Long-term evaluation of HIV antigen and antibodies to p24 and gp41 in patients with hemophilia. Potential clinical importance

Breadth and magnitude of antigen-specific antibody responses in the control of plasma viremia in simian immunodeficiency virus infected macaques

Background

Increasing evidence suggests an unexpected potential for non-neutralizing antibodies to prevent HIV infection. Consequently, identification of functional linear B-cell epitopes for HIV are important for developing preventative and therapeutic strategies. We therefore explored the role of antigen-specific immune responses in controlling plasma viremia in SIV infected rhesus macaques.

Methods

Thirteen rhesus macaques were inoculated either intravaginally or intrarectally with SIV_MAC251. Peripheral blood CD4+ T-cells were quantified. Plasma was examined for viremia, antigen specific IgG, IgA and IgM binding responses and neutralizing antibodies. Regions containing binding epitopes for antigen-specific IgG, IgM and IgA responses were determined, and the minimum size of linear Envelope epitope responsible for binding antibodies was identified.

Results

The presence of neutralizing antibodies did not correlate the outcome of the disease. In a few SIV-infected macaques, antigen-specific IgG and IgM responses in plasma correlated with decreased plasma viremia. Early induction and the breadth of antigen-specific IgG responses were found to be significantly correlated with the control of plasma viral load. Immunoglobulin classes share similar functional linear B-cell epitopes. SIV-specific linear envelope B-cell epitopes were found to be 12 amino-acids in length.

Conclusions

Early induction of combination of peptide-specific IgG responses were found to be responsible for the control of plasma viral load and indicative of disease outcome in SIV-infected rhesus macaques and might be important for the development of therapeutic strategies for control or prevention of HIV/AIDS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-016-0652-x) contains supplementary material, which is available to authorized users.

Site-specific Genome Editing in PBMCs With PLGA Nanoparticle-delivered PNAs Confers HIV-1 Resistance in Humanized Mice

Biodegradable poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) encapsulating triplex-forming peptide nucleic acids (PNAs) and donor DNAs for recombination-mediated editing of the CCR5 gene were synthesized for delivery into human peripheral blood mononuclear cells (PBMCs). NPs containing the CCR5-targeting molecules efficiently entered PBMCs with low cytotoxicity. Deep sequencing revealed that a single treatment with the formulation resulted in a targeting frequency of 0.97% in the CCR5 gene and a low off-target frequency of 0.004% in the CCR2 gene, a 216-fold difference. NP-treated PBMCs efficiently engrafted immunodeficient NOD-scid IL-2rγ^-/- mice, and the targeted CCR5 modification was detected in splenic lymphocytes 4 weeks posttransplantation. After infection with an R5-tropic strain of HIV-1, humanized mice with CCR5-NP–treated PBMCs displayed significantly higher levels of CD4⁺ T cells and significantly reduced plasma viral RNA loads compared with control mice engrafted with mock-treated PBMCs. This work demonstrates the feasibility of PLGA-NP–encapsulated PNA-based gene-editing molecules for the targeted modification of CCR5 in human PBMCs as a platform for conferring HIV-1 resistance.

Characterization of anti-HIV-1 neutralizing and binding antibodies in chronic HIV-1 subtype C infection

Neutralizing (nAbs) and high affinity binding antibodies may be critical for an efficacious HIV-1 vaccine. We characterized virus-specific nAbs and binding antibody responses over 21 months in eight HIV-1 subtype C chronically infected individuals with heterogeneous rates of disease progression. Autologous nAb titers of study exit plasma against study entry viruses were significantly higher than contemporaneous responses at study entry (p=0.002) and exit (p=0.01). NAb breadth and potencies against subtype C viruses were significantly higher than for subtype A (p=0.03 and p=0.01) or B viruses (p=0.03; p=0.05) respectively. Gp41-IgG binding affinity was higher than gp120-IgG (p=0.0002). IgG-FcγR1 affinity was significantly higher than FcγRIIIa (p<0.005) at study entry and FcγRIIb (p<0.05) or FcγRIIIa (p<0.005) at study exit. Evolving IgG binding suggests alteration of immune function mediated by binding antibodies. Evolution of nAbs was a potential marker of HIV-1 disease progression.

Targeted disruption of the CCR5 gene in human hematopoietic stem cells stimulated by peptide nucleic acids

Peptide nucleic acids (PNAs) bind duplex DNA in a sequence-specific manner, creating triplex structures that can provoke DNA repair and produce genome modification. CCR5 encodes a chemokine receptor required for HIV-1 entry into human cells, and individuals carrying mutations in this gene are resistant to HIV-1 infection. Transfection of human cells with PNAs targeted to the CCR5 gene, plus donor DNAs designed to introduce stop codons mimicking the naturally occurring CCR5-delta32 mutation, produced 2.46% targeted gene modification. CCR5 modification was confirmed at the DNA, RNA, and protein levels and was shown to confer resistance to infection with HIV-1. Targeting of CCR5 was achieved in human CD34(+) hematopoietic stem cells (HSCs) with subsequent engraftment into mice and persistence of the gene modification more than four months posttransplantation. This work suggests a therapeutic strategy for CCR5 knockout in HSCs from HIV-1-infected individuals, rendering cells resistant to HIV-1 and preserving immune system function.

HIV-1 matrix protein p17: a candidate antigen for therapeutic vaccines against AIDS

The success in the development of anti-retroviral therapies (HAART) that contain human immunodeficiency virus type 1 (HIV-1) infection is challenged by the cost of this lifelong therapy and by its toxicity. Immune-based therapeutic strategies that boost the immune response against HIV-1 proteins or protein subunits have been recently proposed to control virus replication in order to provide protection from disease development, reduce virus transmission, and help limit the use of anti-retroviral treatments. HIV-1 matrix protein p17 is a structural protein that is critically involved in most stages of the life cycle of the retrovirus. Besides its well established role in the virus life cycle, increasing evidence suggests that p17 may also be active extracellularly in deregulating biological activities of many different immune cells that are directly or indirectly involved in AIDS pathogenesis. Thus, p17 might represent a promising target for developing a therapeutic vaccine as a contribution to combating AIDS. In this article we review the biological characteristics of HIV-1 matrix protein p17 and we describe why a synthetic peptide representative of the p17 functional epitope may work as a vaccine molecule capable of inducing anti-p17 neutralizing response against p17 derived from divergent HIV-1 strains.

