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PubMed1998

Complex evolutionary history of primate lentiviral vpr genes.

Vpx and Vpr are homologous proteins encoded by the human and simian immunodeficiency viruses. Vpr is encoded by each of the five primate lentiviral groups, whereas Vpx is restricted to members of the HIV-2 group. A recent report has proposed that the vpx gene was probably acquired from an ancestral member of the SIVagm group by nonhomologous recombination. Here, we suggest that this transfer event was more likely to have occurred via homologous recombination within the 3' region of another gene, vif. Furthermore, phylogenetic analysis strongly suggests that there have been at least two other horizontal transfer events involving these genes: the first between ancestral members of the HIV-1 and HIV-2 groups, and the second between viruses isolated from the vervet and tantalus subspecies of African green monkey (Cercopithecus aethiops ssp).

Amino Acid Sequence↗

PubMed1999

Increased polymerase fidelity of lamivudine-resistant HIV-1 variants does not limit their evolutionary potential.

OBJECTIVE: Anti HIV-1 therapy with nucleoside reverse transcriptase inhibitors can select for drug-resistant reverse transcriptase variants with altered enzyme properties. Some of the mutations, e.g. Met184Val and Met184Ile, result in an increase in polymerase fidelity of the enzyme as measured in biochemical assays; however, the effect of such changes on the fidelity during viral replication is largely unknown. In this study, the codon 184 variants were used to investigate whether the mutation at codon 184 affects the mutation spectrum and mutation rate of the mutant viruses. DESIGN AND METHOD: In vitro selection experiments with either wild-type or lamivudine-resistant viruses (Met184Val and Met184Ile) were performed using a protease inhibitor as the selective drug. In addition, a novel selection approach was developed using a mixture of viruses, instead of individual viruses, during the selection process. RESULTS: Comparison of a total of 108 protease-resistant variants revealed no significant difference in the mutational spectrum of the wild-type and the lamivudine-resistant variants. In addition, the selection experiments with the viral mixtures demonstrated no delay in the kinetics of mutation generation in response to an antiviral drug. CONCLUSION: This study demonstrates that the Met184Val and Met184Ile mutations in the HIV-1 reverse transcriptase enzyme do not significantly affect the evolutionary potential of the corresponding viruses.

Codon↗

PubMed1998

Molecular epidemiology and trends of HIV-1 subtypes in Taiwan.

To understand the trends of distribution and risk factors associated with different HIV-1 subtypes in different populations in Taiwan, blood samples and questionnaires were collected from 267 male and 21 female HIV-1-infected people in a multicenter survey from 1993 to 1996. This group represented about one quarter of the total registered HIV-1 cases in Taiwan. The HIV-1 subtypes were determined using V3-based peptide-enzyme immunoassays complemented by heteroduplex mobility assay and phylogenetic tree analysis. The results showed that in Taiwan, men were primarily infected with HIV-1B (68.2%) and HIV-1E (27.3%), whereas women were mainly infected with non-B subtypes (4.8% A, 4.8% C, 71.4% E, and 9.5% G). In addition, 71.4% of men with HIV-1B were homosexual or bisexual, whereas 56.2% of men with HIV-1E were heterosexual (p < .001). Although HIV-1E subtype came to Taiwan later than HIV-1B, it has become a major subtype in the heterosexual population.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Compensatory substitutions restore normal core assembly in simian immunodeficiency virus isolates with Gag epitope cytotoxic T-lymphocyte escape mutations.

The evolution of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) as they replicate in infected individuals reflects a balance between the pressure on the virus to mutate away from recognition by dominant epitope-specific cytotoxic T lymphocytes (CTL) and the structural constraints on the virus' ability to mutate. To gain a further understanding of the strategies employed by these viruses to maintain replication competency in the face of the intense selection pressure exerted by CTL, we have examined the replication fitness and morphological ramifications of a dominant epitope mutation and associated flanking amino acid substitutions on the capsid protein (CA) of SIV/simian-human immunodeficiency virus (SHIV). We show that a residue 2 mutation in the immunodominant p11C, C-M epitope (T47I) of SIV/SHIV not only decreased CA protein expression and viral replication, but it also blocked CA assembly in vitro and virion core condensation in vivo. However, these defects were restored by the introduction of upstream I26V and/or downstream I71V substitutions in CA. These findings demonstrate how flanking compensatory amino acid substitutions can facilitate viral escape from a dominant epitope-specific CTL response through the effects of these associated mutations on the structural integrity of SIV/SHIV.

