Vaccination of cattle against Rhipicephalus appendiculatus with detergent solubilized tick tissue proteins and purified 20 kDa protein

Anti-HIV Humoral Response Induced by Different Anti-Idiotype Antibody Formats: An In Silico and In Vivo Approach

Despite advancements in vaccinology, there is currently no effective anti-HIV vaccine. One strategy under investigation is based on the identification of epitopes recognized by broadly neutralizing antibodies to include in vaccine preparation. Taking into account the benefits of anti-idiotype molecules and the diverse biological attributes of different antibody formats, our aim was to identify the most immunogenic antibody format. This format could serve as a foundational element for the development of an oligo-polyclonal anti-idiotype vaccine against HIV-1. For our investigation, we anchored our study on an established b12 anti-idiotype, referred to as P1, and proposed four distinct formats: two single chains and two minibodies, both in two different orientations. For a deeper characterization of these molecules, we used immunoinformatic tools and tested them on rabbits. Our studies have revealed that a particular minibody conformation, MbVHVL, emerges as the most promising candidate. It demonstrates a significant binding affinity with b12 and elicits a humoral anti-HIV-1 response in rabbits similar to the Fab format. This study marks the first instance where the minibody format has been shown to provoke a humoral response against a pathogen. Furthermore, this format presents biological advantages over the Fab format, including bivalency and being encoded by a monocistronic gene, making it better suited for the development of RNA-based vaccines.

Amblyomma americanum: specific uptake of immunoglobulins into tick hemolymph during feeding

The passage of immunoglobulins in the blood meal into hemolymph prompts development of vaccines against internal antigens of ticks, but little is known about kinetics and specificity of the immunoglobulin uptake. We used capillary feeding of adult Amblyomma americanum hard ticks to introduce compounds into the midgut and then examined the hemolymph after various times for their presence and concentration. Immunoglobulins of different sources, albumin, choramphenicol acetyltransferase, inulin, and mannitol were labeled with (125)I, (14)C, or biotin. With the exception of the carbohydrate inulin, all the compounds entered the hemolymph of tick during capillary feeding. The small molecule mannitol had the highest rate of entry at 9% after 6 h. Among proteins, the entry of immunoglobulin G (IgG) of different species into the hemolymph was greater at 6% after 6 h than for the smaller proteins albumin or choramphenicol acetyltransferase at 1 and 3%, respectively. The entry of denatured IgG was equal to that of nondenatured protein. There was no evidence of degradation of the IgG or of its binding to cells once it entered the hemolymph. A monoclonal IgG antibody labeled with biotin entered the hemolymph and retained its ability to bind to its specific antigen in an immunoassay. Although different proteins entered the hemolymph after capillary feeding, there was evidence of a specific mechanism for immunoglobulin uptake.

Issues in tick vaccine development: identification and characterization of potential candidate vaccine antigens

It is well established that acquired immunity against tick infestation can be induced by repeated tick infestation or by active immunization with either crude or purified native as well as recombinant antigens. This review provides insights into the development of tick vaccines with reference to identification, purification and molecular cloning of candidate target antigens.

Immunological control of ectoparasites: past achievements and future research priorities

Recombinant vaccines are available for the control of the tick Boophilus microplus, while progress has been made in the development of vaccines against Lucilia cuprina and Chrysomya bezziana. Literature suggests that the control of other ectoparasites is feasible, either through the duplication in a vaccine of naturally acquired immunity or through 'concealed' antigen vaccines. Major deficiencies in our current knowledge however point to possible research opportunities for the future. The identification of protective antigens from all species is proceeding slowly, particularly for the antigens of naturally acquired immunity. Our capacity to produce effective recombinant antigens has progressed greatly, though there remains a major difficulty where some or all of the protective effect is due to immunogenic oligosaccharide. Our understanding of protective mechanisms is limited. The delivery of the appropriate immunological response remains difficult. Nevertheless, some of the most critical areas of ignorance are in basic biological issues: factors which affect the susceptibility of particular pest species to immunological attack and the implications of vaccine-induced effects for pest and disease control under field conditions. Increasingly too, effective pest control is likely to demand the integration of a variety of control technologies. The study of this integration is in its infancy.