Characterization of immune responses to capsid protein p24 of human immunodeficiency virus type 1 and implications for detection

To further refine our current nanoparticle-based HIV-1 p24 antigen assay, we investigated immune responses to p24 to identify diagnostically significant immune dominant epitopes (IDEs) in HIV-infected human sera, to address cross-reactivity of anti-p24 antibodies to different subtypes, and to identify new biomarkers that distinguish acute from chronic HIV infection for more accurate incidence estimation. We identified two major linear epitope regions, located in the CypA binding loop and adjacent helices and at the end of the C-terminal domain. Most sera (86%) from acutely HIV-1-infected individuals reacted with multiple peptides, while 60% and 30% of AIDS patient samples reacted with multiple and single peptides, respectively. In contrast, 46% and 43% of chronically HIV-1-infected individuals reacted with one and none of the peptides, respectively, and only 11% reacted with multiple p24 peptides, indicating a progression of immune responses from polyclone-like during acute infection to monoclone-like or a nonresponse to linear epitopes during chronic infection. Anti-p24 antibodies (subtype B) show broad cross-reactivity to different HIV-1 subtypes, and the synergistic action of different combinations of anti-HIV antibodies improves capture and detection of divergent HIV-1 subtypes. Our results indicate that the modified peptide immunoassay is sensitive and specific for the rapid identification of HIV-1 p24 IDEs and for investigation of immune responses to p24 during natural HIV-1 infection. The data provide the foundation for development and refinement of new assays for improved p24 antigen testing as future tools for rapid and accurate diagnosis as part of early intervention strategies and estimations of incidence.

Specific adaptive humoral response against a gp41 motif inhibits CD4 T-cell sensitivity to NK lysis during HIV-1 infection

OBJECTIVE

We have recently found that during HIV-1 infection, CD4 T cells overexpress a ligand of the NK activating receptor NKp44 (NKp44L) and are sensitized to NK lysis. Expression of NKp44L is triggered by a motif (3S) from the gp41, highly conserved in all HIV-1 clades. The objectives were to determine whether anti-3S antibodies were produced, could counteract 3S-CD4 interactions and were correlated to CD4 cell count and NKp44L expression in HIV-infected patients.

DESIGN

Anti-3S antibodie production was studied in HIV-infected patients at various stages of the disease, including a longitudinal study in Asymptomatiques à Long Terme (ALT) patients.

METHODS

Specimens from 193 HIV-1 infected patients were examined. Anti-3S antibodies were detected by ELISA, and NKp44L expression was analysed by flow cytometry. NK cytotoxicity against CD4NKp44L cells was determined in the presence of anti-3S antibodies.

RESULTS

Anti-3S antibodies were detected in 28.5% of HIV-infected patients. They were positively correlated to CD4 cell counts (P = 0.01) and inversely correlated to NKp44L expression (P = 0.007). Particularly, in ALT patients, a longitudinal study revealed that the CD4 cell count slope differed according to the presence or absence of anti-3S antibodies (-0.98 cells/month versus -7.48 cells/month, P > 0.001). In addition, a clear inhibition of CD4NKp44L NK lysis was observed in relationship to anti-3S antibodies titres.

CONCLUSIONS

These results strongly suggested that anti-3S antibodies might affect disease course in inhibiting NKp44L expression and CD4 sensitivity to NK lysis. In linking specific adaptive immunity to the innate immunity induced by the 3S motif, this study may have important implications for therapeutic vaccines against AIDS.

Widely varying SIV prevalence rates in naturally infected primate species from Cameroon

Although it is now well established that a substantial proportion of wild-living primates in sub-Saharan Africa harbor SIV, no study to date has examined to what extent the various species are naturally infected. In this study, we first describe the development and validation of sensitive and specific SIV antibody detection assays representing all major known primate lentiviral lineages on a panel of 207 sera from 11 different primate species with known infection status. The newly developed assays were then used to determine SIV prevalence rates in nine primate species native to Cameroon. Analysis of 722 sera revealed widely varying prevalence rates, ranging from an apparent absence of SIV infection in crested mona (0/70), grey cheeked (0/36) and agile mangabeys (0/92), to prevalence rates of 3%, 4%, 11%, 27%, 39% and 52% for mustached (6/203), greater spot-nosed (8/193), northern talapoin (3/26), mantled guereza (14/52), De Brazza's (9/23) and mandrill (14/27) monkeys, respectively. The epidemiology of naturally occurring SIV infections is thus more complex than previously appreciated and the various non-human primate hosts seem to differ in their susceptibility to SIV infection. The newly developed assays should now permit to define with greater accuracy existing SIV reservoirs and associated human zoonotic risk.

Immunofluorescence assay reactivity patterns of serum samples presenting indeterminate Western blot results for antibodies to HIV-1 and HTLV-I/II in Cordoba, Argentina

Serum samples (n: 110) from blood donors and high risk individuals from Cordoba, Argentina with indeterminate HIV-1 and HTLV-I/II Wb profiles were studied for specific antibodies to HTLV-I/II and HIV-1 by indirect immunofluorescence assay (IFA) and for the presence or absence of HIV-1 and HTLV-I/II specific bands by Wb. This study was carried out in order to characterize their putative reactions with HIV-1 and HTLV-I/II proteins and to resolve the retrovirus infection status of these individuals. Results indicated that blood donors sera displaying indeterminate HIV-1 or HTLV-I/II Wb patterns were not immunoreactive to HTLV-I/II and HIV-1 on IFA. However, a high rate of indeterminate HIV-1 and HTLV-I/II Wb samples from high risk individuals had positive HTLV-I/II and HIV-1 IFA results respectively. Our study supports the growing evidence that HTLV-HIV indeterminate seroreactivity in low risk population is due to a cross reaction against nonviral antigens, and in high risk populations the indeterminate samples show serological cross-recognition between HIV-1 proteins and HTLV-I/II proteins on Wb. These results point out the necessity to investigate the HTLV-I/II reactivity in indeterminate HIV-1 samples and vice versa in order to confirm the diagnosis. Finally, this study shows the potential usefulness of IFA in elucidating the status of HIV-1 and HTLV-I/II infection of individuals with indeterminate Wb profiles, thus enabling resolution of retrovirus infection status.

Three stage AIDS incubation period: a worst case scenario using addict-needle interaction assumptions

In this paper we develop and analyse a model for the spread of HIV/AIDS amongst a population of injecting drug users. We start off with a brief literature survey and review; this is followed by the derivation of a model which allows addicts to progress through three distinct stages of variable infectivity prior to the onset of full blown AIDS and where the class of infectious needles is split into three according to the different levels of infectivity in addicts. Given the structure of this model we are required to make assumptions regarding the interaction of addicts and needles of different infectivity levels. We deliberately choose these assumptions so that our model serves as an upper bound for the prevalence of HIV under the assumption of a three stage AIDS incubation period. We then perform an equilibrium and stability analysis on this model. We find that there is a critical threshold parameter R(0) which determines the behaviour of the model. If R(0)< or =1, then irrespective of the initial conditions of the system HIV will die out in all addicts and all needles. If R(0)>1, then there is a unique endemic equilibrium which is locally stable if, as is realistic, the time scale on which addicts inject is much shorter than that of the other epidemiological and demographic processes. Simulations indicate that if R(0)>1, then provided that disease is initially present in at least one addict or needle it will tend to the endemic equilibrium. In addition we derive conditions which guarantee this. We also find that under calibration the long term prevalence of disease in our variable infectivity model is always greater than in an equivalent constant infectivity model. These results are confirmed and explored further by simulation. We conclude with a short discussion.

