No abstract

Olfactory neurons expressing the same odorant receptor converge to a small number of glomeruli in the olfactory bulb. In turn, mitral and tufted cells receive and relay this information to higher cortical regions. In other sensory systems, correlated neuronal activity is thought to refine synaptic connections during development. We asked whether the pattern of connections between olfactory sensory axons and mitral cell dendrites is affected when odor-evoked signaling is eliminated in mice lacking functional olfactory cyclic nucleotide-gated (CNG) channels. We demonstrate that olfactory sensory axons converge normally in the CNG channel mutant background. We further show that the pruning of mitral cell dendrites, although slowed during development, is ultimately unperturbed in mutant animals. Thus, the olfactory CNG channel-and by inference correlated neural activity--is not required for generating synaptic specificity in the olfactory bulb.

Treatment with exogenous interferon (IFN)-a is not effective in the majority of patients with chronic hepatitis B virus (HBV) infection. Recent evidence suggests that HBV has evolved strategies to block the nuclear translocation of signal transducer and activator of transcription (STAT) 1 to limit IFN-a-induced cellular antiviral responses. However, it remains unclear whether STAT1 translocation is impaired in chronic hepatitis B patients and what mechanisms are involved. Here we report that the expression of HBV polymerase (Pol) in human hepatic cell lines inhibited induction of IFN-stimulated genes and resulted in a weakened antiviral activity of IFN-a. Ectopic expression of Pol suppressed IFN-a-induced STAT1 serine 727 phosphorylation and STAT1/2 nuclear accumulation, whereas STAT1 tyrosine 701 phosphorylation, and STAT1-STAT2 heterodimer formation were not affected. Further studies demonstrated that Pol interacted with the catalytic domain of protein kinase C-d (PKC-d) and perturbed PKC-d phosphorylation and its association with STAT1, which resulted in the suppression of STAT1 Ser727 phosphorylation. Moreover, Pol was found to interfere with nuclear transportation of STAT1/2 by competitively binding to the region of importin-a5 required for STAT1/2 recruitment. Truncation analysis suggested that the terminal protein and RNase H domains of Pol were able to bind to PKC-d and importin-a5, respectively, and were responsible for the inhibition of IFN-a signaling. More importantly, the inhibition of STAT1 and PKC-d phosphorylation were confirmed in a hydrodynamicbased HBV mouse model, and the blockage of IFN-a-induced STAT1/2 nuclear translocation was observed in HBV-infected cells from liver biopsies of chronic HBV patients.Conclusions: These results demonstrate a role for Pol in HBV-mediated antagonization of IFN-a signaling and provide a possible molecular mechanism by which HBV resists the IFN therapy and maintains its persistence. (HEPATOLOGY 2013;57:470-482) C hronic hepatitis B (CHB) caused by hepatitis B virus (HBV) is a serious health problem worldwide. The mechanism by which chronic infection is established and maintained is unknown but is thought to be due, in part, to a suppressed host immune response. One key component of the host antiviral responses is the interferon (IFN) system. Viral infection of the host initiates the synthesis of type I IFNs, which consist predominantly of IFN-a and IFN-b (IFN-a/b). By binding to type I IFN receptors,

Objective This report presents tenofovir alafenamide (TAF) and elvitegravir (EVG) fabricated into nanoparticles (NPs) for subcutaneous (SubQ) delivery as prevention strategy. Design Prospective prevention study in hu-BLT mice. Methods Using an oil-in-water emulsion solvent evaporation technique, TAF+EVG drugs were entrapped together into NPs containing poly(lactic-co-glycolic acid) (PLGA). In vitro prophylaxis studies (IC90) compared NPs to drugs in solution. Humanized-BLT (n=5/group) mice were given 200 mg/kg SubQ, and vaginally challenged with HIV-1 (5×105 TCID50) 4 and 14 days (d) post-NP administration (PI). Control mice (n=5) were challenged at 4 d. Weekly plasma viral load (pVL) was performed using RT-PCR. Hu-BLT mice were sacrificed and lymph nodes were harvested for HIV-1 viral RNA detection by in situ hybridization (ISH). In parallel, CD34+ humanized mice (3/time point) compared tenofovir (TFV) and EVG drug levels in vaginal tissues from NPs and solution. TFV and EVG were analyzed from tissue using LC-MS/MS. Results TAF+EVG NPs were < 200 nm in size. In-vitro prophylaxis indicates TAF+EVG NPs IC90 was 0.002 μg/mL and TAF+EVG solution was 0.78 μg/mL. TAF+EVG NPs demonstrated detectable drugs for 14 days and 72 h for solution, respectively. All Hu-BLT control mice became infected within 14 d after HIV-1 challenge. In contrast, hu-BLT mice that received NPs and challenged at 4 d PI, 100% were uninfected, and 60% challenged at 14 d PI were uninfected (p = 0.007; Mantel-Cox test). ISH confirmed these results. Conclusions This proof-of-concept study demonstrated sustained protection for TAF+EVG NPs in a hu-BLT mouse model of HIV vaginal transmission.