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Biomedical subjects

P J Kanki

Publications and source records attributed to P J Kanki.

At least 19 recordsLinked to original sources
PubMed2006

Regulation of adiponectin in adipocytes upon exposure to HIV-1.

OBJECTIVES: Adipose dysregulation, dyslipidemia, and insulin resistance are hallmarks of HIV-related lipodystrophy. The precise mechanisms behind these disturbances are unknown. In HIV-infected patients, we previously demonstrated a strong relationship between lipodystrophy and levels of adiponectin, an adipose peptide implicated in regulation of glucose and lipid metabolisms. In this study we investigated the effect of HIV on adipocytes, to determine whether HIV can directly infect adipocytes and/or alter the regulation and secretion of the adipocyte-derived hormone adiponectin. METHODS: Human subcutaneous preadipocytes and adipocytes were exposed to HIV-1 under various conditions. Adiponectin was measured in supernatants and cell lysates. RESULTS: Although adipocytes expressed CD4, the major HIV receptor, they could not be infected in vitro. However, exposure to HIV dramatically increased the secretion of adiponectin from human adipocytes, in the absence of infection. This was exacerbated with sustained exposure to HIV in a transwell assay. Further, human peripheral mononuclear cells also produced adiponectin, but this was largely dependent upon T-cell activation. CONCLUSIONS: We propose that the stimulation of adiponectin production by HIV can perturb adiponectin regulation, leading to substantially decreased levels upon viral suppression by antiretroviral therapy. These data suggest a potential molecular mechanism of adiponectin regulation in HIV-infected patients.

Adipocytes↗
PubMed2001

Robust HIV type 2 cellular immune response measured by a modified anthrax toxin-based enzyme-linked immunospot assay.

Evaluation of immune mechanisms responsible for control of viral replication is critical to understanding HIV-2 attenuated biological characteristics in pathogenesis and transmission. Evaluation of the cellular immune response is often based on labor-intensive techniques that limit the scope of most studies performed. A simple and rapid anthrax toxin-based ELISPOT method to assess HIV-2 cellular immune response was developed. The modified anthrax toxin-based antigen presentation process performed better than a recombinant vaccinia system and the ELISPOT method significantly enhanced the ease and simplicity of the assay. Using this method, a robust HIV-2 cellular immune response directed toward the p26 core protein was exhibited in 21 of 24 (87.5%) infected women, and all 8 seronegative subjects were negative in both assays. Cellular immune responses were associated with low HIV-2 viral load. This simple and rapid modified anthrax toxin-based ELISPOT method allowed us to demonstrate, strong cellular immune responses that may be critical determinants in the HIV-2 attenuated phenotype.

Antigen Presentation↗
PubMed2001

Omnibus tests for comparison of competing risks with adjustment for covariate effects.

This article develops omnibus tests for comparing cause-specific hazard rates and cumulative incidence functions at specified covariate levels. Confidence bands for the difference and the ratio of two conditional cumulative incidence functions are also constructed. The omnibus test is formulated in terms of a test process given by a weighted difference of estimates of cumulative cause-specific hazard rates under Cox proportional hazards models. A simulation procedure is devised for sampling from the null distribution of the test process, leading to graphical and numerical technques for detecting significant differences in the risks. The approach is applied to a cohort study of type-specific HIV infection rates.

Biometry↗
PubMed2000

High levels of tumor necrosis factor-alpha and interleukin-1beta in bacterial vaginosis may increase susceptibility to human immunodeficiency virus.

Bacterial vaginosis (BV) was identified recently as a cofactor that promotes sexual transmission of human immunodeficiency virus (HIV). This study was done to determine if interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha could be measured consistently in cervical secretions and if high levels of these cytokines were associated with BV. Secretions were obtained from 209 study subjects; most samples had detectable levels of TNF-alpha (84.2%) and IL-1beta (79.8%). BV was detected in 53 (27.0%) of 196 women. High cytokine levels were significantly associated with BV (adjusted odds ratio [AOR], 4.17; 95% confidence interval [CI], 1.69-10.30), oral contraceptive use (AOR, 2.78; 95% CI, 1.04-7.48), and high leukocyte counts on vaginal smear (AOR, 1.18; 95% CI, 1.03-1.36). Since these cytokines could up-regulate local HIV replication through activation of the long terminal repeat promoter region, the association of BV with high levels of IL-1beta or TNF-alpha may partly explain the mechanism by which this risk factor enhances HIV transmission.

Adolescent↗
PubMed2000

In vitro correlates of HIV-2-mediated HIV-1 protection.

