Evidence that exogenous dietary miRNAs enter the bloodstream and tissues of ingesting animals has been accompanied by an indication that at least one plant miRNA, miR168, participates in “cross-kingdom” regulation of a mammalian transcript. If confirmed, these findings would support investigation of miRNA-based dietary interventions in disease. Here, blood was obtained pre- and post-prandially (1, 4, 12 h) from pigtailed macaques that received a miRNA-rich plant-based substance. Plant and endogenous miRNAs were measured by RT-qPCR. Although low-level amplification was observed for some plant miRNA assays, amplification was variable and possibly non-specific, as suggested by droplet digital PCR. A consistent response to dietary intake was not observed. While our results do not support general and consistent uptake of dietary plant miRNAs, additional studies are needed to establish whether or not plant or animal xenomiRs are transferred across the gut in sufficient quantity to regulate endogenous genes.

Macrophage chemoattractant protein-1 (MCP-1) may be a key trigger for the influx of macrophages into the brain in human immunodeficiency virus (HIV) encephalitis. In this study, simian immunodeficiency virus-infected macaques that developed moderate-to-severe encephalitis had significantly higher MCP-1 levels in cerebrospinal fluid (CSF) than in plasma as early as 28 days after inoculation, which was before the development of brain lesions. In contrast, CSF:plasma MCP-1 ratios remained constant at preinoculation levels in macaques that developed minimal or no encephalitis. Abundant MCP-1 protein and mRNA were detected in both macrophages and astrocytes in the brain. Macaques with increased MCP-1 in CSF had significantly greater expression of markers of macrophage and microglia activation and infiltration (CD68; P= .003) and astrocyte activation (glial fibrillary acidic protein; P= .019 and P= .031 in white and gray matter, respectively). The results suggest that the CSF:plasma MCP-1 ratio may be a valuable prognostic marker for the development of HIV-induced central nervous system disease.

Measles virus (MeV) is the poster child for acute infection followed by lifelong immunity. However, recent work shows the presence of MeV RNA in multiple sites for up to 3 mo after infection in a proportion of infected children. Here, we use experimental infection of rhesus macaques to show that prolonged RNA presence is characteristic of primary infection. We found that viral RNA persisted in the blood, respiratory tract, or lymph nodes four to five times longer than the infectious virus and that the clearance of MeV RNA from blood happened in three phases: rapid decline coincident with clearance of infectious virus, a rebound phase with increases up to 10-fold, and a phase of slow decrease to undetectable levels. To examine the effect of individual host immune factors on MeV load dynamics further, we developed a mathematical model that expressed viral replication and elimination in terms of the strength of MeV-specific T-cell responses, antibody responses, target cell limitations, and immunosuppressive activity of regulatory T cells. Based on the model, we demonstrate that viral dynamics, although initially regulated by T cells, require antibody to eliminate viral RNA. These results have profound consequences for our view of acute viral infections, the development of prolonged immunity, and, potentially, viral evolution.immune responses | within-host modeling | virus clearance

Background In the era of highly active antiretroviral therapy (HAART) the prevalence of HIV-associated CNS disease has increased despite suppression of plasma viremia. Methods Using an SIV model system where all animals develop AIDS and 90% develop CNS disease by three months postinoculation (p.i.), pigtailed macaques were treated with a regimen of tenofovir disoproxil fumarate, saquinavir, atazanavir, and an integrase inhibitor starting at 12 days and euthanized at ∼175 days p.i. Results Plasma and CSF viral loads declined rapidly after initiating HAART. Brain viral RNA was undetectable at necropsy but viral DNA levels were not different from untreated SIV-infected macaques. CNS inflammation was significantly reduced, with decreased brain expression of MHC Class II and GFAP and reduced CSF CCL2 and IL-6. Brain from treated macaques had significantly lower levels of IFNβ, the Type I IFN-inducible gene myxovirus (influenza) resistance A (MxA), and indolamine 2,3-dioxygenase (IDO) mRNA suggesting suppressed immune hyperactivation, and fewer CD4+ and CD8+ T cells, suggesting reduced trafficking of T cells from peripheral blood. Brain levels of CD68 protein and TNFα and IFNγ RNA, while reduced, were not significantly lower, indicating continued CNS inflammation. Conclusions These data, generated in a rigorous, high viral load, SIV/macaque model showed benefits of HAART therapy on CNS virus replication and inflammation but no change in the levels of viral DNA and continued CNS inflammation in some individuals.

