Immune Complex-dissociated P24 Antigen Research Articles

Alternatives to HIV-RNA and CD4 count to monitor HIV disease progression: A prospective cohort study in Romania

Little evidence exists on how to efficiently and effectively monitor HIV-disease progression in developing countries. Better understanding regarding cost-effective tests may help to resolve questions regarding treatment. A prospective cohort study was conducted with a 1-year follow-up period. Immune complex-dissociated (ICD) p24 antigen (ICD p24Ag), alone or in combination with HIV p24 antibody (p24Ab), was compared to HIV-RNA and CD4+ count in a cohort of 160 HIV-infected adolescents in Romania. The main outcome measure was disease progression, defined as >50,000 copies/ml of HIV-RNA or death. Among the 160 adolescents, a higher mean ICD p24Ag was significantly associated with clinical disease classification (CDC), plasma HIV-RNA concentration, and p24Ab. Multivariate logistic regression showed detectable ICD p24Ag had an odds ratio of 3.7 (95% CI 1.4-9.7) for disease progression in comparison to undetectable ICD p24Ag. ICD p24Ag is of value in determining the prognosis of disease in HIV-1-infected adolescents in developing countries. Additional studies for validation of this assay for HIV clades primarily affecting developing countries, are now needed.

Alternatives to HIV-1 RNA concentration and CD4 count to predict mortality in HIV-1-infected children in resource-poor settings.

Cheaper, simpler alternatives to CD4 lymphocyte count and HIV-1 RNA detection for assessing the prognosis of HIV-1 infection are needed for resource-poor settings. However, little is known about the predictive value of alternative assays, in particular in children. We assessed the prognostic value of total lymphocyte count, immune complex-dissociated p24 antigen, white blood cell count, packed-cell volume (haematocrit), and serum albumin for mortality in 376 HIV-1-infected, mainly African-American or Hispanic children enrolled during March, 1988 to January, 1991. In a Cox proportional hazards model, including all assay-alternatives to CD4 and RNA, total lymphocyte count (p<0.0001) and serum albumin (p=0.0107) independently predicted mortality. Further assessment of these markers is warranted in resource-poor settings.

Effector HIV-specific cytotoxic T-lymphocyte activity in long-term nonprogressors: associations with viral replication and progression.

Ex vivo effector cytotoxic T-lymphocyte (CTL) activity was assessed in 27 members of the Australian Long-Term Nonprogressor cohort and correlated with genetic, virological, and immunological markers. The 27 individuals were antiretroviral naive with CD4(+) T-cell counts of >500 cells/ microl for more than 8 years after human immunodeficiency virus type 1 (HIV-1) infection. Effector CTL activity was determined using a standard ex vivo chromium release assay. Individuals with CTL activity (HIV-1 env(IIIB) or pol or gag) were then compared to those without CTL activity in relation to plasma HIV-1 RNA, ICD p24 antigen, beta(2)-microglobulin, CD4 and CD8 T-cell counts, CCR5 and CCR2b genotypes, and progression to CD4 <500 cells/microl or commencement of antiretroviral treatment. Of the 27 individuals examined, 19 had no detectable effector CTL activity. The eight individuals with detectable CTL activity had significantly higher plasma levels of HIV-1 RNA (P = 0.014), immune complex dissociated p24 antigen (P = 0.006), and beta(2)-microglobulin (P = 0.009). There was increased risk of progression within 4 years of study entry in individuals with detectable effector CTL activity, higher plasma levels of HIV-1 RNA, higher beta(2)-microglobulin levels, and higher immune complex dissociated p24 antigen levels at enrollment (P = 0.017, P = 0.004, P = 0.027, P = 0.008 respectively). Multivariate analysis demonstrated viral load remained the strongest predictor of disease progression within this group (P = 0.017). There were no significant associations between CTL response and chemokine receptor genotype. These findings demonstrate the importance of HIV replication in generating an effector CTL response and show that effector CTL activity may be an early predictor of progression in people with long-term asymptomatic HIV infection.

HIV-1 ICD p24 antigen detection in ugandan infants: use in early diagnosis of infection and as a marker of disease progression.