Expression of a novel Nef epitope on the surface of HIV type 1-infected cells

We compared antibody responses to various structural and accessory gene products of HIV-1 between long-term nonprogressors and patients who have progressed to AIDS. On the basis of our results, we performed epitope mapping of the Nef protein and identified a novel epitope. This novel epitope of the Nef protein was found to be exposed on the surface of HIV-1-infected cells. The antibody response against it correlated with CD4+ cell counts among HIV-1-infected patients (r = 0.457, p < 0.001). Although further research is necessary, we suspect that antibody response against the epitope may be protective against disease progression.

Serum HIV-1 p24 antibody, HIV-1 RNA copy number and CD4 lymphocyte percentage are independently associated with risk of mortality in HIV-1-infected children. National Institute of Child Health and Human Development Intravenous Immunoglobulin Clinical Trial Study Group

OBJECTIVE

The role of HIV-1 antibody in modulating disease progression must be assessed in the context of other immune and viral load markers. We evaluated the association between HIV-1 p24 antibody, HIV-1 RNA, immune complex-dissociated (ICD) p24 antigen, CD4 cell percentage, and mortality in a cohort of 218 HIV-infected children enrolled in a trial of intravenous immunoglobulin prophylaxis of bacterial infections.

METHODS

CD4 cell percentage was measured and sera collected and stored at baseline and every 3 months on study (1988-1991). Stored sera were assayed for HIV-1 p24 antibody, HIV-1 RNA, and ICD p24 antigen. Mortality was recorded during the trial and updated through 1996 (mean total follow-up, 6.3 years).

RESULTS

Eighty-one (37%) children died; probability of mortality for children with baseline HIV-1 p24 antibody concentrations of undetectable (< 1), 1-4, 5-124, and > or = 125 reciprocal titer units (RTU) was 61, 50, 24, and 10%, respectively. A 3.5-fold increase in the relative risk (RR) of death [95% confidence interval (CI), 2.2-5.5] was observed among children with baseline HIV-1 p24 antibody concentration < 5 RTU compared with > or = 5 RTU. In multivariate analyses, p24 antibody, HIV-1 RNA, and CD4 cell percentage but not ICD p24 antigen were independently associated with mortality; the RR of death increased by 1.7 (95% CI, 1.3-2.1) for each log10 decrement in baseline HIV-1 p24 antibody.

CONCLUSIONS

HIV-1 p24 antibody, HIV-1 RNA and CD4 cell percentage independently predict mortality amongst infected children. Whereas CD4 cell percentage provides an estimate of the general degree of immune suppression, HIV-1 p24 antibody could provide an easily obtained, inexpensive assessment of CD4 cell function and could augment prognostic information provided by CD4 cell count and viral load for clinical management of infected children.

Detection of human immunodeficiency virus type 1 nucleocapsid protein p7 in vitro and in vivo

We developed and evaluated an immunoassay for the detection and quantification of human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein p7 using electrochemiluminescence technology. The assay had a dynamic range of 50 to 20,000 pg/ml and a lower detection limit equivalent to approximately 10(6.5) HIV-1 RNA copies/ml in culture supernatant. In vitro kinetic replication studies showed that the amount of p7 correlated strongly with the amount of p24 (R2 = 0.869; P < 0.0001) and viral RNA (R2 = 0.858; P = 0.0009). On the basis of the p7 and RNA concentrations, we calculated the median p7:RNA ratio to be approximately 1,400 p7 molecules per RNA molecule. HIV-1 p7 could be detected and quantified in culture supernatants of both group M subtype A to E viruses and group O viruses. The presence of p7 in vivo was evaluated in 81 serum samples collected from 62 HIV-1-infected individuals. Five samples were p7 positive, whereas 45 samples were HIV-1 p24 positive. Four of the five p7-positive samples were p24 positive as well. p7 could be detected only when serum HIV-1 RNA levels were greater than 10(6) copies/ml. Anti-p7 antibodies were found in six samples, and all six were p7 negative. In contrast to the in vitro results, it appeared that HIV-1 p7 could not be used as a marker for viral quantification in vivo, since more than 90% of the serum samples were p7 negative. In combination with the low prevalence of anti-p7 antibodies, this may, in turn, be advantageous: the p7 assay may be a good alternative to the p24 assay as the readout system for determination of neutralizing activity against HIV-1 in serum or other fluids containing anti-p24 antibodies.

Prognostic significance of plasma markers of immune activation, HIV viral load and CD4 T-cell measurements

OBJECTIVE

To evaluate the prognostic significance for AIDS occurrence of plasma levels of immune activation markers in comparison with and in conjunction with HIV viral load and CD4 T-cell measurements.

DESIGN

A retrospective analysis was conducted of three plasma activation markers, the soluble tumor necrosis factor (TNF) receptor II (TNF-RII), neopterin and soluble interleukin-2 receptor levels, and of CD4 T-cell levels and plasma HIV viral load.

SUBJECTS

The participants were 659 men taking part in the University of California Los Angeles Multicenter AIDS Cohort Study who were HIV-seropositive but AIDS-free in 1985.

MAIN OUTCOME MEASURE

Clinically defined AIDS within 3 years. Failure time statistical regression models for the time to development of AIDS were used to assess prognostic capacity of the parameters alone and in combination.

RESULTS

All the markers had prognostic capability. The levels of the three plasma activation markers correlated well with each other (median r = 0.61). They related less well with HIV RNA plasma levels (median r = 0.50) and least well with CD4 cell levels (median r = 0.36). Furthermore, plasma marker levels were shown to be able to stratify patients for prognosis within all the major categories of CD4 T-cell and HIV RNA levels.

CONCLUSIONS

Plasma levels of soluble TNF-RII and other soluble markers of immune activation have prognostic capabilities which are different from HIV and CD4 T-cell levels. Combination of a single plasma activation marker measurement (such as soluble TNF-RII) with CD4 T-cell levels improved the prognostic capability of each. A new graphic technique for presenting prognostic capability indicated that plasma soluble TNF-RII and CD4 cell levels are better prognostic factors than HIV plasma level with CD4 cells < 200 x 10(6)/l. Inexpensive tests for one of the plasma activation markers, such as soluble TNF-RII or neopterin, can be useful for evaluations of HIV disease course, especially when expensive equipment, technical expertise and funding required for flow cytometry and for HIV load measurements are not readily available.