Measles remains a major cause of childhood mortality, with questions about virus virulence and pathogenesis still requiring answers. Rhesus macaques were infected with 5 different culture-adapted strains of measles virus, including 2 from patients with progressive vaccine-induced disease, and a sixth nonculture-adapted strain, Bilthoven. All caused infection detectable by reverse transcriptase-polymerase chain reaction and induction of antibody. Chicago-1 and Bilthoven induced viremias detectable by leukocyte cocultivation. Bilthoven induced Koplik's spots, conjunctivitis, and rash. Lymphopenia and depressed interleukin (IL)-2 production were followed by monocytosis and eosinophilia. All monkeys, including 41 involved in a primate facility outbreak, showed suppressed responses to phytohemagglutinin. As the rash resolved production of IL-2, IL-1beta, tumor necrosis factor-alpha, IL-6, and IL-5 mRNA increased. Monkeys are useful for studies of measles immunopathogenesis, but virus strains must be carefully chosen. Increased virulence of vaccine strains isolated from immunocompromised infants with fatal infections was not evident.

AIDS dementia and encephalitis are complications of AIDS occurring most frequently in patients who are immunosuppressed. The simian immunodeficiency virus (SIV) model used in this study was designed to reproducibly induce AIDS in macaques in order to examine the effects of a neurovirulent virus in this context. Pigtailed macaques (Macaca nemestrina) were coinoculated with an immunosuppressive virus (SIV/DeltaB670) and a neurovirulent molecularly cloned virus (SIV/17E-Fr), and more than 90% of the animals developed moderate to severe encephalitis within 6 months of inoculation. Viral load in plasma and cerebrospinal fluid (CSF) was examined longitudinally to onset of AIDS, and viral load was measured in brain tissue at necropsy to examine the relationship of systemic and central nervous system (CNS) viral replication to the development of encephalitis. In all animals, plasma viral load peaked at 10 to 14 days postinfection and remained high throughout infection with no correlation found between plasma viremia and SIV encephalitis. In contrast, persistent high levels of CSF viral RNA after the acute phase of infection correlated with the development of encephalitis. Although high levels of viral RNA were found in the CSF of all macaques (six of six) during the acute phase, this high level was maintained only in macaques developing SIV encephalitis (five of six). Furthermore, the level of both viral RNA and antigen in the brain correlated with the severity of the CNS lesions. The single animal in this group that did not have CNS lesions had no detectable viral RNA in any of the regions of the brain. The results substantiate the use of CSF viral load measurements in the postacute phase of SIV infection as a marker for encephalitis and CNS viral replication.

The severe disease atypical measles occurred when individuals immunized with a poorly protective inactivated vaccine contracted measles, and was postulated to be due to a lack of fusion-inhibiting antibodies. Here, rhesus macaques immunized with formalin-inactivated measles vaccine developed transient neutralizing and fusion-inhibiting antibodies, but no cytotoxic T-cell response. Subsequent infection with measles virus caused an atypical rash and pneumonitis, accompanied by immune complex deposition and an increase in eosinophils. Fusion-inhibiting antibody appeared earlier in these monkeys than in non-immunized monkeys. These data indicate that atypical measles results from previous priming for a nonprotective type 2 CD4 T-cell response rather than from lack of functional antibody against the fusion protein.

We used positron emission tomography (PET) to measure the earliest change in dopaminergic synapses and glial cell markers in a chronic, low‐dose MPTP non‐human primate model of Parkinson’s disease (PD). In vivo levels of dopamine transporters (DAT), vesicular monoamine transporter‐type 2 (VMAT2), amphetamine‐induced dopamine release (AMPH‐DAR), D2‐dopamine receptors (D2R) and translocator protein 18 kDa (TSPO) were measured longitudinally in the striatum of MPTP‐treated animals. We report an early (2 months) decrease (46%) of striatal VMAT2 in asymptomatic MPTP animals that preceded changes in DAT, D2R, and AMPH‐DAR and was associated with increased TSPO levels indicative of a glial response. Subsequent PET studies showed progressive loss of all pre‐synaptic dopamine markers in the striatum with expression of parkinsonism. However, glial cell activation did not track disease progression. These findings indicate that decreased VMAT2 is a key pathogenic event that precedes nigrostriatal dopamine neuron degeneration. The loss of VMAT2 may result from an association with α‐synuclein aggregation induced by oxidative stress. Disruption of dopamine sequestration by reducing VMAT2 is an early pathogenic event in the dopamine neuron degeneration that occurs in the MPTP non‐human primate model of PD. Genetic or environmental factors that decrease VMAT2 function may be important determinants of PD.