Hemorrhagic fever occurs after intravenous, but not after intragastric, inoculation of rhesus macaques with lymphocytic choriomeningitis virus

Abstract

Arenaviruses can cause hemorrhagic fever and death in primates and guinea pigs, but these viruses are not highly pathogenic for most rodent carriers. In the United States, arenaviruses precipitated outbreaks of hepatitis in captive monkeys, and they present an emerging health threat in the tropical areas of Africa and South America. We describe infection of rhesus macaques with the prototype arenavirus, lymphocytic choriome-ningitis virus (LCMV), using the WE strain that has been known to cause both encephalopathy and multifocal hemorrhage. Five macaques were inoculated: two by the intravenous (i.v.) and three by the intragastric (i.g.) route. Whereas the two i.v.-inoculated monkeys developed signs and lesions consistent with fatal hemorrhagic fever, the i.g.-inoculated monkeys had an attenuated infection with no disease. Pathological signs of the primate i.v. infection differ significantly from guinea pig arenavirus infections and make this a superior model for human viral hemorrhagic disease.

Circulating natural killer and γδ T cells decrease soon after infection of rhesus macaques with lymphocytic choriomeningitis virus

“…NK cells are considered CD3 -CD8 + because 99% of these cells are CD16 + or CD56 + (classical NK markers) (Dykhuizen et al 2000). FITC-conjugated monoclonal antibodies against CD3, CD20 (Becton-Dickinson, Mountain View, CA) and Vγ9 TCR (Beckman Coulter, Miami, FL), a PerCP-conjugated monoclonal antibody against CD4, an APC-conjugated monoclonal antibody against CD8 and PE-conjugated monoclonal antibodies against CD16 and CD56 (Becton-Dickinson) were used with relevant isotype controls as described previously (Pauza et al 1997, Lukashevich et al 2002. Samples were analyzed on a FACScan flow cytometer (Becton-Dickinson) and data were processed using FlowJo 2.7.8 software (Three star, 1997(Three star, -1998.…”

“…Detection of infectious virus in plasma -LCMV-WE was detected in plasma by plaque assay as described (Lukashevich et al 2002). In brief, 10-fold dilutions of plasma samples were added to monolayers of Vero cells (about 2.5 x 10 5 cells/well) in 6-well plates and incubated for 1 h at 37ºC.…”

“…The WE strain of LCMV is hepatotropic in mice, guinea pigs and primates (Riviere et al 1985, Zinkernagel et al 1986, Lukashevich et al 2002, but in contrast to murine LCMV infections, LCMV-WE infection of rhesus macaques can resemble Lassa hemorrhagic fever in human beings (Jahrling et al 1980, Peters et al 1987, Lukashevich et al 2002. The Armstrong (ARM) strain of LCMV does not cause overt disease in monkeys, even after intravenous inoculation (Danes et al 1963, Peters et al 1987, Lukashevich et al 2002.Several immunological studies have shown the importance of CD8 T lymphocytes in both protection and in induction of immuno-pathogenesis in the mouse model , Bonilla et al 2002. More recently, we demonstrated the importance of cell-mediated immunity in survival after a lethal intravenous challenge in the primate model .…”

“…The LCMV-WE and LCMV-ARM strains have been well characterized (Salvato & Shimomaye 1989, Djavani et al 1998 and their use in monkeys has been previously described by our group. A dose of 10 3 pfu LCMV-WE inoculated intravenously in unvaccinated macaques is uniformly lethal (Lukashevich et al 2002.Rhesus macaque inoculations and challenges -Rhesus monkeys were housed in a BSL-2/3 facility. The 12 animals used in this study were all 2-5-year-old females with normal weights and activity levels.…”

“…The cells from the human samples were counted at every time point to determine the absolute counts for each cell subset. In all of the cases where error bars are depicted, samples were run in triplicate to estimate the average and standard deviation for each time point and treatment.Detection of infectious virus in plasma -LCMV-WE was detected in plasma by plaque assay as described (Lukashevich et al 2002). In brief, 10-fold dilutions of plasma samples were added to monolayers of Vero cells (about 2.5 x 10 5 cells/well) in 6-well plates and incubated for 1 h at 37ºC.…”