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Biomedical subjects

J Goudsmit

Publications and source records attributed to J Goudsmit.

At least 127 records · Page 7Linked to original sources
PubMed1997

Refocusing neutralizing antibody response by targeted dampening of an immunodominant epitope.

Immunodominant epitopes are known to suppress a primary immune response to other antigenic determinants by a number of mechanisms. Many pathogens have used this strategy to subvert the immune response and may be a mechanism responsible for limited vaccine efficacies. HIV-1 vaccine efficacy appears to be complicated similarly by a limited, immunodominant, isolate-restricted immune response generally directed toward determinants in the third variable domain (V3) of the major envelope glycoprotein, gp120. To overcome this problem, we have investigated an approach based on masking the V3 domain through addition of N-linked carbohydrate and reduction in net positive charge. N-linked modified gp120s were expressed by recombinant vaccinia virus and used to immunize guinea pigs by infection and protein boosting. This modification resulted in variable site-specific glycosylation and antigenic dampening, without loss of gp120/CD4 binding or virus neutralization. Most importantly, V3 epitope dampening shifted the dominant type-specific neutralizing Ab response away from V3 to an epitope in the first variable domain (V1) of gp120. Interestingly, in the presence of V3 dampening V1 changes from an immunodominant non-neutralizing epitope to a primary neutralizing epitope with broader neutralizing properties. In addition, Ab responses were also observed to conserved domains in C1 and C5. These results suggest that selective epitope dampening can lead to qualitative shifts in the immune response resulting in second order neutralizing responses that may prove useful in the fine manipulation of the immune response and in the development of more broadly protective vaccines and therapeutic strategies.

AIDS Vaccines↗
PubMed1997

[AIDS; new developments. III. Predictive value of the quantity of HIV-RNA for the course of the HIV infection and the effect of the treatment].

Standardized tests to measure the quantity of HIV-RNA in blood have been available since early 1995. Individual differences in quantity of HIV-RNA in blood are determined mainly by differences in virus production. Most of the HIV production takes place in infected and activated CD4+ T lymphocytes. The concentration of HIV-RNA in plasma or serum is an important predictor of AIDS and death, in the early stage of the infection even the only one. High concentrations (> or = 10(4) HIV-RNA copies/ml) in the early stage of the infection increase the probability of AIDS from 2.5 to 5 times that with concentrations < 10(4) HIV-RNA copies/ml. The degree of reduction of the HIV-RNA concentration during anti-HIV therapy is of great predictive value for the clinical course. The percentage of persons in whom the amount of HIV-RNA decreases to below the limit of detectability is a good second indicator of a favourable prognosis. Consequently, anti-HIV treatment should be started as early as possible in the infection, and not postponed until the first symptoms of immunodeficiency occur; only then can the virus production be kept at a minimal level as early and as long as possible. The current guideline reads: determination of HIV-RNA concentrations in serum or plasma should be part of the standard clinical practice in monitoring HIV-infected persons. Treatment is started as soon as occasioned by the quantity of HIV-RNA (limit: 10,000 copies/ml), the CD4+ cell count (limit: 500 x 10(6)/l) or the onset of HIV-related symptoms. The quantity of HIV-RNA should diminish substantially during the first three months of treatment. If this is the case, one checkup every three months will suffice. If the HIV-RNA concentration does not decrease sufficiently, resistance or poor compliance may be involved.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Kinetics of response in lymphoid tissues to antiretroviral therapy of HIV-1 infection.

In lymphoid tissue, where human immunodeficiency virus-type 1 (HIV-1) is produced and stored, three-drug treatment with viral protease and reverse transcriptase inhibitors markedly reduced viral burden. This was shown by in situ hybridization and computerized quantitative analysis of serial tonsil biopsies from previously untreated adults. The frequency of productive mononuclear cells (MNCs) initially diminished with a half-life of about 1 day. Surprisingly, the amount of HIV-1 RNA in virus trapped on follicular dendritic cells (FDCs) decreased almost as quickly. After 24 weeks, MNCs with very few copies of HIV-1 RNA per cell were still detectable, as was proviral DNA; however, the amount of FDC-associated virus decreased by >/=3.4 log units. Thus, 6 months of potent therapy controlled active replication and cleared >99.9 percent of virus from the secondary lymphoid tissue reservoir.

Adult↗
PubMed1997

Gross defects in the vpr and vpu genes of HIV type 1 cannot explain the differences in RNA copy number between long-term asymptomatics and progressors.

