Aged care service use by Aboriginal and Torres Strait Islander people after aged care eligibility assessments, 2017-2019: a population-based retrospective cohort study.

OBJECTIVE: To characterise the socio-demographic characteristics, aged and health care needs, and aged care services used by older Aboriginal and Torres Strait Islander people assessed for aged care service eligibility. STUDY DESIGN: Population-based retrospective cohort study; analysis of Registry of Senior Australians (ROSA) National Historical Cohort data. SETTING, PARTICIPANTS: Aboriginal and Torres Strait Islander people aged 50 years or older who were first assessed for aged care service eligibility (permanent residential aged care, home care package, respite care, or transition care) during 1 January 2017 - 31 December 2019. MAJOR OUTCOME MEASURES: Socio-demographic and aged care assessment characteristics; health conditions and functional limitations recorded at the time of the assessment; subsequent aged care service use. RESULTS: The median age of the 6209 people assessed for aged care service eligibility was 67 years (interquartile range [IQR], 60-75 years), 3626 were women (58.4%), and 4043 lived in regional to very remote areas of Australia (65.1%). Aboriginal health workers were involved in 655 eligibility assessments (10.5%). The median number of health conditions was six (IQR, 4-8); 6013 (96.9%) had two or more health conditions, and 2592 (41.8%) had seven or more. Comorbidity was most frequent among people with mental health conditions: 597 of 1136 people with anxiety (52.5%) and 1170 of 2416 people with depression (48.5%) had seven or more other medical conditions. Geriatric syndromes were recorded for 2265 people (36.5%); assistance with at least one functional activity was required by 6190 people (99.7%). A total of 6114 people (98.5%) were approved for at least one aged care service, 3218 of whom (52.6%) subsequently used these services; the first services used were most frequently home care packages (1660 people, 51.6%). CONCLUSION: Despite the high care needs of older Aboriginal and Torres Strait Islander people, only 52% used aged care services for which they were eligible. It is likely that the health and aged care needs of older Aboriginal and Torres Strait Islander people are not being adequately met.

Development and validation of a frailty index based on Australian Aged Care Assessment Program data.

OBJECTIVES: To develop and validate a frailty index, derived from aged care eligibility assessment data. DESIGN: Retrospective cohort study; analysis of the historical national cohort of the Registry of Senior Australians (ROSA). PARTICIPANTS: 903 996 non-Indigenous Australians aged 65 years or more, living in the community and assessed for subsidised aged care eligibility during 2003-2013. MAIN OUTCOME MEASURES: 44-item frailty index; summary statistics for frailty index score distribution; predictive validity with respect to mortality and entry into permanent residential aged care during the five years after assessment. RESULTS: The mean frailty index score during 2003-2013 was 0.20 (SD, 0.07; range, 0-0.41); the proportion of assessed older people with scores exceeding 0.20 increased from 32.1% in 2003-2005 to 75.0% in 2012-2013. The risks of death and entry into permanent residential aged care at one, three and five years increased with frailty index score level (at one year, high [over 0.35] v low scores [under 0.05]: hazard ratio for death, 5.99; 95% CI, 5.69-6.31; for entry into permanent residential aged care, 8.70; 95% CI, 8.32-9.11). The predictive validity (area under the receiver operating characteristic curve) of Cox proportional hazard models including age, sex, and frailty index score was 0.64 (95% CI, 0.63-0.64) for death and 0.63 (95% CI, 0.62-0.63) for entry into permanent residential aged care within one year of assessment. CONCLUSIONS: We used Australian aged care eligibility assessment program data to construct and validate a frailty index. It can be employed in aged care research in Australia, but its application to aged care planning requires further investigation.

The dispensing of psychotropic medicines to older people before and after they enter residential aged care.

