The APOBEC3 cytidine deaminases are part of the intrinsic defense of cells against retroviruses. Lentiviruses and spumaviruses have evolved essential accessory proteins, Vif and Bet, respectively, which counteract the APOBEC3 proteins. We show here that Bet of the Prototype foamy virus inhibits the antiviral APOBEC3C activity by a mechanism distinct to Vif: Bet forms a complex with APOBEC3C without inducing its degradation. Bet abolished APOBEC3C dimerization as shown by coimmunoprecipitation and cross-linking experiments. These findings implicate a physical interaction between Bet and the APOBEC3C. Subsequently, we identified the Bet interaction domain in human APOBEC3C in the predicted APOBEC3C dimerization site. Taken together, these data support the hypothesis that Bet inhibits incorporation of APOBEC3Cs into retroviral particles. Bet likely achieves this by trapping APOBEC3C protein in complexes rendering them unavailable for newly generated viruses due to direct immobilization. The APOBEC3 (A3)3 genes form part of the intrinsic immunity against retroviruses (1), are under a high adaptive selection (2), and have undergone a unique evolutionary expansion from three to seven genes in primates (APOBEC3A (A3A

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Human APOBEC3 (A3) proteins form part of the intrinsic immunity to retroviruses. Carrying 1 or 2 copies of a cytidine deaminase motif, A3s act by deamination of retroviral genomes during reverse transcription. HIV-1 overcomes this inhibition by the Vif protein, which prevents incorporation of A3 into virions. In this study we modeled and probed the structure of APOBEC3C (A3C), a singledomain A3 with strong antilentiviral activity. The 3-dimensional protein model was used to predict the effect of mutations on antiviral activity, which was tested in a ⌬vif simian immunodeficiency virus (SIV) reporter virus assay. We found that A3C activity requires protein dimerization for antiviral activity against SIV. Furthermore, by using a structure-based algorithm for automated pocket extraction, we detected a putative substrate binding pocket of A3C distal from the zinc-coordinating deaminase motif. Mutations in this region diminished antiviral activity by excluding A3C from virions. We found evidence that the small 5.8S RNA specifically binds to this locus and mediates incorporation of A3C into virus particles.Bioinformatics ͉ immunodeficiency ͉ protein structure ͉ proteinϪprotein interaction ͉ retrovirus

In transgenic animal models, humoral immunity directed against the β-amyloid peptide (Aβ), which is deposited in the brains of AD patients, can reduce Aβ plaques and restore memory. However, initial clinical trials using active immunization with Aβ1–42 (plus adjuvant) had to be stopped as a subset of patients developed meningoencephalitis, likely due to cytotoxic T cell reactions against Aβ. Previously, we demonstrated that retrovirus-like particles displaying on their surface repetitive arrays of self and foreign Ags can serve as potent immunogens. In this study, we generated retrovirus-like particles that display the 15 N-terminal residues of human Aβ (lacking known T cell epitopes) fused to the transmembrane domain of platelet-derived growth factor receptor (Aβ retroparticles). Western blot analysis, ELISA, and immunogold electron microscopy revealed efficient incorporation of the fusion proteins into the particle membrane. Without the use of adjuvants, single immunization of WT mice with Aβ retroparticles evoked high and long-lived Aβ-specific IgG titers of noninflammatory Th2 isotypes (IgG1 and IgG2b) and led to restimulatable B cell memory. Likewise, immunization of transgenic APP23 model mice induced comparable Ab levels. The CNS of immunized wild-type mice revealed neither infiltrating lymphocytes nor activated microglia, and no peripheral autoreactive T cells were detectable. Importantly, vaccination not only reduced Aβ plaque load to ∼60% of controls and lowered both insoluble Aβ40 as well as Aβ42 in APP23 brain, but also significantly reduced cerebral soluble Aβ species. In summary, Aβ retroparticle vaccination may thus hold promise as a novel efficient future candidate vaccine for active immunotherapy of Alzheimer’s disease.

Background: Asthma affects up to nearly 40% of patients with allergic rhinitis (AR). Poor control of AR symptoms is associated with poor asthma control. The goal of this study was to evaluate the effect of AR treatment with MP-AzeFlu on symptoms of AR as well as symptoms of asthma. Methods: This prospective study used a visual analog scale (VAS) to assess symptoms of AR and asthma before and after treatment with MP-AzeFlu (Dymista ® ; azelastine hydrochloride plus fluticasone propionate; 1 spray in each nostril twice daily for 2 weeks). Participants suffered from moderate-to-severe AR according to Allergic Rhinitis and its Impact on Asthma criteria, with acute AR symptoms (AR-VAS scores ≥ 50 mm) on inclusion day. In addition to symptom assessment, patients recorded the impact of AR symptoms on quality-of-life measures before, during, and at the conclusion of the treatment period (approximately 14 days). Patients self-reported change in frequency of their usage of asthma reliever medication on the last day of treatment. Results: Of 1103 study participants, 267 (24.2%) had comorbid asthma. These participants reported using a mean of 5.1 puffs of asthma reliever medication in the week before treatment with MP-AzeFlu. A total of 81.8% of patients with comorbid asthma responded to AR therapy (AR-VAS < 50 mm on at least 1 study day). Among patients with AR and comorbid asthma, MP-AzeFlu was associated with improved VAS scores across all study parameters, including AR symptom severity, asthma symptom severity, sleep quality, daily work or school activities, daily social activities, and daily outdoor activities. Asthma symptom severity decreased from a mean of 48.9 mm to 24.1 mm on the VAS. Selfreported frequency of asthma reliever medication use was reduced for 57.6% of participants (n = 139/241). Conclusion: MP-AzeFlu used to relieve AR symptoms was associated with reduced asthma symptom VAS scores and frequency of asthma reliever medication usage. Changes in overall symptoms of AR and asthma were correlated.