The objective of this study was to determine the use of immune-complex dissociated (ICD) p24 antigen detection for the diagnosis and prognosis of HIV-1 infection in Ugandan children. Plasma collected prospectively from children born to HIV-1 infected Ugandan women was stored and later analyzed for the presence of neutralizable HIV-1 p24 antigen using the Coulter ICD p24 antigen and neutralization kits. HIV-1 infection status, disease progression, and survival of the children were determined. Specimens from 311 children born to HIV-1 infected women, including 138 HIV-1 infected children, and 113 children born to negative women were tested. Sixty-nine (50%) infected children were p24 antigen positive at least once. For early HIV-1 diagnosis, the specificity and positive predictive value of the assay were consistently high (>95% and >83% respectively), but the sensitivity was low (6-53%), especially in the first months of life. The presence of p24 antigenemia in the first two years of life was associated with poor survival (20%) by 80 months of age compared with infected children without antigenemia (43%, P < 0.001). Early detection of p24 antigen (</=2 months) was associated with higher mortality than first detection at an older age (>6 months, P < 0.001). The data suggest that ICD p24 antigen detection is not a sensitive method for the determination of infant HIV-1 status in our cohort of HIV-1 infected Ugandan children tested in the first two years of life. There was a strong correlation, however, between the presence and time of onset of p24 antigenemia and mortality among HIV-1 infected children.

Predictors of progression in long-term nonprogressors. Australian Long-Term Nonprogressor Study Group.

It is now apparent that a proportion of individuals (5-8%) remains clinically free of HIV-1 disease with normal levels of CD4+ lymphocytes (> or =500/microl) for more than 8 years following infection. However, the proportion of these individuals who ultimately progress to AIDS remains to be established. We determined the virological and immunological characteristics of a cohort of long-term nonprogressors in Australia and examined the role of these factors in predicting disease progression. Individuals with documented asymptomatic HIV-1 infection for at least 8 years with CD4+ lymphocyte counts >500 cells/microl were recruited from hospital clinics and general practices serving the eastern area of Australia. CD4+ lymphocyte count, rate of CD4+ lymphocyte change, CD8+ lymphocyte count, beta2-microglobulin, immune complex dissociated (ICD) HIV-1 p24 antigen, and plasma HIV-1 RNA were measured at baseline and multiple visits at 6-month intervals over an average period of 2 years. Up to November 1996, 67 study participants were recruited, of whom 72% had been infected with HIV-1 for at least 10 years. HIV-1 RNA correlated with beta2-microglobulin, ICD p24 antigen, and the ability to isolate virus in culture but not with levels of CD4+ or CD8+ lymphocytes. Serum beta2-microglobulin was a stronger predictor of CD4+ lymphocyte decline than HIV-1 RNA and the only factor significantly associated with CD4+ lymphocyte decline. These findings show that the serum concentration of beta2-microglobulin is a strong predictor of immunological progression in people with long-term asymptomatic HIV-1 infection and provides additional prognostic information to HIV-1 RNA in determining the risk of disease progression.

Correlation of ribonucleic acid polymerase chain reaction, acid dissociated p24 antigen, and neopterin with progression of disease: A retrospective, longitudinal study of vertically acquired human immunodeficiency virus type 1 infection in children

Objective: We investigated the relationship between cell-free viral load, neopterin, age-adjusted CD4 + cell concentration, and clinical events in 49 children with vertically acquired human immunodeficiency virus type 1 infection. Study design: Viral load was measured by quantitating viral ribonucleic acid in serum by polymerase chain reaction and measurement of immune complex dissociated p24 antigen in serum and plasma. Children were followed for an average of 2½ years, with an average of 6 samples per child. Medical records were reviewed for weight, CD4 + cell count, and clinical events. Results: High virus copy number in serum was predictive of a decrease in weight-for-age z score during the subsequent 6 months. High viral load, low CD4 + cell count, and high neopterin level were correlated with encephalopathy. High viral load correlated with opportunistic infections. All of these relationships held regardless of treatment status, although viral load decreased significantly after treatment was begun. Conclusions: Measurements of viral load were useful prognostic indicators for poor weight gain. Elevated serum virus levels and neopterin values and low CD4 + cell counts were all associated with encephalopathy. (J Pediatr 1997:130:898-905)

Age- and Time-related Changes in Extracellular Viral Load in Children Vertically Infected by Human Immunodeficiency Virus

