Independent Divergences in the CD4 Binding Site and V3 Loop Encoded in Two Seroprevalent Ugandan HIV‐1 Clinical IsolatesPestano, Gary ; Prince, Alfred ; Guyden, Jerry ; Ntambi, James M.; Atkin, Andrew ; Boto, William M. O.
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Two major epitopes expressed in HIV-1 have been recently shown to play a central role in virus neutralization. One of these important specificities is a type-specific or group-specific, principal neutralizing determinant (PND) located in the V3 loop of gp 120. The other is a more broadly neutralizing determinant associated with the CD4 binding site. Structural and serological studies of the variation in these epitopes have become important in vaccine research. This report describes the analysis of the DNA clones encoding a region of gp120 that overlaps the V3 loop and the putative CD4 recognition site in two new African isolates, UG06c and UG23c. Phylogenetic analyses of the DNA sequences showed that the new African isolates clustered with two very distinct subtypes of HIV-1. UG06c was grouped with U455, D687, and Z321, previously classified as “HIV-1 subtype A” in the AIDS and human retroviruses database; and UG23c was grouped with MAL, JY1, NDK, ELI, and Z2Z6 classified as “HIV-1 subtype D.” Considerable variation was apparent in the V3 loop. The divergence included the presence of the hexapeptides GP-GRSF and GLGQAL at the cap of the loop in UG06c and UG23c, respectively. The GPGR tetrapeptide in UG06c formed a β-turn configuration similar to that of MN or IIIB. The β-turn was not found to be a likely conformation for GLGQ. The amino acids previously implicated in CD4 binding and the associated neutralizing activity were relatively conserved. To assess a possible impact of the sequence and conformational variations on serological reactivity, UG06c and UG23c were subjected to neutralization assay. Each isolate was neutralized by ∼40% of a panel of preselected, Western blot positive serum specimens from asymptomatic African and North American donors. A strong correlation was observed between the divergence in the V3 loop and discordance in the neutralizing potency of some of the test sera. Discrete subsets of the sera were observed to react with UG06c or UG23c. However, a third subset of the serum samples cross-neutralized UG06c, IIIB, and UG23c despite the marked variation in the primary and secondary structures of the region analyzed. These results indicate that UG06c and UG23c are distinct subtypes that express a relatively conserved neutralizing epitope recognized by certain antiviral antibodies of African and North American origins.
Chromosome Studies in HTLV‐I, -II, and HIV‐1, −2 Cell Lines Infected In Vivo and In VitroWhang-Peng, J. ; Chen, Y. M. A.; Knutsen, T. ; Zhao, W-P. ; Tsai, S.
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HTLV-I, II and HIV-1, 2 are T-cell tropic viruses, all belonging to the retrovirus family. These viruses are transmitted horizontally by intimate contact or through blood products. The study of chromosomal changes in these T cells may enhance our understanding of the nature and mechanism of these viral infections. However, because of the cytopathic effect of these viruses on T cells, the direct observation of abnormalities in these cells is sometimes difficult. We performed chromosomal analysis on six HTLV-I cell lines from patients with HTLV-I-positive leukemia/lymphoma, one HTLV-I variant cell line, and two HTLV-II-positive cell lines. The results of these studies were compared with the findings in an earlier (published) study of direct preparations and short-term cultures of cells from II HTLV-I-positive NIH patients. Our study also included cytogenetic analysis of seven established cell lines and six normal peripheral bloods infected in vitro with the HTLV-IIIBstrain of HTLV-I (five cell lines and six bloods) or HIV-2 (two lines); all were studied both before and after viral infection. The results showed that all six HTLV-I cell lines and the variant cell line had multiple chromosomal changes: three lines had deletions of chromosome 6, with breakpoints between q21 and q25. Nine of the 11 NIH patients with HTLV-I had clonal abnormalities, and six of these nine had chromosome 6 deletions with breakpoints ranging from band q11 to band q23. The high incidence of 6q involvement may be of considerable significance in this clinical subgroup of HTLV-I patients. The two HTLV-II cell lines were established from patients suffering from HTLV-II infection. Both of these cell lines had translocations of chromosome 21 at p11, and both had extra copies of chromosome 20; no known oncogenes or receptors are located on these two chromosomes. Chromosome 17 was the chromosome most frequently involved (three lines) in the five HIV-1-infected cell lines, followed by chromosomes 3 and 21; it is of interest that NGL (also known as C-ERBB2 or NEU oncogene), CD7 (a lymphocyte antigen), HTLV-I receptor, NGFR (nerve growth factor receptor), and MIC6 are all cell surface antigens coded by genes on chromosome 17q. No specific chromosome abnormalities were found in the normal blood samples infected with HIV-1, and no unique chromosome changes were noted in the two cell lines infected with HIV-2; however, the infected H9 line had a chromosome 17 abnormality, a translocation involving band 17p11.
