Persistence of attenuated HIV-1 rev alleles in an epidemiologically linked cohort of long-term survivors infected with nef-deleted virus

<p>Abstract</p> <p>Background</p> <p>The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with <it>nef</it>-deleted, attenuated strains of human immunodeficiency virus type 1 (HIV-1). Although the cohort members have experienced differing clinical courses and now comprise slow progressors (SP) as well as long-term nonprogressors (LTNP), longitudinal analysis of <it>nef</it>/long-terminal repeat (LTR) sequences demonstrated convergent <it>nef</it>/LTR sequence evolution in SBBC SP and LTNP. Thus, the <it>in vivo </it>pathogenicity of attenuated HIV-1 strains harboured by SBBC members is dictated by factors other than <it>nef</it>/LTR. Therefore, to determine whether defects in other viral genes contribute to attenuation of these HIV-1 strains, we characterized dominant HIV-1 <it>rev </it>alleles that persisted in 4 SBBC subjects; C18, C64, C98 and D36.</p> <p>Results</p> <p>The ability of Rev derived from D36 and C64 to bind the Rev responsive element (RRE) in RNA binding assays was reduced by approximately 90% compared to Rev derived from HIV-1_NL4-3, C18 or C98. D36 Rev also had a 50–60% reduction in ability to express Rev-dependent reporter constructs in mammalian cells. In contrast, C64 Rev had only marginally decreased Rev function despite attenuated RRE binding. In D36 and C64, attenuated RRE binding was associated with rare amino acid changes at 3 highly conserved residues; Gln to Pro at position 74 immediately N-terminal to the Rev activation domain, and Val to Leu and Ser to Pro at positions 104 and 106 at the Rev C-terminus, respectively. In D36, reduced Rev function was mapped to an unusual 13 amino acid extension at the Rev C-terminus.</p> <p>Conclusion</p> <p>These findings provide new genetic and mechanistic insights important for Rev function, and suggest that Rev function, not Rev/RRE binding may be rate limiting for HIV-1 replication. In addition, attenuated <it>rev </it>alleles may contribute to viral attenuation and long-term survival of HIV-1 infection in a subset of SBBC members.</p

Empowering Teaching Assistants to Support Students: Impact of Training and Experience on Perceptions and Practices

Teaching assistants (TAs) have a major impact on the undergraduate science student experience, and therefore training TAs is critical to support engagement and learning. We ran a one-day TA training program for two years and found that participation in the program increased TAs’ reflective practice and student-centered teaching over a semester of teaching. Open-ended pre-survey responses indicated that in addition to wanting to learn pedagogical approaches, TAs sought help managing challenging situations and student behaviour. Post-surveys confirmed that the program fulfilled most learning goals of TAs and they subsequently applied the new teaching approaches. Participants indicated high levels of empowerment within their teaching roles across the cognitions of impact, competence and meaningfulness, but low self-determination. All aspects of empowerment increased with experience

Sessional staff training for improved student experience

It is widely recognised that the quality of the undergraduate experience in science often depends on student interactions with sessional staff. In some cases, sessional staff have primary responsibility for teaching within tutorials, workshops and practicals, on field trips, and sometimes in lectures. Preparing postgraduate students to teach requires them to accept responsibilities that they may not have signed up for when they decided to become scientists, and they are unlikely to have been exposed to pedagogical theories in their science studies. In their role as teachers, postgraduate students and other sessional staff bring their own experiences, knowledge and attitudes towards teaching, which will influence their personal teaching practice. We held a full-day workshop with the goal of improving the learning experiences of undergraduate students by improving the training of sessional staff in teaching. This was designed based on the latest literature with three aims: 1. To enhance sessional staff’s sense of psychological empowerment; 2. To develop the belief that sessional staff can enhance undergraduate students’ learning experiences; 3. To increase the level of communication and harmonise experiences across campuses. Results from surveys and interviews before and after the workshop will be presented

Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus-1

<p><b>Copyright information:</b></p><p>Taken from "Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus"</p><p>http://www.retrovirology.com/content/4/1/43</p><p>Retrovirology 2007;4():43-43.</p><p>Published online 1 Jul 2007</p><p>PMCID:PMC1933581.</p><p></p>scribed in Materials and Methods. Binding reactions containing increasing concentrations of His-tagged Matrix protein from HIV-1were included as negative controls. Rev/RRE complexes were resolved by electrophoresis in 5% (wt/vol) native polyacrylamide gels and visualized by autoradiography (A). Bands were quantified by phosphorimager analysis, and the percentage of RNA binding was calculated by dividing the signal intensity of bands associated with Rev/RRE complexes by the signal intensity of all bands, and multiplying this number by 100 (B). The data shown are representative of three independent experiments. *< 0.01, Student's test

Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus-2

<p><b>Copyright information:</b></p><p>Taken from "Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus"</p><p>http://www.retrovirology.com/content/4/1/43</p><p>Retrovirology 2007;4():43-43.</p><p>Published online 1 Jul 2007</p><p>PMCID:PMC1933581.</p><p></p>asmid [31], as described in Materials and Methods. Cells co-transfected with pDM128 and pcDNA3.1 expressing HIV-1Matrix protein or empty pcDNA3.1 vector were included as negative controls. Rev protein expression was determined by Western blotting with sheep anti-Rev polyclonal antisera (A). CAT activity in cell lysates was quantified and normalized to CAT activity in lysates of CEM cells co-transfected with pDM128 and NL4-3 Rev (B). Values shown are means of triplicate transfections. Error bars represent standard deviations. Results are representative of three independent experiments. *< 0.01, Student's test

Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus-0

<p><b>Copyright information:</b></p><p>Taken from "Persistence of attenuated HIV-1 alleles in an epidemiologically linked cohort of long-term survivors infected with -deleted virus"</p><p>http://www.retrovirology.com/content/4/1/43</p><p>Retrovirology 2007;4():43-43.</p><p>Published online 1 Jul 2007</p><p>PMCID:PMC1933581.</p><p></p>ts C18, C64, C98 and D36. They are the consensus sequences of multiple independent Rev clones that persisted over a 4- to 6-year period in C64, C98 and D36, or which were dominant in a single blood sample obtained from C18 [see Additional file ]. Amino acid alignments are compared to Rev from HIV-1. Dots indicate residues identical to HIV-1Rev, and dashes indicate gaps. Boxed residues indicate amino acid substitutions which discriminate C18 and C98 Revs from C64 and D36 Revs. NLS; nuclear localization signal, RBD; RNA binding domain, NES; nuclear export signal

Evaluation of In Vitro Capsaicin Release and Antimicrobial Properties of Topical Pharmaceutical Formulation

(1) Background: Capsaicin is the main capsaicinoid of the Capsicum genus and it is responsible for the pungent taste. Medical uses of the fruits of chili peppers date from the ancient time until nowadays. Most of all, they are used topically as analgesic in anti-inflammatory diseases as rheumatism, arthritis and in diabetic neuropathy. Reports state that the Capsicum genus, among other plant genera, is a good source of antimicrobial and antifungal compounds. The aim of this study was the preparation of a pharmaceutical Carbopol-based formulation containing capsaicin and the evaluation of its in vitro release and antimicrobial and antifungal properties. (2) Methods: It was first stabilized with an extraction method from the Capsicum annuum fruits with 98% ethanol and then the identification and determination of Capsaicin in this extract was realized by HPLC. (3) Results and Conclusions: Rheological analyses revealed that the selected formulation exhibited a pseudo-plastic behavior. In vitro release studies of capsaicin from a Carbopol-based formulation reported that approximately 50% of capsaicin was release within 52 h. Additionally, the Carbopol-based formulation significantly increased the antimicrobial effects of capsaicin towards all tested bacteria and fungi strains

Enhanced CD4+cellular apoptosis by CCR5-restricted HIV-1 envelope glycoprotein variants from patients with progressive HIV-1 infection

CCR5-using (R5) human immunodeficiency virus type 1 (HIV-1) strains cause CD4+ T-cell loss in most infected individuals, but mechanisms underlying cytopathicity of R5 viruses are poorly understood. We investigated mechanisms contributing to R5 envelope glycoprotein (Env)-mediated cellular apoptosis by constructing a panel of retroviral vectors engineered to co-express GFP and R5 Envs derived from two HIV-1 infected subjects spanning asymptomatic (Early, E-R5 Envs) to late stages of infection (Late, L-R5 Envs). The L-R5 Envs induced significantly more cellular apoptosis than E-R5 Envs, but only in Env-expressing (GFP-positive) cells, and only in cells where CD4 and CCR5 levels were limiting. Studies with fusion-defective Env mutants showed induction of apoptosis required membrane-fusing events. Our results provide evidence for an intracellular mechanism of R5 Env-induced apoptosis of CD4+ cells that requires membrane fusion. Furthermore, they contribute to a better understanding of mechanisms involved in CD4+ T-cell loss in subjects experiencing progressive R5 HIV-1 infection. (C) 2009 Elsevier Inc. All rights reserved