PubMed Health⌕ Search

Biomedical subjects

G van der Groen

Publications and source records attributed to G van der Groen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Differential diagnosis of HIV type 1 group O and M infection by polymerase chain reaction and PstI restriction analysis of the pol gene fragment.

HIV-1 group O serological screening or confirmation strategies so far have not proved 100% sensitive and specific, indicating a lack of antibody reactivity or cross-reactivity with group O antigens. Therefore, genetic analysis currently represents the only method by which confirm presumed HIV-1 group O or group O/M infections. We have optimized the sensitivity (100%) and specificity (100%) of an HIV-1 group O/M-specific PCR of a pol gene fragment. In addition, we report on a highly sensitive (97.2%) and specific (100%) method for differentiation between HIV-1 group O and group M viruses, using PCR and PstI enzyme restriction fragment analysis of a pol fragment. Compared with sequencing, these methods are fast, inexpensive, and simple.

DNA, Viral↗
PubMed1998

Haptoglobin polymorphism, iron metabolism and mortality in HIV infection.

BACKGROUND: Three phenotypes of the antioxidant protein haptoglobin are known: Hp 1-1, Hp 2-1 and Hp 2-2. OBJECTIVES: To investigate the outcome of HIV infection according to haptoglobin type. DESIGN AND METHODS: Haptoglobin phenotypes were determined using starch gel electrophoresis in serum obtained from 653 HIV-infected Caucasians in the AIDS reference centers of Gent (n = 184), Antwerp (n = 309), and Luxembourg (n = 160). Survival was compared between haptoglobin types using Kaplan-Meier curves. Plasma HIV-1 RNA was quantified by reverse transcriptase PCR. Serum iron, transferrin saturation, ferritin, and vitamin C were assayed to evaluate iron-driven oxidative stress in 184 HIV-infected patients and 204 controls. RESULTS: The haptoglobin type distribution amongst the patients (17.6% Hp 1-1, 49.9% Hp 2-1, 32.5% Hp 2-2) corresponded to that of the controls. Kaplan-Meier curves showed a higher mortality for the Hp 2-2 group (P = 0.0001; adjusted mortality risk ratio, 1.78; 95% confidence interval, 1.25-2.54). Median survival time was 11.0 years (Hp 1-1 and Hp 2-1) versus 7.33 years (Hp 2-2). Plasma HIV-1 RNA levels prior to antiviral therapy and their increase over 1 year were highest in Hp 2-2 patients (P = 0.03 and 0.003, respectively). The Hp 2-2 type was associated with higher serum iron, transferrin saturation, and ferritin levels and with low vitamin C concentrations. Furthermore, ferritin concentrations were higher in HIV-infected patients than in controls (P < 0.0001). CONCLUSION: HIV-infected patients carrying the Hp 2-2 phenotype show a worse prognosis, which is reflected by a more rapid rate of viral replication (in the absence of antiviral treatment). They also accumulate more iron and oxidize more vitamin C, suggesting that less efficient protection against haemoglobin/iron-driven oxidative stress may be a direct mechanism for stimulating viral replication.

Adult↗
PubMed1998

Design and evaluation of an in-house HIV-1 (group M and O), SIVmnd and SIVcpz antigen capture assay.

An enzyme-linked immuno-sorbent assay (ELISA) for the detection of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIVcpz/SIVmnd) antigens was designed using immunoreagents from naturally infected individuals, and compared to the commercially available Vironostika HIV-1 Antigen Microelisa System (Organon Teknika). The in-house assay proved to be specific for HIV-1 isolates belonging to group M (A-H) and group O and for SIVcpz and SIVmnd isolates, but was less sensitive than the Vironostika HIV-1 Antigen Microelisa System, except for SIVmnd. For the strains belonging to HIV-2, SIVmac and SIVagm, the in-house assay could not detect antigen to an appreciable degree. This study shows that a considerably less expensive but sufficiently accurate HIV-1 antigen capture assay can be developed to monitor HIV-1 (group M and O), SIVcpv and SIVmnd antigen in the supernatants of virus cultures.