OBJECTIVE: To examine the prevalence of psychotropic medicine dispensing before and after older people enter residential care. DESIGN: Retrospective national cohort study; analysis of Registry of Senior Australians (ROSA) data. SETTING, PARTICIPANTS: All concession card-holding residents of government-subsidised residential aged care facilities in Australia who entered residential care for at least three months between 1 April 2008 and 30 June 2015. MAIN OUTCOME MEASURES: Proportions of residents dispensed antipsychotic, benzodiazepine, or antidepressant medicines during the year preceding and the year after commencing residential care, by quarter. RESULTS: Of 322 120 included aged care residents, 68 483 received at least one antipsychotic (21.3%; 95% CI, 21.1-21.4%), 98 315 at least one benzodiazepine (30.5%; 95% CI, 30.4-30.7%), and 122 224 residents at least one antidepressant (37.9%; 95% CI, 37.8-38.1%) during their first three months of residential care; 31 326 of those dispensed antipsychotics (45.7%), 38 529 of those dispensed benzodiazepines (39.2%), and 25 259 residents dispensed antidepressants (19.8%) had not received them in the year preceding their entry into care. During the first three months of residential care, the prevalence of antipsychotic (prevalence ratio [PR], 3.37; 95% CI, 3.31-3.43) and antidepressant dispensing (PR, 1.05; 95% CI, 1.04-1.07) were each higher for residents with than for those without dementia; benzodiazepine dispensing was similar for both groups (PR, 1.01; 95% CI, 0.99-1.02). CONCLUSIONS: Dispensing of psychotropic medicines to older Australians is high before they enter residential care but increases markedly soon after entry into care. Non-pharmacological behavioural management strategies are important for limiting the prescribing of psychotropic medicines for older people in the community or in residential care.

Factors associated with success in transition care services among older people in Australia.

BACKGROUND: The Australian Transition Care Program (TCP) is a national intermediate care service aiming to optimise functional independence and delay entry to permanent care for older people leaving hospital. The aim of this study was to describe the outcomes of TCP and identify demographic and clinical factors associated with TCP 'success', to assist with clinical judgements about suitable candidates for the program. METHOD: We conducted a descriptive cohort study of all older Australians accessing TCP for the first time between 2007 and 2015. Logistic regression models assessed demographic and clinical factors associated with change in performance on a modified Barthel Index from TCP entry to discharge and on discharge to community. Fine-Gray regression models estimated factors associated with transition to permanent care within 6 months of TCP discharge, with death as a competing event. RESULTS: Functional independence improved from entry to discharge for 46,712 (38.4%) of 124,301 TCP users. Improvement was more common with younger age, less frailty, shorter hospital stay prior to TCP, and among women, those without a carer, living outside a major city, and without dementia. People who received TCP in a residential setting were far less likely to record improved functional impairment and more likely to be discharged to permanent care than those in a community setting. Discharge to community was more common with younger age and among women and those without dementia. Nearly 12% of community TCP and 63% of residential TCP users had transitioned to permanent care 6 months after discharge. Entry to permanent care was more common with older age, higher levels of frailty, and among those with dementia. CONCLUSIONS: More than half of TCP users are discharged to home and remain at home after 6 months. However, residential-based TCP may have limited efficacy. Age, frailty, carer status, and dementia are key factors to consider when assessing program suitability. Future studies comparing users to a suitably matched control group will be very helpful for confirming whether the TCP program is meeting its aims.

Burkholderia lata Infections from Intrinsically Contaminated Chlorhexidine Mouthwash, Australia, 2016.

Burkholderia lata was isolated from 8 intensive care patients at 2 tertiary hospitals in Australia. Whole-genome sequencing demonstrated that clinical and environmental isolates originated from a batch of contaminated commercial chlorhexidine mouthwash. Genomic analysis identified efflux pump-encoding genes as potential facilitators of bacterial persistence within this biocide.

DNA vaccines encoding membrane-bound or secreted forms of heat shock protein 70 exhibit improved potency.