Disease progression in HIV-1-infected individuals is strongly associated with persistent and high numbers of HIV-1 RNA copies. We previously reported a markedly lower viral RNA load in eight long-term asymptomatics (LTAs) compared to seven matched progressors (at 1 year after seroconversion or entry in the study, p < 0.001) (Hogervorst E, et al.: J Infect Dis 1995;171:811-821). Here we extend our study to examine whether a difference in viral load can be attributed to infection by viruses having distinct vpr and vpu genes. Sequencing of vpr and vpu genes from serum samples collected at seroconversion from both long-term asymptomatics and progressors showed full-length and intact open reading frames of both genes in all subjects. At the protein level, no difference was discerned in domains of putative functional importance within Vpr and Vpu between the two groups. Phylogenetic analysis showed no clustering of LTA sequences, which interdigitated with sequences from progressors. We therefore concluded that nonprogression is not likely to be explained by deletion of vpr and vpu, or by gross sequence abnormality in these genes.

Amino Acid Sequence↗
PubMed1997

Primary infections with HIV-1 of women and their offspring in Rwanda: findings of heterogeneity at seroconversion, coinfection, and recombinants of HIV-1 subtypes A and C.

Variation in HIV-1 genomic RNA was studied in seroconversion samples from mother-child pairs from a Rwandan cohort. The mothers (n = 8) were heterosexually infected and their children (n = 6) were vertically infected by breast milk. Five of the children seroconverted within the same 3-month period as did their mothers. Highly homogeneous subtype A V3 and p17gag sequence populations were observed in three mother-child pairs, one of the two nontransmitting mothers, and one child (mean nucleotide distances 0 to 0.9%). Heterogeneous populations of subtype A V3 and p17gag sequences were found in one mother and a mother-child pair (1.4 to 2.8% for V3, 1.0 to 1.9% for p17). The second nontransmitting mother was infected with a heterogeneous AV1-V3/Cp17-p24 recombinant virus population (3. 8% for V3, 2.4% for p17). Finally, in one woman subtype C V3 sequences were observed, in addition to highly homogeneous subtype A V3 and p17gag sequence populations, also found in the child. Coexistence of subtype AV1-V3 and CV1-V3 env sequences in the mother was confirmed in a follow-up sample. The gag gene of both the maternal and the child's virus population represented an A/C recombinant sequence (Ap17/Cp24). An infection with subtype CV1-V3/p17-p24 was found upon testing of three additional participants of the mother-child cohort, indicating that subtype C is present in Rwanda. In conclusion, heterogeneity, coinfection, and intersubtype recombinants are not uncommon in primary HIV-1 infections in Rwanda.

Amino Acid Sequence↗
PubMed1997

Longitudinal analysis of CD4 T cell counts, T cell reactivity, and human immunodeficiency virus type 1 RNA levels in persons remaining AIDS-free despite CD4 cell counts <200 for >5 years.

CD4 cell count, T cell reactivity, and human immunodeficiency virus type 1 (HIV-1) RNA load were examined in 10 persons remaining free of AIDS while CD4 cell counts were <200/mm3 for >5 years, so-called low CD4 cell count long-term survivors (low CD4 LTS), and 10 matched rapid and 10 matched intermediate progressors (AIDS within 1 and 1-3 years). Longitudinal analysis of CD4 cell count and T cell reactivity revealed slower declines in low CD4 LTS. HIV-1 RNA load was 1 log/mL lower in the low CD4 LTS compared with the rapid progressors, with a similar linear increase over time in low CD4 LTS and progressors of 0.1 log/year. There was considerable overlap between groups. The constant difference between low CD4 LTS and progressors probably reflects HIV RNA load early after infection, but low CD4 LTS and progressors show similar slopes of HIV-1 RNA load rise.

Acquired Immunodeficiency Syndrome↗
PubMed1997

High-dose interferon-alpha2a exerts potent activity against human immunodeficiency virus type 1 not associated with antitumor activity in subjects with Kaposi's sarcoma.

Anti-human immunodeficiency virus type 1 (HIV-1) activity was assessed in HIV-1-infected homosexual and bisexual men receiving 18-36 MIU/day of recombinant interferon (IFN)-alpha2a for Kaposi's sarcoma (KS). The median baseline HIV-1 RNA level was 4.99 log10 copies/mL. Seventeen subjects (68%) showed an RNA decline > or = .5 log10/mL, with a maximum at week 4 (median decline = 1.91, range = 3.64-1.15; P = .0007), after which RNA levels stabilized. Eight subjects (32%) with lower median initial CD4+ T cell counts (60 vs. 350 x 10(6)/L; P = .01) did not show RNA responses. Neither RNA nor KS responses were negatively affected by IFN-alpha2a dose modifications. Anti-HIV responses of KS responders (n = 15) and nonresponders (n = 10) did not differ. High-dose IFN-alpha can exert potent anti-HIV activity that is not associated with anti-KS activity.

