Genetic Detection and Characterization of Lujo Virus, a New Hemorrhagic Fever–Associated Arenavirus from Southern Africa

Lujo virus (LUJV), a new member of the family Arenaviridae and the first hemorrhagic fever–associated arenavirus from the Old World discovered in three decades, was isolated in South Africa during an outbreak of human disease characterized by nosocomial transmission and an unprecedented high case fatality rate of 80% (4/5 cases). Unbiased pyrosequencing of RNA extracts from serum and tissues of outbreak victims enabled identification and detailed phylogenetic characterization within 72 hours of sample receipt. Full genome analyses of LUJV showed it to be unique and branching off the ancestral node of the Old World arenaviruses. The virus G1 glycoprotein sequence was highly diverse and almost equidistant from that of other Old World and New World arenaviruses, consistent with a potential distinctive receptor tropism. LUJV is a novel, genetically distinct, highly pathogenic arenavirus

Pathology of Black Creek Canal Virus Infection in Juvenile Hispid Cotton Rats (Sigmodon hispidus)

The purpose of this study was to assess the effect of inoculum dose on the pathogenesis of Black Creek Canal virus (BCCV) infection in the hispid cotton rat (Sigmodon hispidus), the principal host of BCCV. No sign of illness was observed in any of the 52 juvenile hispid cotton rats inoculated with 3.1, 1.1, −0.9, or −2.9 log10 median infectious dosesVeroE6 (ID50-VeroE6) of BCCV and euthanized on day 9, 18, 27, or 54 postinoculation (PI). Analysis of virus assay and serological data indicated that inoculum dose could significantly affect the pathogenesis of BCCV infection in juvenile hispid cotton rats. For example, the six animals inoculated with 3.1 or 1.1 log10 ID50-VeroE6 and euthanized on day 54 PI were virus positive and antibody positive, whereas the six animals inoculated with −0.9 or −2.9 log10 ID50-VeroE6 and euthanized on day 54 PI were virus positive but antibody negative. Microscopic examination of tissues from the animals inoculated with 3.1 or 1.1 log10 ID50-VeroE6 revealed diffuse, subacute pneumonitis in the lungs of all the animals euthanized on day 18 PI or thereafter, and indicated that the severity of pneumonitis was dependent upon inoculum dose as well as duration of infection (i.e., amount of time elapsed since inoculation)