V3 Loop Sequences Research Articles

Genotypic alteration of HAART-persistent HIV-1 reservoirs in vivo

Three HIV-1-infected individuals, on virally-suppressive highly active anti-retroviral therapy (HAART), were treated in vivo with anti-retroviral inhibitor intensification and cell stimulatory therapies in attempting to eradicate latent viral reservoirs. Afterwards, the patients ceased all anti-retroviral drugs. Sequences of the V3 region of HIV-1 envelope protein (ENV) from patient peripheral blood mononuclear cell (PBMC) proviral DNA, patient blood plasma viral RNA and virion-associated RNA from viruses amplified by patient cell co-culture, were obtained before, during, and certain times after the clinical regimen. As anticipated, the V3 loop sequencing results indicate diversity in viral strain complexity among the individual patients. However, the detection of unique V3 ENV signature sequences or V3 signatures of low frequency, relative to those observed prior to therapy, indicate that the expression of specific viruses, or viruses of low abundance, can be induced through stimulation in vivo. Furthermore, this stimulation or general immune activation therapy (IAT) approach, consisting of administration of the anti-T-cell receptor antibody, OKT3, and IL-2 in vivo, appeared to have subsequently altered the genotype of the persistent viral reservoir in peripheral blood cells for two of the three patients.

High frequency of syncytium-inducing and CXCR4-tropic viruses among human immunodeficiency virus type 1 subtype C-infected patients receiving antiretroviral treatment.

Human immunodeficiency virus type 1 (HIV-1) subtype C viruses have been found to almost exclusively use the chemokine receptor CCR5 as a coreceptor for entry, even in patients with advanced AIDS. We have characterized subtype C virus isolates from 28 patients from Harare, Zimbabwe, 20 of whom were receiving antiretroviral treatment. Virus from 10 of the treated patients induced syncytium formation (SI virus) when cultured with MT2 cells. Only non-syncytium-inducing (NSI) virus was cultured from the peripheral blood mononuclear cells of the eight patients who had not received treatment. The majority of these subtype C SI viruses were capable of using both CCR5 and CXCR4 as coreceptors for viral entry, and the consensus V3 loop sequences from the SI viruses displayed a high net charge compared to those of NSI viruses. While those on treatment had reverse transcriptase (RT) and protease mutations, there was no clear association between RT and protease drug resistance mutations and coreceptor tropism. These results suggest that CXCR4-tropic viruses are present within the quasispecies of patients infected with subtype C virus and that antiretroviral treatment may create an environment for the emergence of CXCR4 tropism.

The CCR5 and CXCR4 coreceptors are both used by human immunodeficiency virus type 1 primary isolates from subtype C.

Human immunodeficiency virus type 1 (HIV-1) subtype C viruses with different coreceptor usage profiles were isolated from 29 South African patients with advanced AIDS. All 24 R5 isolates were inhibited by the CCR5-specific agents, PRO 140 and RANTES, while the two X4 viruses and the three R5X4 viruses were sensitive to the CXCR4-specific inhibitor, AMD3100. The five X4 or R5X4 viruses were all able to replicate in peripheral blood mononuclear cells that did not express CCR5. When tested using coreceptor-transfected cell lines, one R5 virus was also able to use CXCR6, and another R5X4 virus could use CCR3, BOB/GPR15, and CXCR6. The R5X4 and X4 viruses contained more-diverse V3 loop sequences, with a higher overall positive charge, than the R5 viruses. Hence, some HIV-1 subtype C viruses are able to use CCR5, CXCR4, or both CXCR4 and CCR5 for entry, and they are sensitive to specific inhibitors of entry via these coreceptors. These observations are relevant to understanding the rapid spread of HIV-1 subtype C in the developing world and to the design of intervention and treatment strategies.