Traditional vaccine strategies are inefficient against challenge with complex pathogens including HIV; therefore, novel vaccine technologies are required. DNA vaccines are attractive as they are relatively cheap and easy to manufacture, but a major limitation has been their lack of immunogenicity in humans, which may be overcome with the incorporation of an adjuvant. HSP70 is a recognised damage-associated molecular pattern, which is a potential adjuvant. We investigated the immunogenicity of a DNA vaccine encoding HIV gag and HSP70; the latter was genetically modified to produce cytoplasmic, secreted or membrane-bound HSP70, the expression of which was controlled by an independent promoter. The DNA was administered to C57BL/6 mice to evaluate gag-specific T-cell responses. Our results demonstrated the ability of membrane-bound and secreted HSP70 to significantly enhance gag-specific T-cell responses and increase the breadth of T-cell responses to include subdominant epitopes. Membrane-bound or secreted HSP70 also significantly improved the multifunctionality of HIV-specific T cells and T-cell proliferation, which is important for maintaining T-cell integrity. Most importantly, the inclusion of membrane-bound HSP70, secreted HSP70 or a combination significantly increased protection in mice challenged with EcoHIV, a chimeric virus that replicates in mouse leukocytes in vivo.

Government-subsidised mental health services are underused in Australian residential aged care facilities.

Objective To describe patterns of use of the available Government-subsidised mental health services among people living in Australian residential aged care facilities. Methods A retrospective population-based trend analysis was conducted, including all non-Indigenous people living in an Australian facility between 2012 and 2017. Adjusted incidence proportions and trends were estimated for four groups of mental health services. Results The use of Medicare-subsidised mental health services was very low overall. The proportion of residents who accessed primary care mental health services increased from 1.3% in 2012/2013 to 2.4% in 2016/2017, while psychiatry service use increased from 1.9 to 2.3%. Claims for clinical psychology increased from 0.18 to 0.26%, and claims for a registered psychologist, occupational therapist or social worker rose from 0.45 to 1.2%. People with dementia were less likely than people without dementia to access all services aside from psychiatry services. Conclusions Less than 3% of residents accessed funding subsidies for mental health services and people with dementia experienced pronounced barriers to service access. Mental health care is a pillar of the publicly-funded health system in Australia, and low use of these services among aged care residents indicates a need for organisational and policy changes to improve access.

Genetic and functional heterogeneity of CNS-derived tat alleles from patients with HIV-associated dementia.

Human immunodeficiency virus type 1 (HIV-1) demonstrates a high degree of viral diversity which has an impact on viral fitness. Genetic compartmentalization of HIV-1 proteins between central nervous system (CNS) and lymphoid tissues is well established and reflects altered requirements for HIV-1 replication in macrophages/microglia, brain-specific immune selection pressures and possibly the timing of virus invasion of the CNS. Tat-encoding mRNA has been detected in the CNS of HIV-1 infected individuals and its neurotoxic effects in the CNS are well documented. However, while CNS-derived tat sequences have demonstrated significant diversity, the effect of this molecular diversity on transcriptional regulation and its impact on the pathogenesis of HIV-associated dementia (HAD) remains unclear. In this study, we cloned and characterised 44 unique tat alleles from brain, cerebral spinal fluid, spinal cord and blood/lymphoid tissue-derived HIV-1 isolates from five subjects with HAD. While phylogenetic analyses revealed tissue-specific compartmentalization of Tat variants for two patients, broad compartmentalization across the panel of tissue-derived viruses was not observed. Despite the lack of consistent tissue-specific compartmentalization, sequence variations within patients segregated CNS and non-CNS tat alleles. These amino acid alterations predominated within the transactivation domain of Tat and could account for alterations in the ability of particular Tat proteins to transactivate the LTR. Although a subset of patients demonstrated reduced transactivation capacity among CNS-derived Tat proteins compared to those from matched lymphoid tissues, overall Tat proteins from the CNS to lymphoid compartments maintained similar levels of transactivation function. Together, these data suggest that despite the observed heterogeneity in tat alleles isolated from matched lymphoid to CNS compartments, Tat function is maintained, highlighting the importance of Tat function in HIV-1 neuropathogenesis.

CD4 and MHC class 1 down-modulation activities of nef alleles from brain- and lymphoid tissue-derived primary HIV-1 isolates.

