Variable Susceptibility of the Owl Monkey (Aotus nancymae) to Four Serotypes of Dengue Virus

The goal of this study was to determine, for each of four dengue serotypes, whether owl monkeys (Aotus nancymae) become viremic and develop antibody responses in patterns similar to those seen in humans and whether any behavioral parameters are reliably associated with immunologic responses. A secondary goal was to investigate effects of chronic blood sampling on hematologic parameters in this genus. We inoculated 20 owl monkeys with 2×10(4) plaque-forming units of one of four dengue serotypes. Blood samples ranging from 0.4 to 0.7 ml per animal were taken each day for 12 consecutive days after inoculation, as well as on days 21, 28, and 60 post-inoculation. The total amount of blood taken per monkey was 8.0 ml during the first 12 days and 9.5 ml during the first 30 days of the study (i.e., up to 17% total blood volume per week and up to 20% total blood volume per month). Detailed behavioral assessments of all animals were made twice daily on every day of sample collection. The dengue-1 group were viremic for an average of 3.75 days. Dengue-2, -3, and -4 groups had average viremias of 1.00, 1.25, and 1.33 days, respectively. All animals demonstrated appropriate antibody responses as determined by enzyme-linked immunosorbency assay (ELISA). Animals tolerated repeated phlebotomy well, as all animals remained within clinically normal hematocrit (HCT) reference ranges, and no lasting effects on HCT occurred in any monkey. Final HCT for most animals was greater than 45% (mean final hematocrit, 45%). The maximum decrease in HCT ranged from 3.5 to 19 (mean, 8.9) percentage points. No consistent correlation of any behavioral disease parameters with viremia and antibody status was demonstrated, although overt illness did occur in two animals. Aotus can be an affordable and safe model for testing dengue vaccine efficacy; further testing with higher doses of dengue-2, -3 and -4 viruses is warranted.