Immunoinformatics and reverse vaccinology design of self-amplifying RNA vaccine against marburg virus with structural...

Marburg virus disease (MVD), a deadly zoonotic illness in humans, is caused by the Marburg virus (MARV), a single-stranded RNA virus belonging to the Orthomarburgvirus genus of the Filoviridae family. There are currently no approved vaccines or efficient antiviral therapies for MARV, despite high morbidity and fatality rates of the virus, particularly in Africa. Recognizing its epidemic potential and its inclusion on the WHO list of blueprint priority pathogens, an immunoinformatics approach was used to design novel multi-epitope saRNA vaccine candidates (MB-saVaxI and MB-saVaxII) targeting the viral GP, NP, VP40, and VP35 via CD8 + , CD4 + , and B cell epitopes. These epitopes were derived from target protein sequences and incorporated into MB-saVaxI and MB-saVaxII after validation for antigenicity, non-allergenicity, non-toxicity, and conservation. Additionally, the selected epitopes were conjugated to suitable adjuvants via various linkers, thereby enabling the design of a potentially stable vaccine. Additionally, the designed MB-saVaxI and MB-saVaxII were incorporated into the standard saRNA model, in which ORF-2 encodes the target vaccine peptide. Moreover, biophysical analyses unveiled that the developed vaccines are basic (pI < 7), soluble (GRAVY < 0), and stable (aliphatic index < 80). Subsequently, docking of MB-saVaxI to TLR2 (-938.3) and TLR4 (-902.4), and MB-saVaxII to TLR3 (-1485.4) and TLR7 (-1543.6) demonstrated significant affinity, with detailed hydrogen-bond interactions validated by MM-GBSA and molecular dynamics simulations. Furthermore, MB-saVaxI and MB-saVaxII were effectively cloned in-silico into Escherichia coli, and immune simulations indicated that the vaccines triggered robust innate and adaptive immunity, with a sustained memory response and TH cell activation, as evidenced by IFN-γ and IL-2 production. Additionally, the mRNA structure of MB-saVaxI and MB-saVaxII remained stable throughout the expression pathway in the host. However, extensive in-vitro and in-vivo studies are needed to establish the safety and efficacy of this vaccine candidate conclusively.