Human Immunodeficiency Virus Isolates Research Articles

Reverse transcriptase genotype and antiretroviral susceptibility of human immunodeficiency virus isolates from patients with advanced disease treated with didanosine: correlation with virologic response and survival.

To identify correlates of virologic response and survival, the reverse transcriptase (RT) genotype and in vitro antiviral susceptibility of human immunodeficiency virus (HIV) isolates from 20 patients treated with didanosine were studied. Patients had advanced HIV disease and were intolerant to or had failed zidovudine. Neither RT genotype nor antiviral susceptibility testing, as determined by a peripheral blood mononuclear cell-based assay, correlated with a virologic response to didanosine, as determined previously by quantitative serum culture. Only one (8%) of 12 isolates obtained after 6-12 months of treatment showed mutation at codon 74 conferring didanosine resistance. Reversions were seen in three of five patients with pre-treatment zidovudine resistance mutations at codons 70, but in none of eight with mutations at codon 215. Pretreatment isolates encoding mutations at RT codon 215 or encoding codon 123 asp were associated with both significantly greater CD4 lymphocyte depletion and shorter survival. In this cohort of patients with advanced HIV disease, neither rapid emergence of didanosine resistance nor rapid reversion of zidovudine resistance was observed. To better understand the relationship between virologic response and in vitro susceptibility to didanosine, more precise tools may be needed.

Inactivation by phthalocyanine photosensitization of multiple forms of human immunodeficiency virus in red cell concentrates.

The use of phthalocyanines in conjunction with red light has been shown to inactivate model lipid-enveloped viruses in red cell concentrates. The ability of this treatment to inactivate multiple forms of human immunodeficiency virus (HIV) was evaluated in this study. The phthalocyanines used were aluminum phthalocyanine tetrasulfonate (AIPcS4) and the silicon phthalocyanines HOSiPcOSi(CH3)2(CH2)3 N(CH3)2 (Pc 4), and HOSiPcOSi(CH3)2 (CH2)3N+(CH3)3I-(Pc 5). HIV was studied in a cell-free form, in an actively replicating form, in latently infected cells, and in blood from HIV-positive patients. All three phthalocyanines inactivate > or = 10(5) infectious doses of cell-free HIV. However, only Pc 4 effectively inactivated actively replicating HIV and latently infected cells. The latter was about four times as sensitive to inactivation as was actively replicating HIV. Increasing the hematocrit of red cells during treatment decreased the rate of inactivation, especially at lower light doses. Under treatment conditions that completely inactivated the laboratory isolates of HIV, cell-associated HIV in blood from HIV-positive patients was also completely inactivated. The polymerase chain reaction signal from the gag gene of HIV was not affected on treatment of cell-free virus, but it was reduced after treatment of cell-associated HIV, particularly in some latently infected cell lines. Pc 4 and red light are effective in eliminating the infectivity of HIV in red cell concentrates. The usefulness of this approach for blood banking depends on future demonstration of the preservation of red cell circulatory survival and function in vivo.

Cell-mediated infection of cervix derived epithelial cells with primary isolates of human immunodeficiency virus.

We have previously demonstrated that HIV-infected transformed T-cells or monocytes adhere to monolayers of CD4-negative epithelial cells. Adhesion is soon followed by budding of HIV from infected mononuclear cells onto the surface of epithelial cells. Epithelial cells subsequently take up virus and become productively infected. Based on these findings, we proposed that sexual transmission of HIV may involve cell-mediated infection of intact mucosal epithelia of the urogenital tract. However, it has become increasingly clear that primary cells and HIV strains isolated from patients are more appropriate models for HIV infection than established cell lines and lab strains of virus. In the studies described here, we infected cervix-derived epithelial monolayers with primary monocytes infected with patient isolates of non-syncytial inducing (NSI) macrophage-tropic strains of HIV. Under the culture conditions employed, HIV-infected primary monocytes do not remain adherent to the apical surface of the epithelium, as did HIV-infected transformed cells. Instead, following adherence, the primary cells migrate between epithelial cells. Virus is secreted from a pseudopod as HIV-infected primary monocytes pass between cells of the epithelium. Productive infection of the epithelium was detected by p24 ELISA and PCR Southern blot analysis. Infection can be blocked by sera from HIV-seropositive individuals or by certain sulfated polysaccharides. These findings support the supposition that transmission of HIV may occur via cell-mediated infection of intact epithelia. The observations also hint at the possibility that-HIV-infected monocyte/macrophages in semen or cervical-vaginal secretions could cross intact epithelia by passing between epithelial cells. Blocking studies suggest that it may be possible to inhibit sexual transmission of HIV either by antibodies in genital tract secretions or by a topical formulation containing certain sulfated polysaccharides.