Antibodies, Monoclonal↗
PubMed1998

Isolation of HIV-1 RNA from plasma: evaluation of seven different methods for extraction (part two).

Some new commercial methods for the extraction of viral RNA have been introduced recently. In addition to the study published previously (Verhofstede, C., Reniers, S., Van Wanzeele. F., Plum J., 1996. AIDS 8, 1421-1427), seven different methods (four newly developed and three reference methods) for extraction of HIV-1 RNA from plasma have been evaluated. The RNA preparation method that gave the best results (acceptable reproducibility, highest sensitivity, reasonable price, fast and easy to perform), was the QIAamp Viral RNA kit from QIAgen. The High Pure Viral RNA Kit (Boehringer Mannheim) as well as the non-commercialised extraction kits were also very sensitive. The non-commercial tests seem less suitable for routine use and for the processing of large number of samples. Two methods, RNA Insta-Pure LS (Eurogentec) and PANext RNA extraction kit 1 (NTL, PANsystems GmbH) are not adapted for HIV plasma extraction. The single step methods using glass fibre or silica column are rapid (from 60 to 75 min depending on the number of wash steps) and although the price is high they are cheaper than the Boom extraction methods: High Pure Viral RNA Kit (Boehringer Mannheim) ($3.3/sample), QIAamp Viral RNA Kit (Qiagen) ($3.6/sample), Boom extraction ($5/sample). The Qiagen kit is the only kit that combines sensitivity with reproducibility, it is commercialised, rapid and affordable in price and can be automated. For most of the methods evaluated the inter-test variability was acceptable (mean variation coefficient between duplicate extractions varied between 26.4 and 48.6%).

Costs and Cost Analysis↗
PubMed1998

Selection of human anti-human immunodeficiency virus type 1 envelope single-chain antibodies from a peripheral blood cell-based phage repertoire.

Monoclonal antibodies play an important role in the development of diagnostic assays. Instead of using hybridoma technology to isolate human immunodeficiency virus type 1-specific antibodies, a phage-displayed antibody library was generated from a small number (10(7)) of peripheral blood lymphocytes from a seropositive donor. Two families of single-chain antibodies (scFvs) were selected by biopanning with the envelope precursor gp160. ELISA and competition in the BIAcore system revealed that one antibody family recognized a conformation-sensitive epitope within gp120, while the other antibody family was gp41-specific. The latter group had sequence similarity to antibodies recognizing the cluster III epitope of gp41. Binding of scFvs to gp160 could be inhibited with the donor's serum antibodies, indicating that antibodies with a similar specificity were circulating in the donor's blood. Competition experiments suggested that the epitope of the anti-gp41 antibodies was recognized by a broad range of patients' sera: 21 out of 22 sera from North American and all 20 sera from African seropositive patients inhibited binding of scFvs. In contrast, three sera from this panel did not react with the epitope of the anti-gp120 antibodies. These data indicate that, because of the conserved nature of its epitope, the anti-gp41 antibody will be suitable for diagnostic applications.

Amino Acid Sequence↗
PubMed1998

Mapping of epitopes exposed on intact human immunodeficiency virus type 1 (HIV-1) virions: a new strategy for studying the immunologic relatedness of HIV-1.

To study the antigenic conservation of epitopes of human immunodeficiency virus type 1 (HIV-1) isolates of different clades, the abilities of human anti-HIV-1 gp120 and gp41 monoclonal antibodies (MAbs) to bind to intact HIV-1 virions were determined by a newly developed virus-binding assay. Eighteen human anti-HIV MAbs, which were directed at the V2, V3 loop, CD4-binding domain (CD4bd), C5, or gp41 regions, were used. Nine HIV-1 isolates from clades A, B, D, F, G, and H were used. Microtiter wells were coated with the MAbs, after which virus was added. Bound virus was detected after lysis by testing for p24 antigen with a noncommercial p24 enzyme-linked immunosorbent assay. The anti-V3 MAbs strongly bound the four clade B viruses and viruses from the non-B clades, although binding was weaker and more sporadic with the latter. The degrees of binding by the anti-V3 MAbs to CXCR4- and CCR5-tropic viruses were similar, suggesting that the V3 loops of these two categories of viruses are similarly exposed. The anti-C5 MAbs bound isolates of clades A, B, and D. Only weak and sporadic binding of all the viruses tested with anti-CD4bd, anti-V2, and anti-gp41 MAbs was detected. These results suggest that V3 and C5 structures are shared and well exposed on intact virions of different clades compared to the CD4bd, V2, and gp41 regions.