It is known that plasma or serum viral load is high in vertically HIV-infected children during the first year of life, but the changes in these titers after the first birthday have not been described. Information on the natural history of circulating extracellular virus will be useful in elucidating the pathogenesis of pediatric HIV infection and in using viral load measurement to guide prognosis and therapy. We measured serum RNA by reverse transcriptase-polymerase chain reaction and immune complex-dissociated p24 antigen enzyme-linked immunosorbent assay over time in 48 unselected children followed in our clinics and analyzed the findings in relation to age and clinical outcome. In first-available samples from the 48 children there was a gradual reduction in HIV RNA values with increasing age, with a slope of -0.21 log copy/ml/year (P < 0.001, R2 = 0.6022). This downward trend was seen in subsets of children with all degrees of immunodeficiency. The mean slope of repeated HIV RNA measurements in individual children was similarly in a downward direction (slope -0.11 (P = 0.007 for difference from zero)). The slope was more negative in children who were younger at baseline. Immune complex-dissociated p24 antigen values were much less predictable and predictive. Viral load in vertically infected children, measured by reverse transcriptase-polymerase chain reaction, falls very gradually over time, descending from very high titers at the end of the first year, and reaching values seen in horizontally infected adults at approximately 5 years of age.

Plasma levels of soluble CD30, tumour necrosis factor (TNF)-alpha and TNF receptors during primary HIV-1 infection: correlation with HIV-1 RNA and the clinical outcome.

The immunological and virological events associated with primary HIV-1 infection have a major impact on the course of HIV-1 disease, and the identification of early predictors during primary HIV infection is critical for the therapeutic strategy. Eighteen consecutive patients with primary HIV infection were followed for a median of 398 days. Clinical status, CD4+ T-cell counts, and plasma samples were obtained weekly from enrollment until week 6, then at weeks 12, 24 and 52, and every 6 months thereafter. Seroconversion was assessed by anti-HIV-1/2 antibodies and Western blot analysis. HIV-1 RNA in plasma was quantified by Amplicor HIV Monitor test. Samples were assayed for immune complex-dissociated p24 antigen, tumour necrosis factor (TNF)-alpha, soluble TNF receptor (sTNFR)-1, sTNFR-II, sCD30 and sCD8 by enzyme immunoassays. Outcome was defined as entering clinical category B or C according to the Centers for Disease Control and Prevention criteria. As a control group, we included 23 HIV-1-negative healthy blood donors. Plasma levels of sCD30, TNF-alpha and sTNFR were significantly higher in HIV-1-infected patients than in controls, and were positively correlated with each other and with values of HIV-1 RNA. Patients who developed an outcome (n = 4) had significantly higher levels of sCD30, TNF-alpha and sTNFR compared with those who did not. Multivariate logistic regression analysis showed that sCD30 and TNF-alpha were the best predictors of outcome independently of CD4+ T-cell counts. During primary HIV infection, a persistent immune activation may be associated with a poor clinical outcome. The identification of sCD30 and TNF-alpha levels in plasma as early predictors of outcome in primary HIV infection, may direct the implementation of early therapeutic strategies in patients with elevated risk of disease progression.

Safety and efficacy of lamivudine-zidovudine combination therapy in zidovudine-experienced patients. A randomized controlled comparison with zidovudine monotherapy. Lamivudine European HIV Working Group

