Nogo-A, -B, and -C are generated from the Nogo/RTN-4 gene and share a highly conserved C-terminal domain. They lack an N-terminal signal sequence and are predominantly localized to the endoplasmic reticulum (ER). We found the N terminus of endogenous Nogo-A exposed on the surface of fibroblasts, DRG neurons, and myoblasts. Surface-expressed Nogo-A was also present on presynaptic terminals of the neuromuscular junction and on DRG neurons in vivo. Surface biotinylations confirmed the presence of all Nogo isoforms on the surface. To search for proteins that interact with Nogo-A and suggest a function for the large intracellular pool of Nogo-A, immunoprecipitations were performed. Surprisingly, the most predominant proteins that interact with Nogo-A are Nogo-B and Nogo-C as seen with radiolabeled lysates and as confirmed by Western blotting in multiple cell lines. Nogo-A, -B, and -C share a 180-amino acid C-terminal domain with two highly conserved hydrophobic stretches that could form a channel or transporter in the ER and/or on the cell surface.

Early treatment initiation within 2 months after HIV infection compared with later therapy initiation resulted in reduced levels of plasma viraemia and proviral HIV-1 DNA for ≥1 year after subsequent ART cessation. Plasma HIV-1 RNA levels in early starters were also significantly lower than in untreated controls.

BackgroundLong-term benefits of combination antiretroviral therapy (cART) initiation during primary HIV-1 infection are debated.MethodsThe evolution of plasma HIV-RNA (432 measurements) and cell-associated HIV-DNA (325 measurements) after cessation of cART (median exposure 18 months) was described for 33 participants from the Zurich Primary HIV Infection Study using linear regression and compared with 545 measurements from 79 untreated controls with clinically diagnosed primary HIV infection, respectively a known date for seroconversion.ResultsOn average, early treated individuals were followed for 37 months (median) after cART cessation; controls had 34 months of pre-cART follow-up. HIV-RNA levels one year after cART interruption were −0.8 log10 copies/mL [95% confidence interval −1.2;−0.4] lower in early treated patients compared with controls, but this difference was no longer statistically significant by year three of follow-up (−0.3 [−0.9; 0.3]). Mean HIV-DNA levels rebounded from 2 log10 copies [1.8; 2.3] on cART to a stable plateau of 2.7 log10 copies [2.5; 3.0] attained 1 year after therapy stop, which was not significantly different from cross-sectional measurements of 9 untreated members of the control group (2.8 log10 copies [2.5; 3.1]).ConclusionsThe rebound dynamics of viral markers after therapy cessation suggest that early cART may indeed limit reservoir size of latently infected cells, but that much of the initial benefits are only transient. Owing to the non-randomized study design the observed treatment effects must be interpreted with caution.