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With the advent of highly effective antiretroviral therapy (ART), infection with human immunodeficiency virus (HIV) has become a chronic disease rather than a death sentence. Nevertheless, effectively treated individuals have a higher than normal risk for developing noninfectious comorbidities, including cardiovascular and renal disease. Although traditional risk factors of aging as well as treatment toxicity contribute to this risk, many investigators consider chronic HIV-associated inflammation a significant factor in such end-organ disease. Despite effective viral suppression, chronic inflammation persists at levels higher than in uninfected people, yet the stimuli for the inflammation and the mechanism by which inflammation persists and promotes disease pathology remain incompletely understood. This critical gap in scientific understanding complicates and hampers effective decision making about appropriate medical intervention. To better understand the mechanism(s) of chronic immune activation in treated HIV disease, three questions need answers: (1) what is the cause of persistent immune activation during treated HIV infection, (2) what are the best surrogate markers of chronic immune activation in this setting, and (3) what therapeutic intervention(s) could prevent or reverse this process? The NIH sponsored and convened a meeting to discuss the state of knowledge concerning these questions and the best course for developing effective therapeutic strategies. This report summarizes the findings of that NIH meeting.

Many aspects of the human immunodeficiency virus (HIV) life cycle are well understood, yet a key paradox remains. The primary targets for HIV are resting CD4 T lymphocytes that are not permissive to HIV replication unless activated by some external and independent event. Numerous mechanisms for this

The best hope for the prevention of HIV/AIDS, especially in resource-poor countries, is an effective preventive vaccine. Considerable effort is being made to develop a safe and efficacious vaccine that will elicit broad, protective immunity to HIV. Most of the current vaccine development strategies focus on viral subunit immunogens, which tend to be less than optimally immunogenic and thus require methods to enhance their ability to elicit good neutralizing antibody and vigorous cell-mediated responses. Although generalized adjuvants have long been used to enhance the immune response to vaccines, the use of cytokine adjuvants with specific immune modulatory functions allows the manipulation of the host response to both enhance overall immunogenicity and direct the nature of the response toward a Th1 or Th2 pathway. This review describes the various HIV immunogens and cytokine formulations that are being considered and the state of knowledge about in vitro studies, preclinial and clinical trials of these cytokine-adjuvanted HIV vaccines.

Highly active antiretroviral therapy (HAART) suppresses plasma viremia in most patients with human immunodeficiency virus (HIV) infection. Prospective study of HIV-infected children (n=27) shows that, in 8 of 12 who responded to HAART (>/=0.5 log reduction in plasma HIV RNA), HAART restricted the number of coreceptors used by the predominant HIV isolate (mean number of coreceptors used at baseline was 4, vs. 1 coreceptor used at 6 months after treatment). This decrease was most striking in 6 of 8 children whose HIV coreceptor tropism changed from X4-tropic at baseline to R5-tropic. In 6 of 10 children tested, with plasma HIV RNA levels of

CD8 T lymphocytes are an important component of the host immune response to human immunodeficiency virus (HIV). To characterize CD8 cell function, we have studied the in vitro phenomenon of CD8 cell-mediated inhibition of HIV replication from autologous, naturally infected CD4 cells. We describe here a reproducible assay of CD8 T cell-mediated inhibition in HIV-infected individuals. The method involves the use of a commercially available cell separation system and anti-CD3 monoclonal antibody to stimulate CD4 cells to produce HIV. Using this technique, we were able to detect HIV production from the CD4 cells of 25 of 27 HIV-infected individuals who had not progressed to AIDS. Further, in vitro CD8 cell-mediated inhibition of HIV production was noted in all of the 25 subjects whose CD4 cells produced viral p24 antigen. This assay may be useful as an in vitro correlate of protective immunity to HIV, with potential application for assessing disease progression, therapeutic efficacy, and immune mechanisms in HIV disease.