Amino Acid Sequence↗

PubMed2004

Older age and plasma viral load in HIV-1 infection.

BACKGROUND: The purpose of the study was to examine the relationship between age and plasma viral load in HIV-1-infected individuals. DESIGN: The experimental method was to recruit older (> 50 years of age) and younger (18-39 years of age) HIV-1-infected individuals. The plasma viral load was measured using the Roche Molecular Systems UltraSensitive Roche HIV-1 Monitor test reflexively with the standard Amplicor HIV Monitor test to quantify viral load in the range of 50-750,000 copies of HIV-1 RNA/ml plasma. SUBJECTS: A total of 135 HIV-1-seropositive individuals (at Centers for Disease Control and Prevention early symptomatic stage B or late symptomatic stage/AIDS C) were enrolled as part of a larger cohort also consisting of HIV-1-seronegative individuals. RESULTS: A generalized linear models statistical analysis was conducted in order to evaluate age category as a predictor of plasma viral load. The result was a significant effect of age category, with older age associated with a lower plasma viral load. The association held controlling for antiretroviral therapy usage, disease stage, antiretroviral medication adherence, HIV-1 serostatus duration, alcohol and substance use, recent sexually transmitted disease, and sociodemographics (except income). CONCLUSION: Older age was associated with lower levels of HIV-1 replication in this sample, independent of antiretroviral therapy usage, regimen adherence, and disease stage. It is suggested that the effect may be caused by changes in viral evolution or immunological monitoring specific to older individuals with HIV-1 infection.

Adult↗

PubMed1992

HIV-1 ancestry primordial expansions of RRE and RRE related sequences.

The human T-lymphotropic retroviruses HTLV-I and HIV-1/-2 share a complementary patchwork homology in which the RRE regions of HIV-1 and -2 cover 78.1% of a 169 nucleotide (nt) region (PX1,2) positioned precisely between open reading frames PX I and PX II of ATLV (HTLV-I). The sequence character of the PX1,2 region is shown to be influenced by a primordial expansion, CTC2T, originating several hundred nucleotides upstream. A second primordial expansion, AGCU(U/C), is identified and shown to represent 52.1% of the HIV-1 RRE region. It is argued that prior to the present AIDS pandemic the efficiency of the rev receptor was enhanced by an ancestral recombination event.

Base Sequence↗

PubMed2002

Retroviral proteases.

SUMMARY: The proteases of retroviruses, such as leukemia viruses, immunodeficiency viruses (including the human immunodeficiency virus, HIV), infectious anemia viruses, and mammary tumor viruses, form a family with the proteases encoded by several retrotransposons in Drosophila and yeast and endogenous viral sequences in primates. Retroviral proteases are key enzymes in viral propagation and are initially synthesized with other viral proteins as polyprotein precursors that are subsequently cleaved by the viral protease activity at specific sites to produce mature, functional units. Active retroviral proteases are homodimers, with each dimer structurally related to the larger class of single-chain aspartic peptidases. Each monomer has four structural elements: two distinct hairpin loops, a wide loop containing the catalytic aspartic acid and an alpha helix. Retroviral gene sequences can vary between infected individuals, and mutations affecting the binding cleft of the protease or the substrate cleavage sites can alter the response of the virus to therapeutic drugs. The need to develop new drugs against HIV will continue to be, to a large extent, the driving force behind further characterization of retroviral proteases.

Animals↗

PubMed2000

Is seborrhoeic dermatitis a clinical marker of HIV disease?

The Authors have conducted a cohort study on a group of subjects HIV positive, asymptomatic, (group A, according to CDC criteria) who presented Seborrhoeic dermatitis (SD), to evaluate if this cutaneous finding could be considered a marker of the HIV disease. Previously the Authors had shown that healthy subjects affected by SD showed at blood level an imbalance in the ratio of PL-PUFA (fundamental components of cell walls) to the antioxidants Vitamin E (Vit E) and gluthathion peroxidase (GSH-Px); furthermore the Authors reported SD as being constantly present in AIDS patients, in which they found more severe biochemical changes. On these bases they enrolled 72 HIV positive individuals that presented at STD-AIDS Unit of the S Gallicano Institute in the years 1994-1995 and followed them, until the 1998. They were all asymptomatic and were divided at the beginning in two subgroups, respectively with and without SD. Records were made regularly of their clinical, laboratory and biochemical data. The results highlighted the fact that SD-HIV positive individuals had severe biochemical alterations and a worse clinical evolution (higher incidence of opportunistic events). These data confirm on the hand the SD as a cutaneous marker of HIV disease not only, but also its presence could indicate the possibility of a worse progression of the disease. Finally the Authors suggest the possibility of a dietary pharmacological treatment, associated, or not, with antiretroviral therapy, to the aim to improve cell membrane defences and thereby cell immunity itself.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

HIV evolutionary dynamics within and among hosts.