Immunology of the tick-host interaction and the control of ticks and tick-borne diseases

The first experimental vaccination against ticks was carried out 60 years ago. Since then, progress has been slow, although the recent commercial release of a recombinant vaccine against Boophilus microplus is significant. The nature of naturally acquired protective immunity against ticks is poorly understood, particularly in the important, domesticated ruminant hosts. Characterization of the antigens of naturally acquired immunity remains limited, although more has been achieved with 'concealed' antigens. Crucial questions remain about the true impact of tick-induced immunosuppression and the effect of immunity on the transmission of tick-borne diseases, despite some fascinating and important recent results, as discussed here by Peter Willadsen and Frans Jongejan.

Targeting ticks for control of selected hemoparasitic diseases of cattle

Development in and transmission of hemoparasites by tick vectors are phenomena closely synchronized with the tick feeding cycle. In all known life cycles, initial infection of tick tissues occurs in midgut epithelial cells and transmission is effected as ticks feed after parasites have developed and multiplied in salivary glands. Many factors reviewed affect development and transmission of hemoparasites by ticks including age of ticks, artificial temperature, climate and/or season, tick stage or sex, hemoparasite variation, concurrent infection of ticks with other pathogens, host cell susceptibility, transovarial transmission, effect of hemoparasites on tick biology, and the effect of infecting parasitemia level in cattle on infection rates in ticks. Four hemoparasites of cattle, Anaplasma marginale, Cowdria ruminantium, Theileria parva, and Babesia spp., are all dependent on ticks for biological transmission. Babesia is transmitted transovarially whereas the other three are transmitted transstadially. Mechanical transfer of infective blood via fomites and mouthparts of biting arthropods is also a major means of transmission for Anaplasma marginale but not of the others. Potential control methods for hemoparasites that target parasites as they are developing in their respective tick hosts include tick control, vaccines (against ticks and parasites), and drugs (against ticks and parasites). Successful application of control strategies will be dependent upon thorough understanding of parasite developmental cycles, biology of the tick vectors and the immune response of cattle to ticks and to hemoparasites. The most effective control measures will be those that are targeted against both ticks and the hemoparasites they vector.

Cell membrane receptors and regulation of cell function in ticks and blood-sucking insects

Immunoglobulins cross the midgut epithelium and enter the haemolymph of many blood-feeding arthropods without losing their immunological properties. Antigens essential to the survival of the blood-sucking arthropods which may be affected by the small amounts of specific antibody that cross the gut epithelium include membrane receptors or other factors which regulate cell function. Membrane receptors implicated in transmembrane signalling in response to specific neural and endocrine factors fall into three major classes: (1) gated ion channels, (2) agonist-stimulated tyrosine kinases and (3) receptors that interact with GTP-binding (G) proteins. Examples of all three types have been found in insects and ticks. A dopamine receptor interacts with a G-protein essential for controlling fluid secretion by the salivary glands of ixodid ticks. Another receptor in the ixodid tick salivary gland binds a neuropeptide from the tick synganglion and stimulates turnover of plasma membrane phosphoinositides, but its mechanisms of transmembrane signalling and function remain elusive. Another large class of membrane receptors are those concerned with endocytosis. Examples of receptor-mediated endocytosis include incorporation of vitellogenin by developing oocytes in mosquitoes and ticks and uptake of lysed blood-meal components by digest cells of the tick gut. Many cell membrane receptors and possibly hormones could serve as targets for vaccines in blood-feeding insects and ticks. The major challenge is to identify and characterize essential internal receptors and cellular components that are accessible to and affected by specific antibodies that are introduced into the body of blood-feeding arthropods.