Human Immunodeficiency Virus-Induced Cell Death in Cytokine-Treated Macrophages Can Be Prevented by Compounds that Inhibit Late Stages of Viral Replication

The basis of the cytopathic effect induced by a laboratory strain and several clinical isolates of human immunodeficiency virus (HIV) in human macrophages cultured in the presence of macrophage colony-stimulating factor was studied. Infected macrophages die of necrosis, the consequence of the production of mature virions in infected cells. Cell death can be prevented by antiviral compounds that interfere with the assembly and budding of virions. Programmed cell death (apoptosis), a potential mechanism of HIV-mediated cell death in CD4 T lymphocytes, does not occur in infected macrophages as shown by electron microscopy, cytofluorometric and gel electrophoretic DNA analysis, and nuclear fluorescent staining by Hoechst and terminal dUTP-nick-end-labeling (TUNEL) assay. The data suggest that macrophage killing by HIV may occur in vivo. Thus, combination therapies that include compounds that inhibit the cytopathic effect of HIV in macrophages should be considered for AIDS patients.

Synergistic inhibition of human immunodeficiency virus isolates (including 3'-azido-3'-deoxythymidine-resistant isolates) by foscarnet in combination with 2',3'-dideoxyinosine or 2',3'-dideoxycytidine

The combinations of foscarnet plus 2',3'-dideoxyinosine and foscarnet plus 2',3'-dideoxycytidine synergistically inhibit the replication of human immunodeficiency virus type 1 isolates, including two 3'-azido-3'-deoxythymidine-resistant isolates. The combination of 2',3'-dideoxyinosine plus 2',3'-dideoxycytidine showed additive inhibition of the majority of the human immunodeficiency virus isolates tested. All three combinations showed pronounced antagonistic cytotoxicity and thus were less toxic to the growth of peripheral blood mononuclear cells than the separate drugs.

The Emerging Genetic Diversity of HIV

The discovery of highly divergent strains of human immunodeficiency virus (HIV) not reliably detected by a number of commonly used diagnostic tests has underscored the need for effective surveillance to track HIV variants and to direct research and prevention activities. Pathogens such as HIV that mutate extensively present significant challenges to effective monitoring of pathogens and to disease control. To date, relatively few systematic large-scale attempts have been made to characterize and sequence HIV isolates. For most of the world, including the United States, information on the distribution of HIV strains among different population groups is limited. We describe herein the implications resulting from the rapid evolution of HIV and the need for systematic surveillance integrated with laboratory science and applied research. General surveillance guidelines are provided to assist in identifying population groups for screening, in applying descriptive epidemiology and systematic sampling, and in developing and evaluating efficient laboratory testing algorithms. Timely reporting and dissemination of data is also an important element of surveillance efforts. Ultimately, the success of global surveillance network depends on collaboration and on coordination of clinical, laboratory, and epidemiologic efforts.

Protective immune responses induced by secretion of a chimeric soluble protein from a recombinant Mycobacterium bovis bacillus Calmette-Guérin vector candidate vaccine for human immunodeficiency virus type 1 in small animals.

A recombinant Mycobacterium bovis bacillus Calmette-Guérin (BCG) vector-based vaccine that secretes the V3 principal neutralizing epitope of human immunodeficiency virus (HIV) could induce immune response to the epitope and prevent the viral infection. By using the Japanese consensus sequence of HIV-1, we successfully constructed chimeric protein secretion vectors by selecting an appropriate insertion site of a carrier protein and established the principal neutralizing determinant (PND)-peptide secretion system in BCG. The recombinant BCG (rBCG)-inoculated guinea pigs were initially screened by delayed-type hypersensitivity (DTH) skin reactions to the PND peptide, followed by passive transfer of the DTH by the systemic route. Further, immunization of mice with the rBCG resulted in induction of cytotoxic T lymphocytes. The guinea pig immune antisera showed elevated titers to the PND peptide and neutralized HIVMN, and administration of serum IgG from the vaccinated guinea pigs was effective in completely blocking the HIV infection in thymus/liver transplanted severe combined immunodeficiency (SCID)/hu or SCID/PBL mice. In addition, the immune serum IgG was shown to neutralize primary field isolates of HIV that match the neutralizing sequence motif by a peripheral blood mononuclear cell-based virus neutralization assay. The data support the idea that the antigen-secreting rBCG system can be used as a tool for development of HIV vaccines.