Seroepidemiology of Human T‐Cell Lymphotropic Virus Type I/II in Northeastern BrazilMoreira, Edson D.; Ribeiro, Terezinha T.; Swanson, Priscilla ; Filho, Carlos Sampaio; Melo, Ailton ; Brites, Carlos ; Badaró, Roberto ; Toedter, Gary ; Lee, Helen ; Harrington, William
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We investigated the prevalence of human T-lymphotropic virus I/II (HTLV-I/II) infection in Bahia, a state in Northeastern Brazil. Healthy individuals (n = 327) and patients (n = 337) with a variety of diseases were screened for antibodies to HTLV-I/II using an enzyme immunoassay and Western blot. The overall prevalence among healthy subjects was 1.8% (six of 327); among patients it was 18.4% (62 of 337). Patients with AIDS had the highest prevalence of HTLV-I/II infection, 22.7% (20/88), followed by randomly selected patients from an infectious disease hospital, 19.4% (25 of 129), and tuberculosis patients, 11.1% (10 of 90). Four of 14 patients with myelopathy and three of 16 patients with lymphoid leukemia or lymphoma were seropositive for HTLV-I/II. Sixty-three of 68 HTLV-I/II-positive specimens were then typed: 53 patients were HTLV-I positive, three patients were HTLV-II positive, and in seven patients the assay could not distinguish infection by HTLV-I or II. The finding among HIV-seropositive intravenous drug users in Bahia of coinfection with HTLV-I is contrasted with reports from other areas in which dual infection occurs with HTLV-II. Although high prevalence of HTLV-I infection was found in Bahia, the extent and clinical manifestations of HTLV-I/II infection in Brazil remains imprecisely defined, and further studies are needed.
Prevalence and Persistence of Antibody Titers to Recombinant HIV‐1 Core and Matrix Proteins in HIV‐1 InfectionJanvier, Blandine ; Mallet, François ; Cheynet, Valérie ; Dalbon, Pascal ; Vernet, Guy ; Besnier, Jean Marc; Choutet, Patrick ; Goudeau, Alain ; Mandrand, Bernard ; Barin, Francis
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Numerous studies have established the correlation between antibodies to the core protein p24 of HIV-1 and the progression of the acquired immunodeficiency syndrome. In this study, we analyzed the immune response to two recombinant gag proteins, p24 and p17, in order to evaluate their diagnostic or prognostic significance. Immune response to the immunodominant domain of the transmembrane glycoprotein gp41 was used as a reference. Sera collected from individuals from France and Burundi (Central Africa) at various CDC stages of HIV-1 infection were tested using three sandwich enzyme-linked immunoassays developed with a synthetic peptide corresponding to the immunodominant domain of gp41, SP gp41, or recombinant p24 and p17 cloned and expressed in Escherichia coli. These assays allowed detection of titer antibodies to the three cited antigens. Antibodies to SP gp41 were detected in every HIV-1-positive patient from France and Burundi, generally at a high and stable level. Results obtained with p24 confirmed the value of antibodies to p24 as a prognostic marker only in European and North American populations, since the African population had very high levels of these antibodies even at an advanced stage of the disease. They also confirmed that initial antibody response to p24 is more predictive of outcome than antibody titer change over time. Although antibodies to p17 decline during progression to AIDS, they are frequently absent in French patients at early, asymptomatic stages and therefore could not be used as a prognostic marker. In contrast, antibodies to p17 are significantly less common in African patients with AIDS when compared with symptomless HIV-1-infected African individuals. This observation merits further studies to evaluate the prognostic value of antibodies to p17 in Africans.
HIV‐2 Infection in Bissau, West Africa, 1987–1989Poulsen, Anne-Grethe ; Aaby, Peter ; Gottschau, Adam ; Kvinesdal, Birgit B.; Dias, Francisco ; Mølbak, Kåre ; Lauritzen, Edgar
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In a community study, the HIV-1 and HIV-2 antibody status of the inhabitants of 100 randomly chosen houses in Bissau, West Africa, were followed from 1987 to 1989. There was no HIV-1 infection alone, while the HIV-2 seroprevalence in adults was 8.9% (58 of 652) in 1987 and 10.1% (61 of 603) in 1989. HIV-2 seroprevalence in 15− to 39-year-olds was 6.1% in 1987 and 11.3% in newcomers in 1989 [the Mantel-Haentzel weighted relative risk (RRMH) = 1.86; 95% confidence interval (CI): 1.07–3.24]. Three hundred thirty adults who were HIV-2 seronegative in 1987 were reexamined in 1989; seven had seroconverted. Follow-up time was 700 person years, giving an incidence of HIV-2 infection of 1 per 100 person years. With a history of sexually transmitted disease (STD), the RR of seroconverting was 9.95 (2.31–42.80). Blood transfusions received since 1987 did not result in seroconversions. No case of vertical transmission of HIV-2 was seen. There was an excess mortality in those who were HIV-2 seropositive; however, it was statistically significant only for children (RR = 22.27; 95% Cl: 6.92–71.70; p< 0.0001), not for adults (RR = 2.16; 95% CI: 0.81–5.76; p= 0.23), when considering death from disease only.