Infection with human T-cell leukemia virus type II (HTLV-II) has been associated with rare chronic T-cell malignancies and has recently been demonstrated in a significant proportion of American intravenous drug abusers (IVDA). Identification of an HTLV-II-infected cohort of IVDA has allowed analysis of the HTLV-II carrier state. We analyzed clinical, hematologic, and immunologic parameters in 21 HTLV-II- infected IVDA, two HTLV-I-infected IVDA, and 20 uninfected control IVDA identified by serologic screening and by analysis of peripheral blood mononuclear cell (PBMC) DNA by polymerase chain reaction (PCR). An elevated absolute lymphocyte count was observed in 4 of 21 HTLV-II- infected IVDA, 1 of 2 HTLV-I-infected IVDA, and 1 of 20 control IVDA. CD8+ T-cell elevation was observed in three of four HTLV-II IVDA with lymphocytosis and one of two HTLV-I-infected IVDA. Activation of CD8+ T cells in HTLV-II-infected IVDA was suggested by an overall increase in CD8+/HLA-DR+ lymphocytes. Cell fractionation and analysis by PCR of HTLV-II-infected carrier blood showed high levels of HTLV-II provirus in unfractionated PBMC and purified T cells and little or no detectable HTLV-II DNA in B cells or monocytes, indicating that T cells were the most likely target of infection in vivo. The frequency of HTLV-II- infected cells was estimated at approximately 1 in 500 cells or less using dilution analysis by PCR of PBMC DNA. Most HTLV-II-infected IVDA are asymptomatic and have no overt hematologic or immunologic abnormalities, although some manifest benign lymphocytosis.

Previous studies have provided conflicting data on the presence of selective pressures in the transmission of a homogeneous maternal viral subpopulation to the infant. Therefore, the purpose of this study was to definitively characterize the human immunodeficiency virus type 1 (HIV-1) quasispecies transmitted in utero and intrapartum. HIV-1 envelope gene diversity from peripheral blood mononuclear cells and plasma was measured during gestation and at delivery in mothers who did and did not transmit HIV perinatally by using a DNA heteroduplex mobility assay. Children were defined as infected in utero or intrapartum based on the timing of the first detection of HIV. Untreated transmitting mothers ( n = 19) had significantly lower HIV-1 quasispecies diversity at delivery than untreated nontransmittting mothers ( n = 18) (median Shannon entropy, 0.711 [0.642 to 0.816] versus 0.853 [0.762 to 0.925], P = 0.005). Eight mothers transmitted a single major env variant to their infants in utero, and one mother transmitted a single major env variant intrapartum. Four mothers transmitted multiple HIV-1 env variants to their infants in utero, and two mothers transmitted multiple env variants intrapartum. The remaining six intrapartum- and two in utero-infected infants had a homogeneous HIV-1 env quasispecies which did not comigrate with their mothers' bands at their first positive time point. In conclusion, in utero transmitters were more likely to transmit single or multiple major maternal viral variants. In contrast, intrapartum transmitters were more likely to transmit minor HIV-1 variants. These data indicate that different selective pressures, depending on the timing of transmission, may be involved in determining the pattern of maternal HIV-1 variant transmission.

Lymphocyte proliferation assays (LPAs) are widely used to assess T-lymphocyte function of patients with human immunodeficiency virus infection and other primary and secondary immunodeficiency disorders. Since these assays require expertise not readily available at all clinical sites, specimens may be shipped to central labs for testing. We conducted a large multicenter study to evaluate the effects of shipping on assay performance and found significant loss of LPA activity. This may lead to erroneous results for individual subjects and introduce bias into multicenter trials.