Inhibition of the Human Immunodeficiency Virus-1 Protease and Human Immunodeficiency Virus-1 Replication by Bathocuproine Disulfonic Acid Cu 1+

The protease encoded by the human immunodeficiency virus-1 (HIV-1) is essential for processing viral polyproteins which contain the enzymes and structural proteins required for the infectious virus. It was previously found that cupric chloride, in the presence of dithiothreitol or ascorbic acid, could inhibit the HIV-1 protease. It was suggested that a Cu 1+ chelate was the moiety responsible for inhibition of the protease. This hypothesis has now been investigated directly by utilizing the stable Cu 1+ chelate, bathocuproine disulfonic acid Cu 1+ (BCDS-Cu 1+). BCDS-Cu 1+ inhibited the HIV-1 wild type protease as well as a mutant HIV-1 protease lacking cysteines. BCDS-Cu 1+ was a competitive inhibitor of the mutant HIV-1 protease with an apparent K i of 1 μM. Replication of HIV-1 in human lymphocytes and the cytotoxic effect of HIV-1 in CEM cells was inhibited by micromolar BCDS-Cu 1+. Inhibition of the protease and of HIV replication by BCDS-Cu 1+ was dependent on the presence of Cu 1+ as BCDS alone was ineffective. EDTA blocked the inhibition of the protease by Cu 1+ but was unable to block inhibition of the protease by BCDS-Cu 1+, indicating that the Cu 1+ complex was the inhibitory agent. The apparent IC 50 for BCDS-Cu 1+ on the inhibition of replication by primary isolates of HIV-1 was 5 μM. However, BCDS-Cu 1+ did not affect polyprotein processing in an H9 cell line chronically infected with HIV-1, indicating that BCDS-Cu 1+ acts by yet another mechanism to block HIV infection. Other possible targets for BCDS-Cu 1+ include inhibition of viral adsorption and/or inhibition of the HIV-1 integrase.

CT-2576, an inhibitor of phospholipid signaling, suppresses constitutive and induced expression of human immunodeficiency virus.

Viruses such as human immunodeficiency virus (HIV) require cellular activation for expression. Cellular activation in lymphoid cells is associated with augmented accumulation of certain phosphatidic acid (PA) species derived from the hydrolysis of glycan phosphatidylinositol (GPI). This suggests that activation of a phospholipid pathway may play a role in initiation of viral replication. To test this hypothesis, we examined the effect of tat gene expression on the production of cellular PA species, as the Tat protein is essential for HIV expression and has been implicated in activating the expression of multiple host cellular genes. Expression of tat increased the expression of PA. We then tested whether synthetic inhibitors of PA metabolism would inhibit activation of the HIV long terminal repeat by Tat and tumor necrosis factor alpha (TNF-alpha). CT-2576 suppressed both PA generation induced by Tat and HIV long terminal repeat-directed gene expression in response to Tat or TNF-alpha at a posttranscriptional step. CT-2576 also inhibited constitutive as well as TNF-alpha- and interleukin 6-induced expression of HIV p24 antigen in chronically infected U1 cells and in peripheral blood lymphocytes acutely infected with a clinical isolate of HIV. Pharmacological inhibition of synthesis of selected PA species may therefore provide a therapeutic approach to suppression of HIV replication.

Synthesis, absolute configuration, and enantioselectivity of antiretroviral effect of (R)-(-)- and (S)-(+)-cytallene. Lipase-catalyzed enantioselective acylations of (+/-)-N4-acylcytallenes.

