8-modified-2'-deoxyadenosine analogues induce delayed polymerization arrest during HIV-1 reverse transcription

The occurrence of resistant viruses to any of the anti-HIV-1 compounds used in the current therapies against AIDS underlies the urge for the development of new drug targets and/or new drugs acting through novel mechanisms. While all anti-HIV-1 nucleoside analogues in clinical use and in clinical trials rely on ribose modifications for activity, we designed nucleosides with a natural deoxyribose moiety and modifications of position 8 of the adenine base. Such modifications might induce a steric clash with helix αH in the thumb domain of the p66 subunit of HIV-1 RT at a distance from the catalytic site, causing delayed chain termination. Eleven new 2′-deoxyadenosine analogues modified on position 8 of the purine base were synthesized and tested in vitro and in cell-based assays. In this paper we demonstrate for the first time that chemical modifications on position 8 of 2′-deoxyadenosine induce delayed chain termination in vitro, and also inhibit DNA synthesis when incorporated in a DNA template strand. Furthermore, one of them had moderate anti-HIV-1 activity in cell-culture. Our results constitute a proof of concept indicating that modification on the base moiety of nucleosides can induce delayed polymerization arrest and inhibit HIV-1 replication.

Unique IL-13Rα2-based HIV-1 vaccine strategy to enhance mucosal immunity, CD8(+) T-cell avidity and protective immunity.

We have established that mucosal immunization can generate high-avidity human immunodeficiency virus (HIV)- specific CD8þ T cells compared with systemic immunization, and interleukin (IL)-13 is detrimental to the functional avidity of these T cells. We have now constructed two unique recombinant HIV-1 vaccines that co-express soluble or membrane-bound forms of the IL-13 receptor a2 (IL-13Ra2), which can ‘‘transiently’’ block IL-13 activity at the vaccination site causing wild-type animals to behave similar to an IL-13 KO animal. Following intranasal/intramuscular prime-boost immunization, these IL-13Ra2-adjuvanted vaccines have shown to induce (i) enhanced HIV-specific CD8þ Tcells with higher functional avidity, with broader cytokine/chemokine profiles and greater protective immunity using a surrogate mucosal HIV-1 challenge, and also (ii) excellent multifunctional mucosal CD8þ T-cell responses, in the lung, genito-rectal nodes (GN), and Peyer’s patch (PP). Data revealed that intranasal delivery of these IL-13Ra2-adjuvanted HIV vaccines recruited large numbers of unique antigen-presenting cell subsets to the lung mucosae, ultimately promoting the induction of high-avidity CD8þ Tcells. We believe our novel IL-13R cytokine trap vaccine strategy offers great promise for not only HIV-1, but also as a platform technology against range of chronic infections that require strong sustained high-avidity mucosal/systemic immunity for protection.

Gay men's estimates of the likelihood of HIV transmission in sexual behaviours

In 3 studies we recorded gay men's estimates of the likelihood that HIV would be transmitted in various sexual behaviours. In Study 1 (data collected 1993, n=92), the men were found to believe that transmissibility is very much greater than it actually is; that insertive unprotected anal intercourse (UAI) by an HIV-infected partner is made safer by withdrawal before ejaculation, and very much safer by withdrawal before either ejaculation or pre-ejaculation; that UAI is very much safer when an infected partner is receptive rather than insertive; that insertive oral sex by an infected partner is much less risky than even the safest variant of UAI; that HIV is less transmissible very early after infection than later on; and that risk accumulates over repeated acts of UAI less than it actually does. In Study 2 (data collected 1997/8, n=200), it was found that younger and older uninfected men generally gave similar estimates of transmissibility, but that infected men gave somewhat lower estimates than uninfected men; and that estimates were unaffected by asking the men to imagine that they themselves, rather than a hypothetical other gay man, were engaging in the behaviours. Comparison of the 1993 and 1997/8 results suggested that there had been some effect of an educational campaign warning of the dangers of withdrawal; however, there had been no effect either of a campaign warning of the dangers of receptive UAI by an infected partner, or of publicity given to the greater transmissibility of HIV shortly after infection. In Study 3 (data collected 1999, n=59), men induced into a positive mood were found to give lower estimates of transmissibility than either men induced into a neutral mood or men induced into a negative mood. It is argued that the results reveal the important contribution made to gay men's transmissibility estimates by cognitive strategies (such as the 'availability heuristic' and 'anchoring and adjustment') known to be general characteristics of human information-processing. Implications of the findings for AIDS education are discussed.