The HIV evolutionary processes continuously unfold, leaving a measurable footprint in viral gene sequences. A variety of statistical models and inference techniques have been developed to reconstruct the HIV evolutionary history and to investigate the population genetic processes that shape viral diversity. Remarkably different population genetic forces are at work within and among hosts. Population-level HIV phylogenies are mainly shaped by selectively neutral epidemiologic processes, implying that genealogy-based population genetic inference can be useful to study the HIV epidemic history. Such evolutionary analyses have shed light on the origins of HIV, and on the epidemic spread of viral variants in different geographic locations and in different populations. The HIV genealogies reconstructed from within-host sequences indicate the action of selection pressure. In addition, recombination has a significant impact on HIV genetic diversity. Accurately quantifying both the adaptation rate and the population recombination rate of HIV will contribute to a better understanding of immune escape and drug resistance. Characterizing the impact of HIV transmission on viral genetic diversity will be a key factor in reconciling the different population genetic processes within and among hosts.

Adaptation, Biological↗

PubMed1991

AIDS, a social dilemma: detection of seropositives.

At present, we can observe an evolution in ideas about the detection of HIV seropositivity through a qualitative analysis of specialised literature on the ethical aspects of AIDS. In the case of this disease, systematic screening of the population does not correspond to epidemiological criteria: it is wasteful, troublesome and costly. Whether it is voluntary, and therefore biased, or compulsory, and therefore controversial, systematic screening seems an unlikely option. This situation has prompted many versions of target-group screening, which correspond to two options: systematic screening of known risk-groups, discriminatory, confidential and anonymous; target-group screening linked to particular circumstances: recognised as necessary by blood-donors and well-accepted by pregnant mothers. This method can be institutionalised and applied in the armed forces and in prisons,.... Lastly, we consider measures taken by different countries and organisations.

Acquired Immunodeficiency Syndrome↗

PubMed2004

Severe acute respiratory syndrome, a pathological immune response to the new coronavirus--implications for understanding of pathogenesis, therapy, design of vaccines, and epidemiology.

Findings coming from autopsies and serum of SARS patients suggest an important immune-inflammatory implication in the evolution to respiratory distress. Conditions such as HIV infection or treatment with immunosuppressors (in cancer or autoimmune diseases) are not among the bad prognosis factors for development of distress. To date, there have been no reported case fatalities in children, probably due to their more immature immune system. Our conclusions follow: (1) The milder form of SARS in children and the apparent protective factor that immunosupression represent rules out a significant viral cytopathic effect (they would be the most affected). (2) The evidence for immune implication in distress strongly supports immunomodulators for therapy: phosphodiesterase inhibitors (due to their down-modulating activity on proinflammatory cytokines); inhaled corticoids (aimed at producing a local immunomodulation); teophylline or nedocromil sodium (which prevents inflammatory cell recruitment into the airway wall). (3) An early immunomodulatory therapy, based on the levels of proinflammatory cytokines and clinical parameters to evaluate the respiratory function such as arterial oxygen saturation, could prevent the occurrence of distress. (4) Vaccine design should consider the immune origin of distress. (5) Physicians should be aware of mildly symptomatic patients (children, immuno-compromised hosts) to avoid transmission to immunocompetent adults.

Adult↗

PubMed1996

Relation between changes in cellular load, evolution of viral phenotype, and the clonal composition of virus populations in the course of human immunodeficiency virus type 1 infection.

The relationship between the evolution of human immunodeficiency virus type 1 (HIV-1) biologic phenotype, changes in the proportion of infected peripheral blood mononuclear cells, and the relative contribution of non-syncytium-inducing (NSI) and syncytium-inducing (SI) HIV-1 variants to virus load was studied during the course of HIV-1 infection. In 65 HIV-1-infected subjects, the proportion of infected CD4 T cells was higher in persons who carried SI variants. Longitudinal studies revealed that the emergence of SI HIV-1 variants can occur at relatively low numbers of HIV-1-infected cells. Emergence of SI variants frequently coincided with an increase of virus load due to an expansion of both NSI and SI variants, although the contribution of SI viruses to the total virus population significantly increased with time after SI phenotype conversion. These data indicate that NSI to SI phenotype conversion, rather than resulting from high virus load, is part of the sequence of events that leads to increased virus load and CD4 cell depletion.