Enantioselectivity of acylations of (+/-)-cytallene (1b), (+/-)-N4-acetylcytallene (11a), (+/-)-N4-benzoylcytallene (11b), and (+/-)-N4-(9-fluorenylmethoxycarbonyl)cytallene (11c) using vinyl butyrate or acetate catalyzed by lipases in organic solvents was investigated. Reactions with 1b, 11a, and adenallene (1a) did not display a high enantioselectivity but all resulted in a predominant acylation of the (-)-enantiomers. Application of the Lowe-Brewster rule led to a tentative assignment of the R-configuration to all acylated products. Studies of the time course of acylation of (+/-)-N4-benzoylcytallene (11b) in chloroform, tetrahydrofuran (THF), tetrahydropyran (THP), tetrahydrothiophene (THT), and dioxane with lipase PS30 and/or AK showed that the reaction in THF catalyzed by lipase AK was the most promising for resolution of 11b. Indeed, a large-scale acylation afforded, after separation and deprotection of intermediates 3e and 10d, (+)- and (-)-cytallene (3c and 2b) in high yield and enantioselectivity. Acylation of 11c in THF led also to formation of 3c and 2b in high enantioselectivity. Single crystal X-ray diffraction established the S-configuration of (+)-cytallene (3c), thus confirming the assignment made on the basis of Lowe-Brewster rule. An improved large-scale synthesis of (+/-)-cytallene (1b) is also described. The R-enantiomer 2b inhibited the replication of a primary human immunodeficiency virus (HIV-1) isolate in phytohemagglutinin-activated peripheral blood mononuclear cells (PHA-PBM) with IC50 0.4 and IC90 1.7 microM. (+/-)-Cytallene (1b) exhibited IC50 0.8 and IC90 3.4 microM. Both compounds completely suppressed replication of HIV-1 at 10 microM with no detectable cytotoxicity. The S-enantiomer (3c) was inactive.

A rapid, direct test for zidovudine susceptibility in clinical isolates of human immunodeficiency virus type 1 (HIV-1) from infected children

Existing phenotypic tests of antiretroviral susceptibility in clinical isolates of human immunodeficiency virus (HIV) are expensive and slow, and require passage of virus in cell culture with the possible consequence of selecting variants. We sought to develop a rapid 14-day assay for zidovudine susceptibility of cell-associated HIV performed directly in patient blood samples. Twenty-three tests were performed prospectively in 21 children, and the results were compared with those of the AIDS Clinical Trials Group/Department of Defense consensus drug susceptibility assay (DSA) as well as certain clinical parameters. Five strains from ZDV-naive children were sensitive by the rapid test. Three were tested by DSA, and all were sensitive. Six strains from children who had received >/=24 months of ZDV were resistant by the rapid assay. Four of these strains were tested by the DSA, and all were shown resistant. The viral strains from children who received <24 months of therapy or who had switched from ZDV to other antiviral therapy exhibited variable sensitivity by both tests. Changes in CD4 cells in the subsequent 6 months, as well as weight gain during this time were both correlated to the results of the rapid test. The syncytium-inducing capacity of the virus strains was analyzed similarly. The rapid intracellular virus susceptibility assay is a test of drug sensitivity performed on HIV growing in cells obtained directly from an infected patient. The test has a two-week turn-around time and, in this preliminary report, gives results which correlate with both time on zidovudine and also subsequent CD4 cell changes.

Local and Global Structural Properties of the HIV-MN V3 Loop

Studies of the feasibility of a subunit vaccine to protect against human immunodeficiency virus (HIV) infection have principally focused on the third variable (V3) loop. The principal neutralizing determinant (PND) of HIV-1 is located inside the V3 loop of the surface envelope glycoprotein, gp120. However, progress toward a PND-based vaccine has been impeded by the amino acid sequence variability in the V3 loops of different HIV isolates. Theoretical studies revealed that the variability in sequence and structure of the V3 loop is confined to the N- and C-terminal sides of the conserved GPG crest. This leaves three regions of the V3 loop conserved both in sequence and secondary structure. We present the results of NMR studies that test the validity of our theoretical predictions. Structural studies are reported for the HIV-V3 loop (HIV-MN) in the linear and cyclic (S-S-bridged) forms. For the V3 loop sequence of the HIV-MN isolate, the three conserved secondary structural elements are as underlined below: turns turn helix CTRPNYNKRKRIHIGPGRAFYTTKNIIGTIROAHC Finally, the conformational requirement of the PND in the V3 loop-antibody interaction is tested by monitoring the monoclonal antibody binding to the HIV-MN V3 loop in the linear and cyclic forms by enzyme-linked immunosorbent assay. The binding data reveal that the cyclic V3 loop is a better ligand for the monoclonal antibodies than the linear form although the latter has the same sequence. This means that the monoclonal antibodies recognize the PNDs as conformational epitopes.

Anti-human immunodeficiency virus 1 (HIV-1) activities of 3-deazaadenosine analogs: increased potency against 3'-azido-3'-deoxythymidine-resistant HIV-1 strains.