Antibodies, Monoclonal↗
PubMed1998

Genetic variation of HIV type 1: relevance of interclade variation to vaccine development.

Accumulating data in human immunodeficiency virus (HIV)-infected individuals support the hypothesis that in primary human immunodeficiency virus type 1 (HIV-1) isolates of different clades and phenotype (syncytium inducing [SI] and nonsyncytium inducing [NSI]) common antigenic structures must exist that can stimulate the immune response to produce a broad spectrum (cross-clade and cross SI and NSI) neutralization response. Certain vaccination regimens in chimpanzees and human volunteers with clade B SI type HIV-1 derived candidate vaccines induce neutralizing antibodies against intraclade B SI type primary HIV-1 isolates, but not against intraclade B NSI type of viruses. To be effective against the full antigenic spectrum of primary HIV-1 isolates (cross-clade--SI and NSI) candidate vaccines should contain immunogens of primary isolates representative of the whole antigenic spectrum of HIV-1. There is an urgent need to identify these immunogens and to improve their immunogenicity. As long as we have not yet characterized these cross-HIV-1 spectrum conserved immunogens, candidate vaccines against the more prevalent clades C, A, and E should be developed for evaluation in developing countries. In support of the follow-up and evaluation of the hopefully increasing number of phase 1, 2, and 3 HIV-1 vaccine trials in humans, it is considered a high priority to develop a high throughput neutralization assay, to further expand the use of a limited number of key primary HIV-1 isolates as a surrogate for neutralization of the entire HIV-1 antigenic spectrum (cross-clade--SI and NSI), to develop high throughput subtyping as well as a rapid system to monitor the immunogenic relatedness of different HIV-1 clades.

AIDS Vaccines↗
PubMed1997

The neutralization relationship of HIV type 1, HIV type 2, and SIVcpz is reflected in the genetic diversity that distinguishes them.

Neutralizing antibody (NA) patterns in the sera of individuals naturally infected with human immunodeficiency virus (HIV) type 1, HIV-2, and the simian immunodeficiency virus (SIVcpz) to their homologous and heterologous isolates were determined in a peripheral blood mononuclear cell-based neutralization assay. We examined the role of the V3 loop of HIV-1 and SIVcpz in neutralization and the cross-reactivities among them. Cross-neutralization by sera of humans and chimpanzees naturally infected, respectively, with HIV-1 and SIVcpz isolates was more extensive than the infrequent and low-titer cross-neutralizations observed between HIV-1 and HIV-2. Neutralization of 9 of the 16 HIV-1 isolates by 9 of 10 HIV-2 and all 3 SIVcpz antibody-positive sera were weak and sporadic (titer, 1:10-1:160). Twelve of 15 HIV-1 sera neutralized the 2 SIVcpz isolates with titers of 1:10-1:320 but only sporadically neutralized the 6 HIV-2 isolates (titers: 1:10-1:20). The majority of HIV-1 and SIVcpz sera bound to the V3 peptides although their binding capacity did not readily reflect their neutralizing capacity. The HIV-2 sera did not or only weakly bound to the V3 peptides. These results suggest that HIV-1 and SIVcpz share some structural and functional similarities that set them apart from HIV-2.

Animals↗
PubMed1997

Evaluation of a newly developed HIV antigen test.