Association of antibody reactivity to ELDKWA, a glycoprotein 41 neutralization epitope, with disease progression in children perinatally infected with HIV type 1

The association between antibody reactivity to the neutralizing epitope ELDKWA in the transmembrane glycoprotein gp41 and disease progression was investigated in 29 children perinatally infected with HIV-1. Levels of antibody reactivity to this epitope, measured over time, were associated with absolute CD4+ lymphocyte numbers and disease status, and inversely associated with the levels of acid-dissociated p24 antigen in the plasma. Early virus isolates from 10 of 12 children with no detectable antibody reactivity to this epitope were sequenced. Only three contained sequences that differed from the consensus, indicating that this epitope is well conserved in this population. None of these three children developed antibodies to the autologous sequences, indicating that at least 80% of children with negative antibody reactivity to this epitope were true nonresponders. Together, these results indicate that the ELDKWA determinant could be an important component in the formulation of a vaccine or for immunotherapeutic approaches to HIV-1 infection.

Single point dilution method for the quantitative analysis of antibodies to the gag24 protein of HIV-1

In the present work a concept proposed in 1992 by Dopotka and Giesendorf was applied to the quantitative analysis of antibodies to the p24 protein of HIV-1 in infected asymptomatic individuals and AIDS patients. Two approaches were analyzed, a linear model OD = b0 + b1.log(titer) and a nonlinear log(titer) = alpha.OD beta, similar to the Dopotka-Giesendorf's model. The above two proposed models adequately fit the dependence of the optical density values at a single point dilution, and titers achieved by the end point dilution method (EPDM). Nevertheless, the nonlinear model better fits the experimental data, according to residuals analysis. Classical EPDM was compared with the new single point dilution method (SPDM) using both models. The best correlation between titers calculated using both models and titers achieved by EPDM was obtained with the nonlinear model. The correlation coefficients for the nonlinear and linear models were r = 0.85 and r = 0.77, respectively. A new correction factor was introduced into the nonlinear model and this reduced the day-to-day variation of titer values. In general, SPDM saves time, reagents and is more precise and sensitive to changes in antibody levels, and therefore has a higher resolution than EPDM.

Stabilities of free and complexed human immunodeficiency virus p24 antigens during short- and long-term storage

By the standard p24 assay there was a 25 to 27% decrease in free p24 antigen in serum after storage at 4 degrees C over 14 days but no loss at -70 degrees C. There was no loss at either temperature by the immune complex dissociation (ICD) procedure. Furthermore, there was no significant loss of detectable p24 in serum by either the ICD or the standard p24 assay after 700 days of storage at -70 degrees C.

Pharmacokinetics of hyperimmune anti-human immunodeficiency virus immunoglobulin in persons with AIDS

Hyperimmune anti-human immunodeficiency virus immunoglobulin (HIVIG) is an intravenous immunoglobulin prepared from HIV-infected asymptomatic donors with a CD4 cell count greater than 400 cells/microl and a high titer of antibody to HIV-1 p24 protein. Twelve persons with AIDS received four doses of HMG (two at 50 mg/kg of body weight and then two at 200 mg/kg) every 28 days. Pharmacokinetics were evaluated by measurement of anti-p24 antibody. HIVIG was well tolerated, and all participants completed the study. Three subjects who were not receiving Pneumocystis carinii pneumonia (PCP) prophylaxis developed PCP. The mean value for HIVIG clearance was 3.02 ml/kg/day at 50 mg/kg and 3.65 ml/kg/day at 200 mg/kg (P = 0.027); the mean trough antibody titers (reciprocal units) were 1,442 and 4,428, respectively. This study indicates that high titers of anti-p24 antibody can be maintained with a monthly administration schedule of HIVIG and that short-term safety is acceptable. Comparisons to evaluate the therapeutic potential of HIVIG are justified.

Virologic and serologic markers of rapid progression to AIDS after HIV-1 seroconversion

The association between early virologic and immunologic events after human immunodeficiency virus type 1 (HIV-1) infection and progression of HIV-1 infection to acquired immunodeficiency syndrome (AIDS) was studied among 59 homosexual men with documented time of seroconversion. Epidemiologic factors, such as number of lifetime sexual partners, history of sexually transmitted diseases, and other factors, also were studied. All 17 seroconverters in the cohort who developed AIDS within 3 years (rapid progressors = RPs) were compared with 42 men without AIDS for at least 6 years seroconversion (nonrapid progressors = non-RPs). Plasma levels of HIV-1 RNA, p24 antigen, antibodies to HIV-1 structural genes, beta-2 microglobulin, neopterin, and interferon-alpha were measured at four time points: (a) the last seronegative visit, (b) the first seropositive visit, (c) the visit closest to AIDS (or the corresponding visit for the non-RPs) and (d) 6 years after seroconversion (for non-RPs). Up to seroconversion, the RPs had a significantly higher number of lifetime sexual partners than non-RPs (503 versus 171, respectively). At the first seropositive visit, RPs had significantly higher concentrations of plasma HIV-1 RNA (p < 0.01) and prevalence of p24 antigenemia (p < 0.001) and significantly lower levels of antibodies to the HIV-1 gag proteins p17 and p24 (p < 0.01-0.001) compared with non-RPs. These differences increased during follow-up visits. Antibodies to p66 and gp120 were significantly different only at the visit closet to AIDS (p < 0.001), as were beta-2 microglobulin and interferon alpha. These findings suggest that early virologic-immunologic events after HIV-1 infection may determine the rate of progression to AIDS. Anti-gag immune response may prevent rapid progression of HIV-1 disease and should be considered for future vaccine studies.

The use of auxiliary events to improve the analysis of survival for HIV-infected patients: application to the French Prospective Multicenter Cohort (SEROCO)

SUMMARY

A multicenter prospective cohort study, including 512 patients for whom date of HIV infection was known, showed that the use of an appropriate auxiliary event can improve the analysis of survival data and lead to an earlier detection of risk factors for HIV patients. Age at seroconversion and primary symptomatic infection were used as risk factors. Two age groups were defined as age at seroconversion >30 years (n = 203) and < or = 30 years (n = 309). Patients with primary symptomatic infection PSI (n = 215) were compared with patients without any clinical manifestation during primary infection (n = 297). Death was considered as the endpoint of primary interest and occurred in 76 patients in the study. Classical non-parametric methods (Kaplan-Meier estimate and long-rank test) and parametric regression model (Weibull model) were used for a standard analysis of survival data. A parametric approach using auxiliary information was used to estimate the survival function and to test the effect of age at seroconversion and PSI. We also applied a recently proposed distribution-free method to produce a non-parametric estimate of the survival function and to test age at seroconversion and PSI with respect to survival estimates. Both methods are compared for two distinct auxiliary events (Karnofsky score below 75 and a first drop of CD4 lymphocyte counts below 200 cells/MM3). The use of CD4 lymphocyte counts below 200 cells/MM3 as an auxiliary event improved the analysis of survival data available in December 1994. For both methods incorporating CD4 counts below 200 cells/mm3 in addition to survival data, the effect of age at seroconversion on survival was significant in April 1992 whereas it was not significant with standard methods. For PSI exposure group, results shown in this work do not indicate any improvement in using auxiliary information. Conditions for using an appropriate auxiliary event as well as advantages and shortcomings of both methods are discussed. Methods used in this work, with appropriate auxiliary information, are promising either through a reduction in the time to follow-up to detect risk factors for cohort studies or the time needed for drug development in clinical trials.

