Comparative rates of disease progression among persons infected with the same or different HIV-1 strains. The Transfusion Safety Study Group

Transmission cluster of multiclass highly drug-resistant HIV-1 among 9 men who have sex with men in Seattle/King County, WA, 2005-2007

BACKGROUND

From 2005 through 2007, Seattle health care providers identified cases of primary multiclass drug-resistant (MDR) HIV-1 with common patterns of resistance to antiretrovirals (ARVs). Through surveillance activities and genetic analysis, the local Health Department and the University of Washington identified phylogenetically linked cases among ARV treatment-naive and -experienced individuals.

METHODS

HIV-1 pol nucleotide consensus sequences submitted to the University of Washington Clinical Virology Laboratory were assessed for phylogenetically related MDR HIV. Demographic and clinical data collected included HIV diagnosis date, ARV history, and laboratory results.

RESULTS

Seven ARV-naive men had phylogenetically linked MDR strains with resistance to most ARVs; these were linked to 2 ARV-experienced men. All 9 men reported methamphetamine use and multiple anonymous male partners. Primary transmissions were diagnosed for more than a 2-year period, 2005-2007. Three, including the 2 ARV-experienced men, were prescribed ARVs.

CONCLUSIONS

This cluster of 9 men with phylogenetically related highly drug-resistant MDR HIV strains and common risk factors but without reported direct epidemiologic links may have important implications to public health. This cluster demonstrates the importance of primary resistance testing and of collaboration between the public and private medical community in identifying MDR outbreaks. Public health interventions and surveillance are needed to reduce transmission of MDR HIV-1.

Greater effect of highly active antiretroviral therapy on survival in people aged > or =50 years compared with younger people in an urban observational cohort

Although human immunodeficiency virus-infected people aged > or =50 years have a blunted CD4 cell recovery when receiving highly active antiretroviral therapy (HAART), there are few data on mortality. Mortality rates were studied for 253 individuals aged > or =50 years and a younger group of 535 people in a retrospective cohort; for untreated persons in each age group, the proportions surviving at 3 years were 83% and 70% (P<.01), respectively. No significant difference in the survival rate was found between the older (83%) and younger (89%) patients who received HAART (P=.29). The hazard ratio for death in the older untreated group was 2.4 (95% confidence interval [CI], 1.4-3.9) when exposed to HAART. However, compared with older untreated patients, the hazard ratio for death decreased to 0.28 (95% CI, 0.15-0.52) for treated older adults. The effect of HAART substantially improves the survival rate for older individuals and supports the importance of treatment in this group.

HIV disease and advanced age: an increasing therapeutic challenge

The mean age of patients at both first HIV detection and AIDS diagnosis is progressively rising over time. However, reliable epidemiological estimates, clinical data or controlled therapeutic and outcome figures are lacking for elderly patients, especially with regard to laboratory and clinical response to antiretroviral therapy, treatment tolerability, drug-drug interactions, short- and long-term toxicity, and interactions with underlying illnesses and concurrent pharmacological treatment. In fact, the large majority of randomised, controlled trials evaluating and comparing new antiretroviral drugs or anti-HIV therapeutic strategies, as well as antimicrobial treatment or chemoprophylaxis of HIV-related complications, either excluded patients with advanced age and/or concurrent disorders or did not offer substudies or detailed data analysis focusing on older patients compared with younger ones. The life expectancy of HIV-infected persons receiving highly active antiretroviral therapy (HAART) is now extended (approaching that of the general population), so that the definition of AIDS has lost its epidemiological and clinical significance thanks to the immune reconstitution resulting from potent antiretroviral therapy. However, an ever-increasing number of individuals aged > or =50 years with HIV infection is expected in the coming years, as a result of both increased survival of patients with treated disease and delayed recognition of individuals with occult HIV disease. The limited data available about combined antiretroviral therapy in the elderly seem to show an overlapping virological success rate but a slower and blunted immune recovery compared with younger patients. Thymic output, however, seems somewhat preserved even in adulthood and may contribute to the reconstitution of most of the quantitative and functional T cell abnormalities caused by HIV disease. More attention must be paid to underlying end-organ disorders, as well as expected pharmacological interactions and combined drug toxicity that may interfere with HAART efficacy and patients' compliance with recommended regimens and could lead to increased adverse effects. The available guidelines for antiretroviral treatment and therapy and prophylaxis of AIDS-related illnesses should be regularly updated and should include problems related to HIV disease in an aging population. Specific trials or substudies focusing on older people are warranted to obtain controlled data on all issues of antiretroviral therapy in the elderly, including time and mode of initiation, and modification and salvage HAART regimens. Antiretroviral drug dosage adjustment to take into account underlying pathological conditions or other pharmacological treatments is another emerging issue.