AIDS-Related Opportunistic Infections↗
PubMed1997

Temporal relationship between human immunodeficiency virus type 1 RNA levels in serum and cellular infectious load in peripheral blood.

Cross-sectional analysis of 252 paired serum and peripheral blood mononuclear cell (PBMC) samples derived from 54 human immunodeficiency virus type 1 (HIV-1)-infected persons revealed a correlation between HIV-1 RNA load in serum and infectious load in peripheral CD4 T cells after 18 months of follow-up and before an AIDS diagnosis (Pearson's correlation coefficient [r(p)] = .71, P < .001) and during antiviral treatment (r[p] = .78, P < .001). To gain insight into the temporal relationship between both measures of virus load, longitudinally obtained samples from 23 persons with various clinical courses (slow or rapid disease progression, long-term survival) and 22 persons undergoing antiviral therapy (zidovudine or didanosine, or both, or ritonavir) were analyzed. In general, the kinetics of changes in both measures of virus load were similar in the natural course of infection (78% of study participants) and during treatment (82% of participants). These findings suggest that PBMC and serum represent closely related, if not the same, viral compartments.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Overshoot of HIV-1 viraemia after early discontinuation of antiretroviral treatment.

OBJECTIVE: To determine whether, as predicted by predator-prey dynamics, early withdrawal of antiretroviral therapy, i.e. when the number of CD4+ lymphocytes is still elevated, results in an overshoot of HIV-1 viraemia due to infection of increased numbers of available target cells at that time. DESIGN AND METHODS: Five HIV-1-infected individuals were identified who discontinued antiretroviral therapy for various reasons after 8-19 days, and from whom stored serum samples obtained before, during, and shortly after treatment were available for measurement of HIV-1 RNA load. A mathematical model was designed to assess whether increased target cell availability could quantitatively explain the clinical observations. RESULTS: After therapy withdrawal, increases in the HIV-1 RNA load to levels exceeding pretreatment values by log10 0.6-1.5 copies/ml were observed after 2-17 days in all four of the individuals who had treatment-induced increases in CD4+ cell counts at the time of therapy withdrawal. Increases in viraemia were maximal within a few days, and subsequently seemed to wane until the pretreatment equilibrium between virus and its target cells was attained. Mathematical modelling confirms that these transient increases in viraemia can be explained by increased availability of target cells at the time of therapy withdrawal. CONCLUSIONS: Transient rises in HIV-1 viraemia do occur following early therapy withdrawal. These rises especially warrant consideration in short-term antiretroviral regimens for prevention of mother-to-child transmission, as are being studied in developing countries, since they could result in an increased transmission risk during the post-partum period through breast-feeding. This possibility needs to be investigated urgently.

Anti-HIV Agents↗
PubMed1997

Early and late HIV-1 RNA level and its association with other markers and disease progression in long-term AIDS-free homosexual men.

OBJECTIVE: To study the association between virological markers and clinical progression in individuals with long-term AIDS-free HIV infection. DESIGN: Seventy-seven HIV-infected participants in the Amsterdam cohort study who remained AIDS-free for at least 8 years were prospectively followed during that time and during a subsequent period in which 15 developed AIDS. METHODS: Serum HIV-1 RNA levels were evaluated at 1 and 8 years after study entry. Progression to AIDS following the 8 AIDS-free years was studied using Kaplan-Meier estimates and Cox proportional hazard analysis. RESULTS: HIV-1 RNA increased over time in a large proportion of these long-term AIDS-free men. Most subjects showed progressive immune system damage and/or clinical manifestations of HIV disease at year 8. High RNA levels at year 8 were significantly associated with symptomatic HIV Infection, low CD4+ T-cell count, p24 antigenaemia, low T-cell reactivity at year 8 as well as rapid annual CD4+ T-cell decline. High RNA level at year 1 was associated with high RNA levels at year 8 and low CD4+ T-cell count at year 1. In univariate analysis, RNA was associated with progression to AIDS after 8 years. In multivariate analysis, only the CD4+ T-cell count at year 8 remained significantly associated with progression to AIDS. CONCLUSIONS: In later stages of HIV infection, measures of immune deficiency may be more powerful prognostic markers than serum HIV-1 RNA level, indicating that optimal staging of the HIV-infected patient requires the combined use of RNA levels, CD4+ T-cell counts, and T-cell reactivity instead of RNA levels alone.

