Specific blood coagulation inhibitors from hematophagous organisms, with different structures and novel mechanism of action, have been described and they represent promising agents for the treatment of a variety of human diseases related to coagulation and cancer. In our lab, the salivary glands transcriptome of the adult Amblyomma cajennense tick was previously characterized by expressed sequence tags (EST). A transcript that codes for a tissue factor pathway inhibitor (TFPI)-like protein with unique structure was found, and the recombinant form of this protein was named Amblyomin-X. This protein was able to inhibit the factor Xa amidolytic activity and the activation of factor X by the extrinsic tenase complex (FVIIa/TF). Herein, it was performed functional and structural evaluation of Amblyomin-X. The CD assay and molecular dynamics simulations revealed that Amblyomin-X is structurally stable and the naturally unfolded regions as well as the presence of three disulfide bridges in its Kunitz-type domain seem to sustain its inhibitory activity. Regarding the electrostatic potential mapping on the Kunitz-type region, the pattern of charged residues was not quite the same in comparison to human TFPI-1 and TFPI-2, pointing out there might be distinct functional and structural features, which are going to be experimentally exploited.

Neovascularization, a process that includes vasculogenesis and angiogenesis, may be a physiological or pathologic event, but in any cases the phenomenon is related to the formation of vascular net and sprouting of endothelial cells from preexisting blood vessel. The tumor environment, which counts on the tumor cell proliferation, is plenty of proangiogenic factors, such as angiogenin, TGF (α and β), FGF, VEGF, all of them playing a crucial role in angiogenesis, an important hallmark of cancer frequently related to a poor prognosis. Therefore, therapies focusing the inhibition of cancer neovasculogenesis have become an interesting strategy for the development of antitumor therapies. In this work, we investigate the effect of tick saliva on the human endothelial cells, in order to understand its inhibitory effects on angiogenesis. To this end, the HUVEC cells were used as model of angiogenesis in vitro and the anti-proliferative, anti-migratory, cytotoxicity was evaluated. Our data depicts that saliva impairs cell development by causing structural changes while precludes cell proliferation and migration, that are crucial events related to angiogenesis. Aiming the identification of the bioactive components related to antiangiogenic activity, saliva was analyzed through the Mass Spectrometry and among all molecules identified, disintegrins and cathepsin L seems to be primarily responsible for the antiangiogenic effects of saliva.

Anaplasma marginale is a Gram-negative, obligate intraerythrocytic bacterium that causes bovine anaplasmosis. While hard ticks of the genera Dermacentor and Rhipicephalus can be biological vectors, transmitting this pathogen via saliva during blood meals, blood-sucking insects, and fomites play a role as mechanical vectors. Little is known about the interaction between Anaplasma marginale and Argasidae ticks. Among soft ticks, Ornithodoros fonsecai (Labruna and Venzal) and Ornithodoros brasiliensis Aragão inhabit environments surrounding localities where many cases of bovine anaplasmosis have been reported. Ticks of the species O. fonsecai parasitize bats, while O. brasiliensis can parasitize different vertebrate species. Therefore, the present study aimed to feed third-instar nymphs artificially (N3) of O. fonsecai and O. brasiliensis using blood samples obtained from a calf naturally infected with A. marginale and rabbit blood added to A. marginale-containing bovine erythrocytes, to investigate the ability of these nymphs to acquire, infect and transstadially perpetuate this agent. For the artificial feeding system, adapted chambers and parafilm membranes were used. Nymphs of both tick species were submitted to different replications weighed before and after each feeding. Blood samples and molted ticks were submitted to DNA extraction, quantitative real-time PCR for the msp1β gene to detect A. marginale DNA, while a semi-nested polymerase chain reaction for the msp1α gene was performed for genotyping. Using calf blood naturally infected with A. marginale, among the three artificial feeding replications performed with O. fonsecai and O. brasiliensis nymphs, the DNA of A. marginale was detected in both nymphs after 30–50 days of molting. For artificial feeding with rabbit blood added to bovine erythrocytes containing A. marginale, the DNA of this pathogen was also detected in both nymph species. As for the assay for the msp1α gene, strains were found Is9; 78 24-2; 25; 23; α; and β. It was concluded that nymphs (N3) of O. fonsecai and O. brasiliensis could feed artificially through a parafilm membrane using blood from calves and rabbits infected by A. marginale. The DNA of A. marginale was detected in nymphs fed artificially of both tick species studied after molt. However, further studies are needed to confirm transstadial perpetuation in other instars and their host transmission capacity.

Ornithodoros fonsecai is a species of argasid tick endemic to Brazil, described in the “São Miguel” cave located in the municipality of Bonito, state of Mato Grosso do Sul, central-western region of Brazil. The artificial feeding technique makes it possible to study the biology of hematophagous arthropods using artificial or natural membranes, as well as different types of blood and anticoagulants. Thus, the aim of the present study was to feed artificially O. fonsecai second instar (N2) nymphs with rabbit blood using parafilm membrane and the anticoagulant Alsever. Ninety percent of the total N2 nymphs engorged and molted to N3 nymphs between 27 and 30 days after feeding, indicating that the use of this anticoagulant is efficient for artificially feeding O. fonsecai N2 nymphs under laboratory conditions.

The coxal fluid of the tick species Ornithodoros brasiliensis (O. brasiliensis) was subjected to detailed chemical analysis using Instrumental Neutron Activation Analysis (INAA) and Energy Dispersive X-ray Fluorescence (EDXRF). These complementary techniques allowed the identification and quantification of key elements such as sodium (Na), chlorine (Cl), potassium (K), and zinc (Zn), along with others like sulfur (S), phosphorus (P), and iron (Fe). The study demonstrated the consistency between the two analytical methods and revealed significant data about the tick's physiological adaptations related to fluid excretion and blood meal processing. Additionally, the absence of heavy metals in the analyzed samples was confirmed. Understanding the composition of coxal fluid is vital for interpreting metabolic processes and exploring its toxicological potential, given the aggressive nature of O. brasiliensis, known to cause severe health impacts on humans and animals. This research contributes to advancing knowledge about tick biology and supports the development of public health measures against tick-borne hazards.