CD4 Lymphocyte Count↗

PubMed1995

Predicting perinatal human immunodeficiency virus infection by antibody patterns.

The evolution of human immunodeficiency virus type 1 (HIV-1) antibody titers determined by enzyme-linked immunosorbent assay between birth and 18 months of age was investigated in 118 babies born to HIV-1-seropositive South African mothers. By 18 months 41 (34.7%) children were diagnosed as HIV-1-infected by standard criteria. All 77 uninfected babies cleared maternal antibodies by 15 months; 94.5% of these babies seroreverted by 12 months. By 9 months of age a significant difference (P < 0.05) was noted between antibody decay rates in infected and uninfected children. Of the children subsequently shown to be uninfected, 95.8% demonstrated > or = 50% decay in antibody titers between 6 and 9 months; only 1 in the infected group showed a similar pattern (sensitivity, 97.8%; specificity, 93.8%). The approach of assessing the progression of antibody decay in infected and uninfected babies makes it a feasible and useful tool for estimating vertical transmission rates and diagnosis of perinatal HIV-1 infection earlier than standard practice.

AIDS Serodiagnosis↗

PubMed2002

Nelfinavir-resistant, amprenavir-hypersusceptible strains of human immunodeficiency virus type 1 carrying an N88S mutation in protease have reduced infectivity, reduced replication capacity, and reduced fitness and process the Gag polyprotein precursor aberrantly.

The evolution of human immunodeficiency virus type 1 (HIV-1) strains with reduced susceptibility to protease inhibitors (PIs) is a major cause of PI treatment failure. A subset of subjects failing a therapy regimen containing the PI nelfinavir developed mutations at position 88 in the protease region. The N88S mutation occurring in some of these subjects induces amprenavir hypersusceptibility and a reduction of fitness and replication capacity. Here we demonstrate that substitutions L63P and V77I in protease, in combination, partially compensate for the loss of fitness, loss of replication capacity, loss of specific infectivity, and aberrant Gag processing induced by the N88S mutation. In addition, these mutations partially ablate amprenavir hypersusceptibility. Addition of mutation M46L to a strain harboring mutations L63P, V77I, and N88S resulted in a reduction of fitness and infectivity without changing Gag-processing efficiency, while amprenavir hypersusceptibility was further diminished. The ratio of reverse transcriptase activity to p24 protein was reduced in this strain compared to that in the other variants, suggesting that the M46L effect on fitness occurred through a mechanism different from a Gag-processing defect. We utilized these mutant strains to undertake a systematic comparison of indirect, single, cycle-based measures of fitness with direct, replication-based fitness assays and demonstrated that both yield consistent results. However, we observed that the magnitude of the fitness loss for one of the mutants varied depending on the assay used.

Carbamates↗

PubMed2003

Genetic and functional analysis of full-length human immunodeficiency virus type 1 env genes derived from brain and blood of patients with AIDS.

The genetic evolution of human immunodeficiency virus type 1 (HIV-1) in the brain is distinct from that in lymphoid tissues, indicating tissue-specific compartmentalization of the virus. Few primary HIV-1 envelope glycoproteins (Envs) from uncultured brain tissues have been biologically well characterized. In this study, we analyzed 37 full-length env genes from uncultured brain biopsy and blood samples from four patients with AIDS. Phylogenetic analysis of intrapatient sequence sets showed distinct clustering of brain relative to blood env sequences. However, no brain-specific signature sequence was identified. Furthermore, there was no significant difference in the number or positions of N-linked glycosylation sites between brain and blood env sequences. The patterns of coreceptor usage were heterogeneous, with no clear distinction between brain and blood env clones. Nine Envs used CCR5 as a coreceptor, one used CXCR4, and two used both CCR5 and CXCR4 in cell-to-cell fusion assays. Eight Envs could also use CCR3, CCR8, GPR15, STRL33, Apj, and/or GPR1, but these coreceptors did not play a major role in virus entry into microglia. Recognition of epitopes by the 2F5, T30, AG10H9, F105, 17b, and C11 monoclonal antibodies varied among env clones, reflecting genetic and conformational heterogeneity. Envs from two patients contained 28 to 32 N-glycosylation sites in gp120, compared to around 25 in lab strains and well-characterized primary isolates. These results suggest that HIV-1 Envs in brain cannot be distinguished from those in blood on the basis of coreceptor usage or the number or positions of N-glycosylation sites, indicating that other properties underlie neurotropism. The study also demonstrates characteristics of primary HIV-1 Envs from uncultured tissues and implies that Env variants that are glycosylated more extensively than lab strains and well-characterized primary isolates should be considered during development of vaccines and neutralizing antibodies.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

[Neuropsychiatric development of children with acquired immunodeficiency].