A new monoclonal antibody-based enzyme immunoassay (Innogenetics) for the detection and quantification of p24 core antigens of HIV-1 (group M and group O) and of HIV-2 was evaluated on 2745 serum samples and 18 culture supernatants and compared with a reference (Coulter) HIV-1 p24 antigen assay. Positive results were confirmed by neutralization with the reagents of the respective tests. As demonstrated by dilution series of HIV cocultures, the new test recognizes p24 antigen of the most common HIV genetic subtypes, including group O and HIV-2. Titres ranged from 729 to 531441. Therefore p24 antigen assay is but very weakly reactive with HIV-2 (titres from 9 to 81). The new test is considerably more sensitive than the reference. In a population of 365 follow-up samples from 86 different patients, representing all stages of infection, the new test detected p24 antigen at least once in 52% (45/86) of these patients, whereas the reference was positive in 31% (27/86). The newly designed test detected antigen in 40% (145/365) of the samples, while the reference was positive in 21% (75/365). In a group of PCR and/or culture positive neonates, 33% (9/27) of the samples were positive with the new test versus 18% (5/27) with the reference. The specificity of the new test, as determined on 2,000 blood donor samples, was 99.65% (initially), 99.80% (after repetition), and 100% (with neutralization). The reference scored 99.95%, 100%, and 100%, respectively. In 300 seronegative samples from persons at risk, the initial specificity of the new test was 98.67% (the reference, 99.00%). With neutralization, both assays were 100% specific.

Antibodies, Monoclonal↗
PubMed1997

Reactivity and amplification efficiency of the NASBA HIV-1 RNA amplification system with regard to different HIV-1 subtypes.

In view of the genetic diversity of the human immunodeficiency virus Type 1, we assessed the sensitivity and quantification efficiency of the HIV-1 RNA NASBA amplification system with respect to different HIV-1 subtypes and recombinants. Twenty cell culture supernatants representing 17 HIV-1 group M and 3 group O strains were tested, and NASBA RNA loads were compared with results obtained with a RT-PCR based HIV-1 RNA quantitation method, with p24-antigen concentrations and with the infective dose. The current HIV-1 RNA NASBA seemed suitable to quantitate representatives of different HIV-1 M subtypes. Differences between NASBA and RT-PCR loads were observed for certain HIV-1 M strains. Significantly lower RT-PCR loads were measured for most gag A, gag B and gag F strains, whereas NASBA detected lower copy numbers in 1 gag H strain and 1 gag H/env G recombinant. NASBA was not able to quantify 1 HIV-1 group M recombinant. Some of these differences could be explained by the presence and position of mismatches with primers. HIV-1 group O strains were not detectable by both RNA amplification methods. A firm correlation was not observed between the measured RNA loads and either the p24-antigen concentration or the infective dose.

HIV-1↗
PubMed1997

Study of the dynamics of neutralization escape mutants in a chimpanzee naturally infected with the simian immunodeficiency virus SIVcpz-ant.

Here we report on the use of spectral map analysis of time-paired sequential neutralization data of 11 serum samples of a chimpanzee naturally infected with a simian immunodeficiency virus (SIVcpz-ant) and 8 primary consecutive SIVcpz-ant isolates, taken at about 4-month intervals. The analysis reveals the existence of three SIVcpz-ant isolate and serum neutralization clusters. Each cluster groups virus isolates and/or sera based on similarities of their neutralization spectra. On average, neutralization escape mutants emerged after 15 months and mounted a neutralization response approximately 8 months later. The entire gp160 regions of eight consecutive isolates were sequenced and analyzed by a new statistical method called polygram, which allowed the deduction of amino acid sequence motifs of gp160 which were specific for SIVcpz-ant isolates belonging to the same isolate neutralization clusters. Changes in specific amino acid quadruplets in V1, V2, C3, V4, V5, and CD4 domains of gp120 and gp40 were seen to correlate with the neutralization clusters with most of the specific changes occurring in the V4 region. This method of analysis may facilitate an understanding of the study of the dynamic interplay between human immunodeficiency virus (HIV) and host neutralization responses as well as providing possible insights into mechanisms of persistence of HIV-1-related lentiviruses in their natural hosts.

