Antibody-enhanced dengue disease generates a marked CNS inflammatory response in the black-tufted marmoset Callithrix penicillata.

Severe dengue disease is often associated with long-term neurological impairments, but it is unclear what mechanisms are associated with neurological sequelae. Previously, we demonstrated antibody-enhanced dengue disease (ADE) dengue in an immunocompetent mouse model with a dengue virus 2 (DENV2) antibody injection followed by DENV3 virus infection. Here we migrated this ADE model to Callithrix penicillata. To mimic human multiple infections of endemic zones where abundant vectors and multiple serotypes co-exist, three animals received weekly subcutaneous injections of DENV3 (genotype III)-infected supernatant of C6/36 cell cultures, followed 24 h later by anti-DENV2 antibody for 12 weeks. There were six control animals, two of which received weekly anti-DENV2 antibodies, and four further animals received no injections. After multiple infections, brain, liver, and spleen samples were collected and tissue was immunolabeled for DENV3 antigens, ionized calcium binding adapter molecule 1, Ki-67, TNFα. There were marked morphological changes in the microglial population of ADE monkeys characterized by more highly ramified microglial processes, higher numbers of trees and larger surface areas. These changes were associated with intense TNFα-positive immunolabeling. It is unclear why ADE should generate such microglial activation given that IgG does not cross the blood-brain barrier, but this study reveals that in ADE dengue therapy targeting the CNS host response is likely to be important.

Polymorphic color vision in captive Uta Hick's cuxiús, or bearded sakis (Chiropotes utahickae).

The pitheciines (Chiropotes, Pithecia, and Cacajao) are frugivorous Neotropical primates that specialize on the predation of seeds from unripe fruits, usually cryptic against the foliage. However, little is known about the color vision distribution within this taxon, and even less about the abilities shared by these animals regarding discrimination of chromatic targets. The aim of this study was to evaluate the color vision perception of captive Uta Hick's cuxiús, or bearded sakis (Chiropotes utahickae) through a behavioral paradigm of color visual discrimination, as well as to estimate, by genetic studies, the number and kinds of medium to long wavelength cone photopigment (opsins) encoded by this species. Among 12 cuxiús (7 males and 5 females) studied only 1 female was diagnosed as a trichromat. Results from genotyping were in line with our behavioral data and showed that cuxiús carried one (dichromat) or two (trichromat) medium to long wavelength pigments alleles, demonstrating a color vision polymorphism in C. utahickae similar to the majority of Neotropical Primates.

Renal evaluation of Aotus azarai infulatus by ultrasonography and serum chemistry profile.

This study aimed to characterize anatomical and biochemical properties of owl monkey kidneys in order to provide normal reference values. Sixty-nine Aotus azarai infulatus (45 males and 24 females) were divided into four different age groups (AG1: 3 months-1 year; AG2: 2-3 years; AG3: 4-6 years; and AG4: over 7 years old). The monkeys were evaluated with a serum chemistry profile, focusing on serum creatinine (SCr) and blood urea nitrogen (BUN) and with ultrasound. Mean body mass differed among the age groups. This significance was attributed to AG1 body mass being significantly lower than in AG2 and that in both AG2 and AG3 being significantly lower than in the two older age groups (AG3 and AG4). SCr and BUN concentrations differed significantly between the sexes and SCr level correlated positively with age. In contrast, renal measurements did not differ between males and females. Left and right renal volumes did not differ significantly within age groups, or among AG2, AG3, and AG4. Renal volumes in AG1, however, while not differing from those in AG2, did differ significantly from those in AG3 and AG4. In conclusion, this study provides ultrasonographic reference values for the morphology the kidneys in A. a. infulatus. Evidence is also provided that SCr and BUN levels in owl monkeys are influenced by the sex and age of the individual, factors that should be considered when interpreting test results.

Callithrix penicillata: a feasible experimental model for dengue virus infection.

Although the murine models have the feasibility to reproduce some signs of dengue Virus (DENV) infection, the use of isogenic hosts with polarized immune response patterns does not reproduce the particularities of human disease. Our goal was to investigate the kinetics of peripheral blood biomarkers in immunocompetent Callithrix penicillata non-human primates subcutaneously infected with DENV-3. The viral load of infected animals was determinated by quantitative real time PCR. Measurements of DENV-3/IgM were performed, and several parameters were assessed by hemogram: red blood cells count, hemoglobin, hematocrit, white blood cells count, neutrophils, monocytes, lymphocytes, and platelets count. The coagulogram was performed by prothrombin time (PT), and activated partial thromboplastin time (APTT) assays. The renal function was monitored by urea and creatinine, and the liver function by the aspartate (AST), and alanine (ALT) aminotransferases. Also, the level of the cytokines IL-6, TNF-α, IL-2, IFN-γ, IL-4 and IL-5 was quantified during the experimental study. Data analysis was performed considering relevant differences when baseline fold changes were found outside from 0.75 to 1.5 range. Our data demonstrated that infected animals presented relevant signs of dengue disease, including peaks of viremia at 5 days-post-infection (dpi), peaks of anti-DENV-3 IgM at 15 dpi and hemaglutination inhibition assay (HIA) from 15 to at 60 dpi. Despite early monocytosis, slight neutrophilia and lymphocytosis, animals developed persistent leucopenia starting at 4 dpi. Anemia episodes were steady at 3-4 dpi. Patent thrombocytopenia was observed from 1 to 15 dpi with sporadic decrease of APTT. A substantial increase of ALT and AST was observed with higher peak at 4 dpi. Moreover, early increases of TNF-alpha and IFN-gamma besides late increase of IFN-gamma were observed. The analysis of biomarkers network pointed out two relevant strong axes during early stages of dengue fever, a protective axes TNF-alpha/Lymphocytes/Platelets, and a pathological IL-2/IL-6/Viremia/Monocyte/PT bond. Later on, the biomarker network highlighted the interaction IFN-gamma/PLT/DENV-3(IgM;HAI)/PT, and the involvement of type-2 cytokines (IL-4; IL-5). Our findings demonstrated that C. penicillata is a feasible experimental model for dengue virus infection, which could be useful to pathogenesis studies, discovery of novel antiviral drugs as well as to evaluate vaccine candidates against DENV.