To compare the safety and efficacy of 2 doses of lamivudine given in combination with zidovudine with continued zidovudine monotherapy. Double-blind, randomized, multicenter, comparative trial of 223 patients treated for 24 weeks. Patients from 32 hospitals in Europe were enrolled throughout a 1-year period. Adult human immunodeficiency virus type 1 (HIV-1)-positive, zidovudine-experienced ( > or = 24 weeks prior zidovudine) patients with CD4+ cell counts between 0.10 and 0.40 x 10(9)/L (100-400 cells/microL). Patients received either 200 mg of zidovudine every 8 hours, 150 mg of lamivudine every 12 hours plus zidovudine, or 300 mg of lamivudine every 12 hours plus zidovudine for 24 weeks. All patients were then allowed to receive zidovudine and open-label lamivudine combination therapy. Twelve patients withdrew because of adverse events during the 24-week treatment period. Efficacy was measured by evaluating immunological and viral load changes, and safety was assessed by evaluating clinical manifestations and laboratory indexes of toxic effects. Patients receiving low- or high-dose combination therapy had greater treatment effects compared with patients receiving continued zidovudine monotherapy during the first 24 weeks as documented by changes in CD4+ cell counts (+0.04 vs +0.03 vs -0.02 x 10(9)/L, respectively; P < .001); log10 HIV-1 RNA as measured by the Roche assay (-0.96 vs -0.77 vs +0.07 copies/mL, respectively; P < .001) or log10 HIV-1 RNA measured by the quantitative nucleic acid sequence-based amplification assay (-0.59 vs -1.06 vs -0.02 copies/mL, respectively; P < .011); and immune-complex dissociated (ICD) p24 antigen (-74% vs -68% vs +27%, respectively; P < .001). There were no statistically significant differences in viral measurements, in CD4+ cell counts, or in safety profile between the groups receiving 2 doses of lamivudine in combination with zidovudine. The effects on CD4+ cell counts and ICD p24 antigen were sustained throughout 48 weeks for patients continuing combination therapy. Patients switching to combination therapy at week 24 showed improvement. In zidovudine-experienced HIV-1-infected patients, combination treatment with lamivudine and zidovudine is well tolerated and provides greater and more sustained increases in CD4+ cell counts and decreases in viral load than continued zidovudine monotherapy.

Variation in plasma RNA levels, CD4 cell counts, and p24 antigen levels in clinically stable men with human immunodeficiency virus infection.

Short-term variability in CD4 cell counts, plasma RNA levels, and p24 antigenemia was measured in clinically stable men with human immunodeficiency virus infection. Blood samples were obtained three times in each of 2 weeks 4 weeks apart. Differences between duplicate assays were considered to be due to technical factors; variation among visits was attributed to physiologic factors. Median enrollment values of CD4 cell counts, plasma RNA levels, and immune complex-dissociated (ICD) p24 antigenemia were 400 cells/mm3, 3.4 log10 copies/mL, and 38 pg/mL, respectively. Median absolute differences between duplicate CD4 cell counts, plasma RNA levels, and ICD p24 antigen were 16 cells/mm3, 0.21 log10 copies/mL, and 9.3 pg/mL. Median intraindividual ranges were 119 cells/mm3, 0.83 log10 copies/mL, and 18 pg/mL. Above 500 copies/mL, plasma RNA levels have a variability of 0.5 log10; the test is unreliable below this level.

Lamivudine in Children with Human Immunodeficiency Virus Infection: A Phase I/II Study

The safety, tolerability, pharmacokinetic profile, and preliminary activity of lamivudine (2'-deoxy-3'-thiacytidine), a novel cytidine nucleoside analogue with antiretroviral activity, in human immunodeficiency virus (HIV)-infected children beyond the neonatal period were studied. Ninety children received dosages of 1-20 mg/kg/day. Pharmacokinetic evaluation demonstrated serum and cerebrospinal fluid concentrations that increased proportionally to dose. As of January 1994, 11 children had been withdrawn from study for disease progression and 10 because of possible lamivudine-related toxicity, and 6 had died. CD4 and CD8 cell counts remained stable over 24 weeks in therapy-naive children and decrease slightly in previously treated children. Quantitative immune complex-dissociated p24 antigen and HIV RNA were decreased significantly at 12 and 24 weeks. In vitro resistance to lamivudine was documented in sequential virus isolates from some patients by 12 weeks. Lamivudine was well-tolerated and exhibited virologic activity in children, although future use in children is likely to be in combination antiretroviral regimens.

Comparison of a rapid nonisotopic polymerase chain reaction assay with four commonly used methods for the early diagnosis of human immunodeficiency virus type 1 infection in neonates and children

