Crimean–Congo Hemorrhagic Fever Virus: Progress in Vaccine Development

Abstract

Crimean–Congo hemorrhagic fever virus (CCHFV), a member of the Nairoviridae family and Bunyavirales order, is transmitted to humans via tick bites or contact with the blood of infected animals. It can cause severe symptoms, including hemorrhagic fever, with a mortality rate between 5 to 30%. CCHFV is classified as a high-priority pathogen by the World Health Organization (WHO) due to its high fatality rate and the absence of effective medical countermeasures. CCHFV is endemic in several regions across the world, including Africa, Europe, the Middle East, and Asia, and has the potential for global spread. The emergence of the disease in new areas, as well as the presence of the tick vector in countries without reported cases, emphasizes the need for preventive measures to be taken. In the past, the lack of a suitable animal model susceptible to CCHFV infection has been a major obstacle in the development of vaccines and treatments. However, recent advances in biotechnology and the availability of suitable animal models have significantly expedited the development of vaccines against CCHF. These advancements have not only contributed to an enhanced understanding of the pathogenesis of CCHF but have also facilitated the evaluation of potential vaccine candidates. This review outlines the immune response to CCHFV and animal models utilized for the study of CCHFV and highlights the progress made in CCHFV vaccine studies. Despite remarkable advancements in vaccine development for CCHFV, it remains crucial to prioritize continued research, collaboration, and investment in this field.

Recent Advances in Crimean-Congo Hemorrhagic Fever Virus Detection, Treatment, and Vaccination: Overview of Current Status and Challenges

“…Heterologous challenge studies are necessary to develop more dependable vaccines that offer comprehensive protection against various strains of the CCHFV to address these challenges. Despite promising preclinical investigations, the efficacy of these vaccines in human trials is yet to be determined; thus, the applicability of these findings in human clinical trials is uncertain [ 40 ].…”

“…However, it has been significantly accelerated by recent developments in biotechnology and the availability of appropriate animal models. These developments have aided in the assessment of possible vaccine candidates in addition to improving our knowledge of the pathophysiology of CCHF [ 40 ].…”

Looking Beyond the Lens of Crimean-Congo Hemorrhagic Fever in Africa

“…Those options are being investigated to determine their efficacy and potential as preventive strategies against CCHF. To optimize CCHF vaccine efficacy and investigate other therapeutic approaches, comprehensive detailed research, including preclinical research, clinical trials, and continuous surveillance, is required ( 42 ). Since 1974, Bulgaria has used the Bulgarian vaccine, an inactivated vaccine made from the brain tissue of suckling mice infected with CCHFV ( 43 ).…”

Persistence of IgG and neutralizing antibodies in Crimean−Congo hemorrhagic fever survivors

“…15 Usually, neutralizing antibodies are traceable 10 days after disease onset but in fatal cases cannot be detected. 16 This highlight the essential role of humoral immunity in protecting against lethal CCHFV infections, although the long-term stability of the antibody response in survivors has not been well understood. This study aimed to investigate the stability of anti CCHFV IgG and neutralizing antibodies in Iranian CCHF survivors.…”

“…In contrast, IgM titers decline within 3 weeks and become undetectable between 3 and 5 months 15 . Usually, neutralizing antibodies are traceable 10 days after disease onset but in fatal cases cannot be detected 16 . This highlight the essential role of humoral immunity in protecting against lethal CCHFV infections, although the long‐term stability of the antibody response in survivors has not been well understood.…”