Clinical, biologic, and behavioral predictors of early immunologic and virologic response in HIV-infected patients initiating protease inhibitors

Predictors of virologic (plasma HIV RNA viral load [VL] < 500 copies/ml) and immunologic (rise in CD4+ cell count > 50 cells/mm3) response after 4 months of therapy (M4) were studied in 750 HIV-1-infected patients prospectively enrolled at the initiation of a protease inhibitor (PI)-containing regimen. A virologic response was observed in 80% of patients, and an immunologic response was observed in 64%. Sixty-two percent of patients self-reported full adherence to therapy at 1 month of therapy (M1) and M4. In multivariate analysis, a virologic response was more frequent in fully adherent patients (odds ratio [OR] = 2.0; p =.001). An immunologic response was associated with age < 36 years (OR =1.4; p =.03), baseline VL (OR = 1.5 per 1 log10 copies/ml higher; p <.01), decrease in VL at M1 (OR = 1.5 per 1 log10 copies/ml decrease; p <.01), baseline total lymphocyte count (OR = 1.7 per 50% lower; p <.001), and baseline CD4+ cell percentage > or = 20% (OR =1.9; p <.001) but not with adherence to therapy. Full adherence seems to be a major predictor of a virologic response to PI-containing triple therapy. An immunologic response may be possible despite incomplete adherence, at least early in therapy.

Global survey of genetic variation in CCR5, RANTES, and MIP-1alpha: impact on the epidemiology of the HIV-1 pandemic

Expression of CC chemokine receptor 5 (CCR5), the major coreceptor for HIV-1 cell entry, and its ligands (e.g., RANTES and MIP-1alpha) is widely regarded as central to the pathogenesis of HIV-1 infection. By surveying nearly 3,000 HIV+ and HIV- individuals from worldwide populations for polymorphisms in the genes encoding RANTES, MIP-1alpha, and CCR5, we show that the evolutionary histories of human populations have had a significant impact on the distribution of variation in these genes, and that this may be responsible, in part, for the heterogeneous nature of the epidemiology of the HIV-1 pandemic. The varied distribution of RANTES haplotypes (AC, GC, and AG) associated with population-specific HIV-1 transmission- and disease-modifying effects is a striking example. Homozygosity for the AC haplotype was associated with an increased risk of acquiring HIV-1 as well as accelerated disease progression in European Americans, but not in African Americans. Yet, the prevalence of the ancestral AC haplotype is high in individuals of African origin, but substantially lower in non-Africans. In a Japanese cohort, AG-containing RANTES haplotype pairs were associated with a delay in disease progression; however, we now show that their contribution to HIV-1 pathogenesis and epidemiology in other parts of the world is negligible because the AG haplotype is infrequent in non-Far East Asians. Thus, the varied distribution of RANTES, MIP-1alpha, and CCR5 haplotype pairs and their population-specific phenotypic effects on HIV-1 susceptibility and disease progression results in a complex pattern of biological determinants of HIV-1 epidemiology. These findings have important implications for the design, assessment, and implementation of effective HIV-1 intervention and prevention strategies.

Relationship between HIV-1 Env subtypes A and D and disease progression in a rural Ugandan cohort

OBJECTIVE

To investigate the role of HIV-1 envelope subtypes on disease progression in a rural cohort of Ugandan adults where two major HIV-1 subtypes (A and D) exist.

METHODS

Participants of a clinical cohort seen between December 1995 and December 1998 had blood collected for HIV-1 subtyping. These included prevalent cases (people already infected with HIV at the start of the study in 1990) and incident cases (those who seroconverted between 1990 and December 1998). HIV-1 subtyping was carried out by heteroduplex mobility assay and DNA sequencing in the V3 env region. Disease progression was measured by the rate of CD4 lymphocyte count decline, clinical progression for the incident cases as time from seroconversion to AIDS or death, to first CD4 lymphocyte count < 200 x 10(6)/l and to the World Health Organization clinical stage 3. All analyses were adjusted for age and sex.

RESULTS

One hundred and sixty-four individuals, including 47 prevalent and 117 incident cases, had V3 env subtype data of which 65 (40%) were subtyped as A and 99 as D. In the incident cases, 44 (38%) were subtyped as A and 73 as D. There was a suggestion that for most end-points A had a slower progression than D. The cumulative probability of remaining free from AIDS or death at 6 years post-seroconversion was 0.72 [95% confidence interval (CI), 0.50 to 0.85] for A and 0.58 (95% CI, 0.42 to 0.71) for D, and the adjusted hazard ratio of subtype D compared to A was estimated to be 1.39 (95% CI, 0.66 to 2.94; P = 0.39). The estimated difference in rates of decline in square root CD4 lymphocyte counts was -0.41 per year (95% CI, -0.98 to 0.15; P = 0.15).

CONCLUSION

This study suggests that although subtype A may have a slower progression than D, HIV-1 envelope subtype is not a major factor in determining the progression of HIV-1 disease in a rural population in Uganda.