To initiate antiretroviral therapy and prophylaxis for Pneumocystis carinii pneumonia, it is important to identify human immunodeficiency virus (HIV-1)-infected infants as soon after birth as possible. This study was undertaken to evaluate a novel 5-hour nonisotopic (NI) polymerase chain reaction (PCR) assay (Amplicor PCR; Roche Molecular Systems) and four other commonly used HIV-1 diagnostic tests including culture, oligonucleotide hybridization PCR, p24 antigen and immune complex-dissociated (ICD) p24 antigen tests and to determine the optimal age at which to perform these tests for the early and rapid diagnosis of HIV-1 in infants and children. We prospectively evaluated 225 infants and children, including 114 neonates, for HIV-1 infection. HIV-1 infection was defined as 2 positive HIV cultures. Of the 225 infants and children, 57 were infected, 138 were uninfected and 30 were of unknown (Centers for Disease Control and Prevention Classification P0) status. The sensitivity of NI PCR was 60% in cord blood, 40% at 0 to 2 days, 67 to 80% in the neonate (3 to 30 days) and 95 to 100% after 1 month of age. NI PCR was as sensitive as oligonucleotide hybridization PCR, culture, p24 antigen and ICD p24 antigen in the first 2 months of life and was more sensitive than p24 antigen or ICD p24 antigen thereafter. Specificity was 94% for cord blood and 99 to 100% for all age groups. The majority of HIV-1-infected newborns can be identified with NI PCR if testing is performed at birth and again between the third and fourth weeks of life. For older infants and children 2 NI PCR tests can correctly diagnose 98.5% of infected and uninfected infants and children. NI PCR of umbilical cord blood might also be useful as an initial screening test to identify infants who may be infected with HIV-1.

Assessment of Antiretroviral Therapy by Plasma Viral Load Testing

To assess the utility of quantitative competitive-polymerase chain reaction (QC-PCR) measurements of plasma human immunodeficiency virus type 1 (HIV-1) RNA and other viral load markers for assessment of antiretroviral therapy, we used archived cryopreserved specimens from a randomized controlled clinical trial of 135 patients (CD4+ T cell count < or = 500/mm3), comparing zidovudine (500 mg/day) versus the nonnucleoside reverse transcriptase inhibitor L-697, 661 (50, 300, or 1,000 mg daily). We evaluated treatment-associated changes in plasma viral load by standard and immune complex-dissociated (ICD) HIV-1 p24 antigen assays, and, in a representative subset of patients (n = 46), by QC-PCR determination of virion-associated HIV-1 RNA. At baseline, HIV-1 RNA was quantifiable by QC-PCR in all patients tested (100%), whereas standard and ICD HIV-1 p24 antigen tests were positive (> or = 30 pg/ml) in 42% and 56%, respectively. All viral load parameters showed significant decreases from baseline within 1 week of initiation of zidovudine, as measured by standard p24 antigen assay, ICD p24 assay, and QC-PCR. At 1 week, patients treated with either 300 or 1,000 mg/day of L-697,661 showed significant decreases from baseline in plasma standard and ICD p24 antigen and QC-PCR-determined HIV-1 RNA levels. Whereas viral load decreases seen with zidovudine were sustained for the duration of treatment, plasma viral markers often returned to pretreatment levels despite ongoing L-697,661 treatment, with evidence of the emergence of drug-resistant virus. Whereas standard p24, ICD p24, and viral RNA levels changed similarly in response to treatment, the superior sensitivity and available dynamic range of plasma viral RNA assays like QC-PCR analysis provide an advantage for clinical monitoring of plasma viral load, allowing tracking of treatment-related changes even in patients with earlier stage disease and lower levels of viral load.

Plasma viremia titration and RNA quantitation in ICD-p24 negative HIV type-1-infected patients.

Quantitative culture of human immunodeficiency virus (HIV) was performed on 202 plasma samples obtained from asymptomatic and early symptomatic HIV-1 infected patients (mean CD4+ count: 186/mm3) before antiretroviral therapy was started. HIV could be isolated from 84% of the plasma samples (titers ranging from 10(0) to 10(2.75) TCID50/ml). Immune complex dissociated p24 antigen (ICD-p24) was detected in 66% of the samples. Only 23 samples (11%) were negative for both ICD-p24 as well as HIV culture. Discordant results were obtained in 55 samples, and 45 samples negative for ICD-p24 were positive for HIV culture. A significant proportion (42%) of patients that were negative for ICD-p24 belonged to a very advanced group with very low CD4+ cell count. However, almost 90% of these ICD-p24 negative samples were positive for HIV plasma viremia, stressing the value of this virological marker in patients with low CD4+ cell count and without any detectable ICD-p24 antigenemia. HIV-1 RNA was detected in all ICD-p24 negative plasma samples tested by the branched DNA (bDNA) assay. A very good correlation was found between high RNA copy number and HIV plasma isolation in samples obtained from patients with low CD4+ cell count, suggesting that HIV-1 RNA quantitation may also reflect viral infectivity of plasma.

