Nucleotide sequence analysis of the env gene of a new Zairian isolate of HIV-1

Study of different coupling agents in the conjugation of a V3-based synthetic MAP to carrier proteins

The conjugation of synthetic peptides to carrier proteins is a widely used method for immunological studies. Different coupling agents have been described to form the conjugate with carrier proteins. In this paper, we demonstrate that the antibody response toward V3-based synthetic MAPs derived from HIV-1, JY1 isolate, conjugated to two different carrier proteins using either m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS) or beta-maleimidopropionic acid N-hydroxysuccinimide ester (MPS), or succinic anhydride (SA) show different behaviors. An excellent anti-JY1 response without a strong response to the coupling agent is observed in the case of succinic anhydride spacer. In contrast, MBS produces total abrogation of the antibody response with a high response toward the coupling agent.

Anti-HIV-1 activity in vitro of ceftazidime degradation products

Cephalosporins in aqueous solutions generate degradation products that inhibit in vitro HIV-1 replication in cell lines, as well as in primary cells (lymphocytes and macrophages). This effect is observed at concentrations that do not interfere with the normal functions of these cells. Upon chromatographic fractionation of an aqueous solution of hydrolysed ceftazidime, a high molecular weight fraction (MW 8000) with antiviral activity was isolated. The exact chemical nature of the active component responsible for the anti-HIV activity in vitro appears to be complex and is currently unknown. Inhibition of HIV-1 reverse transcriptase and RNase H activity was observed, however, higher concentrations than those needed to inhibit HIV replication were required. The inhibitory action of the hydrolysed ceftazidime was manifested during the early phase of the HIV-1 life-cycle. Despite a lack of a direct effect of the CD4/gp120 interaction, HIV-1 mediated cell fusion was inhibited by the hydrolysed ceftazidime, suggesting that the active principle acts in a very early stage of the viral life-cycle.

Immunogenicity comparison of a multi-antigenic peptide bearing V3 sequences of the human immunodeficiency virus type 1 with TAB9 protein in mice

The multiple antigenic peptide system (MAP) has been proposed as a novel and valuable approach for eliciting antibodies for peptides and developing synthetic vaccines. Multi-epitope polypeptides (MEP) have also been developed as an alternative to the recombinant approach for vaccines. The V3 loop from the HIV type 1 (HIV-1) external glycoprotein (gp120) contains the principal neutralization domain (PND). Antibodies against this region neutralize HIV-1 in vitro and in vivo. In this work, a novel presentation of di-epitope MAP was synthesized. A monomeric MAP carrying two identical JY1 V3 sequences as B-cell epitopes and the 830-843 region of tetanus toxoid as a T-helper cell epitope was synthesized. This basic structure was covalently linked to produce a four-JY1-branched homodimer (JY1-MAP4). Additionally, six different monomeric MAPs, bearing four copies of V3 from isolates LR150, JY1, RF, MN, BRVA and IIIB, were synthesized. These monomers were conveniently linked among themselves to produce homodimeric and heterodimeric MAPs of eight V3 branches (V3-MAP8). JY1-MAP8 elicited higher antibody titers in Balb/c mice than JY1-MAP4. The immunogenicity of two different, hexavalent V3-MAP8 mixtures and the MEP TAB9, which tandems the same six V3 sequences in a single molecule, were compared. The antibody response against the mixtures of the heterodimeric MAP showed a wider recognition pattern of the V3 region, while the homodimeric cocktail showed an intermediate pattern. Antibodies elicited by TAB9 recognized only the JY1, LR150 peptides. These results emphasize the influence of V3 epitope presentation upon the characteristics of the antibody response generated.

Genetic heterogeneity of HIV type 1 subtypes in Kimpese, rural Democratic Republic of Congo