Generating neutralizing antibodies, Th1 response and MHC non restricted immunogenicity of HIV-I env and gag peptides in liposomes and ISCOMs with in-built adjuvanticity

For enhancing immunogenicity and develop vaccine strategies using peptide based constructs against HIV-1, a chimeric peptide containing V3 loop and transmembrane sequence of gp41 with two glycine motifs as spacer was constructed. The V3-gp41, gp41 peptide and p17 and p24 peptides separately or in a cocktail were entrapped with or without MA729 as an immunoadjuvant in liposomes or ISCOMs. The immunogenicity, antigen induced T-cell proliferation and cytokine profiles of various formulations were studied in four different inbred strains of mice of H-2d, H-2b, H-2k and H-2q haplotypes, keeping alum as a control adjuvant. Both liposomes and ISCOM preparations elicited high titer and long lasting antibody response (60 days and above). When compared to the alum formulation, the liposomes co-entrapped with MA729 produced high antibody levels, comparable with that induced by ISCOMs. Peptide in alum, liposomes and ISCOMs enhanced both antigen specific IgG2a and IgG2b isotypes and high T-cell stimulation index. Peptide formulations also induced antibodies with high affinity and in vitro neutralizated the formation of HIV-1 syncytia. T-cell supernatants contained high levels of IFN-γ and IL-2. Thus formulation in these adjuvants induced a predominant Th1 like response with MA729 as a versatile novel delivery vehicle for stimulating the appropriate arm of the immune response that can selectively modulate MHC class I or MHC class II response. The above peptide can be of wide vaccination interest as a means to improve immune responses to several other HIV-1 antigens and may serve as candidates for vaccine development.

CD4-independent infection of HIV and SIV: implications for envelope conformation and cell tropism in vivo.

CD4-independent infection of HIV and SIV: implications for envelope conformation and cell tropism in vivo.

The sequential introduction of HIV-1 subtype B and CRF01AE in Singapore by sexual transmission: accelerated V3 region evolution in a subpopulation of Asian CRF01 viruses.

The rapid spread of the human immunodeficiency virus type 1 (HIV-1) circulating recombinant form (CRF) 01AE throughout Asia demonstrates the dynamic nature of emerging epidemics. To further characterize the dissemination of these strains regionally, we sequenced 58 strains from Singapore and found that subtype B and CRF01 were introduced separately, by homosexual and heterosexual transmission, respectively. Protein similarity scores of the Singapore CRF01, as well as all Asian strains, demonstrated a complex distribution of scores in the V3 loop--some strains had very similar V3 loop sequences, while others were highly divergent. Furthermore, we found a strong correlation between the loss of a V3 glycosylation site and the divergent strains. This suggests that loss of this glycosylation site may make the V3 loop more susceptible to immune surveillance. The identification of a rapidly evolving population of CRF01AE variants should be considered when designing new candidate vaccines and when evaluating breakthrough strains from current vaccine trials.

Crystal Structure of a Human Rhinovirus that Displays Part of the HIV-1 V3 Loop and Induces Neutralizing Antibodies against HIV-1

We report the 2.7 Å resolution structure of a chimeric rhinovirus, MN-III-2, that displays part of the HIV-1 gp120 V3 loop and elicits HIV-neutralizing antibodies. The V3 loop insert is dominated by two type I β turns. The structures of two adjacent tripeptides resemble those of analogous segments in three Fab/V3 loop peptide complexes. Although two of the three corresponding antibodies bind and neutralize MN-III-2 well, only one of the three can bind without significant rearrangement. These results suggest that the V3 loop insert: (1) can share some local conformational similarity to V3 loop sequences presented on different structural frameworks; (2) must be able to adopt multiple conformations, even in a relatively constrained environment; and (3) may mimic the conformational variability of the epitope on HIV-1, increasing the likelihood of eliciting appropriate neutralizing immune responses.

Envelope-dependent, cyclophilin-independent effects of glycosaminoglycans on human immunodeficiency virus type 1 attachment and infection.

