Recent research advances in the development of Dabie Banda virus vaccines

Abstract

Severe fever with thrombocytopenia syndrome (SFTS) is a newly identified tick-borne viral hemorrhagic fever caused by Dabie Banda virus (DBV). The virus was first discovered in eastern China in 2009 and is now considered an infectious disease with a mortality rate ranging from 6.3% to 30%. The best strategy for controlling SFTS is to develop effective vaccines. However, no approved vaccines are currently available to prevent this disease, despite the number of extensive and in-depth studies conducted on DBV in the past few years. This review focuses on the structure of DBV and the induced host immune responses which are the fundamental factors in vaccine development, and thoroughly summarizes the current research progress on DBV vaccines. The developing DBV vaccines include protein subunit vaccines, live attenuated vaccines, recombinant virus vector vaccines, and DNA vaccines. At present, almost all candidate vaccines for DBV are in the laboratory development or preclinical stages. There remain challenges in successfully developing clinically approved DBV vaccines.

Fig 1. DBV life cycle and host immune responses.

The attachment of the virus to host cell receptors and subsequent entry into the cell are facilitated by viral glycoproteins and mediated through clathrin-dependent endocytosis. The process of endocytosis leads to the formation of the endosomes that encapsulate the virus. As the pH value within the endosome decreases, it induces conformational changes in the glycoprotein structure on the viral surface, facilitating membrane fusion and subsequent release of the viral genome. RdRp and NPs are involved in viral RNA replication, followed with the transportation to Golgi complexes where they will interact with newly translated glycoproteins to commence assembly processes. The newly synthesized viruses are released from the Golgi apparatus to infect neighboring cells and trigger immune responses. Neutralizing antibodies secreted by B cells primarily bind to Gn and Gc, while non-neutralizing antibodies bind to Np. Additionally, cytotoxic T cells recognize and eliminate the infected cells.