Clinical Evaluation of Branched DNA Signal Amplification for Quantifying HIV Type 1 in Human Plasma

Quantification of HIV-1 RNA in human plasma has provided unique insight into AIDS pathogenesis and promises to hasten progress in antiretroviral therapy and vaccine research. However, no generally available HIV-1 RNA assay has yet been subjected to rigorous clinical testing or to comparative evaluation with research-based RNA assays using large numbers of well-characterized clinical specimens. In this study, the Chiron Quantiplex branched DNA (bDNA) signal amplification assay was used to measure viral RNA in the plasma of 152 HIV-1-positive individuals at all stages of infection and in 12 patients before and after initiating zidovudine therapy. Eighty-six percent of patients had bDNA assay results above the 10,000-RNA Eq/ml sensitivity cutoff. Branched DNA values were significantly correlated with plasma viral RNA levels determined by quantitative competitive polymerase chain reaction (QC-PCR) assay (Spearman rank correlation, r = 0.89), infectious plasma virus titers (r = 0.72), p24 antigen levels (r = 0.51), immune complex dissociated p24 antigen levels (r = 0.56), and CD4+ lymphocyte counts (r = -0.72; p < 0.0001 for all comparisons). Plasma viral RNA determinations by bDNA and QC-PCR assays were quantitatively similar in the range of 10(4) to 10(7) RNA molecules/ml [log bDNA = 0.93 + 0.80 (log QC-PCR); R2 = 0.81, p < 0.0001] and declined identically following the institution of zidovudine therapy (68-73% decrease from baseline). The close quantitative correlation between bDNA and QC-PCR results, and their significant association with other viral markers and CD4+ counts, support the use of plasma viral RNA measurement in HIV-1 clinical trials.

IMMUNE COMPLEX-DISSOCIATED P24 ANTIGENEMIA IN THE DIAGNOSIS OF HUMAN IMMUNODEFICIENCY VIRUS INFECTION IN VERTICALLY INFECTED BRAZILIAN CHILDREN

A retrospective cohort study evaluated the presence of immune complex-dissociated (ICD) p24 antigen in frozen plasma samples of 40 children born to HIV-seropositive mothers and followed in the outpatient clinic of Gaffree-Guinle University Hospital. ICD has been helpful in the early diagnosis of infants born of HIV-seropositive mothers within the first 2 months of life. After testing all charts were reviewed for evidence of HIV-related clinical findings and determination of HIV serology until the child reached 24 months of age. The children were all born to HIV-infected Brazilian women between 1984 and 1992. 17 boys (mean age at first evaluation for HIV infection, 17.3 months) and 23 girls (mean age at first evaluation, 16.8 months) were included. Of the 17 boys, 9 were Caucasian and 8 were African-Brazilian; 11 girls were Caucasian and 12 were African-Brazilian. An immune complex disruption procedure was performed at the Universidade do Rio de Janeiro on 100-mcl aliquots of serial plasma samples from the 40 patients enrolled. 200 mcl of treated plasma were then assayed for the presence of p24 antigen through a quantitative enzyme immunoassay. 21 of 40 (52%) infants were identified as HIV-infected through persistent HIV seropositivity after 18 months of age. ICD p24 antigen was detected in at least 1 plasma specimen from 15 of 21 (71.4%) of HIV-infected children, whereas p24 antigen was present in 11 of 21 (52.4%) children infected with HIV. The sensitivity of ICD p24 antigen in diagnosing HIV infection in this cohort of children was 71.4%, whereas that of p24 antigen was 52.4%. The highest mean titers of HIV ICD p24 antigen were observed between 7 and 12 months of life. A history of breast-feeding was present in 18 of 21 (86%) of the HIV-infected infants and in only 5 of 19 (26%) of the uninfected children (p 0.001). In 21 HIV-infected children, 12 (57%) were asymptomatic and 9 (43%) were symptomatic at the time the first ICD p24 antigen test was obtained.