Acquired Immunodeficiency Syndrome↗
PubMed1997

AIDS prognosis based on HIV-1 RNA, CD4+ T-cell count and function: markers with reciprocal predictive value over time after seroconversion.

OBJECTIVE: HIV-1 RNA levels in peripheral blood are strongly associated with progression to AIDS, CD4+ T-cell decline, or death. Their predictive value is reportedly independent of the predictive value of CD4+ T-cell counts. Because the interrelations between these parameters of HIV-1 infection are poorly understood, we studied the kinetics and predictive value of serum HIV-1 RNA levels, CD4+ T-cell counts, and T-cell function. DESIGN AND METHODS: HIV RNA levels, CD4+ T-cell counts, and T-cell function were measured from seroconversion to AIDS in 123 homosexual men who seroconverted during a prospective study and were followed over 10 years. RESULTS: Two patterns of median HIV-1 RNA levels were found during infection: a steady-state and a 'U-shaped' curve. Steady-state high RNA levels were related to rapid disease progression. For the U-shaped curve, there were groups with high and low RNA levels related to disease progression. At 1 year after seroconversion, RNA level was the only marker that was strongly predictive. Furthermore, decreasing RNA levels in the first year following seroconversion were related to better prognosis than stable low levels. Low CD4+ T-cell count and T-cell function became predictive of progression to AIDS at 2 and 5 years after seroconversion, respectively. CONCLUSIONS: With ongoing infection, the predictive value of low CD4+ T-cell count and T-cell function increases, whereas the predictive value of high HIV-1 RNA level decreases. These findings reflect the observation that infection with HIV progressively leads towards immune deficiency, which in later stages is most predictive of disease progression.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Evolution of human immunodeficiency virus subtype A in women seroconverting post partum and in their offspring post-natally infected by ingestion of breast milk.

The evolution of genomic RNA of human immunodeficiency virus type 1 (HIV-1), subtype A, was studied in three Rwandan mother-child pairs over a period of 12-30 months. In two pairs a homogeneous subtype A V3 sequence population was observed at seroconversion and the virus populations in the children resembled those in the mothers. One of these mother-child pairs was infected with an A/C recombinant virus (Ap17/Cp24). In the third pair, a heterogeneous V3 sequence population was observed in the maternal seroconversion sample but the V3 sequence population in the child's sample was homogeneous. In each individual the intra- and intersample variation (between the seroconversion and follow-up samples) increased over time in both the V3 region and p17gag. Independent evolution for 1-2 years did not abolish the epidemiological relationship between virus populations in mother and child.

Amino Acid Sequence↗
PubMed1997

Founder virus population related to route of virus transmission: a determinant of intrahost human immunodeficiency virus type 1 evolution?

We and others have shown that in individual human immunodeficiency virus type 1 (HIV-1) infection, the adaptive evolution of HIV-1 is influenced by host immune competence. In this study, we tested the hypothesis that in addition to selective forces operating within the host, transmission bottlenecks have an impact on HIV-1 intrahost evolution. Therefore, we studied the intrahost evolution of the V3 region of the external glycoprotein gp120 of HIV-1 during the 3- and 5-year periods following seroconversion after parenteral versus sexual (male-to-male) transmission in 41 participants of the Amsterdam prospective cohorts of homosexual men (n = 31) and intravenous drug users (IVDUs; n = 10) who were AIDS free and had comparable numbers of CD4+ cells. We observed that HIV-1 strains in homosexual men accumulated over 5 years more nonsynonymous substitutions within the V3 loop than HIV-1 strains in IVDUs as a result of lower rates of nonsynonymous evolution in both the initial 3-year period from seroconversion and the following 2-year period as well as a larger proportion of nonsynonymous back substitutions in IVDUs. The mean numbers of synonymous substitutions did not differ between the two risk groups. Since HIV-1 strains in IVDUs could be distinguished from the viruses of homosexual men based on several nucleotide substitutions of which the most conserved is a synonymous substitution at the tip of the V3 loop (GGC pattern), we studied whether the founder virus population itself has an impact on the intrahost evolution of HIV-1. The mean number of nonsynonymous substitutions accumulated over 5 years within the V3 loop was lower in 10 IVDUs infected by the HIV-1 strains with the GGC signature than in 4 IVDUs infected by HIV-1 strains lacking this pattern, while the mean numbers of synonymous substitutions were similar in the two groups.