Unrealistic optimism about becoming infected with HIV: different causes in different populations

People tend to believe that their chance of experiencing undesirable events is lower and their chance of experiencing desirable events is higher than that of the average person like them. Two explanatory models of such 'unrealistic optimism' (UO) have been proposed: While the motivational account holds that UO serves the function of bringing comfort, the cognitive account holds that UO serves no particular function, being simply a by-product of normal cognitive strategies. UO for HIV infection was studied in samples of uninfected students (Study 1, n = 68) and gay men (Study 2, n = 63). In each case, participants rated either their relative likelihood of becoming infected (negative valence condition) or their relative likelihood of remaining uninfected (positive valence condition). As predicted, in Study 1 UO was greater where valence was negative and in Study 2 valence had no effect. The findings suggest that the students' UO is better explained by the motivational account, while the gay men's UO is better explained by the cognitive account. Implications for AIDS education are discussed.

HIV, stigma, and rates of infections : a rumour without evidence

The modern concept of a social stigma comes from the work of American sociologist Erving Goffman, who described it as a response to a deeply discrediting attribute that devalues the person [1]. In the medical literature, stigma is almost inevitably written about in terms of adverse social sequelae of a disease—such as leprosy, tuberculosis, epilepsy, schizophrenia, or filariasis [2–6]—or a physical characteristic or functional loss, such as obesity, deafness, or paraplegia [7–9]. The consequences of stigma range from moderate opprobrium at one end of the spectrum to death [10].

Markers and risk factors for HCV, HBV and HIV in a network of injecting drug users in Melbourne

Background and aims: Current injecting drug users (IDU) in major street drug markets within greater Melbourne were recruited to a longitudinal study on blood borne viruses. Here we investigated risk factors for hepatitis C virus (HCV), hepatitis B virus (HBV) and HIV infection in these IDU at the time of their recruitment.

Methods : Three hundred and eighty-two IDU completed detailed questionnaires on their drug use and risk behaviours, and provided blood samples for serology testing. These data were analysed using univariate and multivariate techniques.

Results : The overall prevalence of exposure to HCV, HBV and HIV was estimated at 70%, 34% and <1%, respectively. Independent predictors of HCV exposure were history of imprisonment (RR 1.34, 95% CI 1.19–1.52), use of someone else's needle or syringe (RR 1.23, 95% CI 1.07–1.42), >7.6 years length of time injecting (RR 1.21, 95% CI 1.07–1.37), and originating from Vietnam (RR 1.12, 95% CI 1.07–1.18). Independent predictors of HBV exposure were HCV exposure (RR 2.15, 95% CI 1.35–3.43), >7.6 years length of time injecting (RR 1.57, 95% CI 1.17–2.13) and originating from outside Australia (RR 1.60, 95% CI 1.22–2.10). Neither prison- nor community-applied tattoos predicted HCV or HBV exposure. Up to 31% of IDU who injected for 1 year or less were HCV antibody positive, as were 53% of those who injected for 2 years or less.

Conclusions : Ongoing engagement with young IDU, through the provision of harm reduction education and resources, is critical if we are to address blood borne viral infections and other health and social harms associated with injecting drug use.

Cost-effectiveness of adult circumcision in a resource-rich setting for HIV prevention among men who have sex with men

Background.  We examined the effects and cost‐effectiveness of 4 strategies of circumcision in a resource‐rich setting (Australia) in a population of men who have sex with men (MSM).

Method.  We created a dynamic mathematical transmission model and performed an economic analysis to estimate the costs, outcomes, and cost‐effectiveness of different strategies, compared with those of the status quo. Strategies included circumcision of all MSM at age 18 years, circumcision of all MSM aged 35–44 years, circumcision of all insertive MSM aged 18 years, and circumcision of all MSM aged 18 years . All costs are reported in US dollars, with a cost‐effectiveness threshold of $42,000 per quality‐adjusted life‐year.

Results.  We find that 2%–5% of human immunodeficiency virus (HIV) infections would be averted per year, with initial costs ranging from $3.6 million to $95.1 million, depending on the strategy. The number of circumcisions needed to prevent 1 HIV infection would range from 118 through 338. Circumcision of predominately insertive MSM would save $21.7 million over 25 years with a $62.2 million investment. Strategies to circumcise 100% of all MSM and to circumcise MSM aged 35–44 years would be cost‐effective; the latter would require a smaller investment. The least cost‐effective approach is circumcision of young MSM close to their sexual debut. Results are very sensitive to assumptions about the cost of circumcision, the efficacy of circumcision, sexual preferences, and behavioral disinhibition.

Conclusions.  Circumcision of adult MSM may be cost‐effective in this resource‐rich setting. However, the intervention costs are high relative to the costs spent on other HIV prevention programs.