The replicative capacity of rhesus macaque peripheral blood mononuclear cells for simian immunodeficiency virus in vitro is predictive of the rate of progression to AIDS in vivo

Survival of rhesus macaques (Macaca mulatta) experimentally infected with simian immunodeficiency virus (SIV) varies significantly from animal to animal. Some animals die within 2 months while others survive for more than 5 years, even when identical inocula are used. This diversity in survival creates a significant problem in the design of therapeutic and vaccine trials using the SIV-macaque model because the use of small numbers of animals may provide results that are misleading. Identifying an in vitro assay that could determine the survival of monkeys prior to infection would prove extremely useful for stratifying experimental groups. Analysis of the survival of a cohort of 59 control animals obtained from over a decade of vaccine and therapeutic trials has demonstrated that the ability of peripheral blood mononuclear cells (PBMC) from a naïve animal to produce virus in vitro was highly predictive of disease progression in vivo following experimental inoculation. Animals classified in vitro as high producers of virus progressed to disease significantly more rapidly than animals classified as either low (P=0.002) or intermediate (P=0.013) producers of virus. The hierarchy of high and low virus production was maintained in purified CD4(+) T cell cultures, indicating that this phenotype is an intrinsic property of the CD4(+) T cell itself. These findings should significantly aid in the design of vaccine and therapeutic trials using the SIV-macaque model. Furthermore, since these studies suggest that the rate of virus replication is controlled by innate characteristics of the individual, they provide new insight into the pathogenesis of AIDS.

Homozygosity for a conserved Mhc class II DQ-DRB haplotype is associated with rapid disease progression in simian immunodeficiency virus-infected macaques: results from a prospective study

In human immunodeficiency virus type 1 (HIV-1)-infected individuals, disease progression varies considerably. This is also observed after experimental infection of macaques with simian immunodeficiency virus (SIV). Major histocompatibility complex (MHC) genes may influence disease progression in both species. Homozygosity for Mhc-Mamu (Macaca mulatta)-DQB1*0601 was previously identified to be associated with rapid disease progression in SIV-infected macaques. To validate the association of this genotype with disease progression, a prospective study was carried out. Six unrelated monkeys homozygous for Mamu-DQB1*0601 and DRB1*0309-DRB*W201 and 6 heterozygous monkeys were infected with SIVmac. Five of the homozygous and only 1 of the heterozygous monkeys died rapidly after infection, with manifestations of AIDS. These results were validated by a retrospective survival analysis of 71 SIV-infected monkeys. The identified DQ-DRB genotype is frequent among monkeys of different breeding colonies and allows a fairly reliable selection before infection of monkeys predisposed for rapid disease progression.

Simian immunodeficiency virus disease course is predicted by the extent of virus replication during primary infection

To elucidate the relationship between early viral infection events and immunodeficiency virus disease progression, quantitative-competitive and branched-DNA methods of simian immunodeficiency virus (SIV) RNA quantitation were cross-validated and used to measure viremia following infection of rhesus macaques with the pathogenic SIVmac251 virus isolate. Excellent correlation between the methods suggests that both accurately approximate SIV copy number. Plasma viremia was evident 4 days postinfection, and rapid viral expansion led to peak viremia levels of 10(7) to 10(9) SIV RNA copies/ml by days 8 to 17. Limited resolution of primary viremia was accompanied by relatively short, though variable, times to the development of AIDS (81 to 630 days). The persistent high-level viremia observed following intravenous inoculation of SIVmac251 explains the aggressive disease course in this model. Survival analyses demonstrated that the disease course is established 8 to 17 days postinfection, when peak viremia is observed. The most significant predictor of disease progression was the extent of viral decline following peak viremia; larger decrements in viremia were associated with both lower steady-state viremia (P = 0.0005) and a reduced hazard of AIDS (P = 0.004). The data also unexpectedly suggested that following SIVmac251 infection, animals with the highest peak viremia were better able to control virus replication rather than more rapidly developing disease. Analysis of early viral replication dynamics should help define host responses that protect from disease progression and should provide quantitative measures to assess the extent to which protective responses may be induced by prophylactic vaccination.

The extent of early viral replication is a critical determinant of the natural history of simian immunodeficiency virus infection

Different patterns of viral replication correlate with the natural history of disease progression in humans and macaques infected with human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV), respectively. However, the viral and host factors influencing these patterns of viral replication in vivo are poorly understood. We intensively studied viral replication in macaques receiving identical inocula of SIV. Marked differences in viral replication patterns were apparent within the first week following inoculation, a time prior to the development of measurable specific immune effector responses to viral antigens. Plasma viral RNA levels measured on day 7 postinoculation correlated with levels measured in the postacute phase of infection. Differences in the susceptibility of host cells from different animals to in vitro SIV infection correlated with the permissiveness of the animals for early in vivo viral replication and hence with the postacute set point level of plasma viremia. These results suggest that host factors that exert their effects prior to full development of specific immune responses are critical in establishing the in vivo viral replication pattern and associated clinical course in subjects infected with SIV and, by extension, with HIV-1.