A relatively low and stable seroprevalence of HIV-1 was previously reported among pregnant women attending for antenatal care between 1988 and 1993 in Kimpese, a rural town in the Democratic Republic of Congo (DRC, formerly Zaire). To characterize the HIV-1 subtypes circulating in this area, we have examined a 330-bp fragment of the p17 region of the gag gene of HIV-1 strains obtained from 70 patients (55 mothers, 15 children), of whom 61 were epidemiologically unlinked. Phylogenetic analyses revealed the existence of at least seven HIV-1 subtypes within the Kimpese region. Among the 61 epidemiologically unlinked patients, subtype A was predominant and found in 29 (47.5%) individuals. Other subtypes cocirculating in this rural part of DRC include subtypes C (1.6%), D (9.8%), F (3.2%), G (6.5%), H (21.3%), and J (4.9%). Sequences from four patients did not cluster with any of the currently documented HIV-1 subtypes, in analyses of fragments of both the gag (247 to 330 bp, 197 bp, and 310 bp) and env (340 bp) genes. Overall, comparisons of the gag(p17) gene regions revealed high pairwise divergences (mean, 19.9%; range, 1 to 46%). This level of gag(p17) gene variation in the DRC is considerably greater than previously appreciated. These results are relevant for the molecular epidemiology of HIV-1 in Africa and for the design of a future vaccine against HIV-1 in this region.

HIV/SIV glycoproteins: structure-function relationships

The various functions of human (HIV) and simian (SIV) immunodeficiency virus glycoproteins are similar, so it may be assumed that the overall structure of the folded proteins will be maintained. To preserve structure there must be constraints on sequence variation. The majority of mutations tolerated will be involved in immune escape but changes at some positions are known to have direct effects on glycoprotein expression and function. This allows the virus to change its phenotype and escape immune pressure. These properties will influence the fitness of the virus to infect and replicate in potential hosts. A better understanding of the structure-function relationships of HIV/SIV glycoproteins will assist in the development of vaccines and antivirals. Here, we identify similarities and differences between HIV-1 subtypes and HIV/SIV types that may be relevant to the phenotypes of the various groups. The results are discussed in relation to what is known of domain-function associations for HIV/SIV glycoproteins.

CGP 53437, an orally bioavailable inhibitor of human immunodeficiency virus type 1 protease with potent antiviral activity

CGP 53437 is a peptidomimetic inhibitor of human immunodeficiency virus type 1 (HIV-1) protease containing a hydroxyethylene isostere. The compound inhibited recombinant HIV-1 protease with a Ki of 0.2 nM. The inhibition constant versus human cathepsin D and human cathepsin E was 4 nM. Human pepsin and gastricsin were inhibited with Kis of 8 and 500 nM, respectively, and human renin was inhibited with a Ki of 190 microM. The replication of HIV-1/LAV, HIV-1/Z-84, and HIV-1/pLAI was inhibited with a 90% effective dose of 0.1 microM in acutely infected MT-2 cells. The 50% cytotoxic dose was 100 microM. Similar antiviral activity was observed when the compound was added up to 10 h after infection. At the effective concentration, processing of Gag precursor protein p55 was greatly reduced, confirming an action on the late stage of the virus life cycle, as expected. The efficacy of the inhibitor was also demonstrated by using primary human peripheral blood lymphocytes infected with the HIV-1/LAV strain, low-passage clinical isolates obtained from HIV-1-seropositive individuals (including a zidovudine-resistant strain), and HIV-2/ROD. In these cells, CGP 53437 delayed the onset of HIV replication in a dose-dependent fashion (substantial effects with concentrations of > or = 0.1 microM) as long as the inhibitor was maintained in the culture. CGP 53437 was orally bioavailable in mice. Concentrations in plasma 10-fold in excess of the in vitro antiviral 90% effective dose could be sustained for several hours after oral application of 120 mg/kg. Therefore, CGP 53437 has the potential to be a therapeutically useful anti-HIV agent for the treatment of AIDS.

Genetic diversity of human immunodeficiency virus type 1 strains in Kinshasa, Zaire

The envelope (env) gene of human immunodeficiency virus type 1 (HIV-1) was amplified by polymerase chain reaction (PCR) from the peripheral blood mononuclear cells (PBMCs) of 14 HIV-1-infected women from Kinshasa, Zaire. Amplified DNA was directly sequenced with a primer specific for the HIV-1 env C2 region. The predicted amino acid sequences for the C2-V3 region for the 14 specimens are presented. The tetrapeptide sequence, GPGQ, located at the crown of the V3 loop, is conserved in all specimens. The same tetrapeptide sequence is present in the Zairian isolate MAL, but not in other published Zairian isolates (Z6, ELI, Z321, JY1, and NDK). Sequence comparison of the env C2-V3 region among the 14 specimens from Kinshasa revealed a 9-25% range of nucleotide divergence, with an average of 16%. Divergence between the 14 specimens and the Zairian isolates MAL, Z6, ELI, Z321, JY1, and NDK ranged from 13 to 31%. A range of 18-28% nucleotide sequence divergence was demonstrated between the 14 Kinshasa specimens and the North American isolate MN. These results demonstrate the importance of examining HIV-1 samples from diverse geographic origins in the development of effective HIV-1 vaccines.

