Distribution of human immunodeficiency virus type 1 subtypes in the state of Amazonas, Brazil, and subtype C identification

Few studies have reported the molecular epidemiological characterization of HIV-1 in the Northern region of Brazil. The present study reports the molecular and epidemiological characterization of 31 HIV-1 isolates from blood donors from the State of Amazonas who donated blood between April 2006 and March 2007. Serum/plasma samples from all donors were screened for HIV antibodies by ELISA and the results confirmed by Western blot analysis. Genomic DNA was extracted from the buffy coat using the Super Quik-Gene-DNA Isolation kit. Nested PCR was performed on the env, gag, and pol regions of HIV-1 using the Gene Amp PCR System 9700. Sequencing reactions were performed using the inner PCR primers and the DYEnamic͐2; ET Dye Terminator Kit, and phylogenetic analysis was performed using the gag, pol, and env gene sequences. We collected samples from 31 blood donors who tested positive for HIV-1 in confirmatory experiments. The male:female ratio of blood donors was 3.4:1, and the mean age was 32.4 years (range: 19 to 61 years). Phylogenetic analysis showed that subtype B is the most prevalent among Northern Brazilian HIV-1-seropositive blood donors. One HIV-1 subtype C and one circulating recombinant form (CRF_BF) of HIV-1 were identified in the State of Amazonas. This is the first study showing the occurrence of a possible "homogenous" subtype C in this region of Brazil. This finding could contribute to a better characterization of the HIV-1 strains that circulate in the country.

Factors associated with the incidence of type 2 diabetes mellitus in HIV-infected participants in the Swiss HIV Cohort Study

BACKGROUND: Human immunodeficiency virus (HIV)-infected persons may be at increased risk for developing type 2 diabetes mellitus because of viral coinfection and adverse effects of treatment. METHODS: We studied associations of new-onset diabetes mellitus with hepatitis B virus and hepatitis C virus coinfections and antiretroviral therapy in participants in the Swiss HIV Cohort Study, using Poisson regression. RESULTS: A total of 123 of 6513 persons experienced diabetes mellitus during 27,798 person-years of follow-up (PYFU), resulting in an incidence of 4.4 cases per 1000 PYFU (95% confidence interval [CI], 3.7-5.3 cases per 1000 PYFU). An increased incidence rate ratio (IRR) was found for male subjects (IRR, 2.5; 95% CI, 1.5-4.2), older age (IRR for subjects >60 years old, 4.3; 95% CI, 2.3-8.2), black (IRR, 2.1; 95% CI, 1.1-4.0) and Asian (IRR, 4.9; 95% CI, 2.2-10.9) ethnicity, Centers for Disease Control and Prevention disease stage C (IRR, 1.6; 95% CI, 1.04-2.4), and obesity (IRR, 4.7; 95% CI, 3.1-7.0), but results for hepatitis C virus infection or active hepatitis B virus infection were inconclusive. Strong associations were found for current treatment with nucleoside reverse-transcriptase inhibitors (IRR, 2.22; 95% CI, 1.11-4.45), nucleoside reverse-transcriptase inhibitors plus protease inhibitors (IRR, 2.48; 95% CI, 1.42-4.31), and nucleoside reverse-transcriptase inhibitors plus protease inhibitors and nonnucleoside reverse-transcriptase inhibitors (IRR, 3.25; 95% CI, 1.59-6.67) but were not found for treatment with nucleoside reverse-transcriptase inhibitors plus nonnucleoside reverse-transcriptase inhibitors (IRR, 1.47; 95% CI, 0.77-2.82). CONCLUSIONS: In addition to traditional risk factors, current treatment with protease inhibitor- and nucleoside reverse-transcriptase inhibitor-containing regimens was associated with the risk of developing type 2 diabetes mellitus. Our study did not find a significant association between viral hepatitis infection and risk of incident diabetes.

Human adrenal corticocarcinoma NCI-H295R cells produce more androgens than NCI-H295A cells and differ in 3beta-hydroxysteroid dehydrogenase type 2 and 17,20 lyase activities