A prospective study of high-risk commercial sex workers in Senegal has shown that HIV-2 infection may reduce the risk of subsequent HIV-1 infection; these findings have been confirmed and extended, now with 13 years of observation. While exploring the biological mechanisms behind this natural protection, we found that a significant proportion of peripheral blood mononuclear cells obtained from HIV-2-infected subjects resisted in vitro challenge with CCR5-dependent HIV-1 viruses but not CXCR4-dependent viruses. High levels of beta-chemokines, the natural ligands of the CCR5 coreceptor, were correlated with low levels of viral replication, and resistance was abrogated by antibodies to beta-chemokines. Our results suggest that beta-chemokine-mediated resistance may be an important correlate of HIV protection against HIV-1 infection and relevant to HIV vaccine design.

AIDS Vaccines↗
PubMed2000

Interaction with human immunodeficiency virus (HIV) type 2 predicts HIV type 1 genotype.

In West Africa, India, and certain regions of Europe, both human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2) are known to cocirculate. To investigate the HIV-1 subtypes involved in dual HIV-1 and HIV-2 infections, we sequenced the envelope C2-V3 region from 29 dually infected female commercial sex workers from Senegal. The majority of women (23 of 29) were infected by HIV-1 subtype A. Within the HIV-1 subtype A sequences, 14 of 23 (60.8%) clustered with the West African associated A/G recombinant form (IbNG), and 9 of 23 (39.2%) formed a separate cluster distinct from the A/G IbNG. In contrast, in HIV-1 singly infected individuals, non-IbNG subtype A was found in only 13 of 98 (13.3%). Therefore, the lack of protection and/or interaction with HIV-2 was associated with a distinct HIV-1 A genotype. These results suggest differences in the biological properties of HIV-1 genotypes and their in vivo interaction with HIV-2.

Amino Acid Motifs↗
PubMed2000

Genetic analysis of HIV type 2 in monotypic and dual HIV infections.

A significant level of genetic variation among HIV-1 and HIV-2 has been described. The interaction of specific HIV-2 subtypes with HIV-1 may serve to identify potential biological properties associated with dual infection. To genetically characterize the HIV-2 strains circulating in Senegal and their relationship to coinfection with HIV-1, we sequenced the HIV-2 envelope C2-C3 region of 12 subjects coinfected with HIV-1 and HIV-2 and 9 subjects singly infected with HIV-2. The phylogenetic analysis showed that all subjects were infected with HIV-2 subtype A, confirming its predominance in West Africa. We did not observe specific sequences or genetic clustering based on coinfection status.

Base Sequence↗
PubMed2000

Molecular epidemiology of genital Chlamydia trachomatis infection in high-risk women in Senegal, West Africa.

The prevalence and heterogeneity of Chlamydia trachomatis infections in a cohort of female sex workers in Dakar (Senegal) were determined by using endocervical-swab-based PCR DNA amplification assays. The overall prevalence of cervical chlamydial infection was 28.5% (206 of 722), and most of these infections were asymptomatic. An increased number of sexual partners was significantly associated with infection (adjusted odds ratio [AOR] = 1.37; 95% confidence interval [CI] = 1.06 to 1.77), while the presence of a yeast infection was negatively associated with chlamydial infection (AOR = 0.28; 95% CI = 0.10 to 0.83). Six different C. trachomatis genotypes were identified based on phylogenetic analysis of the omp1 gene sequences. Interestingly, genotype E predominated (47.6%) and was not associated with visible signs of cervical inflammation compared to non-E genotypes (P < 0.05). Overall, the high rate of asymptomatic C. trachomatis infection by genotype E may suggest genotype-specific properties that confer a transmission advantage in this high risk population.

Adult↗
PubMed2000

Low plasma human immunodeficiency virus type 2 viral load is independent of proviral load: low virus production in vivo.

Levels of virus in the plasma are closely related to the pathogenicity of human immunodeficiency virus type 1 (HIV-1). HIV-2 is much less pathogenic than HIV-1, and infection with HIV-2 leads to significantly lower plasma viral load. To identify the source of this difference, we measured both viral RNA and proviral DNA in matched samples from 34 HIV-2-infected individuals. Nearly half had undetectable viral RNA loads (<100 copies/ml), but levels of proviral DNA were relatively high and confirmed that quantities of provirus in HIV-1 and HIV-2 infection were similar. Overall, HIV-2 proviral DNA load did not correlate with viral RNA load, and higher viral RNA load was associated with increased production of plasma virus from the proviral template. These results suggest that low viral load in HIV-2 infection is due to decreased rates of viral production, rather than differences in target cell infectivity.

CD4 Lymphocyte Count↗
PubMed1999

Human immunodeficiency virus type 1 subtypes differ in disease progression.

