Protective Efficacy of Multiple Epitope-Based Vaccine against Hyalomma anatolicum, Vector of Theileria annulata and Crimean-Congo Hemorrhagic Fever Virus

Research and product development for Crimean-Congo haemorrhagic fever: priorities for 2024-30

Crimean-Congo haemorrhagic fever (CCHF) is a widely distributed and potentially fatal tick-borne viral disease with no licensed specific treatments or vaccines. In 2019, WHO published an advanced draft of a research and development roadmap for CCHF that prioritised the development and deployment of the medical countermeasures most needed by CCHF-affected countries. This Personal View presents updated CCHF research and development priorities and is the product of broad consultation with a working group of 20 leading experts in 2023-24. The strategic goals, milestones, and timelines have been revised and expanded to reflect scientific advances since 2019, including the identification of antibodies with therapeutic potential and the progression of four vaccine candidates through phase 1 clinical trials. This update emphasises the need for a One Health approach to manage CCHF, from integrated cross-sectoral surveillance to novel interventions that target ticks and their vertebrate hosts to reduce CCHF virus transmission to humans. The overarching vision for rapid diagnostics and specific therapeutics by 2028, followed by options to limit CCHF virus transmission and control disease by 2030, is deliberately ambitious and will only be achieved through coordinated international action from affected countries, funders, scientists, product developers, manufacturers, regulators, national authorities, and policy makers.

Challenges and considerations in multi-epitope vaccine design surrounding toll-like receptors

Epitope-based peptide vaccines elicit targeted immune responses, making them effective for diseases requiring focused immune activation, such as targeting cancer-associated antigens. Strategies like peptide cocktails and mRNA-based epitope vaccines have revolutionized the field; however, the term 'multi-epitope peptide vaccine' has been overextended, especially concerning the use of toll-like receptors (TLRs), their ligands, and peptide linkers. TLRs are often conflated with T cell receptors (TCRs) and B cell receptors (BCRs), which recognize immunogenic peptides within vaccines. This Opinion clarifies the role of TLRs and highlights challenges linked to their indiscriminate use in multi-epitope vaccine design. While peptide linkers are crucial in creating multivalent vaccines, their unsupervised application is increasing and warrants attention. After highlighting their role in advancing peptide vaccines, we discuss critical factors in linker implementation and caution against their misuse, which could undermine vaccines' efficacy.

Interventions for the control of Crimean-Congo hemorrhagic fever and tick vectors

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease associated with its principal tick vector, Hyalomma spp. with increasing fatal incidence worldwide. Accordingly, CCHF is a World Health Organization-prioritized disease with the absence of effective preventive interventions and approved vaccines or effective treatments. This perspective raised from a multidisciplinary gap analysis considering a One Health approach beneficial for human and animal health and the environment exploring international collaborations, gaps and recommendations.

Evolution of tick vaccinology

Ticks represent a major concern for society worldwide. Ticks are also difficult to control, and vaccines represent the most efficacious, safe, economically feasible and environmentally sustainable intervention. The evolution of tick vaccinology has been driven by multiple challenges such as (1) Ticks are difficult to control, (2) Vaccines control tick infestations by reducing ectoparasite fitness and reproduction, (3) Vaccine efficacy against multiple tick species, (4) Impact of tick strain genetic diversity on vaccine efficacy, (5) Antigen combination to improve vaccine efficacy, (6) Vaccine formulations and delivery platforms and (7) Combination of vaccines with transgenesis and paratransgenesis. Tick vaccine antigens evolved from organ protein extracts to recombinant proteins to chimera designed by vaccinomics and quantum vaccinomics. Future directions will advance in these areas together with other novel technologies such as multiomics, AI and Big Data, mRNA vaccines, microbiota-driven probiotics and vaccines, and combination of vaccines with other interventions in collaboration with regions with high incidence of tick infestations and tick-borne diseases for a personalized medicine approach.

The interplay of cytokines in bovine tropical theileriosis: a mini review

Studying cytokine profiling in Theleria annulata infection enhances our understanding of how the immune response unfolds, the intricate interactions between the host and the parasite, the strategies employed by the parasite to evade the immune system, and potential avenues for developing treatments. The generation of pro-inflammatory cytokines plays a pivotal role in the immune response against T. annulata infection. Elevated concentrations of these cytokines potentially contribute to the manifestation of clinical symptoms associated with the disease, such as fever, anemia, exophthalmia, and weight loss. The production of anti-inflammatory cytokines potentially serves as a regulatory mechanism for the immune response, preventing the development of severe disease. Nevertheless, in animals afflicted by T. annulata infection, there is often a notable decrease in the levels of these cytokines, suggesting that they may not be as effective in mitigating the disease as they are in uninfected animals. This knowledge can be harnessed to develop improved diagnostic methods, treatments, and vaccines for tropical theileriosis. The objective of this current mini review is to achieve the same goal by consolidating the available knowledge of cytokine interactions in Bovine Tropical Theileriosis (BTT).

A case of gynandromorphism in Hyalomma anatolicum (Ixodida: Ixodidae)

We present a field-collected Hyalomma anatolicum gynandromorph in Xinjiang, China. Compared to the normal H. anatolicum, the gynandromorphic tick was a typical bipartite protogynander: half of the tick body displayed normal female traits, whereas the other side showed normal male traits. The engorged gynandromorphic tick laid hundreds of eggs, and the eggs looked normal.