SummaryStudies were undertaken to determine whether interleukin 10, (Ibl0) a cytokine shown to inhibit interferon 3' (IFN-~/) production, was involved in Tryfanosoma cruzi infections in mice. Exogenous IFN-3, protects mice from fatal infection with T. ctuzi. Furthermore, resistant B6D2 mice developed fatal T. cruzi infections when treated with neutralizing anti-IFN-3, monoclonal antibody (mAb). Thus, endogenous as well as exogenous IFN-3' is important in mediating resistance to this parasite. Because both T. cruzi-susceptible (B6) and -resistant (B6D2) mouse strains produced IFN-3, during acute infection, we looked for the concomitant production of mediators that could interfere with IFN-3,-mediated resistance to T. cruzi. We found that IL-10-specific mRNA was produced in the spleens of mice with acute T. cruzi infections. In addition, spleen cell culture supernatants from infected B6 mice, and to a lesser extent B6D2 mice, elaborated an inhibitor(s) of IFN-3' production. This inhibitor(s) was neutralized by anti-Ibl0 mAb. These experiments demonstrated the production of biologically active IL-10 during T. cruzi infection. In further studies in vitro, it was shown that IL-10 blocked the ability of IFN-'y to inhibit the intraceUular replication of T. cruzi in mouse peritoneal macrophages. Thus, in addition to its known ability to inhibit the production of IFN-% Ibl0 (cytokine synthesis inhibitory factor), may also inhibit the effects of IFN-% These experiments demonstrate that IL-10 is produced during infection with a protozoan parasite and suggest a regulatory role for this cytokine in the mediation of susceptibility to acute disease.

Analysis of indinavir levels in HIV-positive patients indicated that drug concentrations in lymph node mononuclear cells (LNMCs) were about 25-35% of mononuclear cells in blood. To enhance lymphatic delivery of anti-HIV drugs, a novel drug delivery strategy was designed consisting of lipid-associated indinavir (50-80 nm in diameter) complexes in suspension for subcutaneous (SC) injection. Due to the pH-dependent lipophilicity of indinavir, practically all the drug molecules are incorporated into lipid phase when formulated at pH 7.4 and 5:1 lipid-to-drug (m/m) ratio. At pH 5.5, about 20% of drugs were found in lipid-drug complexes. Effects of lipid association on the time course of plasma indinavir concentrations were determined in macaques (Macaca nemestrina) administered with either soluble or lipid-associated formulation of indinavir (10 mg/kg, SC). Results yielded about a 10-fold reduction in peak plasma concentration and a 6-fold enhancement in terminal half-life (t1/2beta = 12 vs. 2 hours). In addition, indinavir concentrations in both peripheral and visceral lymph nodes were 250-2270% higher than plasma (compared with <35% with soluble lipid-free drug administration in humans). Administration of lipid-associated indinavir (20 mg/kg daily) to HIV-2287-infected macaques (at 30-33 weeks after infection) resulted in significantly reduced viral RNA load and increased CD4 T cell number concentrations. Collectively, these data indicate that lipid association greatly enhances delivery of the anti-HIV drug indinavir to lymph nodes at levels that cannot be achieved with soluble drug, provides significant virus load reduction, and could potentially reverse CD4 T cell depletion due to HIV infection.

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Among Old World monkeys, pig-tailed macaques (Pt) are uniquely susceptible to human immunodeficiency virus type 1 (HIV-1), although the infection does not persist. We demonstrate that the susceptibility of Pt T cells to HIV-1 infection is due to the absence of postentry inhibition by a TRIM5 isoform. Notably, substitution of the viral infectivity factor protein, Vif, with that from pathogenic SIVmne enabled replication of HIV-1 in Pt T cells in vitro. When inoculated into juvenile pig-tailed macaques, the Pt-tropic HIV-1 persistently replicated for more than 1.5 to 2 years, producing low but measurable plasma viral loads and persistent proviral DNA in peripheral blood mononuclear cells. It also elicited strong antibody responses. However, there was no decline in CD4؉ T cells or evidence of disease. Surprisingly, the Pt-tropic HIV-1 was rapidly controlled when inoculated into newborn Pt macaques, although it transiently rebounded after 6 months. We identified two notable differences between the Pt-tropic HIV-1 and SIVmne. First, SIV Vif does not associate with Pt-tropic HIV-1 viral particles. Second, while Pt-tropic HIV-1 degrades both Pt APOBEC3G and APOBEC3F, it prevents their inclusion in virions to a lesser extent than pathogenic SIVmne. Thus, while SIV Vif is necessary for persistent infection by Pt-tropic HIV-1, improved expression and inhibition of APOBEC3 proteins may be required for robust viral replication in vivo. Additional adaptation of the virus may also be necessary to enhance viral replication. Nevertheless, our data suggest the potential for the pig-tailed macaque to be developed as an animal model of HIV-1 infection and disease.

Abstract. The Last Millennium Reanalysis utilizes an ensemble methodology to assimilate paleoclimate data for the production of annually resolved climate field reconstructions of the Common Era. Two key elements are the focus of this work: the set of assimilated proxy records, and the forward models that map climate variables to proxy measurements. Results based on an extensive proxy database and seasonal regression-based forward models are compared to the prototype reanalysis of Hakim et al. (2016), which was based on a smaller set of proxy records and simpler proxy models formulated as univariate linear regressions against annual temperature. Validation against various instrumental–era gridded analyses shows that the new reconstructions of surface air temperature, 500 hPa geopotential height and the Palmer Drought Severity Index are significantly improved, with skill scores increasing from 10 % to more than 200 %, depending on the variable and verification measure. Additional experiments designed to isolate the sources of improvement reveal the importance of additional proxy records, including coral records for improving tropical reconstructions; tree-ring-width chronologies, including moisture-sensitive trees, for thermodynamic and hydroclimate variables in mid-latitudes; and tree-ring density records for temperature reconstructions, particularly in high northern latitudes. Proxy forward models that account for seasonal responses, and the dual sensitivity to temperature and moisture characterizing tree-ring-width proxies, are also found to be particularly important. Other experiments highlight the beneficial role of covariance localization on reanalysis ensemble characteristics. This improved paleoclimate data assimilation system served as the basis for the production of the first publicly released NOAA Last Millennium Reanalysis.