CALOMYS MUSCULINUS, THE NATURAL RESERVOIR OF ARGENTINE HEMORRHAGIC-FEVER, IS A SEMIPERMISSIVE HOST FOR A MOUSE-ATTENUATED MUTANT OF JUNIN VIRUS

C167, a mouse-attenuated strain of Junin virus derived from the XJC13 strain, also displayed reduced virulence for the South American cricet id Calomys musculinus, a natural reservoir of this virus in nature. In tracerebral inoculation of C. musculinus with 500 PFU of C167 produced only 25% mortality, whereas the parental XJC13 killed 85% of the anim als. The attenuation of C167 for this cricetid was lower than for albi no mice. The multiplication of C167 in C. musculinus-derived embryo or kidney fibroblasts was diminished with respect to XJC13, allowing us to define C. mosculinus cells as a semipermissive system for C167, whe reas murine and Vero cells were restrictive and permissive cultures, r espectively. As a consequence, C167 as well as XJC13 were able to esta blish a persistent infection in C. musculinus embryo fibroblasts and V ero cells, but the mutant could not induce a carrier state in murine c ells. Thus, the degree of susceptibility of C. musculinus to C167 was linked to the semipermissiveness of cricetid cells to virus multiplica tion.