HIV Reactivation from Latency after Treatment Interruption Occurs on Average Every 5-8 Days—Implications for HIV Remission

HIV infection can be effectively controlled by anti-retroviral therapy (ART) in most patients. However therapy must be continued for life, because interruption of ART leads to rapid recrudescence of infection from long-lived latently infected cells. A number of approaches are currently being developed to ‘purge’ the reservoir of latently infected cells in order to either eliminate infection completely, or significantly delay the time to viral recrudescence after therapy interruption. A fundamental question in HIV research is how frequently the virus reactivates from latency, and thus how much the reservoir might need to be reduced to produce a prolonged antiretroviral-free HIV remission. Here we provide the first direct estimates of the frequency of viral recrudescence after ART interruption, combining data from four independent cohorts of patients undergoing treatment interruption, comprising 100 patients in total. We estimate that viral replication is initiated on average once every ≈6 days (range 5.1- 7.6 days). This rate is around 24 times lower than previous thought, and is very similar across the cohorts. In addition, we analyse data on the ratios of different ‘reactivation founder’ viruses in a separate cohort of patients undergoing ART-interruption, and estimate the frequency of successful reactivation to be once every 3.6 days. This suggests that a reduction in the reservoir size of around 50-70-fold would be required to increase the average time-to-recrudescence to about one year, and thus achieve at least a short period of anti-retroviral free HIV remission. Our analyses suggests that time-to-recrudescence studies will need to be large in order to detect modest changes in the reservoir, and that macaque models of SIV latency may have much higher frequencies of viral recrudescence after ART interruption than seen in human HIV infection. Understanding the mean frequency of recrudescence from latency is an important first step in approaches to prolong antiretroviral-free viral remission in HIV.     

Discovery,validation and characterization of 1039 cattle single nucleotide polymorphisms

We identified ～13 000 putative single nucleotide polymorphisms (SNPs) by comparison of repeat‐masked BAC‐end sequences from the cattle RPCI‐42 BAC library with whole‐genome shotgun contigs of cattle genome assembly Btau 1.0. Genotyping of a subset of these SNPs was performed on a panel containing 186 DNA samples from 18 cattle breeds including 43 trios. Of 1039 SNPs confirmed as polymorphic in the panel, 998 had minor allele frequency ≥0.25 among unrelated individuals of at least one breed. When Btau 4.0 became available, 974 of these validated SNPs were assigned in silico to known cattle chromosomes, while 41 SNPs were mapped to unassigned sequence scaffolds, yielding one SNP every ～3 Mbp on average. Twenty‐four SNPs identified in Btau 1.0 were not mapped to Btau 4.0. Of the 1015 SNPs mapped to Btau 4.0, 959 SNPs had nucleotide bases identical in Btau 4.0 and Btau 1.0 contigs, whereas 56 bases were changed, resulting in the loss of the in silico SNP in Btau 4.0. Because these 1039 SNPs were all directly confirmed by genotyping on the multi‐breed panel, it is likely that the original polymorphisms were correctly identified. The 1039 validated SNPs identified in this study represent a new and useful resource for genome‐wide association studies and applications in animal breeding.     

The CD16+ monocyte subset is more permissive to infection and preferentially harbors HIV-1 in vivo

HIV-1 persists in peripheral blood monocytes in individuals receiving highly active antiretroviral therapy (HAART) with viral suppression, despite these cells being poorly susceptible to infection in vitro. Because very few monocytes harbor HIV-1 in vivo, we considered whether a subset of monocytes might be more permissive to infection. We show that a minor CD16+ monocyte subset preferentially harbors HIV-1 in infected individuals on HAART when compared with the majority of monocytes (CD14highCD16-). We confirmed this by in vitro experiments showing that CD16+ monocytes were more susceptible to CCR5-using strains of HIV-1, a finding that is associated with higher CCR5 expression on these cells. CD16+ monocytes were also more permissive to infection with a vesicular stomatitis virus G protein-pseudotyped reporter strain of HIV-1 than the majority of monocytes, suggesting that they are better able to support HIV-1 replication after entry. Consistent with this observation, high molecular mass complexes of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) were observed in CD16+ monocytes that were similar to those observed in highly permissive T cells. In contrast, CD14highCD16- monocytes contained low molecular mass active APOBEC3G, suggesting this is a mechanism of resistance to HIV-1 infection in these cells. Collectively, these data show that CD16+ monocytes are preferentially susceptible to HIV-1 entry, more permissive for replication, and constitute a continuing source of viral persistence during HAART.     