Human immunodeficiency virus type 1 (HIV-1) nef undergoes adaptive evolution in the central nervous system (CNS), reflecting altered requirements for HIV-1 replication in macrophages/microglia and brain-specific immune selection pressures. The role of Nef in HIV-1 neurotropism and pathogenesis of HIV-associated dementia (HAD) is unclear. In this study, we characterized 82 nef alleles cloned from brain, cerebral spinal fluid, spinal cord, and blood/lymphoid tissue-derived HIV-1 isolates from seven subjects with HAD. CNS isolate-derived nef alleles were genetically compartmentalized and had reduced sequence diversity compared to those from lymphoid tissue isolates. Defective nef alleles predominated in a brain-derived isolate from one of the seven subjects (MACS2-br). The ability of Nef to down-modulate CD4 and MHC class 1 (MHC-1) was generally conserved among nef alleles from both CNS and lymphoid tissues. However, the potency of CD4 and MHC-1 down-modulation was variable, which was associated with sequence alterations known to influence these Nef functions. These results suggest that CD4 and MHC-1 down-modulations are highly conserved functions among nef alleles from CNS- and lymphoid tissue-derived HIV-1 isolates that may contribute to viral replication and escape from immune surveillance in the CNS.

Tissue-specific sequence alterations in the human immunodeficiency virus type 1 envelope favoring CCR5 usage contribute to persistence of dual-tropic virus in the brain.

Most human immunodeficiency virus type 1 (HIV-1) strains isolated from the brain use CCR5 for entry into macrophages and microglia. Strains that use both CCR5 and CXCR4 for entry (R5X4 strains) have been identified in the brains of some individuals, but mechanisms underlying the persistence of R5X4 viruses compartmentalized between the brain and other tissue reservoirs are unknown. Here, we characterized changes in the HIV-1 envelope (Env) that enhance the tropism of R5X4 variants for brain or lymphoid tissue. R5X4 Envs derived from the brains of two individuals had enhanced CCR5 usage in fusion assays compared to R5X4 Envs derived from matched spleen or blood, which was associated with reduced dependence on specific residues in the CCR5 N terminus and extracellular loop 1 (ECL1) and ECL3 regions. In contrast, spleen/blood-derived Envs had enhanced CXCR4 usage compared to brain-derived Envs, which was associated with reduced dependence on residues in the CXCR4 N terminus and ECL2 region. Consequently, brain-derived Envs had preferential CCR5 usage for HIV-1 entry into the JC53 cell line, could use either CCR5 or CXCR4 for entry into monocyte-derived macrophages (MDM), and could use CCR5 (albeit inefficiently) for entry into peripheral blood mononuclear cells (PBMC), whereas the entry of spleen-derived Envs was CXCR4 dependent in all three cell types. Mutagenesis studies of Env amino acid variants influencing coreceptor usage showed that S306 in the gp120 V3 region of brain-derived Envs reduces dependence on the CCR5 N terminus and enhances CCR5 usage for HIV-1 entry into PBMC and MDM, whereas R306 in spleen-derived Envs reduces dependence on the CXCR4 N terminus and confers the CXCR4 restricted phenotype. These results identify mechanisms underlying R5X4 HIV-1 persistence in different tissue reservoirs. Tissue-specific changes in the gp120 V3 region that increase the efficiency of CCR5 or CXCR4 usage, and thereby influence coreceptor preference, may enhance the tropism of R5X4 strains for CCR5-expressing macrophage lineage cells in the brain and CXCR4-expressing T cells in lymphoid tissues, respectively.

Extensive astrocyte infection is prominent in human immunodeficiency virus-associated dementia.

