Purpose: Chitosan is a natural polymer that has excellent properties include biocompatibility, biodegradability, no cytotoxicity, high charge density, low cost, mucoadhesive, permeation enhancing (ability to cross tight junction), and immunomodulating ability that makes the spectrum of its applicability much broader. This study was conducted to investigate the stabilizing, preservative and immunogenicity properties of N-trimethyl chitosan nanospheres (N-TMCNS). Materials and Methods: The tetanus toxoid (TT) was encapsulated into N-TMCNS and then characterized by scanning electron microscope, atomic force microscope, and dynamic light scattering. For stabilizer assay of N-TMCNS after storage of TT-N-TMCNS at different temperatures for 3 weeks, they were used for immunization of mice and different temperatures groups’ anti-TT-N-TMCNS production compared with other groups. Finally, the immunized mice were challenged with tetanus toxin. The preservation activity of TT-N-TMCNS against Escherichia coli was compared with thimerosal formulated TT. Results: Our results revealed that heat-treated TT-N-TMCNS could induce higher titer of neutralizing immunoglobulin G in compared to TT vaccine and was able to protect the mice better than TT vaccine in challenge test. Furthermore, N-TMCNS as a preservative inhibited the growth of E. coli more effective than thimerosal. Conclusion Overall, the obtained results indicated that the N-TMCNS is one of the best stabilizer and preservative agent that can be used in the formulation of TT vaccine.

Crimean-Congo hemorrhagic fever virus (CCHFV) is responsible for widespread tick-borne zoonotic viral disease CCHF in African, Middle Eastern, Asian, and European countries. CCHFV can be spread to humans through tick bites or contact with infected animals or humans, and it often progresses from asymptomatic to severe/lethal illness, with fatality rates ranging from 10% to 40% in humans. Today, CCHF is growing into a significant public health concern due to its very high prevalence, severity of the condition, and lack of available vaccines and specific treatments. Recent research has been drawn towards a more accurate study of CCHFV characteristics, including the structure, genetic diversity, mechanisms involved in pathogenesis and immunopathogenesis, and clinical features. In addition, the use of animal models (mouse and non-human primates) and advanced diagnostic tools in recent years has resulted in a significant advance in CCHF related studies. In this context, we summarized the latest findings about CCHF research, its health complications, animal models, current diagnosis, vaccination, and CCHF treatments, and therapeutic strategies. Furthermore, we discussed existing deficiencies and problems in CCHFV analysis, as well as areas that still need to yield conclusive answers.