New 1,2,3,4-tetrahydropyrrolo[3,4-b]indole derivatives as selective CB2 receptor agonists

The preparation and evaluation of a novel class of CB2 agonists based on a 1,2,3,4-tetrahydropyrrolo[3,4-b]indole moiety are reported. They showed binding affinities up to 4.2 nM toward CB2 with sub-nanomolar EC(50) values. They also showed moderate to good (>350-fold) selectivity over the CB1 receptor.     

Immunopathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) infection is a non-cytopathic hepatotropic virus that can lead to severe liver disease including acute hepatitis, cirrhosis and hepatocellular carcinoma. Successful clearance of the virus as well as the establishment of liver disease is largely driven by a complex interaction between the virus and the host immune response. In this review, the immunological events, including both the innate and adaptive immune response are discussed in the setting of both acute and chronic HBV infection and liver disease.     

Validation of density functional modeling protocols on experimental bis(μ-oxo)/μ-η<Superscript>2</Superscript>:η<Superscript>2</Superscript>-peroxo dicopper equilibria

The bis(μ-oxo)/μ-η²:η²-peroxo equilibria for seven supported Cu₂O₂ cores were studied with different hybrid and nonhybrid density functional theory models, namely, BLYP, mPWPW, TPSS, TPSSh, B3LYP, mPW1PW, and MPW1K. Supporting ligands 3,3′-iminobis(N,N-dimethylpropylamine), N,N,N′,N′,N″-pentamethyldipropylenetriamine, N-[2-(pyridin-2-yl)ethyl]-N,N,N′-trimethylpropane-1,3-diamine, bis[2-(2-pyridin-2-yl)ethyl]methylamine, bis[2-(4-methoxy-2-pyridin-2-yl)ethyl]methylamine, bis[2-(4-N,N-dimethylamino-2-pyridin-2-yl)ethyl]methylamine, and 1,4,7-triisopropyl-1,4,7-triazacyclononane were chosen on the basis of the availability of experimental data for comparison. Density functionals were examined with respect to their ability accurately to reproduce experimental properties, including, in particular, geometries and relative energies for the bis(μ-oxo) and side-on peroxo forms. While geometries from both hybrid and nonhybrid functionals were in good agreement with experiment, the incorporation of Hartree–Fock (HF) exchange in hybrid density functionals was found to have a large, degrading effect on predicted relative isomer energies. Specifically, hybrid functionals predicted the μ-η²:η²-peroxo isomer to be too stable by roughly 5–10 kcal mol⁻¹ for each 10% of HF exchange incorporated into the model. Continuum solvation calculations predict electrostatic effects to favor bis(μ-oxo) isomers by 1–4 kcal mol⁻¹ depending on ligand size, with larger ligands having smaller differential solvation effects. Analysis of computed molecular partition functions suggests that nonzero measured entropies of isomerization are likely to be primarily associated with interactions between molecular solutes and their first solvation shell. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The molecular and cellular identity of peripheral osmoreceptors

In mammals, the osmolality of the extracellular fluid (ECF) is highly stable despite radical changes in salt/water intake and excretion. Afferent systems are required to detect hypo- or hyperosmotic shifts in the ECF to trigger homeostatic control of osmolality. In humans, a pressor reflex is triggered by simply drinking water which may be mediated by peripheral osmoreceptors. Here, we identified afferent neurons in the thoracic dorsal root ganglia (DRG) of mice that innervate hepatic blood vessels and detect physiological hypo-osmotic shifts in blood osmolality. Hepatic sensory neurons are equipped with an inward current that faithfully transduces graded changes in osmolality within the physiological range (~15 mOsm). In mice lacking the osmotically activated ion channel, TRPV4, hepatic sensory neurons no longer exhibit osmosensitive inward currents and activation of peripheral osmoreceptors in vivo is abolished. We have thus identified a new population of sensory neurons that transduce ongoing changes in hepatic osmolality.