Phylogenetic and serological characterization of two Ugandan HIV-1 isolates

HIV-1 isolates Ug06 and Ug23 were established in culture from peripheral blood mononuclear cells (PBMCs) of Ugandan subjects. The isolates were studied for phylogenetic and serological relationships with each other and with the laboratory strains, HTLV-IIIB and HIV-1MN. The results suggest that the Ugandan isolates are related to different subgroups of African viruses with 17.3% of genetic distance between UG06 and the U455 provirus (Uganda); and 12.6% of genetic distance between UG23 and the JY1 provirus (Zaire). Analysis of the predicted amino acid sequences for Ug06 and Ug23 showed marked sequence heterogeneity in the V3 region and CD4-binding site. A conserved amino acid sequence was identified in the C-terminal immunodominant region of the envelope glycoprotein gp120. The isolates were compared in virus-neutralization experiments with HTLV-IIIB and HIV-1MN stocks, using panels of Western blot-positive North American and Ugandan sera. The North American serum samples showed broad neutralizing activity against both of the Ugandan isolates. However, the Ugandan serum panel demonstrated strain-specific activity against either Ug06 or Ug23. Furthermore, the African serum specimens showed higher prevalence and titers of neutralizing activity against the HIV-1MN stock as compared with HTLV-IIIB.

Sequence analysis of the gp120 region of the env gene of Ugandan human immunodeficiency proviruses from a single individual

DNA sequences encoding the surface glycoprotein gp120 of the human immunodeficiency virus type 1 (HIV-1) were amplified by the polymerase chain reaction (PCR) from peripheral blood mononuclear cells obtained from a Ugandan AIDS patient. The PCR-amplified DNA was cloned into a phagemid vector and nine clones sequenced. The gp120 sequences of the proviruses were similar to that of the Zairian isolate HIV-JY1 and unlike that of another Ugandan provirus, U455. Six of the clones were closely related to each other (maximum nucleotide sequence divergence 1.9%), and had a V3 amino acid sequence similar to that frequently seen in recent isolates from Uganda. Two others formed a second group that diverged from the first by an average of 6.0% at the nucleotide level, resulting in a 12.5% divergence of amino acid sequence. These divergent clones had extensive amino acid sequence changes not only in the V3 region, which was highly atypical, but also in V1 and V4, and to a lesser extent in V2 and V5. A further proviral clone had a sequence intermediate between those of the other two groups of clones.

The replicative restriction of lymphocytotropic isolates of HIV-1 in macrophages is overcome by TGF-beta

In vitro exposure of human blood monocyte-derived macrophages to T-cell tropic human immunodeficiency virus (HIV) isolates fails to establish a productive viral infection. Several studies have shown that such preferential HIV-1 replication in T cells or in mononuclear phagocytes (HIV tropism) may be determined by distinct viral characteristics. In the present study it was demonstrated that transforming growth factor-beta (TGF-beta), a factor known to be produced by platelets, macrophages, and other cells present at a wound site, can act as a mediator in overcoming the lymphocytotropic restriction of several well-characterized viral isolates of HIV-1 (i.e., LAV, Z84, pLAI, NY5). Macrophages infected with these isolates show cytopathic changes comparable to those seen upon infection with the monocytotropic isolate ADA. To achieve this effect with TGF-beta, the factor must be present after the infection period. The emerging virus retains its original cellular tropism. Based on these observations the authors propose a role for TGF-beta in the establishment and progression of HIV infection and disease.

Sequence analysis of the V3 loop regions of the env genes of Ugandan human immunodeficiency proviruses

Ugandan strains of human immunodeficiency virus type 1 (HIV-1) were isolated by cocultivation of peripheral blood lymphocytes from infected individuals with cord blood lymphocytes. Sequences from the V3 region of the env gene were amplified by the polymerase chain reaction (PCR) from chromosomal DNA obtained from low passage virus cultures. The PCR products from 13 Ugandan isolates were cloned into a phagemid vector and sequenced. Many isolates contained divergent V3 loop sequences and adjacent regions: diversity was associated with codon deletions or duplications and with nucleotide substitutions, especially G----A transitions. Proviruses from some of the cultures showed extensive diversity within the V3 loop sequences but others were more homogeneous. The V3 loop apices were conserved in 6 of the Ugandan proviruses and these were very similar to the equivalent regions of several Zairean proviruses. The V3 loop apices of African isolates of HIV-1 are divergent from those of North American isolates. The possible biological consequences of this divergence are discussed.

