Biomedical subjects

M Ait-Khaled

Publications and source records attributed to M Ait-Khaled.

8 recordsLinked to original sources

PubMed1998

Review of uptake of interventions to reduce mother to child transmission of HIV by women aware of their HIV status.

OBJECTIVES: To examine the change in uptake of interventions to reduce transmission of HIV from mothers to infants from January 1994 to July 1997. DESIGN: Review of mother-infant pairs who presented for infant diagnosis of HIV infection. SETTING: Central London hospital with facilities for diagnosis of infant HIV infection. SUBJECTS: 57 consecutive mother-infant pairs, mainly from central London but also referred from surrounding hospitals. INTERVENTIONS: Data were collected on mother's country of origin; CD4 count at delivery; plasma HIV RNA copies/ml; mode of delivery; antiretroviral therapy; infant feeding; and HIV infection in infants. MAIN OUTCOME MEASURES: HIV infection of infants. RESULTS: The vertical transmission rate was 12% (7 pairs; 95% confidence interval 3% to 22%). All mothers chose not to breast feed. The caesarean section rate was 53% (30/57). Antiretroviral therapy was taken by 68.5% (39/57) of mother-infant pairs. With antiretroviral therapy or caesarean section, or both, transmission occurred in 6% (0% to 13%) of pairs (3/50). During the 24 months of 1994 and 1995, 21% (4/19) of infants were infected with HIV; 7.9% (3/38) were infected over the 19 months January 1996 to July 1997. The caesarean section rate did not change over these periods. Use of antiretroviral therapy increased from 31.5% (6/19) to 86.8% (33/38) (P < 0.0001). CONCLUSION: Women with a diagnosis of HIV infection acted to reduce the risk of transmission to their infants. Uptake of antiretroviral therapy increased significantly over time, and the caesarean section rate was persistently high.

Africa↗

PubMed1998

Intrapartum mucosal exposure to human immunodeficiency virus type 1 (HIV-1) of infants born to HIV-1-infected mothers correlates with maternal plasma virus burden.

The majority of vertical infections with human immunodeficiency virus type 1 (HIV-1) occur at or near delivery, strongly suggesting a mucosal route of transmission. The frequency and level of intrapartum mucosal exposure to HIV-1 of 22 infants born to infected mothers was investigated. Maternal plasma HIV-1 RNA and CD4 cell count were measured at delivery. Infant oropharyngeal aspirates obtained at birth were examined for HIV-1 RNA by reverse transcription-polymerase chain reaction and qualitative nucleic acid sequence-based amplification. Nine infants (41%) had detectable levels of HIV-1 RNA, 3 of which were quantifiable (mean, 3000 copies/mL). This mucosal exposure to HIV-1 during delivery did not lead to infection of any infant. Cesarian delivery did not reduce mucosal exposure to HIV-1. Mucosal exposure did not correlate with maternal CD4 cell count but did correlate with maternal plasma virus load and was reduced by antiretroviral therapy.

Adult↗

PubMed1996

Measurement of human herpesvirus 7 load in peripheral blood and saliva of healthy subjects by quantitative polymerase chain reaction.

Qualitative and competitive-quantitative nested polymerase chain reaction (PCR) assays were developed for human herpesvirus 7 (HHV-7). These assays amplify a DNA sequence encoding part of the HHV-7 homologue of the human herpesvirus 6 (HHV-6) U42 gene. The PCR assays were used to analyze peripheral blood DNA (pbDNA) and saliva from 24 healthy volunteers. The prevalence of HHV-7 in saliva was 96%, with a median virus load of 1.1 x 10(6) copies/mL. Longitudinal analysis revealed sustained virus load, suggesting continued active viral replication. Analysis of 1 microgram of pbDNA showed the prevalence of HHV-7 to be 83%, with a median virus load of 40 copies (267 copies/10(6) cells). Analysis of sequential pbDNA samples showed individuals to have stable levels of HHV-7 virus load. These data demonstrate persistence of HHV-7 at two distinct sites and provide baseline data allowing comparisons with HHV-7 load in immunocompromised patients.

Base Sequence↗

PubMed1996

Quantification of human herpesvirus 6 in immunocompetent persons and post-mortem tissues from AIDS patients by PCR.

A quantitative competitive PCR assay for human herpesvirus 6 (HHV-6) was developed. Firstly, viral burden was determined in the blood of 25 healthy persons. Using 1 microgram of DNA, the prevalence of HHV-6 was 36% (9/25). Eight persons had viral loads of < or = 32 HHV-6 genomes/microgram DNA. The viral burden in the ninth individual was 1.2 x 10(6) HHV-6 genome copies/microgram DNA, which remained constant over a period of 10 months. This demonstrates the persistence of a high HHV-6 load in the absence of apparent disease. Secondly, HHV-6 burden was determined in 100 post-mortem tissues from seven AIDS patients and three controls. For all tissues combined, there was a statistically significant higher median viral load in AIDS patients (56 copies/microgram DNA, range 0-43321) compared to controls (10 copies/microgram DNA, range 0-423) (P = 0.04). The precision and reproducibility of this assay will allow hypotheses concerning the pathogenic potential of HHV-6 to be tested quantitatively.