Fluctuations in steady state level of genomic HIV-1 RNA and replication intermediates related to disease progression rate

Steady state levels of HIV-1 genomic RNA and unintegrated circular DNA fluctuate in the course of HIV-1 infection. Genomic RNA in serum was detected using the NASBA technique and the amount of circular DNA was assessed by PCR. Quantification was done by competitive techniques using co-amplification of internal standards. Within the Amsterdam Cohort Studies it was possible to distinguish rapid progressors, intermediate progressors, slow progressors and non-progressors. Rapid progressors show persistently high viral RNA loads from seroconversion on, while all other HIV-1-infected individuals show a steady decline after seroconversion. Subsequent rises in viral RNA levels herald disease progression in later stages of infection. Unintegrated circular DNA shows similar, but somewhat delayed kinetics. These results indicate that the distribution of AIDS and the average length of the symptom-free period in an HIV-1-infected host population is determined by the steady state levels of genomic RNA and of replication intermediates that are produced by a particular HIV-1 virus population in the average seropositive individual.

A novel protein immunoassay with predetermined specificity using monoclonal antibodies against tryptic fragments: application to HIV P24 antigen

We have developed a new protein immunoassay method which uses antibodies raised against synthetic peptides. These synthetic peptides are selected to correspond to fragments of the protein that can be obtained by proteolytic treatment of the protein by trypsin. Just before assay, biological samples are treated with trypsin to liberate the fragments which bind to the anti-peptide antibodies with high affinity. The exact specificity of the assay is predetermined by the amino acid sequence of the fragment which may be either conserved within a family of antigens or, conversely, entirely specific for a particular protein. This method has been successfully employed in the development of an immunoassay for HIV P24 antigen. In that case, peptides were selected that were strongly conserved among the different HIV-1 and HIV-2 strains. This methodology has permitted the development of a sensitive immunoassay with a broad specificity despite many amino acid variations between HIV strains. The methodology could be extended to other protein antigens.

Overproduction, purification, and diagnostic use of the recombinant HIV-1 Gag proteins, the precursor protein p55 and the processed products p17, p24, and p15

HIV-1 Gag protein precursor p55, and its processed products, p17, p24, and p15 were overproduced in Escherichia coli and purified to near homogeneity. To study the antigenic properties and the potentiality as the diagnostic and prognostic reagents, varying amounts of the purified Gag proteins were dotted onto the polyvinylidene difluoride membrane and reacted with 40 sera of HIV-1-infected individuals (35 AC, 1 ARC, and 4 AIDS patients) and 10 sera of normal healthy donors. p55 reacted with 40 (100%) sera of HIV-1 carriers, while p17, p24, and p15 reacted with 37 (92.5%), 35 (87.5%) and 34 (85%) of the 40 sera of HIV-1 carriers, respectively. On the whole, the reaction of p55 was especially strong and that of p15 was the weakest. p55 showed the strongest reaction among the four Gag proteins with all specimens, and it showed a positive reaction with a carrier serum with which none of the processed Gag proteins showed a positive reaction. Therefore, p55 is the most useful antigen among the four Gag proteins for detection of the Gag antibodies and may even be one of the most useful antigens for the diagnosis of HIV-1 infection.

Antiviral action of oligodeoxyguanylic acids against human immunodeficiency virus type 1

Deoxyguanylic acids, but not other deoxynucleotides, as short as 3- to 4-mer, were effective in preventing HIV-1-induced cytopathicity. In addition, they prevented giant cell formation of infected Sup-T1 cells, and p24 production in HIV-1 infected H9 cells. Phosphorylation at either the 5'- or 3'-end enhanced these activities. Furthermore, 5'-phosphorylated phosphorothioate tetradeoxyguanylic acid was effective in reducing HIV production in chronically infected cells (H9/IIIB). The search for the target steps of this compound revealed that it inhibits at least 3 steps in the life cycle of HIV: interaction with CD4 (measured by inhibitory effect on the syncytia formation between Sup-T1 and H9/IIIB cells), reverse transcriptase, and step(s) after integration. These results suggest that phosphorylated phosphorothioate tetradeoxyguanylic acid may be a novel candidate for a therapeutic agent of AIDS.

Factor VIII, HIV and AIDS in haemophiliacs: an analysis of their relationship

In this review, the association between the Acquired Immune Deficiency Syndrome (AIDS) and haemophilia has been carefully examined, especially the data that have been interpreted as indicating transmission of the human immunodeficiency virus (HIV) to the recipients of purportedly contaminated factor VIII preparations. In our view, the published data do not prove the hypothesis that such transmission occurs, and therefore HIV cannot account for AIDS in haemophiliacs.

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.

Prognostic value of adenosine deaminase compared to other markers for progression to acquired immunodeficiency syndrome among intravenous drug users

This study was designed to determine the prognostic value of erythrocyte adenosine deaminase (ADA) as a possible indicator of progression to AIDS, and compare this with other known cellular and serological markers. At the end of a 3-year study, a cohort of 114 human immunodeficiency virus-1 (HIV-1) seropositive intravenous drug users (IVDUs) from the five different Center for Disease Control (CDC) groups was examined in order to estimate the prognostic relevance with respect to the progression to acquired immunodeficiency syndrome (AIDS) of each of the following markers at baseline value: number and percentage of CD4+ T cells, number of CD8+ T cells, CD4+/CD8+ ratio, IgA and beta 2 microglobulin and ADA levels, and the presence of HIV antigens. Moreover, 57 IVDUs belonging to II and III CDC groups were analyzed in a follow-up study at 6-month intervals, in order to evaluate and compare the behavior of each marker over time. The prognostic significance of each marker was assessed by computing the survival distribution and the Cox analysis in a multivariate model providing the set of markers with greatest predictive value. The levels of ADA and the CD4+/CD8+ ratio showed a linear association with disease staging, whereas beta 2 microglobulin and CD4+/CD8+ ratio were the best predictors for AIDS progression. A highly significant increase in ADA and beta 2 microglobulin was observed during follow-up. The results obtained among HIV-positive IVDUs clearly indicate that the erythrocyte ADA may be considered a reliable marker of the development of HIV infection from the intermediate stages of the disease onwards.(ABSTRACT TRUNCATED AT 250 WORDS)

The affinity of IgG antibodies to gag p24 and p17 in HIV-1-infected patients correlates with disease progression