Lived experience of gay men caring for others with HIV/AIDS : living, loving and dying in the era of HIV/AIDS

This thesis explored gay male carers’ experience of caring for their partner, brother or friend who had HIV/AIDS. Through using phenomenological methodology (van Manen, 1990), the day-to-day caring experiences were uncovered. The data gathered were then analysed through a nursing ‘lens’, with the concept of stigma as an anchoring point. The dual stigmas of homophobia and AIDS phobia impacted on the daily lives of these men as they cared for their loved one. The research identified six themes. These were: 1) the relationship; 2) coping with HIV and AIDS; 3) the corporal impact of HIV/AIDS; 4) experiences of carers including the absence of others; 5) living daily with the virus: Demands of people living with HIV/AIDS (PLWHA); and 6) saying goodbye, but wanting to keep the memory alive. The caring these men undertook, for which they were frequently unprepared, was intensive and complex, but because of their commitment and love they battled on. Because of a sense of shame associated with AIDS phobia on the part of the PLWHA, the carer often had to undertake this care in isolation, without support from family, friends or home health care agencies. The carers struggled with not only the demands of day-to-day care, but also with non-acceptance from family, both of the nature of the relationship with their partner and of their homosexuality. Family members were forced, often with great difficulty, to acknowledge the close commitment the men had to each other. Recognition that one had a terminal disease, HIV/AIDS was also required. The fear of potential transmission was high among carers, friends and family members. Notably, there was an absence of blame on the part of the carer towards his partner for contracting HIV/AIDS. The physical decline and marking of the body further stigmatised the PLWHA, which added to carers’ burdens. They endeavoured to minimise the physical decline in their partner, so he could continue to pass as healthy, and attempted to make the day-to-day living as normal as possible. The methods of combating weight loss and opportunistic infections meant frequent medical appointments, complex intensive medical procedures and help with personal care, which was undertaken at home largely without support from health care staff. Carers frequently struggled also with their partner’s denial of being ill. One strategy all carers used was to escape with their partners from their everyday life in Melbourne and attempt metaphorically to leave the HIV/AIDS behind; this was a time when they could rekindle their life together as it was before HIV/AIDS came into their lives. Some carers chose to holiday without their partner, to give themselves a break from the day-to-day caring, while others planned and took holidays with their partner. The decline of the health in the PLWHA meant that family members had to recognise and accept both the nature of the relationship and the presence of the disease. This recognition and acceptance often came only when the partner was very ill, even at the point of dying. Carers and their partners discussed the potential use of euthanasia, as a means of ending the final phase of life with some dignity. One carer and his partner used euthanasia, despite its illegal status. The main concern for all carers was providing comfort and a reduction in the pain associated with HIV/AIDS for the partner. The widespread grief associated with HIV/AIDS was evident amongst these carers. All had known other gay men who had died, some carers own partner had died, or was about to die. There was an overwhelming sense of grief, which at times was repressed as a means of coping day-to-day. All carers felt it was important and necessary to remember those lost to HIV/AIDS through the various public memorials, as they did not want their partner to be just another faceless person lost to this disease. This phenomenological study of carers’ experience highlights the need for health care workers to be aware of the differing strategies that gay men use to cope with HIV/AIDS. While it may seem that the carers are coping with care of their partner, the outer façade is not always an accurate portrayal of the true situation. Health care workers should enquire as to the assistance these carers need from health care services in order to continue to care for their loved one. Such assistance can be the simple recognition of the partner and acceptance of them as part of the PLWHA’s network; this inclusion and acceptance is half the battle.

Rhotekin 2, a novel GTPase effector involved in resistance to apoptosis

This thesis describes the discovery, characterization, and function of a new protein, Rhotekin 2. It is a signaling protein with a significant role in resistance to cell death in human lymphocytes and therefore may be a potential new target in future treatments of immune diseases such a HIV and leukemia.

Clade, country and region-specific HIV-1 vaccines : are they necessary?

Today, scientists are often encouraged to custom-design vaccines based on a particular country or clade. Here, we review the scientific literature and then suggest that the overwhelming endeavor to produce a unique vaccine for every world region or virus subtype may not be necessary.

HIV infection of dendritic cells subverts the IFN induction pathway via IRF-1 and inhibits type 1 IFN production

Many viruses have developed mechanisms to evade the IFN response. Here, HIV-1 was shown to induce a distinct subset of IFN-stimulated genes (ISGs) in monocyte-derived dendritic cells (DCs), without detectable type I or II IFN. These ISGs all contained an IFN regulatory factor 1 (IRF-1) binding site in their promoters, and their expression was shown to be driven by IRF-1, indicating this subset was induced directly by viral infection by IRF-1. IRF-1 and -7 protein expression was enriched in HIV p24 antigen-positive DCs. A HIV deletion mutant with the IRF-1 binding site deleted from the long terminal repeat showed reduced growth kinetics. Early and persistent induction of IRF-1 was coupled with sequential transient up-regulation of its 2 inhibitors, IRF-8, followed by IRF-2, suggesting a mechanism for IFN inhibition. HIV-1 mutants with Vpr deleted induced IFN, showing that Vpr is inhibitory. However, HIV IFN inhibition was mediated by failure of IRF-3 activation rather than by its degradation, as in T cells. In contrast, herpes simplex virus type 2 markedly induced IFNβ and a broader range of ISGs to higher levels, supporting the hypothesis that HIV-1 specifically manipulates the induction of IFN and ISGs to enhance its noncytopathic replication in DCs.

