A Multi-Valent Hantavirus Vaccine Based on Recombinant Modified Vaccinia Ankara Reduces Viral Load in a Mouse Infection Model

<b>Background</b>: Old World orthohantaviruses are the aetiological agent of Haemorrhagic Fever with Renal Syndrome (HFRS) disease. Worldwide, the two most prominent pathogens of HFRS are Seoul orthohantavirus (SEOV) and Hantaan orthohantavirus (HTNV). There is currently no specific treatment nor widely licensed vaccine form hantaviruses. <b>Methods</b>: This study developed a virus-vectored vaccine approach using modified vaccinia Ankara (MVA) incorporating a SEOV-HTNV chimeric nucleoprotein antigen. <b>Results</b>: The vaccine demonstrated the induction of humoral and cellular immunity. In the absence of a disease model, a reduction in the viral load of a susceptible mouse strain with type-I interferon receptor deficiency (A129) was used to ascertain protective effects after challenge with SEOV. Results demonstrated a significant reduction in and/or clearance of viral RNA in immunised animals. <b>Conclusions</b>: An MVA viral vector vaccine incorporating the nucleoprotein as antigen offers a promising approach for Hantavirus vaccine development.