The affinity of anti-gag antibody was studied for up to 9 years (1984-1993) in sera from 15 HIV-1+ patients with haemophilia. On the basis of their 1993 clinical status patients were divided into two groups: (i) patients who remained asymptomatic (n = 9); and (ii) those who progressed to AIDS between late 1987 and 1993. The affinity constants of antibody for p24 and p17 were determined by a double isotope fluid-phase radioimmunoassay; and the relationships between antibody affinity and titre, patient clinical course, CD4 cell counts and p24 antigenaemia were analysed. The affinity of p24- and p17-specific antibody was up to 100 times greater in asymptomatic patients than in patients who progressed to AIDS. Patients who developed AIDS either lost or failed to develop high-affinity antibodies early in the infection. Asymptomatic patients maintained high-affinity antibodies for several years; however, in some of these patients the affinity of anti-p24 and p17 antibodies subsequently fell later in the study period. The presence of low-affinity antibody and progressive reduction in the titre of specific antibody were earlier predictors of disease onset than CD4 cell counts. The failure to either develop or maintain high affinity gag-specific antibody suggests an early impairment of T helper function in individuals who progressed to AIDS. The presence of antibody of high affinity could be essential in controlling virus replication and the onset of AIDS.

Loss of Gag-specific antibody reactivity in cattle experimentally infected with bovine immunodeficiency-like virus

The development and persistence of virus-specific antibodies were investigated in eight cattle experimentally infected with the R29 isolate of bovine immunodeficiency-like virus (BIV). By 4 weeks postinoculation (p.i.), antibodies reactive to BIV gag- and env-encoded recombinant fusion proteins were detectable by immunoblotting in all animals. By 40 weeks p.i., seven of eight cattle had dramatically decreased Gag-specific antibodies, and anti-Gag reactivity remained very low or undetectable through 190 weeks p.i. Immunoprecipitation experiments revealed a similar loss of reactivity to nondenatured BIV Gag in these animals. In contrast, antibodies to a recombinant BIV Env protein were readily detectable throughout the study in all eight cattle. During the period of declining Gag antibody, infectious virus was recoverable from peripheral blood mononuclear cells of each animal. However, there was no evidence for sufficient amounts of BIV p26-containing immune complexes to explain the loss of anti-Gag reactivity. Interestingly, the single animal that maintained detectable anti-Gag reactivity throughout the study was repeatedly negative for virus recovery beyond 17 weeks p.i. All animals have remained clinically normal for over 4 years p.i., with no evidence of consistent changes in mononuclear cell subsets. These findings provide evidence that in BIV infection an early decline in Gag-specific antibody reactivity can occur without evidence of increasing viral replication or progression to overt clinical disease.

Quantification of human immunodeficiency virus in plasma by RNA PCR, viral culture, and p24 antigen detection

A semiquantitative PCR technique for detecting human immunodeficiency virus type 1 (HIV-1) RNA in plasma was compared with quantitative viral culture and p24 antigen detection in plasma. Ninety-three samples from 20 symptomatic, 10 asymptomatic, and 10 seronegative individuals were tested. For most of the seropositive patients, consecutives samples were examined. Viral RNA was extracted from plasma by the method described by Boom et al. (R. Boom, C.J. A. Sol, M. M. M. Salimans, C.L. Jansen, P. M. E. Wertheim-van Dillen, and J. van der Noordaa, J. Clin. Microbiol. 28:495-503, 1990). The RNA PCR was the most sensitive method (100 and 74% sensitivity for symptomatic and asymptomatic patients, respectively) and produced less divergent results with the consecutive samples from individual patients compared with the other techniques. All samples positive by viral culture or p24 antigen assay were also positive in the RNA PCR. For each of the three assays, the number of positive results obtained correlated with the disease stage. The estimated mean number of HIV-1 RNA copies was significantly higher in symptomatic patients (22,750 copies per ml) than in asymptomatic patients (1,820 copies per ml). It was also higher in samples positive for viral culture than in culture-negative samples. No close correlation was found between the amount of HIV-1 RNA and the amount of p24 antigen or the titer of infectious virus in plasma or between this titer and the level of p24 antigen. The plasma RNA PCR may be a useful additional marker of disease progression and may be valuable for monitoring the effects of antiviral therapy.

Cerebrospinal fluid human immunodeficiency virus type 1 (HIV-1) p24 antigen levels in HIV-1-related dementia

Human immunodeficiency virus type 1 (HIV-1) p24 antigen, a putative marker of virus load, was assayed in 79 blood and 83 cerebrospinal fluid (CSF) samples from 90 HIV-1-seropositive individuals with or without dementia. Twenty-eight subjects had no evidence of neuropsychological impairment, 17 had mild impairment without objective evidence of dementia, and 45 were demented. HIV-1 p24 antigen was detected more frequently in CSF samples from demented (19/40) than normal (1/26) or mildly impaired (1/17) subjects and in 67% of individuals with significant dementia (MSK stages 2-4). p24 Antigen was detected less frequently in CSF from demented subjects on antiretroviral drugs than untreated demented individuals. Overall, the sensitivity of the antigen capture assay in CSF among demented individuals was 47.5%; the specificity, 95.0%; positive predictive value, 90.4%; negative predictive value, 66.1%; and the efficiency, 72.2%. A direct relationship was also noted between the degree of cognitive impairment and blood p24 antigen detection frequency and antigen concentration. CD4+ blood lymphocyte counts were lower for demented individuals, and HIV-1 p24 antigen was detected more frequently and p24 antigen concentration was higher in blood and CSF from individuals with low CD4+ blood lymphocyte counts. beta 2-Microglobulin levels were higher in CSF from demented subjects and correlated directly with CSF p24 antigen concentration. However, in contrast to CD4+ blood lymphocyte counts and beta 2-microglobulin levels, only p24 antigen concentration correlated with dementia severity. Therefore, p24 antigen can be a useful marker for dementia related to HIV-1 infection.

HIV-1 reactivation after an oxidative stress mediated by different reactive oxygen species

An important aspect of infection by the human immunodeficiency virus (HIV-1) type 1 is its long clinical latency period, suggesting that the provirus may remain latent for extended periods of time after primary infection. Numerous factors such as cytokines, tumor promoters, co-infection by several viruses and physical agents are able to reactivate latent virus. Since a common denominator, shared by several of these agents, is their ability to cause stress conditions, we have examined the effects of an oxidative stress mediated by reactive oxygen species on HIV-1 latently infected monocytes (U1) or lymphocytes (ACH-2). Exposure of these two cell lines to hydrogen peroxide causes a decrease of cell viability but among the cells surviving the treatment, a HIV-1 reactivation can be observed as measured by increased RT activities depicted in cell supernatants or by the appearance of HIV-1 antigens inside cells. Singlet oxygen (1O2) when generated either in the cytoplasm or in the cell nucleus can also promote an important HIV-1 reactivation from treated cells. However, extracellular generation of 1O2 cannot trigger the HIV-1 reactivation although this kind of treatment is highly cytotoxic. These experiments demonstrate that different reactive oxygen species are able to lead to an intracellular pro-oxidant state initiating one or several signalling pathways which lead in fine to the HIV-1 LTR transactivation by regulatory proteins.