Sensitivity of immune complex-dissociated p24 antigen testing for early detection of human immunodeficiency virus in infants.

Several investigators have suggested that early diagnosis of human immunodeficiency virus (HIV) infection in infants could be accomplished with a modified, more-sensitive, acid-dissociated p24 antigen enzyme-linked immunosorbent assay (ELISA) technique (p24 antigen immune complex dissociation [ICD]). We compared detection of HIV infection by HIV culture, PCR, and p24 antigen ICD assays in 46 infants by using samples collected independently. The detection sensitivity of the p24 antigen ICD assay was 0% with cord blood samples (2 HIV-positive infants), 38% with plasma samples from infants under 3 months of age (8 HIV-positive infants), and 58% overall (12 HIV-positive infants). By contrast, the sensitivities of HIV culture and PCR were 50% for cord blood samples, 75% for plasma samples from infants under 3 months of age, and 83% overall. These results indicate that the p24 antigen ICD does not offer the sensitivity necessary for this assay to be used as an indicator of HIV infection in infants.

Antiretroviral Therapy Is Associated with a Decrease in Unintegrated HIV-1 DNA in Pediatric Patients

Good markers for monitoring the efficacy of antiretroviral therapy in children do not currently exist. This study examined the effect of antiretroviral therapy on human immunodeficiency virus (HIV-1) unintegrated DNA (uDNA), integrated DNA (iDNA), percent uDNA, immune complex dissociated (ICD) p24 antigenemia, and plasma viral titer. Seven children were followed at therapy initiation and at approximately 3- and 10-month intervals. HIV-1 uDNA was detected in all children prior to start of therapy (average percent uDNA, 43%). At 3 months, the percent HIV uDNA decreased in all patients to an average of 18% (p = 0.01) and at 10 months decreased to an average of 1%. In contrast, the amount of HIV iDNA was relatively constant after initiation of therapy. ICD HIV p24 antigen was detected in all patients prior to therapy (average, 538 pg/ml). Over the study period, the ICD p24 antigen level decreased in three patients and remained relatively unchanged in four patients. Plasma cultures of HIV-1 were positive in only one of the seven patients prior to therapy. Among the methods evaluated, measurement of uDNA was the only parameter which reliable decreased after initiation of nucleoside therapy.

Rapid increases in load of human immunodeficiency virus correlate with early disease progression and loss of CD4 cells in vertically infected infants.

The relationship between viral burden, timing of transmission, and clinical progression was investigated in 110 children at risk for vertical human immunodeficiency virus (HIV) infection using quantitative polymerase chain reaction, coculture, and immune complex-dissociated p24 antigen assay. In a cross-sectional study, the mean HIV DNA copy number in 19 symptomatic children was significantly higher than in 31 infected, asymptomatic children (420 +/- 125 vs. 87 +/- 78; P < .0001). In a second group of 8 vertically infected infants followed prospectively from birth, 4 defined as infected in utero showed a more rapid increase in virus load, an accelerated loss of CD4 cells, and early progression to symptomatic disease (3-12 weeks) compared with 4 children with late in utero or intrapartum transmission (10-31 months). These data suggest that a direct relationship exists between HIV replication, the timing of transmission and onset and progression of HIV disease in vertically infected children.

Multicenter Evaluation Of Quantification Methods For Plasma Human Immunodeficiency Virus Type 1 Rna

Six procedures for quantifying plasma human immunodeficiency virus type 1 (HIV-1) RNA were evaluated by nine laboratories. The procedures differed in their sample volume and preparation of samples and methods of amplification and detection. Coded samples in a 10-fold dilution series of HIV-1-spiked plasma were correctly ranked by all six procedures. Subsequently, coded duplicate plasma samples from 16 HIV-1-infected patients were tested using a common set of standards. Several HIV-1 RNA procedures were sufficiently reproducible so that an empiric 4-fold change could be viewed as significant. HIV-1 RNA levels in the patients (up to 370,000 RNA copies/mL) correlated with proviral HIV-1 DNA and were inversely correlated with CD4 cell counts; HIV-1 RNA assays were more sensitive than plasma viremia, standard p24 antigen, or immune complex-dissociated p24 antigen assays. This study demonstrated that several HIV-1 RNA quantitative assays are ready for use in clinical trials.