The human adrenal cortex produces mineralocorticoids, glucocorticoids, and androgens in a species-specific, hormonally regulated, zone-specific, and developmentally characteristic fashion. Most molecular studies of adrenal steroidogenesis use human adrenocortical NCI-H295A and NCI-H295R cells as a model because appropriate animal models do not exist. NCI-H295A and NCI-H295R cells originate from the same adrenocortical carcinoma which produced predominantly androgens but also smaller amounts of mineralocorticoids and glucocorticoids. Research data obtained from either NCI-H295A or NCI-H295R cells are generally compared, although for the same experiments no direct comparison between the two cell lines has been performed. Therefore, we compared the steroid profile and the expression pattern of important genes involved in steroidogenesis in both cell lines. We found that steroidogenesis differs profoundly. NCI-H295A cells produce more mineralocorticoids, whereas NCI-H295R cells produce more androgens. Expression of the 3beta-hydroxysteroid dehydrogenase (HSD3B2), cytochrome b5, and sulfonyltransferase genes is higher in NCI-H295A cells, whereas expression of the cytochrome P450c17 (CYP17), 21-hydroxylase (CYP21), and P450 oxidoreductase genes does not differ between the cell lines. We found lower 3beta-hydroxysteroid dehydrogenase type 2 but higher 17,20-lyase activity in NCI-H295R cells explaining the 'androgenic' steroid profile for these cells and resembling the zona reticularis of the human adrenal cortex. Both cell lines were found to express the ACTH receptor at low levels consistent with low stimulation by ACTH. By contrast, both cell lines were readily stimulated by 8Br-cAMP. The angiotensin type 1 receptor was highly expressed in NCI-H295R than NCI-H295A cells and angiotensin II stimulated steroidogenesis in NCI-H295R but not NCI-H295A cells. Our data suggest that comparative studies between NCI-H295A and NCI-H295R cells may help find important regulators of mineralocorticoid or androgen biosynthesis.

Effects of anticonvulsants on human p450c17 (17alpha-hydroxylase/17,20 lyase) and 3beta-hydroxysteroid dehydrogenase type 2.

PURPOSE Women with epilepsy apparently have a higher incidence of polycystic ovary syndrome (PCOS) than do women without epilepsy. Whether the underlying disease or the antiepileptic drug (AED) treatment is responsible for this increased risk is unknown, although clinical reports implicate valproic acid (VPA) as a potential cause. The steroidogenic enzymes 3beta HSDII (3beta-hydroxysteroid dehydrogenase) and P450c17 (17alpha-hydroxylase/17,20 lyase) are essential for C19 steroid biosynthesis, which is enhanced during adrenarche and in PCOS. METHODS To determine whether the AEDs VPA, carbamazepine (CBZ), topiramate (TPM), or lamotrigine (LYG) directly affect the activities of human 3beta HSDII and P450c17, we added them to yeast expressing human P450c17 or 3beta HSDII and assayed enzymatic activities in the microsomal fraction. RESULTS Concentrations of VPA < or = 10 mM had no effect on activities of P450c17; however, VPA inhibited 3beta HSDII activity starting at 0.3 mM (reference serum unbound concentration, 0.035-0.1 mM) with an IC50 of 10.1 mM. CBZ, TPM, and LTG did not influence 3beta HSDII or P450c17 activities at typical reference serum unbound concentrations, but did inhibit 3beta HSDII and P450c17 at concentrations >10-fold higher. CONCLUSIONS None of the tested AEDs influenced 3beta HSDII or P450c17 activities at concentrations normally used in AED therapy. However, VPA started to inhibit 3beta HSDII activity at concentrations 3 times above the typical reference serum unbound concentration. Because inhibition of 3beta HSDII activity will shift steroidogenesis toward C19 steroid production when P450c17 activities are unchanged, very high doses of VPA may promote C19 steroid biosynthesis, thus resembling PCOS. CBZ, TPM, and LTG influenced 3beta HSDII and P450c17 only at toxic concentrations.

Glucocorticoid alterations in the human type-1/type-2 cytokine balance and the role of CD28/B7 costimulation

