RESUMO
Genetic factors from an HIV-1 host can affect the rate of progression to AIDS and HIV infection. To investigate the frequency of mutations in the CCR5 gene, HIV-1 samples from infected women and uninfected individuals were selected for sequencing of the CCR5 gene regions encoding the N- and C-terminal protein domains. Physicochemical CCR5 modeling and potential protein domain analysis were performed in order to evaluate the impact of the mutations found in the properties and structure of CCR5. The p.L55Q mutation in the N-terminal protein domain was observed only in uninfected individuals, with an allelic frequency of 1.8%. Physicochemical analysis revealed that the p.L55Q mutation magnified the flexibility and accessibility profiles and the modeling of CCR5 structures showed resulting in a small deviation to the right, as well as a hydrophobic to hydrophilic property alteration. The p.L55Q mutation also resulted in a slight modification of the electrostatic load of this region. Additionally, three novel silent mutations were found at the C-terminal coding region among HIV-1-infected women. The results suggest that the p.L55Q mutation might alter CCR5 conformation. Further studies should be conducted to verify the role of this mutation in HIV-1 susceptibility.
Assuntos
Infecções por HIV/genética , Proteínas Mutantes/genética , Mutação , Receptores CCR5/genética , Receptores de HIV/genética , Adulto , Idoso , Brasil , Fenômenos Químicos , Feminino , Frequência do Gene , HIV-1 , Humanos , Interações Hidrofóbicas e Hidrofílicas , Masculino , Pessoa de Meia-Idade , Modelos Moleculares , Proteínas Mutantes/química , Conformação Proteica , Receptores CCR5/química , Receptores de HIV/química , Adulto JovemRESUMO
Genotypic prediction of HIV-1 tropism has been considered a practical surrogate for phenotypic tests and recently an European Consensus has set up recommendations for its use in clinical practice. Twenty-five antiretroviral-experienced patients, all heavily treated cases with a median of 16 years of antiretroviral therapy, had viral tropism determined by the Trofile assay and predicted by HIV-1 sequencing of partial env, followed by interpretation using web-based tools. Trofile determined 17/24 (71%) as X4 tropic or dual/mixed viruses, with one nonreportable result. The use of European consensus recommendations for single sequences (geno2pheno false-positive rates 20% cutoff) would lead to 4/24 (16.7%) misclassifications, whereas a composite algorithm misclassified 1/24 (4%). The use of the geno2pheno clinical option using CD4 T cell counts at collection was useful in resolving some discrepancies. Applying the European recommendations followed by additional web-based tools for cases around the recommended cutoff would resolve most misclassifications.
Assuntos
Proteína gp120 do Envelope de HIV/genética , Soropositividade para HIV/genética , HIV-1/genética , Internet , Receptores CCR5/genética , Receptores de HIV/genética , Tropismo Viral/genética , Adolescente , Adulto , Algoritmos , Linfócitos T CD4-Positivos , DNA Viral , Feminino , Soropositividade para HIV/imunologia , HIV-1/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Valor Preditivo dos Testes , Adulto JovemRESUMO
BACKGROUND: The CX3CR1 is a fractalkine chemokine receptor expressed by leukocytes attracting them to the arterial wall inflammation. The endothelial nitric oxide synthase (eNOS) produces nitric oxide that acts on the vascular wall and circulating blood cells, lessening the inflammatory atherogenic damage. We determined if -786T > C and E298D eNOS and 745G>A CX3CR1 variants were associated with CAD risk and/or severity in Southern Brazilians of European descent. METHODS: We investigated these polymorphisms in 358 patients who had undergone coronary angiography and 129 non-symptomatic controls by PCR followed by restriction analyses. RESULTS: The 745 G > A CX3CR1 variant was not associated with CAD in this sample. Patients with significant CAD (coronary stenosis >or = 75%) presented higher frequencies of the eNOS -786C, but not of 298D allele than those observed among patients in whom significant CAD was ruled out by angiography (control group 1, p = 0.022) and non-symptomatic controls (control group 2, p < 0.001). The eNOS haplotypes derived from these 2 sites revealed that the frequency of haplotypes carrying the -786C allele (-786C/298D and -786C/298E) was increased and of the wild haplotype (-786T/298E) was decreased in patients with significant CAD (p = 0.003). After controlling for other classical risk factors carriers of haplotypes containing the -786C allele were at increased CAD risk (-786C/298D, OR = 2.95, p = 0.007; and -786C/298E, OR = 2.41, p = 0.030). CONCLUSIONS: The -786T > C was the polymorphism associated with severe CAD in this study. Haplotype analyses can be extremely helpful in unraveling the influence of different markers within a gene.
Assuntos
Doença da Artéria Coronariana/genética , Doença da Artéria Coronariana/patologia , Óxido Nítrico Sintase Tipo III/genética , Polimorfismo Genético/genética , Receptores de Citocinas/genética , Receptores de HIV/genética , Receptor 1 de Quimiocina CX3C , Estudos de Casos e Controles , Feminino , Frequência do Gene , Haplótipos , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
In addition to the CD4 molecule that binds to the human immunodeficiency virus type-1 (HIV-1) envelope glycoprotein gp120, productive HIV-1 infection requires interaction with cellular receptors for alpha- or beta- chemokines (CXCR4 and CCR5 respectively). Isolates of HIV-1 exhibit different tropism depending on the chemokine receptor type that they use to infect their cellular targets. HIV-1 strains that use preferentially CCR5 are known as R5 strains. They are more frequently found in asymptomatic individuals during the initial stages of the disease and are involved in the transmision of infection from mother to child. HIV-1 species using CXCR4 (X4 strains) are observed mainly in patients with advanced disease. While X4 isolates are associated with syncitium formation, in general R5 strains are not. Interaction of X4 and R5 with their specific receptors is necessary to establish productive HIV-1 infection and trigger a series of intracellular signals. Modulation of CXCR4 and CCR5 expression after HIV-1 infection is one of the results of such interaction and may have important consequences on the course of the infection. Down regulation of CCR5 and CXCR4 after HIV-1 infection could be the result of indirect events linked to HIV-1 infection, such as the induction of alpha- or beta-chemokines competing with the virions for receptor binding. They could also reflect direct effects of HIV-1 on chemokine-receptor turnover. In this review, the mechanisms of modulation of CXCR4 and CCR5 expression after HIV-1 infection will be discussed.