Astrocyte infection with human immunodeficiency virus (HIV) is considered rare, so astrocytes are thought to play a secondary role in HIV neuropathogenesis. By combining double immunohistochemistry, laser capture microdissection, and highly sensitive multiplexed polymerase chain reaction to detect HIV DNA in single astrocytes in vivo, we showed that astrocyte infection is extensive in subjects with HIV-associated dementia, occurring in up to 19% of GFAP+ cells. In addition, astrocyte infection frequency correlated with the severity of neuropathological changes and proximity to perivascular macrophages. Our data indicate that astrocytes can be extensively infected with HIV, and suggest an important role for HIV-infected astrocytes in HIV neuropathogenesis.

Measuring and monitoring apoptosis and drug toxicity in HIV patients by ligation-mediated polymerase chain reaction.

Apoptosis has a critical role in normal physiology while its dysregulation has causal links with certain pathologies. A biochemical hallmark of apoptosis, internucleosomal genomic DNA fragmentation, is detectable by ligation-mediated polymerase chain reaction (LM-PCR). Here we converted LM-PCR into a new apoptosis quantifier by dividing trace quantities of 600 bp apoptotic amplicons into those of a single copy house-keeping gene, generating the LM-PCR 'value'. Dynamic range was approximately 17-fold correlating with a approximately 200-fold difference in degree of apoptotic fragmentation. Inter- and intra-gel reliability were both excellent, supporting LM-PCR's utility with large sample sets. Validation experiments comprising cell exposure to staurosporine over time revealed LM-PCR is as sensitive as caspase-3/ELISA and more sensitive than terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling/flourescence-activated cell sorting (TUNEL/FACS) for distinguishing low degrees of apoptosis (the spectrum most relevant in vivo). The LM-PCR profile mirrored that of caspase-3/ELISA but not TUNEL/FACS. We then applied this molecular tool to clinical investigation. Increased apoptosis is implicated in lipoatrophy (subcutaneous fat wasting), a serious, persistent toxicity of some nucleoside analogue reverse transcriptase inhibitors (NRTIs) used in anti-HIV highly active antiretroviral therapy (HAART). We demonstrated in 105 peripheral blood mononuclear cell samples that elevated LM-PCR values are seen during therapy with stavudine (d4T), a particularly toxic NRTI (P< 0.0001 versus no HAART, unpaired t-test). Elevated values were also independently associated with clinical evidence of lipoatrophy (P= 0.007, multiple logistic regression modelling) but not with patient age, CD4 T-cell count nor HIV viral load (P> 0.8 for each). Together these data demonstrate that LM-PCR is a robust and reliable quantifier of apoptosis with potential for basic science and clinical investigation.

Cell-specific temporal infection of the brain in a simian immunodeficiency virus model of human immunodeficiency virus encephalitis.

Increasing evidence supports early brain infection by human immunodeficiency virus (HIV). Definitive temporal studies determining when and within which brain cells viral DNA is present are lacking. This study utilized simian immunodeficiency virus (SIV)-infected macaques sacrificed at days 10, 21, 56, and 84 post inoculation. Laser-microdissection isolated pure perivascular macrophage, parenchymal microglia, and astrocyte populations. Nested polymerase chain reaction (PCR) and sequencing determined the presence and characteristics of SIV V3 and V1 env DNA from each population. At day 10, SIV DNA was detected in perivascular macrophage and astrocytes but not parenchymal microglia. gp41 expression was restricted to perivascular macrophage. At day 21, SIV DNA was not detected in any cell type. At day 56, SIV DNA was detectable in perivascular macrophage from one of two macaques, with no gp41 expression detected. At day 84 (morphologic and clinical encephalitis), SIV DNA was detected in all cell types, gp41 was only detected in perivascular macrophage and parenchymal microglia. The neurovirulent molecular clone, SIV/17E-Fr, was the only genotype identified in the brain cell populations. Early, productive brain SIV infection was transient and restricted to trafficking perivascular macrophage. During the nonencephalitic stage, there was a period of time when no SIV DNA could be detected in the brain cell populations. SIV was then seen to reenter the brain via infected perivascular macrophage, leading to productive infection of brain parenchymal macrophage/microglia with a terminal phase of encephalitis. These data challenge current notions of a HIV reservoir within latently infected, semipermanent brain cells and has significant implications for the timing and design of therapies to prevent HIV encephalitis (HIVE).