AIDS-Related Opportunistic Infections↗

PubMed1995

Distinct HIV-1 long terminal repeat quasispecies present in nervous tissues compared to that in lung, blood and lymphoid tissues of an AIDS patient.

OBJECTIVE: To investigate the phylogenetic relationship of HIV-1 proviral long terminal repeat (LTR) variants present in postmortem samples of lymph node, spleen, lung, dorsal root ganglion and spinal cord as well as in the peripheral blood of an HIV-1-infected patient dying with AIDS. DESIGN AND METHODS: Postmortem tissues were studied by a combination of histology, cell culture and molecular analyses. The patient had a stable CD4 count of 10 x 10(6)/I during the 12 months preceding death. A 540 base-pair fragment of the LTR including U3/R/U5 was amplified using polymerase chain reaction on proviral DNA from the five postmortem tissues and peripheral blood mononuclear cells obtained 2 months prior to death. The population of viral variants was determined by sequencing at least five plasmid clones of the amplicons. The relationship between the variants present in different body sites was investigated using molecular phylogeny methods. RESULTS: HIV-1 was present in all organs analysed and correlated with the presence of abnormal histology. Genetic variation leading to divergence from the consensus sequence was more frequently present in characterized transcription factor binding sites within the LTR (P < 0.0001) although the HIV-1 LTR quasispecies in the different body sites showed similar, relatively low levels of divergence (intra-organ median heterogeneity ranging from 0.0094 to 0.017). Phylogenetic analysis showed that the spinal cord and dorsal root ganglion harboured an LTR population genetically distinct from that present in other organs and more closely related to a previously characterized neurotropic strain of HIV (strain JRcsf). CONCLUSION: The independent clustering of HIV-1 LTR variants present in spinal cord and dorsal root ganglion shows that HIV-1 LTR evolution can occur in a compartmentalized fashion. The data show that the LTR is an important region to analyse in sequence variation studies of HIV since it may play a role in nervous tissue adaptation of HIV-1 and neuropathogenicity. Outgrowth of HIV-1 LTR variants that are most fit for the utilization of tissue-specific transcription factors can occur in the nervous tissue.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Phylogenetic relationship between human immunodeficiency virus type 1 (HIV-1) long terminal repeat natural variants present in the lymph node and peripheral blood of three HIV-1-infected individuals.

PCR has been used to amplify a 540 base pair fragment of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat region encompassing the U5/R/U3 regions from proviral HIV DNA that was present in the lymph nodes and peripheral blood mononuclear cells of three HIV-infected individuals. The resulting PCR products were cloned and the DNA sequence of multiple clones from each reaction was determined to enable the distribution and phylogenetic relationship between the variants in each body site to be assessed. The results of bootstrapped parsimony phylogenetic analyses showed that a distinct polarization was evident between peripheral blood and lymph node variants in the patient who possessed a histologically intact lymph node. In contrast, similar analyses conducted on samples from two patients with extensive lymph node disruption showed similar variants in lymph node and peripheral blood. In the patient with an intact lymph node, lymph node variants were significantly more heterogeneous than those present in blood samples taken either simultaneously or 11 months later. No differences in heterogeneity between lymph node and peripheral blood were observed in patients with disrupted lymph nodes. The significance of these results for our understanding of HIV pathogenesis is discussed.

Base Sequence↗

PubMed1993

Sequence variation within the human immunodeficiency virus V3 loop at seroconversion.

Analysis of the HIV-1 V3 quasispecies present in an individual at the time of seroconversion was carried out. The polymerase chain reaction (PCR) was used to amplify proviral HIV-1 DNA extracted from peripheral blood mononuclear cells from a patient who was viraemic (p24 = 15 pg/ml) and had an equivocal HIV-1 antibody status. The PCR products were cloned and the DNA sequence determined for 15 clones. These data showed that the V3 region contained only limited sequence heterogeneity with a major variant accounting for 66% of the protein quasispecies present. The protein sequence of the principal neutralising domain on all species contained the relatively rare GPGKTL motif rather than GPGRAF. The relevance of these data for early stages of HIV infection are discussed.

Amino Acid Sequence↗

PubMed1991

Eliminating PCR contamination: is UV irradiation the answer?

The sensitivity of the polymerase chain reaction (PCR) can mean that even very low levels of contamination with the target DNA will result in a positive signal. At present this aspect is a major limitation in the use of PCR as a routine diagnostic method. By exposing PCR reagents to UV light, contaminating DNA can be inactivated, thus providing an opportunity to eradicate false positive reactions. UV irradiation was applied to PCR systems used for the detection of human cytomegalovirus (CMV) and human immunodeficiency virus (HIV) and shown to be effective in eradicating both laboratory encountered contamination and plasmid DNA (below 100 pg) added to PCR systems prior to UV exposure. The sensitivity of a PCR system to amplify the long terminal repeat (LTR) sequence of HIV-1 was not affected by the irradiation procedure; however, the ultimate sensitivity of a PCR system for the amplification of an early gene promotor sequence of the CMV genome was reduced 1000-fold. UV irradiation did not affect the size of the PCR product as determined by strand separating polyacrylamide gel electrophoresis of a 32P-labelled amplimer. Thus, a simple pre-exposure to UV light would seem a worthwhile step to incorporate into PCR protocols provided that the effects on sensitivity have been determined empirically for each PCR system.

Base Sequence↗