Innate immunity and intracellular trafficking : insights for novel anti-HIV-1 therapeutics

It is now evident that host cells have evolved a remarkable variety of antiretroviral activities to defend themselves against viral invaders and in return viruses have developed ingenious ways to circumvent these defences and, in some cases, actually hijack cellular proteins in order to facilitate their replication. Study of this cat and mouse interplay between viruses and their host cells throughout evolution has lead to the identification of some of the most sophisticated antiviral strategies that mammals have developed to prevent viral infection. Recently, a wave of publications has significantly enhanced our understanding of the relationship between human immunodeficiency virus type 1 (HIV-1) and its host, including: 1) the HIV-1 protein Vif and its interaction with host cell nucleic acid editing enzymes; 2) the host cell restrictive factors that provide protection against retroviral infection, such as TRIM5; and 3) the late domains of retroviruses and their relationship with the host cell vacuolar protein sorting pathway. The focus of this review is to provide an up-to-date account of these important areas of HIV-1 research and highlight how some of these new discoveries can potentially be exploited for the development of novel anti-retroviral therapeutics.

Lipid rafts and HIV-1 : from viral entry to assembly of progeny virions

Background: Lipid rafts are currently an intensely investigated topic of cell biology. In addition to a demonstrated role in signal transduction of the host cell, lipid rafts serve as entry and exit sites for microbial pathogens and toxins, such as FimH-expressing enterobacteria, influenza virus, measles virus and cholera toxin. Furthermore, caveolae, a specialised form of lipid raft, are required for the conversion of the non-pathogenic prion protein to the pathogenic scrapie isoform.

Objectives: A number of reports have shown, directly or indirectly, that lipid rafts are important at various stages of the human immunodeficiency virus type-1 (HIV-1) replication cycle. The purpose of this paper is to provide a brief overview of the role of membrane-associated lipid rafts in cell biology, and to evaluate how HIV-1 has hijacked this cellular component to support HIV-1 replication. Special sections are devoted to discussing the role of lipid rafts in (1) the entry of HIV-1, (2) signal transduction regulation in HIV-1-infected cells, (3) the trafficking of HIV-1 proteins via lipid rafts during HIV-1 assembly; and a further section discusses the role of cholesterol in mature HIV-1.

Summary: Like a number of other pathogens, HIV-1 has evolved to rely on the host cell lipid rafts to support its propagation during multiple stages of the HIV-1 replication cycle. This review has highlighted the importance of lipid rafts in HIV-1 replication.

“I call it the blame and shame disease”: a qualitative study about perceptions of social stigma surrounding type 2 diabetes

Abstract
Objectives While health-related stigma has been the subject of considerable research in other conditions (obesity and HIV/AIDS), it has not received substantial attention in diabetes. The aim of the current study was to explore the social experiences of Australian adults living with type 2 diabetes mellitus (T2DM), with a particular focus on the perception and experience of diabetes-related stigma.

Design A qualitative study using semistructured interviews, which were audio recorded, transcribed and subject to thematic analysis.

Setting This study was conducted in non-clinical settings in metropolitan and regional areas in the Australian state of Victoria. Participants were recruited primarily through the state consumer organisation representing people with diabetes.

Participants All adults aged ≥18 years with T2DM living in Victoria were eligible to take part. Twenty-five adults with T2DM participated (12 women; median age 61 years; median diabetes duration 5 years).

Results A total of 21 (84%) participants indicated that they believed T2DM was stigmatised, or reported evidence of stigmatisation. Specific themes about the experience of stigma were feeling blamed by others for causing their own condition, being subject to negative stereotyping, being discriminated against or having restricted opportunities in life. Other themes focused on sources of stigma, which included the media, healthcare professionals, friends, family and colleagues. Themes relating to the consequences of this stigma were also evident, including participants’ unwillingness to disclose their condition to others and psychological distress. Participants believed that people with type 1 diabetes do not experience similar stigmatisation.

Conclusions Our study found evidence of people with T2DM experiencing and perceiving diabetes-related social stigma. Further research is needed to explore ways to measure and minimise diabetes-related stigma at the individual and societal levels, and also to explore perceptions and experiences of stigma in people with type 1 diabetes