Cytokine genotype suggests a role for inflammation in nucleoside analog-associated sensory neuropathy (NRTI-SN) and predicts an individual's NRTI-SN risk.

Nucleoside analog-associated sensory neuropathy (NRTI-SN) attributed to stavudine, didanosine, or zalcitabine (the dNRTIs) and distal sensory polyneuropathy (DSP) attributed to HIV are clinically indistinguishable. As inflammatory cytokines are involved in DSP, we addressed a role for inflammation in NRTI-SN by determining the alleles of immune-related genes carried by patients with and without NRTI-SN. Demographic details associated with risk of various neuropathies were included in the analysis. Alleles of 14 polymorphisms in 10 genes were determined in Australian HIV patients with definite NRTI-SN (symptom onset <6 months after first dNRTI exposure, n = 16), NRTI-SN-resistant patients (no neuropathy despite >6 months on dNRTIs, n = 20), patients with late onset NRTI-SN (neuropathy onset after >6 months of dNRTIs, n = 19), and HIV-negative controls. Carriage of TNFA-1031*2 was highest in NRTI-SN patients, suggesting potentiation of NRTI-SN. Carriage of IL12B (3' UTR)*2 was higher in NRTI-SN-resistant patients than controls or NRTI-SN patients, suggesting a protective role. BAT1 (intron 10)*2 was more common in NRTI-SN than resistant patients, but neither group differed from controls. This marks the conserved HLA-A1, B8, DR3 haplotype. Of the demographic details considered, increasing height was associated with NRTI-SN risk. A model including cytokine genotype and height predicted NRTI-SN status (p < 0.0001, R(2) = 0.54). Late onset NRTI-SN patients clustered genetically with NRTI-SN-resistant patients, so these patients may be genetically "protected." In addition to patient height, cytokine genotype influenced NRTI-SN risk following dNRTI exposure, suggesting inflammation contributes to NRTI-SN.

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

BACKGROUND: The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with nef-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 nef/long-terminal repeat (LTR) sequences demonstrated convergent nef/LTR sequence evolution in SBBC SP and LTNP. Thus, the in vivo pathogenicity of attenuated HIV-1 strains harboured by SBBC members is dictated by factors other than nef/LTR. Therefore, to determine whether defects in other viral genes contribute to attenuation of these HIV-1 strains, we characterized dominant HIV-1 rev alleles that persisted in 4 SBBC subjects; C18, C64, C98 and D36. RESULTS: 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-1NL4-3, 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. CONCLUSION: 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 rev alleles may contribute to viral attenuation and long-term survival of HIV-1 infection in a subset of SBBC members.

Asn 362 in gp120 contributes to enhanced fusogenicity by CCR5-restricted HIV-1 envelope glycoprotein variants from patients with AIDS.

BACKGROUND: CCR5-restricted (R5) human immunodeficiency virus type 1 (HIV-1) variants cause CD4+ T-cell loss in the majority of individuals who progress to AIDS, but mechanisms underlying the pathogenicity of R5 strains are poorly understood. To better understand envelope glycoprotein (Env) determinants contributing to pathogenicity of R5 viruses, we characterized 37 full-length R5 Envs from cross-sectional and longitudinal R5 viruses isolated from blood of patients with asymptomatic infection or AIDS, referred to as pre-AIDS (PA) and AIDS (A) R5 Envs, respectively. RESULTS: Compared to PA-R5 Envs, A-R5 Envs had enhanced fusogenicity in quantitative cell-cell fusion assays, and reduced sensitivity to inhibition by the fusion inhibitor T-20. Sequence analysis identified the presence of Asn 362 (N362), a potential N-linked glycosylation site immediately N-terminal to CD4-binding site (CD4bs) residues in the C3 region of gp120, more frequently in A-R5 Envs than PA-R5 Envs. N362 was associated with enhanced fusogenicity, faster entry kinetics, and increased sensitivity of Env-pseudotyped reporter viruses to neutralization by the CD4bs-directed Env mAb IgG1b12. Mutagenesis studies showed N362 contributes to enhanced fusogenicity of most A-R5 Envs. Molecular models indicate N362 is located adjacent to the CD4 binding loop of gp120, and suggest N362 may enhance fusogenicity by promoting greater exposure of the CD4bs and/or stabilizing the CD4-bound Env structure. CONCLUSION: Enhanced fusogenicity is a phenotype of the A-R5 Envs studied, which was associated with the presence of N362, enhanced HIV-1 entry kinetics and increased CD4bs exposure in gp120. N362 contributes to fusogenicity of R5 Envs in a strain dependent manner. Our studies suggest enhanced fusogenicity of A-R5 Envs may contribute to CD4+ T-cell loss in subjects who progress to AIDS whilst harbouring R5 HIV-1 variants. N362 may contribute to this effect in some individuals.