3-Deazaadenosine (DZA), 3-deaza-(+/-)-aristeromycin (DZAri), and 3-deazaneplanocin A (DZNep) are powerful modulators of cellular processes. When tested against H9 cells infected acutely with two different strains of human immunodeficiency virus 1 (HIV-1) and in the chronically infected monocytoid cell lines U1 and THP-1, the 3-deazanucleosides caused a marked reduction in p24 antigen production. Similar reductions in p24 antigen were seen in phytohemagglutinin-stimulated peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Strikingly, in comparing the therapeutic indices between the paired pre- and post-3'-azido-3'-deoxythymidine (AZT) treatment HIV-1 isolates, DZNep and neplanocin A showed an increase of 3- to 18-fold in their potency against AZT-resistant HIV-1 isolates. In H9 cells treated with DZNep and DZAri, the formation of triphosphate nucleotides of DZNep and DZAri was observed. The mode of action of DZNep and DZAri appears complex, at least in part, at the level of infectivity as shown by decreases in syncytia formation in HIV-1-infected H9 cells and at the level of transcription as both drugs inhibited the expression of basal or tat-induced HIV-1 long terminal repeat chloramphenicol acetyltransferase activity in stably transfected cell lines. Since DZNep induced in H9 cells a rapid expression of nuclear binding factors that recognize the AP-1 transcription site, the anti-HIV-1 activity of the DZA analogs could partly be the induction of critical factors in the host cells. Thus, the 3-deazanucleoside drugs belong to an unusual class of anti-HIV-1 drugs, which may have therapeutic potential, in particular against AZT-resistant strains.

Mother-to-infant HIV transmission: timing, risk factors and prevention.

Identifying when--during pregnancy, delivery or the postnatal period--transmission of human immunodeficiency virus (HIV) from mother to infant usually takes place is critical to the development of methods to prevent maternal-infant transmission. Evidence is reviewed in this paper as to whether transmission occurs prepartum (early or late in gestation), intrapartum, or postpartum with breast feeding. Evidence in support of the notion of prepartum transmission has come from isolation of HIV from aborted fetal organs, comparison of maternal-child viral genotypes and study of neonatal cell-mediated immune responses. Evidence against prepartum transmission is that fewer than half of the children later known to be HIV-infected can be identified by virological tests carried out close to birth. A reduced rate of transmission in infants delivered by Caesarean section, and a reduced risk of transmission to second-born twins delivered vaginally, offers support to the view that intrapartum factors influence the risk of HIV transmission. Transmission through breast feeding can occur if a mother is infected postpartum and seems to pose some additional risk if she is already infected at parturition. The risk of infection increases with the stage of maternal HIV disease, but specific immunological, clinical and viral characteristics need to be investigated further. A clinical trial of zidovudine, used during late pregnancy and delivery and given to the infant at birth, has reported a significant reduction in transmission. Primary prevention of HIV infection in women remains a principal priority.

Gene therapy in the treatment of disease

Gene therapy or transfer is increasingly used as a therapeutic modality in diseases that span the medical spectrum. The American Academy of Allergy and Immunology and the National Institute of Allergy and Infectious Diseases jointly sponsored the Symposium, "Gene Therapy in the Treatment of Disease," which was held December 6, 1993 at the National Institutes of Health (NIH). The program committee consisted of Lawrence Lichtenstein, MD, PhD, (Baltimore) Chairman; Philip Fireman, MD, (Pittsburgh); Howard B. Dickler, MD, (Bethesda); William Paul, MD, (Bethesda); and Raif Geha, MD, (Boston). Eight outstanding presentations on current and potential uses of gene therapy were provided by speakers who are leading researchers in this area of broad interest and unusually promising clinical application. This report summarizes the highlights of those presentations.

Influence of host cell type and V3 loop of the surface glycoprotein on susceptibility of human immunodeficiency virus type 1 to polyanion compounds

Dextran sulfate is a potent inhibitor of human immunodeficiency virus (HIV) binding and replication in lymphocytic cell lines. In this study, we demonstrate that the effect of dextran sulfate and heparin depends on the host cell type and on the V3 loop, the principal neutralizing determinant of HIV gp120. In particular, when dextran sulfate was tested on primary human macrophages infected with macrophage-tropic viruses, enhancement of infection was observed in 6 of 11 independent macrophage preparations and with 5 of 13 primary HIV isolates. Our in vitro observations might explain why enhanced HIV replication was observed in HIV-infected patients treated with dextran sulfate.