At least 10 different genetic human immunodeficiency virus type 1 (HIV-1) subtypes (A-J) are responsible for the AIDS pandemic. Much of the understanding of HIV-1 disease progression derives from studies in the developed world where HIV infection is almost exclusively subtype B. This has led many to question whether the properties and consequences of HIV-1 infection can be generalized across subtypes that afflict the majority of infected persons in the developing world. From 1985 to 1997, a prospective study of registered female sex workers in Senegal tracked the introduction and spread of HIV-1 subtypes A, C, D, and G. In clinical follow-up, the AIDS-free survival curves differed by HIV-1 subtype. Women infected with a non-A subtype were 8 times more likely to develop AIDS than were those infected with subtype A (hazard ratio=8.23; P=. 009), the predominant subtype in the study. These data suggest that HIV-1 subtypes may differ in rates of progression to AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Lower human immunodeficiency virus (HIV) type 2 viral load reflects the difference in pathogenicity of HIV-1 and HIV-2.

Human immunodeficiency virus type 2 (HIV-2) is less pathogenic than HIV type 1 (HIV-1), but the mechanisms underlying this difference have not been defined. We developed an internally controlled quantitative reverse transcriptase-polymerase chain reaction to measure HIV-2 viral load and determined levels of plasma virus in a cohort of registered commercial sex workers in Dakar, Senegal. The assay has a lower limit of detection of 100 copies/mL and is linear over 4 logs. HIV-2 viral RNA was detectable in 56% of all samples tested; the median load was 141 copies/mL. Levels of viral RNA in the plasma were inversely related to CD4+ cell counts. HIV-2 and HIV-1 viral loads were compared among the seroincident women in the cohort; the median viral load was 30x lower in the HIV-2-infected women (P<.001, Wilcoxon rank sum test), irrespective of the length of time infected. This suggests that plasma viremia is linked to the differences in the pathogenicity of the 2 viruses.

Adult↗
PubMed1998

Genetic characterization of viral quasispecies in blood and cervical secretions of HIV-1- and HIV-2-infected women.

We evaluated cervical samples from 11 HIV-1- and 25 HIV-2-infected individuals. The rate of viral shedding was 36.4% for HIV-1 and 16% for HIV-2, after repeat PCRs. We sequenced multiple clones of the C2-C3 env region from cervical secretions and PBMC samples from three HIV-2-infected individuals, and the C2-V3 env region from four HIV-1-infected individuals. In most cases, phylogenetic analysis showed that the viral sequences from blood and genital secretions were intermingled and subclusters did not segregate according to sample site. In rare cases, however, tissue-specific sequences were observed, suggesting a complex relationship between quasispecies in the two sites where preferential transmission of HIV variants may be due to multiple factors.

Adult↗
PubMed1998

Antibodies to the HIV type 2 core protein p26 and Vpx: association with disease progression.

A longitudinal cohort study was conducted to define the prevalence and temporal pattern of antibody response to the HIV-2 virion-associated proteins p26gag and Vpx. One hundred and forty-one asymptomatic HIV-2-infected women were enrolled, and followed for up to 11 years. Eighty-one percent of the subjects had antibodies to p26, and 51% to Vpx; response to these two antigens was not correlated. The response to both proteins was determined early in infection, and remained stable over time. The absence of antibodies to p26 was a highly significant predictor of CDC category IV HIV-related disease (p < 0.01) in both univariate and multivariate analysis. Antibody response to Vpx alone was not associated with disease progression. However, those individuals lacking anti-p26 antibodies, and with anti-Vpx antibodies, were six times more likely to be classified as CDC category IV by the end of the study (p < 0.01). This represents the first identification of virus-specific serological markers for HIV-2-related disease progression.

Amino Acid Sequence↗
PubMed1998

HIV-1 and HIV-2 dual infection: lack of HIV-2 provirus correlates with low CD4+ lymphocyte counts.

OBJECTIVE: We conducted this study to genetically characterize dual infection in individuals demonstrating a dual serological profile. METHODS: All subjects were first evaluated by immunoblot for antibody reactivity to the major viral antigens for HIV-1 and HIV-2. Sera were judged to be dual-seropositive if they reacted with strong and equal intensity with the envelope antigens of both HIV-1 and HIV-2 and were confirmed with type-specific recombinant env peptides. We used nested polymerase chain reaction (PCR) to amplify proviral gag and env sequence from peripheral blood mononuclear cell (PBMC) DNA from HIV-1- and HIV-2-infected individuals. Positive amplification was detected after Southern blot hybridization. RESULTS: Plasmid dilution and mixing showed equivalent sensitivity of HIV-1 and HIV-2 primers that was not altered by heterologous target sequences. The DNA PCR showed 100% sensitivity and specificity for detection of monotypic HIV infection. Serologically defined HIV-dual reactives were evaluated by this assay, with 100% detection in female sex workers (21 out of 21), but only 38.5% detection (five out of 13) in hospitalized patients; all being HIV-1 positive only. The lack of HIV-2 proviral signal was significantly correlated with low CD4+ lymphocyte counts (Pvalue = 0.04). CONCLUSION: The results suggest that HIV dual infection may not be a static condition. Levels of HIV-2 may decrease with disease progression or sequester in tissue reservoirs; our results may also suggest that HIV-1 effectively overgrows HIV-2 in the dually exposed host individual.

Blotting, Southern↗