Pathogenicity and immunogenicity of attenuated, nef-deleted HIV-1 strains in vivo.

In efforts to develop an effective vaccine, sterilizing immunity to primate lentiviruses has only been achieved by the use of live attenuated viruses carrying major deletions in nef and other accessory genes. Although live attenuated HIV vaccines are unlikely to be developed due to a myriad of safety concerns, opportunities exist to better understand the correlates of immune protection against HIV infection by studying rare cohorts of long-term survivors infected with attenuated, nef-deleted HIV strains such as the Sydney blood bank cohort (SBBC). Here, we review studies of viral evolution, pathogenicity, and immune responses to HIV infection in SBBC members. The studies show that potent, broadly neutralizing anti-HIV antibodies and robust CD8+ T-cell responses to HIV infection were not necessary for long-term control of HIV infection in a subset of SBBC members, and were not sufficient to prevent HIV sequence evolution, augmentation of pathogenicity and eventual progression of HIV infection in another subset. However, a persistent T-helper proliferative response to HIV p24 antigen was associated with long-term control of infection. Together, these results underscore the importance of the host in the eventual outcome of infection. Thus, whilst generating an effective antibody and CD8+ T-cell response are an essential component of vaccines aimed at preventing primary HIV infection, T-helper responses may be important in the generation of an effective therapeutic vaccine aimed at blunting chronic HIV infection.

Phenotype and envelope gene diversity of nef-deleted HIV-1 isolated from long-term survivors infected from a single source.

BACKGROUND: The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with attenuated, nef-deleted variants of human immunodeficiency virus type 1 (HIV-1) acquired from a single source. Long-term prospective studies have demonstrated that the SBBC now comprises slow progressors (SP) as well as long-term nonprogressors (LTNP). Convergent evolution of nef sequences in SBBC SP and LTNP indicates the in vivo pathogenicity of HIV-1 in SBBC members is dictated by factors other than nef. To better understand mechanisms underlying the pathogenicity of nef-deleted HIV-1, we examined the phenotype and env sequence diversity of sequentially isolated viruses (n = 2) from 3 SBBC members. RESULTS: The viruses characterized here were isolated from two SP spanning a three or six year period during progressive HIV-1 infection (subjects D36 and C98, respectively) and from a LTNP spanning a two year period during asymptomatic, nonprogressive infection (subject C18). Both isolates from D36 were R5X4 phenotype and, compared to control HIV-1 strains, replicated to low levels in peripheral blood mononuclear cells (PBMC). In contrast, both isolates from C98 and C18 were CCR5-restricted. Both viruses isolated from C98 replicated to barely detectable levels in PBMC, whereas both viruses isolated from C18 replicated to low levels, similar to those isolated from D36. Analysis of env by V1V2 and V3 heteroduplex tracking assay, V1V2 length polymorphisms, sequencing and phylogenetic analysis showed distinct intra- and inter-patient env evolution. CONCLUSION: Independent evolution of env despite convergent evolution of nef may contribute to the in vivo pathogenicity of nef-deleted HIV-1 in SBBC members, which may not necessarily be associated with changes in replication capacity or viral coreceptor specificity.