Objective. HIV-infected children receiving influenza vaccine, pneumococcal vaccine and both vaccines concurrently were studied to examine the effect of immunization on plasma HIV viral load. Methods. Thirteen children received immunizations: pneumococcal vaccine, 5; pneumococcal and influenza vaccines, 7; and influenza vaccine, 1. Most patients (12 of 13) were receiving combination reverse transcriptase inhibitor antiretroviral therapy without protease inhibitors at the time of immunization. Baseline plasma HIV RNA was determined 1 month prior (11 of 13), 2 weeks prior (12 of 13) and on the day of immunization (12 of 13). Plasma HIV RNA was assayed at 2 weeks (11 of 13), 4 weeks (12 of 13) and 3 months (5 of 13) after immunization. T cell activation markers (HLA-DR + , CD38 + and CD45RO + , CD28 + ) were examined for both CD4 + and CD8 + lymphocytes on the day of immunization and 2 weeks after immunization for 11 children. Results. Only one child developed a >0.5-log increase in viral load at any time after immunization. There was no correlation between an increase in viral load and antibody response to pneumococcal vaccine. At least one activation marker increased (>10%) for two children receiving pneumococcal vaccine and two children receiving pneumococcal and influenza vaccines. One of these children experienced an increase in viral load. Conclusion. Immunization with pneumococcal and influenza vaccines, alone or in combination, is rarely associated with a significant increase in HIV plasma RNA in children receiving combination antiretroviral therapy.

The potential role of human immunodeficiency virus type 1 (HIV-1)-specific immune responses in controlling viral replication in vivo has stimulated interest in enhancing virus-specific immunity by vaccinating infected individuals with HIV-1 or its components. These studies were undertaken to define patient populations most likely to respond to vaccination, with the induction of novel HIV-1-specific cellular immune responses, and to compare the safety and immunogenicity of several candidate recombinant HIV-1 envelope vaccines and adjuvants. New lymphoproliferative responses (LPRs) developed in30% of vaccine recipients. LPRs were elicited primarily in study participants with a CD4 cell count350 cells/mm(3) and were usually strain restricted. Responders tended to be more likely than nonresponders to have an undetectable level of HIV-1 RNA at baseline (P=.067). Induction of new cellular immune responses by HIV-1 envelope vaccines is a function of the immunologic stage of disease and baseline plasma HIV-1 RNA level and exhibits considerable vaccine strain specificity.

RANTES (regulated on activation, normal T expressed and secreted), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta are human immunodeficiency virus (HIV) suppressor factors by virtue of their ability to compete with HIV for access to cell surface R5. Their ability to block HIV infection in vitro is unequivocal; however, their role as HIV suppressor factors in vivo is not firmly established. We therefore conducted a study to test the hypothesis that production of these factors in vitro was a correlate of decreased virus burden in vivo. Moreover, we asked whether higher beta chemokine production could be demonstrated with cells from people who are R5D32 heterozygotes, compared with people who are R5 wild-type homozygotes. Our data support the thesis that RANTES, MIP-1alpha, and MIP-1beta production is associated with decreased in vivo virus load. Moreover, enhanced production of these factors may be explained in part by the genetic background of the host.

CD8 T cell function, lymphocyte surface phenotype, serum markers of immunologic activation, and viral burden were assessed in 75 human immunodeficiency virus (HIV)-infected pregnant women, including 9 who transmitted infection to their infants. Serial studies during and after pregnancy showed no significant differences in levels of cell-surface or serum activation molecules in transmitting compared to nontransmitting mothers, with the exception of a postpartum increase in tumor necrosis factor alpha in transmitting women. The transmitting women had a median plasma viral load of 65,516 RNA copies/mL at delivery versus 5139 in nontransmitting women. During the third trimester, the CD8 cells of 81% of the nontransmitting and 44% of the transmitting mothers suppressed HIV production in vitro by >50%. Women with

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

Increased permissiveness of macrophages for herpes simplex virus (HSV) replication may be a mechanism for the dissemination and severity of neonatal herpetic infection. We have assessed the replication of HSV in neonatal blood monocytes and placental macrophages using several criteria for viral permissiveness. Assay of production of infectious progeny virus indicated that cord blood monocytes, like adult monocytes, were nonpermissive for HSV (about 1% of cells producing virus). In vitro culture of cord blood monocytes resulted in increased replication of HSV, but no greater extent than virus production in cultured adult cells. HSV infection of fetal placental macrophages was weak but present (4.4% of cells). Assay of production of viral antigens and electron microscopic analysis of structural elements indicated that a larger number of cord blood monocytes and placental macrophages were abortively infected than were productively infected. These results indicate that monocytes and macrophages from human neonates do not show the enhanced permissiveness for HSV demonstrated in newborn mice and suggest that dissemination of herpetic infection in human newborns cannot be explained by increased neonatal monocyte permissiveness for HSV.