Nucleotide sequence of a Ugandan HIV-1 provirus reveals genetic diversity from other HIV-1 isolates

A Ugandan isolate of human immunodeficiency virus type 1 (HIV-1), designated U455, was adapted to growth in U937 cells, the provirus cloned into the lambda L47.1 vector, and its DNA sequence determined. The sequences of some of the U455 genes showed a marked divergence from those of North American and other African isolates. The sequenced clone was defective with single in-phase stop codons in the vpr and env genes and frame shift, resulting in a stop codon, within the vpu gene.

Molecular cloning and characterization of a German HIV-1 isolate

The genetic diversity of HIV-1 is well documented. Except for the HIV-1 isolate LAV-1BRU, no nucleic acid sequence of a European isolate of HIV-1 has been published to date. To further investigate the extent of the genetic variability and the evolution of HIV-1, we have isolated, cloned, and subsequently sequenced HIV-1 from a German patient with AIDS-related complex. Comparative studies of the nucleic acid sequence revealed that this isolate, designated HAN2, is highly divergent from the North American and African subtypes of HIV-1 and may represent a European subtype of HIV-1. Furthermore, a full-length molecular clone was derived from this isolate which was infectious in human T-cell lines. Therefore this new isolate will be particularly useful for studies on the genetic evolution and biology of HIV-1 as well as for testing antiviral substances and for developing vaccines.

Evolutionary origin of human and simian immunodeficiency viruses

From what viruses the human immunodeficiency viruses (HIVs) originated is an extremely controversial question. To address this question, we have analyzed nucleotide sequences of simian immunodeficiency viruses (SIVs) and HIVs by using the techniques for understanding molecular evolution. In particular, we compared the nucleotide sequences of whole genomes, gene region by gene region, between a given pair of viruses, including four types of SIVs--isolated from mandrills (Papio sphinx), African green monkeys (Cercopithecus aethiops), sooty mangabeys (Cercocebus atys), and rhesus macaques (Macaca mulatta)--as well as HIVs. Phylogenetic trees for all gene regions examined showed that the present HIVs may have emerged as different variants of SIVs of Old World monkeys, possibly from recombination between viruses related to SIVs.

A recombinant clone of HIV-1 preferentially transmitted in normal peripheral blood mononuclear cells

To study biologic properties associated with specific regions of HIV-1, a chimera, pHX-JY1, was constructed by exchanging the vif-env region of a Zairian molecular clone (JY1) with that of pHXB2gpt, a full-length biologically active proviral clone of North American origin. Virus was produced by transfection of permissive cells with parental and recombinant clones, and the biologic and molecular properties of these viruses were compared. Virus derived from pHXB2gpt infected phytohemagglutinin (PHA)-activated normal peripheral blood mononuclear cells (PBMC) and CD4+ leukemic T cell lines equally well. In contrast, virus derived from pHX-JY1 was transmitted slowly to both PBMC and cell lines, and the infectivity of pHX-JY1 virus was two orders of magnitude greater for PBMC than for T cell lines. All essential viral genes in the exchanged JY1 vif-env region were intact and functioned comparably to those of the parent clone in transfected COS-1 cells. The findings suggest differences in these regions of the HIV-1 genome may play an important role in differential cell tropism.

Nucleotide sequences of gag and env genes of a Japanese isolate of HIV-1 and their expression in bacteria

A DNA clone of HIV-1, JH3, was isolated from a Japanese patient with hemophilia and the gag and env genes were sequenced. The nucleotide and deduced amino acid sequences were similar to those reported and showed high divergence in the env gene, particularly in the extracellular domain of the env. The genetic variation of JH3 isolated from a Mongolian was within the range of those of isolates from whites and blacks. The gag and env polypeptides were efficiently expressed in E. coli as fusion proteins with beta-galactosidase, and the products were shown to be useful as diagnostic reagents.