Generation of recombinant lymphocytic choriomeningitis viruses with trisegmented genomes stably expressing two additional genes of interest

Several arenaviruses cause hemorrhagic fever disease in humans for which no licensed vaccines are available and current therapeutic intervention is limited to the off-label use of the wide-spectrum antiviral ribavirin. However, the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) has proven to be a Rosetta stone for the investigation of virus–host interactions. Arenaviruses have a bisegmented negative-strand RNA genome. The S segment encodes for the virus nucleoprotein and glycoprotein, whereas the L segment encodes for the virus polymerase (L) and Z protein. The ability to generate recombinant LCMV (rLCMV) expressing additional foreign genes of interest would open novel avenues for the study of virus–host interactions and the development of novel vaccine strategies and high-throughput screens to identify antiarenaviral molecules. To this end, we have developed a trisegmented (1L + 2S) rLCMV-based approach (r3LCMV). Each of the two S segments in r3LCMV was altered to replace one of the viral genes by a gene of interest. All r3LCMVs examined expressing different reported genes were stable both genetically and phenotypically and exhibited wild-type growth properties in cultured cells. Reporter gene expression in r3LCMV-infected cells provided an accurate surrogate of levels of virus multiplication. Notably, some r3LCMVs displayed highly attenuated virulence in mice but induced protective immunity against a subsequent lethal challenge with wild-type LCMV, supporting the potential development of r3LCMV-based vaccines.