In vivo induction of human immunodeficiency virus type 1-specific cytotoxic T lymphocytes and delayed-type hypersensitivity by a 23-amino acid peptide from the highly conserved region in major core protein p24

Cell-mediated immune responses are a major immune defence mechanism against the spread of human immunodeficiency virus type 1 (HIV-1) which may lead to acquired immune deficiency syndrome (AIDS). Therefore, the best candidate for a peptide vaccine preventive from the onset of the disease might be a chain section containing both B- and T-cell epitopes in regions of conserved sequences between the different HIV-1 isolates. We previously identified the highly conserved linear B-cell epitope (23 amino acids in the major core protein p24). Since the epitopes of cytotoxic T lymphocytes (CTLs) can be defined by short synthetic peptides, we examined whether this highly conserved region can elicit viral-specific, cell-mediated immune responses. The results showed specific induction of CD8+ CTLs in mice by immunization with the Gag 13-mer peptide. Lysis of targets is specific since unpulsed cells with the same MHC haplotype or cells with a different MHC haplotype pulsed with the peptide were resistant to lysis. This in vivo response induced by the Gag 23-mer peptide was almost the same as that induced by the 15-amino acid peptide from the HIV-1 Env gp120 which is an immunodominant domain in the V3 loop. Lymphocyte proliferation of T-cell fraction from immune spleen cells was observed after in vitro stimulation with the Gag 23-mer peptide, whereas there was no apparent lymphocyte proliferation with the Env 15-mer peptide. In addition, specific antibodies were raised against Gag p24 in mice immunized with the Gag 23-mer peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of intracellular HIV in lymphocytes by flow cytometry

Various permeabilization procedures and defined gating techniques were tested in order to optimize existing flow cytometric assays and devise a specific assay for the direct detection of intracellular HIV-1 antigens in clinical blood specimens. In our optimal procedure, blood lysed with Orthomune Lysing Reagent was fixed with 3.7% formaldehyde for 10 min at room temperature and then permeabilized with 0.2% Tween 20 for 15 min at room temperature. Cells from whole blood were labeled with either FITC-anti-p18 or FITC-anti-p24 monoclonal antibodies and PE-anti-Leu M9 (CD33) in order to exclude monocytes and granulocytes from the lymphocyte gate. The assay demonstrated that mean percentages of HIV p24 antigen positive cells were increased in patients with advanced disease. The assay in its present form is useful for monitoring disease progression and for monitoring the effects of antiviral therapy in individuals, but it is not currently sensitive enough to detect consistently the low levels of HIV infected peripheral blood cells in asymptomatic individuals.

A phase II study of effect of addition of trichosanthin to zidovudine in patients with HIV disease and failing antiretroviral agents

Patients infected with HIV, including those with AIDS-related complex and AIDS, and failing treatment with antiretroviral agents such as zidovudine, have been evaluated following addition of trichosanthin to the antiretroviral agent regimen. This ribosomal inhibitory protein is specifically cytotoxic for HIV-infected macrophages and lymphocytes. Ninety-three patients were treated with trichosanthin, using a schedule of weekly, then monthly, intravenous injections of 1.2 mg of drug in combination with antiretroviral agents, usually zidovudine. Side effects included myalgias, fevers, mild elevation in liver function tests, and mild-moderate anaphylactic reactions, which respond well to therapy with steroids and/or benedryl. Reversible mental status changes were noted in two patients, both receiving concomitant therapy with ddI. Clinical responses to trichosanthin treatment were monitored primarily by changes in laboratory parameters, particularly levels of CD4+ T lymphocytes. In the total population evaluated for efficacy (85 patients) there was a significant increase in CD4+ cell levels after initiation of trichosanthin therapy. A second analysis performed on 72 patients measured the rate of change of CD4+ cells during therapy, using an "area under the curve" analysis. During therapy there was a median increase of 1.2 cells/mm3/month. In patients in the top 25th percentile, this increase was greater than 8.4 cells/mm3/month. In 59 of the 72 patients, responses could also be monitored by comparing the rate of loss of CD4+ cell levels on antiretroviral agents (zidovudine or ddI) alone, during the year prior to initiation of trichosanthin, to the rate of change when trichosanthin was added to the treatment regimen. During the period before trichosanthin treatment (311 +/- 11.7 days) the median loss of CD4+ cells was 6.91 cells/mm3/month. Addition of trichosanthin to the treatment regimen resulted in a median gain of 1.1 CD4+ cells/mm3/month.

Detection of feline immunodeficiency virus p24 antigen and p24-specific antibodies by monoclonal antibody-based assays

A panel of monoclonal antibodies (mAbs) detecting distinct B-cell epitopes on p24 core viral protein of feline immunodeficiency virus (FIV) were employed to develop immunoassays to measure p24 concentration in culture and serum samples, to localize p24 in FIV-infected cells and tissues, and to detect anti-p24 antibodies in cat sera. In its optimized configuration the p24 capture assay detected as little as 0.25 ng/ml of protein. The assay was found at least as sensitive as the reverse transcriptase activity assay in FIV-infected lymphocyte cultures and proved capable of detecting p24 antigen in acid pretreated sera from a high proportion of FIV-infected cats. The mAbs were also successfully used to detect the p24 antigen in permeated FIV-infected cells by flow cytometry and in tissue sections from FIV-infected cats by immunohistochemical staining. Anti-p24 antibodies in FIV-infected cat sera were assayed by a competitive capture ELISA which readily identified occasional false positive results provided by a standard ELISA using purified whole FIV-coated wells.

gag- and env-specific serum antibodies in cats after natural and experimental infection with feline immunodeficiency virus

In order to monitor the antibody response to feline immunodeficiency virus (FIV) in cats, following experimental and natural infection, enzyme-linked immunosorbent assays (ELISAs) were developed using recombinant env and gag proteins and p24-specific monoclonal antibodies. It was shown that in experimentally infected cats an env protein-specific antibody response was directly followed by a gag protein-specific response. Furthermore, an ELISA for the detection of env protein-specific serum antibodies proved more sensitive in identifying experimentally and naturally infected cats than ELISAs demonstrating gag protein-specific antibodies. It was concluded that, like in HIV infection of humans, the detection of env protein-specific serum antibodies in addition to gag protein-specific antibodies is not only an important tool in the diagnosis of the infection but also in studies concerning the pathogenesis of the disease.