We have recently reported that psychological stress is associated with a shift in the human type-1/type-2 cytokine balance toward a type-2 cytokine response. The mechanisms of these cytokine alterations are unknown, but likely involve glucocorticoid (GC) modulation of cytokine production. Therefore we sought to characterize the effects of GC on the in vitro human type-1/type-2 cytokine balance. We hypothesized that GC induce a type-2 cytokine shift through modulation of critical regulatory cytokines and alterations in the CD28/B7 costimulatory pathway. ^ We first sought to characterize the effect of the GC, dexamethasone (DEX), on type-1 (IFN-γ, IL-12) and type-2 (IL-4, IL-10) cytokine production by human peripheral blood mononuclear blood cells (pBMC) stimulated with a variety of T-lymphocyte and monocyte stimuli. DEX, at concentrations mimicking stress and supraphysiologic levels of cortisol, decreased IFN-γ and IL-12 production and increased IL-4 and IL-10 production, indicating a shift in the type-1/type-2 cytokine balance toward a type-2 response. Furthermore, both CD4+ and CD8+ T-lymphocytes were susceptible to the cytokine modulating effects of DEX. Furthermore, in the absence of the monocyte, the DEX-induced alterations in T-lymphocyte cytokine production were reduced, indicating that the interaction between the monocyte and T-lymphocyte plays a significant role. ^ We next determined the role of regulatory cytokines, known to modulate the type-1/type-2 cytokine balance, in the DEX-induced cytokine alterations. The addition of the recombinant IL-12p70 and IFN-γ, but not the neutralization of IL-4, IL-10 or IL-13 using monoclonal antibodies, attenuated the DEX-induced type-1/type-2 cytokine alterations. These data suggest that the DEX-induced cytokine alterations are mediated, at least in part, through the initial inhibition type-1 cytokines. Lastly, we investigated the role of the CD28/B7 costimulatory pathway in these cytokine alterations. DEX decreased the expression of CD80 and CD86 on THP-1 cells, a monocyte cell line, and the expression of CD28 and CTLA-4 on PHA-stimulated pBMC. The DEX-induced decrease in CD28 and CTLA-4 expression was attenuated by rhIL-12. Finally, CD28 activation attenuated the DEX-induced decrease in IFN-γ production, suggesting that modulation of the CD28/B7 costimulatory pathway may contribute to the DEX-induced type-1/type-2 cytokine alterations. ^

17-beta estradiol and progesterone-induced alterations in human type-1/type-2 cytokine balance and the role of costimulatory and apoptotic mechanisms

Evidence suggests that sex-based differences in immune function may predispose women to numerous hypersensitivity conditions such as Systemic lupus erythematosus (SLE), Hashimoto's thyroiditis and asthma. To date, the exact mechanisms of sexual dimorphism in immunity are not fully characterized but sex hormones such as 17-β estradiol (E2) and progesterone (PR) are believed to be involved. Since E2 and PR may modulate the production of critical regulatory cytokines, we sought to characterize their effects on the in vitro human type-1/type-2 cytokine balance. We hypothesized that E2 and/or PR vary cytokine production and influence costimulatory molecule expression and apoptosis. We first described the effect of E2 and/or PR on type-1 (IFN-γ and IL-12) and type-2 (IL-4 and IL-10) cytokine production by human peripheral blood mononuclear cells (PBMC) treated with various T-lymphocyte and monocyte stimuli. E2 and/or PR were each used at concentrations similar to those found at the maternal-fetal interface during pregnancy. At this dose, E2 increased IFN-γ and IL-12 production and PR decreased IFN-γ production and tended to increase IL-4 production. Furthermore, the combination of E2+PR decreased IL-12 production. This suggests that E2 shifts the type-1/type-2 cytokine balance towards a type-1 response and that PR and E2+PR shift the balance towards a type-2 response. Next, we used intracellular cytokine detection to demonstrate that E2 and/or PR are capable of altering cytokine production of CD3+ T-cells and the CD3+CD4+ and CD3+CD8+ subsets. In addition, we used the H9 T-lymphocyte cell line and the THP-1 monocyte cell line to show that E2 and/or PR can induce cytokine effects in both T-cells and monocytes independent of their interaction. Lastly, we determined the effect of E2 and/or PR on costimulatory molecule expression and apoptosis as potential mechanisms for the cytokine-induced alterations. E2 increased and PR decreased CD80 expression on THP-1 cells and PR and E2+PR decreased CD28 expression in PBMC and Jurkat cells. Furthermore, E2, PR and E2+PR increased Fas-mediated apoptosis in Jurkat cells and E2 increased FasL expression on THP-1 cells. Thus, E2 and/or PR may alter the cytokine balance by modulating the CD28/CD80 costimulatory pathway and apoptosis. ^

The roles of costimulatory molecules in the cooperative effects of combination epinephrine and dexamethasone on type-1/type-2 cytokine production in tetanus-toxoid specific stimulated human peripheral blood mononuclear cells