CD4 Lymphocyte Count↗
PubMed1997

Complete nucleotide sequence of simian endogenous type D retrovirus with intact genome organization: evidence for ancestry to simian retrovirus and baboon endogenous virus.

A complete endogenous type D viral genome has been isolated from a baboon genomic library. The provirus, simian endogenous retrovirus (SERV), is 8,393 nucleotides long and contains two long terminal repeats and complete genes for gag, pro, pol, and env. The primer binding site is complementary to tRNA(Lys)3, like in lentiviruses. The env GP70 protein is highly homologous to that of baboon endogenous virus (BaEV). PCR analysis of primate DNA showed that related proviral sequences are present in Old World monkeys of the subfamily Cercopithecinae but not in apes and humans. Analysis of virus and host sequences indicated that the proviral genomes were inherited from a common ancestor. Comparison of the evolution of BaEV, exogenous simian retrovirus types 1 to 3 (SRV1 to SRV3), and SERV suggests that SERV is ancestral to both BaEV and the SRVs.

Amino Acid Sequence↗
PubMed1997

Broad spectrum of in vivo fitness of human immunodeficiency virus type 1 subpopulations differing at reverse transcriptase codons 41 and 215.

Viral populations in a human immunodeficiency virus type 1 (HIV-1)-infected individual behave as a quasispecies with a rated distribution of fitness variants. Fitness distributions in naturally occurring viral populations have been difficult to study due to the lack of markers for individual virus clones and complicating inter- and intrahost factors like the presence of multiple cell types with distinct tropisms, differences in route of transmission, and intervening immunity. Here, we quantitated the relative fitness in vivo of three subpopulations of HIV-1 marked by mutations at codons 41 and 215 of reverse transcriptase (RT) directly related to zidovudine resistance in an untreated individual who was infected by a zidovudine-resistant strain transmitted from a donor on therapy. The transmission event did not have a substantial impact on the distribution of mutants within the dominant virus population replicating to high levels in the recipient. The evolution of the RT gene was monitored for 20 months. All 102 clones obtained from the donor and the recipient at the different time points contained the M41L mutation, which is associated with a fourfold reduction in zidovudine sensitivity. The leucine at position 41 was stable, although it was encoded by TTG and CTG triplets that fluctuated in abundance partially due to founder effects of clones with nonsilent mutations at codon 215. Of the three subpopulations in the patient, distinguished by a tyrosine (TAC), aspartic acid (GAC), or serine (TCC) at the 215 position of RT, the relative fitness of the GAC variant was calculated to be 10 to 25% higher than the initial TAC variant, and the relative fitness of the TCC variant was 1% higher than that of the GAC variant. Similar to other RNA viruses, lentivirus populations like HIV-1 in patients with a high virus load apparently consist of a broader spectrum of fitness variants than the 1 to 2% fitness difference sufficient for significant replicative advantage.

Base Sequence↗
PubMed1997

Evolution of the human immunodeficiency virus type 1 subtype-specific V3 domain is confined to a sequence space with a fixed distance to the subtype consensus.

Human immunodeficiency virus type 1 (HIV-1) strains can be separated into genetic subtypes based on phylogenetic analysis of the envelope gene. Once it had been shown that population-wide intrasubtype genetic variation of HIV-1 strains increases in the course of the AIDS epidemic, it remained uncertain whether HIV-1 subtypes are phenotypic entities spreading as distinct virus populations. To examine this, we applied Eigen's concepts of sequence geometry and fitness topography to the analysis of intrasubtype evolution of the gp120 V3 domain of HIV-1 subtypes A, B, C, and D in the course of the global AIDS epidemic. We observed that despite the high evolution rate of HIV-1, the nonsynonymous distances to the subtype consensus of sequences obtained early in the epidemic are similar to those obtained more than 10 years later, in contrast to the synonymous distances, which increased steadily over time. For HIV-1 subtype B, we observed that the evolution rate of the individual sequences is independent of their distance from the subtype B consensus, but for the individual sequences most distant from the consensus evolution away from the consensus is constrained. As a result, individual HIV-1 genomes fluctuate within a sequence space with fixed distance to the subtype consensus. Our findings suggest that the evolution of the V3 domain of HIV-1 subtypes A, B, C, and D is confined to an area in sequence space within a fixed distance to the consensus of a respective subtype. This in turn indicates that each HIV-1 subtype is a distinct viral quasispecies that is well adapted to the present environment, able to maintain its identity in the V3 region over time, and unlikely to merge during progression of the AIDS epidemic.

Consensus Sequence↗