Human immunodeficiency virus type 1 mRNA expression in peripheral blood cells predicts disease progression independently of the numbers of CD4+ lymphocytes

To address the significance of human immunodeficiency virus (HIV) replication in peripheral blood mononuclear cells (PBMCs), we have used reverse transcriptase-initiated PCR to measure HIV-1 mRNA expression in PBMC specimens collected from a cohort of HIV-infected individuals during a long-term prospective study. We found dramatic differences in HIV mRNA expression among individuals with very similar clinical and laboratory indices, and this variation strongly correlated with the future course of the disease. No evidence of viral replication was detected in PBMCs from asymptomatic individuals who, thereafter, had normal levels of CD4+ cells for at least 5 years. Irrespective of whether the CD4+ cell numbers were normal at the time of sampling, abundant expression of HIV-1 mRNA in PBMCs predicted accelerated disease progression within the next 2 years. Thus, independently of what may be the rate of HIV replication in other viral reservoirs, such as lymphatic tissue, the amount of HIV mRNA in PBMCs appears to reflect the subsequent development of HIV disease. We have also used the reverse transcriptase-initiated PCR assay to demonstrate a transient response to 3'-azido-3'-deoxythymidine treatment. Determination of HIV-1 mRNA expression in the PBMCs of infected individuals could, therefore, have significant clinical utility as a prognostic indicator and as a means to guiding and monitoring antiviral therapies.

Markers predicting progression of human immunodeficiency virus-related disease

Human immunodeficiency virus (HIV) interacts with the immune system throughout the course of infection. For most of the disease process, HIV activates the immune system, and the degree of activation can be assessed by measuring serum levels of molecules such as beta 2-microglobulin and neopterin, as well as other serum and cell surface phenotype markers. The levels of some of these markers correlate with clinical progression of HIV disease, and these markers may be useful as surrogate markers for development of clinical AIDS. Because the likelihood and timing of development of clinical AIDS following seroconversion, for any particular individual, are not readily predictable, the use of nonclinical disease markers has become critically important to patient management. Surrogate markers of HIV infection are, by definition, measurable traits that correlate with disease progression. An ideal marker should identify patients at highest risk of disease progression, provide information on how long an individual has been infected, help in staging HIV disease, predict development of opportunistic infections associated with AIDS, monitor the therapeutic efficacy of immunomodulating or antiviral treatments, and the easily quantifiable, reliable, clinically available, and affordable. This review examines the current state of knowledge and the role of surrogate markers in the natural history and treatment of HIV infection. The clinical usefulness of each marker is assessed with respect to the criteria outlined for the ideal surrogate marker for HIV disease progression.

Improbability of harmful autoimmune responses resulting from immunization with HIV-1 envelope glycoproteins

Autoimmunity mediated by cross-reactive antibodies, elicited by HIV-1 envelope glycoproteins gp120/gp160, has been postulated to contribute to the pathogenesis of AIDS. Partial amino acid sequence homology between gp120/gp160 and several human host proteins, including MHC antigens and immunoglobulins, has been perceived as the basis for immunological cross-reactivity. Binding of antibodies from sera of HIV-1-infected individuals to selected host proteins and/or to synthetic peptides derived from them and the inhibitory activity of such sera in assays measuring the functional activity of T cells provided apparent support for the autoimmunity hypothesis, which is also relevant to the issue of safety of anti-HIV-1 vaccines. Considering the possibility that the detected autoantibodies may arise for reasons other than antibody responses to gp120/gp160, the immunological cross-reactivity between gp120/gp160 and the relevant host proteins was investigated using hyperimmune rabbit anti-gp120/gp160 and monoclonal antibodies. As determined from dilution end-point comparisons for polyclonal anti-gp120, the cross-reactivity of anti-gp120 with CD4 was undetectable (< 10(-5)%). The cross-reactivity of anti-gp120/gp160 with HLA-I and HLA-II antigens was also undetectable (< 4 x 10(-4)%) and that with other human proteins reported to have partial sequence homology with gp120/gp41 was < or = 0.013%. Anti-gp120/gp160 did not have detectable inhibitory effects in functional assays measuring proliferative T cell responses. Therefore, immunization with gp120/gp160 is unlikely to elicit harmful autoimmune responses.

Molecular and biological characteristics of a novel HIV-2 isolate, HIV-2HOM

In 1991 a new HIV-2 isolate (HIV-2HOM) was isolated first from a German individual most likely infected in West Africa in the beginning of the 1970s. The virus was isolated from both, the plasma and the peripheral blood lymphocytes of the patient by using OKT-3-stimulated cord blood lymphocytes. The recovered viruses could be further propagated on Jurkat cells and exhibited a broad cell tropism. Biochemical and antigenic properties of HIV-2HOM were examined by radioimmunoprecipitations. For a more detailed molecular characterization, a 1520 bp DNA fragment from the env gene and a 722 bp DNA fragment from the pol gene were amplified by polymerase chain reactions, cloned and sequenced. A comparison of both sequences to prototypic HIV-2 and SIV isolates revealed a close relationship to HIV-2ST. This strain originated from an asymptomatic Senegalese individual and is supposed to be of reduced pathogenicity. Taking into account genetic data, it may be assumed that HIV-2HOM and HIV-2ST are closely related strains with different growth characteristics and pathogenic features.

HIV-related emergencies: frequency, diagnoses, and outcome

OBJECTIVE

To study the clinical epidemiology and outcome of HIV-related emergencies, and to identify clinical predictors of HIV-related emergency hospitalizations.

DESIGN

Case series.

SETTING

Emergency facility of a tertiary care teaching hospital.

PATIENTS

350 HIV/AIDS patients followed at the authors' center.

MEASUREMENTS AND MAIN RESULTS

69 of 356 patients made 92 emergency visits with a frequency of 8% per month and 20% per quarter in a three-month study period. Forty-three visits (47%) resulted in hospitalization and contributed to 70% of total AIDS hospitalizations in the period. The five most common acute diagnoses were pneumonia (n = 22; 24%), fever (n = 15; 16%), upper respiratory infection (n = 9; 10%), cellulitis (n = 6; 7%), and gastroenteritis (n = 6; 7%). Three diagnoses accounted for 70% of acute HIV hospitalizations: pneumonia (n = 19), fever (n = 4), and sepsis (n = 4). Analysis of patient disposition as it relates to the patient's clinical presentation and HIV history using multivariate analysis yielded 1) the presence of dyspnea or cough (p = 0.015) and 2) fever with an abnormal chest x-ray (p = 0.008) as independently predictive of hospitalization.

CONCLUSION

The findings indicate that HIV/AIDS patients have a frequent need for emergency care and most HIV/AIDS hospitalizations are emergency-related. The acute problems of these patients are related to a limited number of diagnostic categories, and the presence of respiratory or constitutional symptoms with an abnormal chest radiograph are the only reliable factors predictive of hospitalization.