A growing number of studies show strong associations between stress and altered immune function. In vivo studies of chronic and acute stress have demonstrated that cognitive stressors are strongly correlated with high circulating levels of catecholamines (CT) and corticosteroids (CS) that are associated with changes in type-1/type-2 cytokine expression. Although individual pharmacologic doses of CS and CT can inhibit the expression of T-helper 1 (Th1, type-1 like) and promote the production of T-helper 2 (Th2, type-2 like) cytokines in antigen-specific and mitogen stimulated human leukocyte cultures in vitro, little attention has been focused on the effects of combination physiologic-stress doses of CT and CS that may be more physiologically relevant. In addition, both in-vivo and in-vitro studies suggest that the differential expression of the B7 family of costimulatory molecules CD80 and CD86 may promote the expression of type-1 or type-2 cytokines, respectively. Furthermore, corticosteroids can influence the expression of β2-adrenergic receptors in various human tissues. We therefore investigated the combined effects of physiologic-stress doses of in vitro CT and CS upon the type-1/type-2 cytokine balance and expression of B7 costimulatory molecules of human peripheral blood mononuclear cells (PBMC) as a model to study the immunomodulatory effects of physiologic stress. Results demonstrated a significant decrease in type-1 cytokine expression and a significant increase in type-2 cytokine production in our CS+CT incubated cultures when compared to either CT or CS agents alone. In addition, we demonstrated the differential expression of CD80/CD86 in favor of CD86 at the cellular and population level as determined by flow cytometry in lipopolysaccharide stimulated human Monocytes. Furthermore, we developed flow cytometry based assays to detect total β2AR in human CD4+ T-lymphocytes that demonstrated decreased expression of β2AR in mitogen stimulated CD4+ T-lymphocytes in the presence of physiologic stress levels of CS and CT as single in vitro agents, however, when both CS and CT were combined, significantly higher expression of β2AR was observed. In summary, our in vitro data suggest that both CS and CT work cooperatively to shift immunity towards type-2 responses. ^

Host-parasite dynamics and outgrowth of virus containing a single K70R amino acid change in reverse transcriptase are responsible for the loss of human immunodeficiency virus type 1 RNA load suppression by zidovudine.

The association between human immunodeficiency virus type I (HIV-1) RNA load changes and the emergence of resistant virus variants was investigated in 24 HIV-1-infected asymptomatic persons during 2 years of treatment with zidovudine by sequentially measuring serum HIV-1 RNA load and the relative amounts of HIV-1 RNA containing mutations at reverse transcriptase (RT) codons 70 (K-->R), 41 (M-->L), and 215 (T-->Y/F). A mean maximum decline in RNA load occurred during the first month, followed by a resurgence between 1 and 3 months, which appeared independent of drug-resistance. Mathematical modeling suggests that this resurgence is caused by host-parasite dynamics, and thus reflects infection of the transiently increased numbers of CD4+ lymphocytes. Between 3 and 6 months of treatment, the RNA load returned to baseline values, which was associated with the emergence of virus containing a single lysine to arginine amino acid change at RT codon 70, only conferring an 8-fold reduction in susceptibility. Despite the relative loss of RNA load suppression, selection toward mutations at RT codons 215 and 41 continued. Identical patterns were observed in the mathematical model. While host-parasite dynamics and outgrowth of low-level resistant virus thus appear responsible for the loss of HIV-1 RNA load suppression, zidovudine continues to select for alternative mutations, conferring increasing levels of resistance.

Human immunodeficiency virus type 1 infection despite prior immunization with a recombinant envelope vaccine regimen.

With efforts underway to develop a preventive human immunodeficiency virus type 1 (HIV-1) vaccine, it remains unclear which immune responses are sufficient to protect against infection and whether prior HIV-1 immunity can alter the subsequent course of HIV-1 infection. We investigated these issues in the context of a volunteer who received six HIV-1LAI envelope immunizations and 10 weeks thereafter acquired HIV-1 infection through a high-risk sexual exposure. In contrast to nonvaccinated acutely infected individuals, anamnestic HIV-1-specific B- and T-cell responses appeared within 3 weeks in this individual, and neutralizing antibody preceded CD8+ cytotoxic responses. Despite an asymptomatic course and an initial low level of detectable infectious virus, a progressive CD4+ cell decline and dysfunction occurred within 2 years. Although vaccination elicited immunity to HIV-1 envelope, which was recalled upon HIV-1 exposure, it was insufficient to prevent infection and subsequent immunodeficiency.

Kinetics of cytokine expression during primary human immunodeficiency virus type 1 infection.

In the present study, we have determined the kinetics of constitutive expression of a panel of cytokines [interleukin (IL) 2, IL-4, IL-6, IL-10, interferon gamma (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha)] in sequential peripheral blood mononuclear cell samples from nine individuals with primary human immunodeficiency virus infection. Expression of IL-2 and IL-4 was barely detected in peripheral blood mononuclear cells. However, substantial levels of IL-2 expression were found in mononuclear cells isolated from lymph node. Expression of IL-6 was detected in only three of nine patients, and IL-6 expression was observed when transition from the acute to the chronic phase had already occurred. Expression of IL-10 and TNF-alpha was consistently observed in all patients tested, and levels of both cytokines were either stable or progressively increased over time. Similar to IL-10 and TNF-alpha, IFN-gamma expression was detected in all patients; however, in five of nine patients, IFN-gamma expression peaked very early during primary infection. The early peak in IFN-gamma expression coincided with oligoclonal expansions of CD8+ T cells in five of six patients, and CD8+ T cells mostly accounted for the expression of this cytokine. These results indicate that high levels of expression of proinflammatory cytokines are associated with primary infection and that the cytokine response during this phase of infection is strongly influenced by oligoclonal expansions of CD8+ T cells.