Nonviral and viral delivery of a human immunodeficiency virus protective gene into primary human T cells.

Because AIDS has been refractory to traditional pharmacologic interventions, alternative approaches have been developed. Although the introduction of specific antiviral genes into T leukemia cells can provide relative resistance to human immunodeficiency virus (HIV) replication, the testing of such genes against primary viral isolates in human CD4+ lymphocytes has been limited, and safety questions remain regarding gene delivery into cells from HIV-infected patients. In this report, we evaluate the efficacy of a transdominant mutant protein, Rev M10, against cloned and primary HIV isolates in human peripheral blood lymphocytes and describe different methods of gene transfer into peripheral blood lymphocytes from HIV-infected individuals. We show that gold microparticles can mediate stable Rev M10 gene transfer into these cells. Introduction of Rev M10 by these techniques conferred resistance to HIV infection in vitro to cloned and clinical isolates. Nonviral delivery of HIV protective genes will facilitate the development of gene therapy for AIDS and the analysis of viral and cellular gene expression in human T lymphocytes.

Rapid Genetic Characterization of HIV Type 1 Strains from Four World Health Organization-Sponsored Vaccine Evaluation Sites Using a Heteroduplex Mobility Assay

To assist in the preparation for the testing of vaccines against human immunodeficiency virus (HIV) we, as part of the World Health Organization Network for HIV Isolation and Characterization (WHO-NHIC), evaluated the genotypic variation of HIV-1 in cohorts from Brazil, Rwanda, Thailand, and Uganda. Here we report the results from a pilot study of 65 HIV-1-infected individuals. In all cases in which viral envelope gene fragments could be amplified by polymerase chain reaction, subtypes could be assigned using a heteroduplex mobility assay (HMA)1 by comparison with HIV-1 strains representing six HIV-1 envelope subtypes. All subtype classifications matched those found by envelope gene sequencing. Phylogenetic relationships were further clarified by heteroduplex formation between samples within each subtype. A relatively homogeneous subtype E virus population predominated over subtype B viruses in the sample set from Thailand. Viruses from the other countries were also limited to one or two subtypes but were more divergent within each subtype. All samples from Rwanda (13/13) and some from Uganda (3/16) were of subtype A; all Brazilian samples were of subtype B, except for one belonging to subtype C; most samples from Uganda (13/16) clustered with the subtype D. Analysis by HMA is therefore applicable for screening of HIV-1 genotypes in countries under consideration for large-scale vaccine trials. It should be generally useful when samples containing at least one variable genetic locus need to be rapidly classified by genotype and/or analyzed for epidemiological clustering.

Failure Of Short-Term Cd4-Pe40 Infusions To Reduce Virus Load In Human Immunodeficiency Virus-Infected Persons

The safety, immunologic, and antiviral effects of a recombinant biologic product that combines the second and third domains of the CD4 molecule and Pseudomonas exotoxin A (PE40) were evaluated in 21 human immunodeficiency virus (HIV)-infected subjects in a phase III open-label dose-ranging study. Subjects with CD4+ lymphocyte counts of 100-500/mm3 received CD4-PE40 at 40, 80, or 160 micrograms/m2 by infusion three to seven times over 10 days. At the maximum tolerated dose (80 micrograms/m2), peak CD4-PE40 levels were 65-130 ng/mL with a serum half-life of 3.6 +/- 1.5 h. Toxicity, primarily increased hepatic transaminases, was dose-related and reversible. HIV DNA proviral levels in peripheral blood mononuclear cells and plasma HIV RNA remained stable during and after CD4-PE40 infusions. The relative resistance of clinical isolates of HIV, limits of the tolerated dose, and the immunogenicity and short half-life of the protein may explain the lack of in vivo antiviral effect of CD4-PE40.

Effective use of frozen donor peripheral blood mononuclear cells for human immunodeficiency virus type 1 isolation from vertically infected pediatric patients

In this study, we examined variables related to human immunodeficiency virus (HIV) isolation utilizing samples from 51 HIV-infected (153 plasma and 122 peripheral blood mononuclear cell [PBMC] samples) and 57 uninfected (182 plasma and 163 PBMC samples) infants. Our chief observation was that cryopreservation of donor PBMCs does not significantly alter their sensitivity or specificity for isolation of HIV from patient PBMCs or plasma.