Mining gene expression data for rational identification of novel drug targets and vaccine candidates against the cattle tick, Rhipicephalus microplus

Control of complex parasites via vaccination remains challenging, with the current combination of vaccines and small drugs remaining the choice for an integrated control strategy. Studies conducted to date, are providing evidence that multicomponent vaccines will be needed for the development of protective vaccines against endo- and ectoparasites, though multicomponent vaccines require an in-depth understanding of parasite biology which remains insufficient for ticks. With the rapid development and spread of acaricide resistance in ticks, new targets for acaricide development also remains to be identified, along with novel targets that can be exploited for the design of lead compounds. In this study, we analysed the differential gene expression of Rhipicephalus microplus ticks that were fed on cattle vaccinated with a multi-component vaccine (Bm86 and 3 putative Bm86-binding proteins). The data was scrutinised for the identification of vaccine targets, small drug targets and novel pathways that can be evaluated in future studies. Limitations associated with targeting novel proteins for vaccine and/or drug design is also discussed and placed into the context of challenges arising when targeting large protein families and intracellular localised proteins. Lastly, this study provide insight into how Bm86-based vaccines may reduce successful uptake and digestion of the bloodmeal and overall tick fecundity.

Dissolving undercut microneedle arrays for multicomponent cutaneous vaccination

The skin is an attractive tissue target for vaccination, as it is readily accessible and contains a dense population of antigen-presenting and immune-accessory cells. Microneedle arrays (MNAs) are emerging as an effective tool for in situ engineering of the cutaneous microenvironment to enable diverse immunization strategies. Here, we present novel dissolving undercut MNAs and demonstrate their application for effective multicomponent cutaneous vaccination. The MNAs are composed of micron-scale needles featuring pyramidal heads supported by undercut stem regions with filleted bases to ensure successful skin penetration and retention during application. Prior efforts to fabricate dissolving undercut microstructures were limited and required complex and lengthy processing and assembly steps. In the current study, we strategically combine three-dimensional (3D) laser lithography, an emerging micro-additive manufacturing method with unique geometric capabilities and nanoscale resolution, and micromolding with favorable materials. This approach enables reproducible production of dissolving MNAs with undercut microneedles that can be tip-loaded with multiple biocargos, such as antigen (ovalbumin) and adjuvant (Poly(I:C)). The resulting MNAs fulfill the geometric (sharp tips and smooth edges) and mechanical-strength requirements for failure-free penetration of human and murine skin to simultaneously deliver multicomponent (antigen plus adjuvant) vaccines to the same cutaneous microenvironment. Cutaneous vaccination of mice using these MNAs induces more potent antigen-specific cellular and humoral immune responses than those elicited by traditional intramuscular injection. Together, the unique geometric features of these undercut MNAs and the associated manufacturing strategy, which is compatible with diverse drugs and biologics, could enable a broad range of non-cutaneous and cutaneous drug delivery applications, including multicomponent vaccination.

Potential benefits of using a multicomponent vaccine for prevention of serogroup B meningococcal disease

Meningococcal serogroup B (MenB) has become the main cause of invasive meningococcal disease in industrialized countries in recent years. The diversity of MenB strains and poor immunogenicity of the MenB capsular polysaccharide have made vaccine development challenging. Two MenB vaccines, including factor H binding protein (fHbp) as a major antigenic component, are now licensed for use. In addition to fHbp variant 1, the multicomponent vaccine 4CMenB contains neisserial heparin binding antigen, Neisseria adhesin A, and outer membrane vesicles containing porin A. The vast majority of circulating MenB strains contain genes encoding at least one 4CMenB component and many express genes for more than one vaccine antigen. Recent studies have suggested that serum bactericidal activity is enhanced against strains that express two or more vaccine antigens. Bacterial killing may also occur when antibodies to vaccine components are collectively present at levels that would individually be sub-lethal. The evaluation of immune responses to separate vaccine components does not take cooperative activity into account and may underestimate the overall protection. Available data on 4CMenB effectiveness indicate that this multicomponent vaccine affords broad coverage and protection against MenB disease. 4CMenB also has the potential to protect against disease caused by non-MenB meningococci and Neisseria gonorrhoeae.