The Authors describe the neuropsychological evolution of 88 children (86 born from HIV infected mothers and, 2 infected by blood products) followed up at the Institute of Infectious Diseases of the University of Pavia. All patients had a clinical, serological and immunologic evaluation done by a pediatric infectivologist and a neurological assessment (Amyeli-Tison and Towen) done by a pediatric neurologist every three months. The Mental Development was examined using the Griffith scales. Electroencephalographic, TC scan, liquor test and other invasive tests were done only in symptomatic patients when indicated. The incidence of Central Nervous System involvement by HIV virus was 24% in infected patients and 37% in children with symptomatic HIV infection; neurological symptoms were observed in coincidence with worsening of AIDS disease. Fifty-five percent of the patients had a serious developmental delays. The Authors stress the importance of an early psychological care of these patients done by a specialist physician in order to reduce the onset of developmental problems in children facing a life expectancy longer than before due to the continuous improvement in the therapeutic management of AIDS.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

[Principle aspects of acquired immunodeficiency syndrome (AIDS) in adults in Burundi].

The authors describe their experience of the infection by the virus of the human immunodeficiency HIV-1 in Burundi. The acquired immunodeficiency syndrome was brought to light in 1983 by the emergence of cryptococcal meningitis, Kaposi's sarcomas, disseminated candidiasis. 109 cases of infection by the virus of the human immunodeficiency (HIV) AIDS related complex, or acquired immunodeficiency syndromes, were observed in 8 months and are related in this paper. The authors elucidate the spread and amplify the role played by lorry drivers. The frequency of recent case history: tuberculosis, zona, sexually transmitted diseases (41%). Clinical manifestations have been studied according to their clinical stage: 28 patients are AIDS related complex (25%), 81 are acquired immunodeficiency syndrome. One have to notice the frequency of tuberculosis at the stage of acquired immunodeficiency syndrome, of digestive parasitoses, not only coccidiosis, but also strongyloidiasis and colonic amoebiasis, cryptococcal meningitis, and encephalopathies caused by the virus of human immunodeficiency (HIV) at the period of AIDS. Lethal evolution is fast: 28 out of the 81 AIDS were observed up to their end, occurring in less than 60 days, as an average. Lastly, numerous opportunistic infections cannot be diagnosed because the lack of technical facilities.

AIDS-Related Complex↗

PubMed1997

Tuberculosis and human immunodeficiency virus infection in west Burkina Faso: clinical presentation and clinical evolution.

OBJECTIVE: To study the relationship between human immunodeficiency virus (HIV) infection and tuberculosis (TB) in a West African country. DESIGN: A cohort study in TB patients at the TB centre of Bobo Dioulasso, Burkina Faso. RESULTS: HIV seroprevalence rose from 12.5% in 1987 to 24.7% in 1990. Analysis of clinical findings showed that extra-pulmonary TB was not more frequent in HIV-positive patients (18.5%) than in HIV negative patients (17.3%). Four symptoms were independently associated with HIV infection: diarrhoea, lymphadenopathy, weight loss and oral candidiasis. At the end of six months of chemotherapy for TB (2SHRZ/4HR), the mortality rate among HIV-positive TB patients was 27%, versus 10% among HIV-negative TB patients (P < 0.001). There was no difference between treatment failure rates among HIV-positive patients (3.8%) and HIV-negative patients (3.9%). At the final evaluation, 18 months after the start of chemotherapy, the relapse rate was 8% in HIV-positive patients versus 5.6% in HIV-negative patients (NS). Global mortality rate during the whole study period was significantly higher in HIV-1 (40.3%) and HIV-1 + 2 (20%) patients than in HIV-2 (11.1%) and HIV-negative (12.9%) patients. CONCLUSION: We conclude that, according to previous African studies, despite a higher mortality rate due generally to HIV disease itself, short-course chemotherapy of 6 months is as effective in HIV-positive patients as in HIV-negative patients, and must be continued.

AIDS-Related Opportunistic Infections↗