Amino Acid Sequence↗
PubMed1997

Virologic, immunologic, and clinical follow-up of a couple infected by the human immunodeficiency virus type one, group O.

The pathogenic course (virologic, immunologic, and clinical changes) of infection due to human immunodeficiency virus type one (HIV-1) group O viruses is unknown at present. To address this issue, serial HIV-1 isolates from a married couple (patients A and B) infected with a group O virus were analyzed to determine the temporal association between disease status and alterations in several parameters including plasma viral burden as measured by semiquantitative polymerase chain reaction, changes in CD4+ T cells, presence of neutralizing antibodies, and the ability to induce syncytia on the MT2 cells. For patient A who has been asymptomatic for at least 8 years, both the absence of syncytium-inducing (SI) variants and the presence of autologous and heterologous neutralizing antibodies correlated with a clinically healthier status. In contrast, a switch from NSI to SI variants was observed in patient B in 1990, followed by an expanded in vitro host range, increased viral burden, and a sharp decrease in CD4+ T cells 4 years later. Moreover, plasma obtained from this patient uniformly failed to neutralize both autologous and heterologous viruses. These observations in patient B correlated with a slightly unfavorable clinical status. Based on our preliminary results, it appears that the pathogenic course of infections due to group O viruses is similar to that reported previously for infections due to group M viruses.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Sequence analysis of a highly divergent HIV-1-related lentivirus isolated from a wild captured chimpanzee.

Two strains of simian immunodeficiency viruses (SIV) isolated from chimpanzees (SIVCPZ-GAB and SIVCPZ-GAB2) originating from Gabon have previously been genetically characterized and shown to belong phylogenetically to the same lineage as the human immunodeficiency virus type 1 (HIV-1). We describe the sequence analysis of a third HIV-1-related virus, SIVCPZ-ANT, isolated from a wild captured chimpanzee originating from Zaire. This virus displayed the same genetic organization as HIV-1 and was found to fall on the same lineage as HIV-1 and SIVCPZ-GAB. Protein sequence identity with SIVCPZ-GAB ranged from 72% (Pol) to 48% (Env) for the structural proteins, while a particularly divergent Vpu was found (only 25% identity to SIVCPZ-GAB). The V3 regions of the SIVCPZ isolates were exceptionally conserved in contrast to the high divergence of V3 among HIV-1 isolates. However, SIVCPZ-ANT did not show a greater degree of sequence similarity with SIVCPZ-GAB than with HIV-1 isolates and represents a quite divergent outgroup of the HIV-1 lineage. Our data suggest multiple introductions of HIV-1 in the human population and shed new light on the origin of the HIV-1 pandemic.

Amino Acid Sequence↗
PubMed1996

Mother-to-child transmission of human T-cell lymphotropic virus types I and II (HTLV-I/II) in Gabon: a prospective follow-up of 4 years.

SUMMARY: For 4 years. we determined the mode and risk of mother-to-child transmission of HTLV-I in a prospective cohort of 34 children born to seropositive mothers in Franceville, Gabon. We also determined the prevalence of antibodies to HTLV-I/II in siblings born to seropositive mothers. Antibodies to HTLV-I/II were detected by Western blot, and the proviral DNA was detected by the polymerase chain reaction (PCR). The risk of seroconversion to anti-HTLV-I for the 4 years of follow-up was 17.5 percent. Anti-HTLV-I/II and proviral DNA were only detected after age 18 months. We observed a seroprevalence rate of 15 percent among the siblings born to HTLV-I/II seropositive mothers. Furthermore, we report a case of mother-to-child transmission of HTLV-II infection in a population of HTLV-II-infected pregnant women that is emerging in Gabon. The lack of detection of HTLV-I/II proviral DNA in cord blood and amniotic fluid and, furthermore, the late seroconversion observed in the children indirectly indicate that mother-to-child transmission occurred postnatally, probably through breast milk.

Amniotic Fluid↗