultures from both lineages was found, with emphasis on the presence of Coxiella in all samples, albeit in different proportions. The Coxiella species present in the two lineages of ticks may be different and may have co-evolved with them, thus driving different patterns of interactions between ticks and the pathogens that they can harbor or transmit to vertebrate hosts.