SummaryResults from examination of peripheral blood leukocytes from five subjects, three with antibody to HSV and two without, showed that HSV type 1 may replicate in mitogen-stimulated T and B lymphocytes and in continuous lymphoblastoid cell lines derived from either B or T cells. Significant replication was also noted in monocytes from each subject but not in polymorphonuclear leukocyte subpopulations. Replication in monocytes was found to be dependent on certain conditions of culture and viral inoculation. Only adherent cells cultured for 72-hr prior to infection produced significant yields of virus.

Testing of cytotoxic function using a panel of natural killer (NK)-sensitive target cells, including a unique herpes simplex virus-infected Raji-cell target, was performed in conjunction with phenotypic cell analysis by dual-color flow cytometry to characterize the NK system. Subjects included in the study were at risk for or infected with the etiologic agent of the acquired immune deficiency syndrome (AIDS), human immunodeficiency virus (HIV). A generalized defect in NK function was temporally correlated with disease manifestations, as evidenced by deficient NK lytic function in patients with AIDS and AIDS-related complex (ARC). Healthy at-risk subjects, including those seropositive for HIV, exhibited robust NK-cell function. Phenotypic analysis revealed that normal proportions of the NK-associated CD16+ (Leu11) Leu7− and CD16+(Leu11)Leu7+ lymphocyte subsets were maintained throughout the clinical progression of HIV infection. However, the proportion and numbers of cells of the CD8+(Leu2)Leu7+ subset were increased in AIDS, ARC, and healthy at-risk subjects, including those seronegative for HIV. These results are consistent with a qualitative defect in the NK system in AIDS, perhaps secondary to CD4-cell depletion and a concomitant lack of essential accessory factors. The elevation in CD8+(Leu2)/Leu7+ cells is not solely the result of HIV infection and may be a general response to viruses and/or other antigenic stimulation.

Strong LAK cell activity induced by interleukin-2 (IL-2) of cord (and adult) mononuclear cells (Pediatr. Res. 19: 271A, 1985) has suggested a possible role for LAK and/or IL-2 therapy in newborns with certain infections. The effect of HSV (type 1) on the LAK effector cell was studied by adding live or irradiated virus (10,000 R) (MOI=10) to 10 cells which have been incubated for 4-6 days with IL-2 (50-100 U/ml). The cells were tested 18-24 hrs later for cytotoxic activity against Cr-labelled K562 and Raji target cells. Live HSV inhibited LAK cytotoxicity of adult cells to K562 by 44% (72 ± 2.4%) to 40 ± 6.2%, n=15) and by 62% against Raji (50 ± 5.6% to 19 ± 4.4%). There was similar inhibition of cord LAK activity. Inhibition was dose dependent and independent of virus replication, since inhibition was observed with irradiated virus. The addition of live virus at the time of the cytotoxic assay or at the beginning of the IL-2 incubation did not affect LAK activity. By contrast, HSV stimulated cytotoxic activity against both targets in the absence of IL-2. The cytotoxicity of adult cells in the presence of live HSV (MOI=10) for 5-7 days increased from 3.3 ± 1.1% in the absence of virus and IL-2 to 19 ± 3.6% against K562 and from 2.2 ± 0.6% to 14 ± 4.4% against Raji targets (n=10). Cord cytotoxicity was stimulated but to a lesser degree. In sum, HSV inhibits LAK effector cell activity independent of virus replication. Further, HSV alone induces natural cytotoxicity which may represent a unique antiviral defense system.