Rescue of Infectious Recombinant Hazara Nairovirus from cDNA Reveals the Nucleocapsid Protein DQVD Caspase Cleavage Motif Performs an Essential Role other than Cleavage

Abstract

family with CCHFV, which is one of the most lethal human pathogens in existence, requiring the highest biosafety level (BSL) containment (BSL4). In contrast, HAZV is not associated with human disease and thus can be studied using less-restrictive BSL2 protocols. Here, we report a system that is able to rescue HAZV from cDNAs, thus permitting reverse genetic interrogation of the HAZV replication cycle. We used this system to examine the role of a caspase cleavage site, DQVD, within the HAZV nucleocapsid protein that is also conserved in CCHFV. By engineering mutant viruses, we showed caspase cleavage at this site was not required for productive infection and this sequence performs a critical role in the virus life cycle aside from caspase cleavage. This system will accelerate nairovirus research due to its efficiency and utility under amenable BSL2 protocols.