322,833 research outputs found
CARATTERIZZAZIONE VIROLOGICA E DETERMINAZIONE DELLA RISPOSTA NEUTRALIZZANTE IN PAZIENTI PEDIATRICI CON INFEZIONE DA HIV-1.
No full textThe study of HIV-1 phenotypic, genotypic and antigenic variability is fundamental to understand pathogenic processes but also for the development of immunogens for vaccines. Mother-to-child transmission of HIV-1 and disease progression of infected children are still a major problem at world-wide level. The aim of the thesis was to study the phenotypic and genotypic variation of R5 viruses, in mother-child pairs as well as to characterize the neutralizing response in seropositive children with different disease progression. We have investigated in detail the phenotype of the clonal viral population and in specific the capacity to infect in vitro target cells expressing CCR5/CXCR4 chimeric besides wild-type receptors. We showed that virus variation goes beyond the simple characterization of R5 and X4. Indeed, R5 virus populations were able to use multiple chimeric receptors and thus had an expanded phenotype, were highly heterogenous and variable throughout time. Viruses with expanded R5 phenotype were transmitted as much as those of narrow phenotype suggesting that no selective process occurs. The study of the autologous neutralization showed a low or no response before 6 months of age in the infected child followed by a continues formation of escape variants with time. Interestingly, children with slow progressing disease developed an increasing broadening neutralizing response against heterologous viruses while fast progressors did not. A further study of the specificity of the antibody response will be of utmost relevance for the development of immunogens able to elicit a broad neutralizing response
GB individuals virus C replication in cerebrospinal fluid of HIV positive
No full textBackground GB virus C (GBV-C) is an orphan Flavivirus distantly related to hepatitis C virus (HCV). GBV-C infection in
humans is common and its transmission is similar to both HCV and HIV, including sexual, parenteral and vertical transmission.
The aim of this study was to investigate the presence and compartimentalization of GBV-C strains in plasma, PBMC and
cerebrospinal fluid (CSF) of HIV positive patients in an attempt to identify GBV-C replication in CSF.
Methods This retrospective study involved 22 HIV positive patients who underwent a lumbar puncture for diagnostic purposes. To
evaluate the prevalence of GBV-C infection in our Centre, a control group of 150 HIV positive patients was included in the study.
GBV-C-RNA was searched for in paired plasma, CSF and PBMC by means of nested PCR for 5’UTR. GBV-C genotype was
identified by direct sequencing and phylogenetical analysis. GBV-C population in plasma and CSF was characterized by analysis
of at least 25 clones for each compartment. HIV load was measured by a quantitative PCR (Amplicor HIV Monitor).
Results GBV-C-RNA was detected in plasma from 37/150 (25%) control patients and in the PBMC from 3/34 (9%) patients with
GBV-C detected in plasma.
GBV-C-RNA was identified in 5/22 (23%) plasma, in none of PBMC and in 2/5 (40%) CSF samples obtained from the 5 GBV-C
positive patients in plasma. This data showed that the presence of GBV-C-RNA in plasma was similar in control group and study
population. Albeit GBV-C-RNA was detected in 3 PBMC of control group and in none PBMC of the study population, the
difference was not statistically significant. Direct sequencing of GBV-C 5’UTR detected in plasma revealed the presence of
genotype 2 in three patients GBV-C-RNA negative in CSF.
Analysis of GBV-C population within the 5’UTR showed the presence of GBV-C genotype 2 in plasma and genotype 3 in CSF of
one patient, whereas the other case had mixed infection in plasma (genotype 3/1) and genotype 3 alone in CSF.
Plasma HIV-RNA levels were significantly higher in patients with CSF positive for GBV-C than in those with GBV-C negative
CSF (mean values 5.35 vs 4.39 Log copies/ml, p=0.027). HIV viral load in CSF was similar in all patients (mean values 3.66 vs