Elevated Levels of CD38+CD8+T Cells in HIV Infection Add to the Prognostic Value of Low CD4+T Cell LevelsGiorgi, Janis V.; Liu, Zhiyuan ; Hultin, Lance E.; Cumberland, William G.; Hennessey, Karen ; Detels, Roger
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A cohort of 98 HIV-infected initially AIDS-free homosexual men from the Multicenter AIDS Cohort Study (MACS) was followed for 6 years to investigate whether CD8+cell subsets have prognostic value for progression to AIDS. In the present study, four subsets of CD8+T cells that previously have been shown to be selectively elevated in HIV-infected asymptomatic persons, specifically the CD8+T cell subsets that were CD38+, HLA-DR+, CD57+and L-selectin negative (Leu8-), were measured. Forty-nine of the 98 developed AIDS. Prognostic value of these CD8+cell subsets was evaluated using the proportional hazards model. Levels of both CD38+CD8+and Leu8-CD8+cells individually had prognostic value for progression to AIDS. In contrast, CD57+CD8+and HLA-DR+CD8+cell subset levels did not have prognostic value. After adjustment for level of CD4+T cells, however, only the elevation in the CD38+CD8+cell subset had additional prognostic value. These results suggest that the level of CD38+CD8+cells could be used together with the CD4+T cell level to more accurately predict progression to AIDS among HIV-infected men. These results provide further support for the observation that dramatic and progressive activation of CD8+T cells in HIV infection occurs. The power of elevated levels of the CD38+CD8+subset to predict poor prognosis in this cohort suggests these CD8+T cells reflect an immune stimulation that is ultimately unable to control disease progression.
Induction of HIV‐1 Replication in a Chronically Infected T‐Cell Line by Cytotoxic T LymphocytesHarrer, Thomas ; Jassoy, Christian ; Harrer, Ellen ; Johnson, R. Paul; Walker, Bruce D.
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CD8-positive cytotoxic T cells (CTLs) are activated by recognition of peptide bound to MHC class I molecules on target cells. This human leukocyte antigen-restricted process induces not only lysis of target cells but also secretion of lymphokines by the CTLs, including TNF-α, TNF-β, and IFN-γ. In this study we show that activation of HIV-1-specific CTL clones by their cognate peptide epitopes induces HIV-1 replication in the chronically HIV-1-infected T-cell line ACH-2. The HIV-1-inducing activity correlates with increased levels of TNF-α produced by these CTLs, and can be inhibited by anti-TNF-α antibodies, indicating that the effect is mediated by this cytokine. These studies suggest that activation of CTL in vivo could lead to enhanced viral replication. Although HIV-1-specific CTLs may serve as a host defense to inhibit virus replication, the induction of TNF-α production by these cells may facilitate viral replication in infected bystander cells, contributing to viral persistence and disease pathogenesis.
Effects of Adjuvants and Multiple Antigen Peptides on Humoral and Cellular Immune Responses to gp160 of HIV‐1Levi, Michael ; Rudén, Ulla ; Birx, Deborah ; Loomis, Lawrence ; Redfield, Robert ; Lövgren, Karin ; Åkerblom, Lennart ; Sandström, Eric ; Wahren, Britta
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The capacity of five different adjuvants. AIPO4, a muramyldipeptide formulation (MDP.tsl), Freund's adjuvant, immunostimulating complex and its matrix components to elicit humoral and cellular responses in rabbits immunized with the human immunodeficiency virus type 1 (HIV-1) envelope protein rgp160IIIBwas compared. The highest antibody titers against gp160 and gp41/gp120 epitopes were seen with rgp160 in MDP.tsl or Freund's adjuvant, whereas the broadest responses were seen in rabbits immunized with rgp160 in matrix or MDP.tsl. The broadest spectrum of high-avidity antibodies was also induced by rgp160 in MDP.tsl. Neutralizing titers against HIV-1IIIB, low titers to HIV-1MN, and the most efficient inhibition of viral cell-to-cell spread was seen with rgp160 in MDP.tsl. The strongest and most persisting cellular responses were induced by rgp160 in AIPO4or MDP.tsl. Using MDP.tsl as the adjuvant, we also improved the immune response against gp120 epitopes by boosting rgp160-primed rabbits with rgp160, multiple antigenic peptides (MAPs), or unconjugated peptides. The MAPs induced high neutralizing titers and were superior to rgp160 alone in inducing both humoral and cellular reactivity. MAPs are therefore strong candidates for inclusion into future HIV-1 vaccines.