Crystal structures of the trimeric human immunodeficiency virus type 1 matrix protein: implications for membrane association and assembly.

The human immunodeficiency virus type 1 (HIV-1) matrix protein forms a structural shell associated with the inner viral membrane and performs other essential functions throughout the viral life cycle. The crystal structure of the HIV-1 matrix protein, determined at 2.3 angstrom resolution, reveals that individual matrix molecules are composed of five major helices capped by a three-stranded mixed beta-sheet. Unexpectedly, the protein assembles into a trimer in three different crystal lattices, burying 1880 angstrom2 of accessible surface area at the trimer interfaces. Trimerization appears to create a large, bipartite membrane binding surface in which exposed basic residues could cooperate with the N-terminal myristoyl groups to anchor the protein on the acidic inner membrane of the virus.

Selective pressure of a quinoxaline nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) on HIV-1 replication results in the emergence of nucleoside RT-inhibitor-specific (RT Leu-74-->Val or Ile and Val-75-->Leu or Ile) HIV-1 mutants.

The quinoxaline nonnucleoside RT inhibitor (NNRTI) (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4- dihydroquinoxaline-2(1H)-thione (HBY 097) was used to select for drug-resistant HIV-1 variants in vitro. The viruses first developed mutations affecting the NNRTI-binding pocket, and five of six strains displayed the RT G190-->E substitution, which is characteristic for HIV-1 resistance against quinoxalines. In one variant, a new mutant (G190-->Q) most likely evolved from preexisting G190-->E mutants. The negative charge introduced by the G190-->E substitution was maintained at that site of the pocket by simultaneous selection for V179-->D together with G190-->Q. After continued exposure to the drug, mutations at positions so far known to be specific for resistance against nucleoside RT inhibitors (NRTIs) (L74-->V/I and V75-->L/I) were consistently detected in all cultures. The inhibitory activities of the cellular conversion product of 2',3'-dideoxyinosine (ddI, didanosine), 2',3'-dideoxyadenosine (ddA) and of 2',3'-didehydro-3'-deoxythymidine (d4T, stavudine) against these late-passage viruses were shown to be enhanced with the L74-->V/I RT mutant virus as compared with the wild-type (wt) HIV-1MN isolate. Clonal analysis proved linkage of the codon 74 and codon 75 mutations to the NNRTI-specific mutations in all RT gene fragments. The nonnucleoside- and nucleoside-resistance mutation sites are separated by approximately 35 A. We propose that the two sites "communicate" through the template-primer which is situated in the DNA-binding cleft between these two sites. Quinoxalines cause high selective pressure on HIV-1 replication in vitro; however, the implication of these findings for the treatment of HIV-1 infection has yet to be determined.

Catalytic domain of human immunodeficiency virus type 1 integrase: identification of a soluble mutant by systematic replacement of hydrophobic residues.

The integrase protein of human immunodeficiency virus type 1 is necessary for the stable integration of the viral genome into host DNA. Integrase catalyzes the 3' processing of the linear viral DNA and the subsequent DNA strand transfer reaction that inserts the viral DNA ends into host DNA. Although full-length integrase is required for 3' processing and DNA strand transfer activities in vitro, the central core domain of integrase is sufficient to catalyze an apparent reversal of the DNA strand transfer reaction, termed disintegration. This catalytic core domain, as well as the full-length integrase, has been refractory to structural studies by x-ray crystallography or NMR because of its low solubility and propensity to aggregate. In an attempt to improve protein solubility, we used site-directed mutagenesis to replace hydrophobic residues within the core domain with either alanine or lysine. The single substitution of lysine for phenylalanine at position 185 resulted in a core domain that was highly soluble, monodisperse in solution, and retained catalytic activity. This amino acid change has enabled the catalytic domain of integrase to be crystallized and the structure has been solved to 2.5-A resolution [Dyda, F., Hickman, A. B., Jenkins, T. M., Engelman, A., Craigie, R. & Davies, D. R. (1994) Science 266, 1981-1986]. Systematic replacement of hydrophobic residues may be a useful strategy to improve the solubility of other proteins to facilitate structural and biochemical studies.