3.14 Log copies/ml).
Conclusion These findings suggest the replication of GBV-C in CSF and the selection of genotype 3 in this compartment. The
presence of discordant genotypes in paired plasma/CSF of one patient could be due to a past mixed infection in plasma
REPLICAZIONE DEL GB-C VIRUS NEL LIQUIDO CEREBROSPINALE DI INDIVIDUI HIV POSITIVI
No full textPremessa e scopo dello studio Il GB-C virus (GBV-C) è un Flavivirus orfano, filogeneticamente correlato al virus dell’epatite C (HCV). Le vie di trasmissione sono le medesime di HIV e HCV: sessuale, parenterale e verticale. Questo studio si propone di analizzare la presenza e la compartimentalizzazione delle varianti di GBV-C nel plasma, nei PBMC e nel liquido cerebrospinale (LCS) di pazienti HIV positivi. Pazienti e metodi Sono stati inclusi nello studio 22 pazienti HIV positivi sottoposti a puntura lombare a scopo diagnostico. Un gruppo di 150 pazienti sieropositivi in cura presso il nostro Centro è stato incluso come controllo. La presenza di GBV-C è stata ricercata nei campioni accoppiati di plasma, PBMC e LCS mediante una nested PCR specifica per la regione 5’UTR. Il genotipo di GBV-C è stato identificato mediante sequenziamento diretto e analisi filogenetica. La popolazione virale è stata studiata, all’interno di ciascun compartimento, mediante l’analisi di almeno 25 cloni. Risultati Nel gruppo di controllo il GBV-C-RNA è stato rilevato nel plasma di 37/150 (25%) pazienti e nei PBMC di 3/34 (9%) individui risultati GBV-C positivi nel plasma. Nella popolazione analizzata, il GBV-C-RNA è stato identificato in 5/22 (23%) campioni di plasma, in nessun PBMC e in 2/5 (40%) campioni di LCS ottenuti dai 5 pazienti risultati positivi nel plasma. La prevalenza dell’infezione da GBV-C nel plasma risulta quindi simile nella popolazione studiata e nel gruppo di controllo. Nonostante il GBV-C-RNA sia stato evidenziato in 3 PBMC ottenuti dal gruppo di controllo e in nessuno di quelli isolati dalla popolazione analizzata, la differenza non risulta statisticamente significativa. Il sequenziamento diretto della regione 5’UTR del GBV-C ha rivelato la presenza del genotipo 2 nel plasma degli individui negativi nel LCS. L’analisi della popolazione virale nei 2 pazienti LCS positivi, ha mostrato, in un caso il genotipo 2 e 3 rispettivamente in plasma e LCS e nell’altro un’infezione mista nel plasma (genotipo 3/1) e solo il genotipo 3 nel LCS. La viremia HIV plasmatica risulta significativamente più elevata nei pazienti GBV-C positivi rispetto a quelli GBV-C negativi nel LCS (viremia media: 5.35 vs 4.39 Log copie/ml, p=0.027). Tutti i pazienti mostrano livelli di HIV-RNA simili nel LCS ( media: 3.66 vs 3.14 Log copie/ml). Conclusioni Questi risultati suggeriscono che GBV-C sia in grado di replicare nel LCS e che il genotipo 3 possa essere selezionato in questo compartimento
Dissecting the humoral antibody specificity in relation to virus evolution in pediatric HIV infection
No full textWorldwide there more than 30 million people living with HIV: 2,5 million are children under 15 years of age who mainly acquired the infection through mother to child transmission (MTCT); 90% of these children lives in Sub Saharan Africa. Transmission can occur during pregnancy (15-20%), at delivery (45-55%) or via breastfeeding (30-35%). maternal RNA levels, CD4+T cells count, mode of delivery and gestional age have been associated with MTCT. HIV-1 infected children display different pattern of clinical evolution with fast progressors, delayed progressors and long term non progressors. This different clinical evolution could be determined by the interaction of virological, cellular and immunological factors already established at birth. The fact that during the first month of life the viral RNA load in plasma and proviral DNA in PBMC of the newborn rise up to levels which are higher than those observed in adults supports thei dea that the newborn immune system is not able to contain virus replication. Despite this enormous viral burden it appears that evident genotypic variation of the HIV quasispecies appears only after 6 months of age, i.e. when an immune response has established. It has been observed that the increase in length and glycosylation of the gp120 env is a response to the neutralizing antibody response in infected adults and may serve as an escape mechanism. Emergence of virus variants in children resistant to neutralization by autologous sera has been described in a few reports but lacks a clear association with progressive HIV-1 disease. So far, the humoral immune response in mother or in children has never shown a clear correlation with the infection event
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Broad spectrum neutralizing monoclonal antibodies against HIV-1 elicited by immunizing with fusion complexes
No full textabstract 14
Mutations in the natural strains of NS3 protease domain that confer resistance to anti-HCV protease inhibitors in HIV/HCV coinfected patients
No full text
Virus phenotype variability during disease progression of HIV-1 infected children
No full textBackground
HIV-1 infected children display different clinical evolution,
i.e., “fast progression” (FP), “slow progression” (SP)
and “long term non progression” (LTNP). One important
phenotypic trait linked to disease progression is the evolution
of the viral co-receptor use [1], involving a change
from CCR5 to CXCR4 use [2]. However, AIDS symptoms
can appear in absence of X4 viruses. Recently chimeric
receptors between CCR5 and CXCR4 were developed, in
which subsequent parts of CCR5 were replaced with corresponding
parts of CXCR4 [3]. Their use allowed to document
the biological variability of R5 isolates during the
pathogenic process in adults [4].
Aim
To examine the HIV biological variability in children with
different modes of disease progression.
Materials and methods
119 isolates from19 HIV-1 positive children were tested
for their ability to infect U87.CD4+ cells expressing the
wild type receptor CCR5, CXCR4, or one of the 6 chimeric
CCR5/CXCR4 receptors.
Results
Early during infection, all the viruses isolated from 8 SP
children used only wild type CCR5 (called R5narrow). In
one case, this phenotype persisted during disease progression,
whereas in 2 children the virus evolved and was able
to use multiple chimeric receptors (called R5broad), and in
additional 5 children the virus evolved to CXCR4 usage.
Interestengly the FP children, carried close to birth in 2
cases R5narrow virus, in 2 cases R5broad and in one case a
dualtropic R5X4 virus. Virus with R5narrow evolved to
R5broad in one of the 2 children carrying such phenotype.
Both children with R5broad phenotype developed CXCR4
variants during the follow-up.
Evolution was observed also in the LTNP, although followed
from later on in life (>8 years of age): all tested isolates
from 2/6 LTNP remained R5narrow during disease
progression; in one child an evolution from R5narrow to
R5broad was observed whereas in another child the virus
evolved from R5narrow to R5X4. The remaining two children
showed R5broad phenotype during the whole followup.
Conclusions
Our results show that HIV-1 with broad chimeric receptor
use is not hampered in transmission, and is more frequent
close to birth in FP than in SP children. Viruses from LTNP
show a similar phenotypic evolution though at later age
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