Cell surface glycosaminoglycans (GAGs), in particular heparan sulfate (HS), have been proposed to mediate the attachment of human immunodeficiency virus type 1 (HIV-1) to target cells prior to virus entry, and both the viral gp120 envelope protein and virion-associated cyclophilin A (CypA) have been shown to directly interact with HS and its analogues. To determine the role of GAGs in HIV attachment and infection, we generated HIV-susceptible derivatives of CHO cell lines that either express high levels of GAGs (CHO-K1) or lack GAGs (pgsA745). Using a panel of HIV-1 envelopes, we found that cell surface GAG-mediated effects on virion attachment and infection vary in an envelope strain-dependent but coreceptor-independent manner. In fact, cell surface GAG-mediated enhancement of infection is confined to isolates that contain a highly positively charged V3-loop sequence, while infection by most strains is apparently inhibited by the presence of GAGs. Moreover, the enhancing and inhibitory effects of polycations and polyanions on HIV-1 infection are largely dependent on the presence of cell surface GAGs. These observations are consistent with a model in which GAGs influence in vitro HIV-1 infection primarily by modifying the charge characteristics of the target cell surface. Finally, the effects of GAGs on HIV-1 infection are observed to an equivalent extent whether CypA is present in or absent from virions. Overall, these data exclude a major role for GAGs in mediating the attachment of many HIV-1 strains to target cells via interactions with virion-associated gp120 or CypA.

Replication and compartmentalization of HIV-1 in kidney epithelium of patients with HIV-associated nephropathy.

HIV-associated nephropathy is a clinicopathologic entity that includes proteinuria, focal segmental glomerulosclerosis often of the collapsing variant, and microcystic tubulointerstitial disease. Increasing evidence supports a role for HIV-1 infection of renal epithelium in the pathogenesis of HIV-associated nephropathy. Using in situ hybridization, we previously demonstrated HIV-1 gag and nef mRNA in renal epithelial cells of patients with HIV-associated nephropathy. Here, to investigate whether renal epithelial cells were productively infected by HIV-1, we examined renal tissue for the presence of HIV-1 DNA and mRNA by in situ hybridization and PCR, and we molecularly characterized the HIV-1 quasispecies in the renal compartment. Infected renal epithelial cells were removed by laser-capture microdissection from biopsies of two patients, DNA was extracted, and HIV-1 V3-loop or gp120-envelope sequences were amplified from individually dissected cells by nested PCR. Phylogenetic analysis of kidney-derived sequences as well as corresponding sequences from peripheral blood mononuclear cells of the same patients revealed evidence of tissue-specific viral evolution. In phylogenetic trees constructed from V3 and gp120 sequences, kidney-derived sequences formed tissue-specific subclusters within the radiation of blood mononuclear cell-derived viral sequences from both patients. These data, along with the detection of HIV-1-specific proviral DNA and mRNA in tubular epithelium cells, argue strongly for localized replication of HIV-1 in the kidney and the existence of a renal viral reservoir.

Homogeneous quasispecies in 16 out of 17 individuals during very early HIV-1 primary infection.

To measure HIV-1 quasispecies diversity in very recently infected male and female plasma donors. HIV-1 RNA testing of blood and plasma donations was used to select anti HIV-1 antibody negative, HIV-1 RNA positive plasma samples from 13 males and four females undergoing primary infection. To determine whether these early viral populations were clonal or oligoclonal, heteroduplex mobility assays were performed on multiple independently generated envelope PCR products. Genetically heterogeneous quasispecies where subcloned and their divergent envelope variants sequenced. Because of frequent plasma donations in this population, HIV-1 RNA quasispecies could be studied during very early primary infection. Heteroduplex mobility assays detected the presence of genetically distinct variants in four of the 17 plasma donors. DNA sequence analysis showed that one case was due to a G to A hyper-mutation event and that two cases were caused by the presence of in-frame insertions/deletions resulting in DNA heteroduplex mobility shifts. The early plasma quasispecies of one female contained highly divergent variants differing by up to 6% substitution and multiple insertions/deletions, a level of divergence unlikely to have been generated de novo following transmission. V3 loop sequences analysis indicated the presence of non-syncitium inducing genotypes in 14 out of 17 primary infection cases. Plasma viremia is generally genetically homogeneous even during the very early phase of primary infection when viremia is first detected and still rising exponentially. Evidence for the transmission of multiple variants was detected in only one out of four women and none of 13 men undergoing primary infection with subtype B HIV-1.

Resistance to neutralizing antibody and expanded coreceptor usage are associated with human immunodeficiency virus type 1 isolates derived from chimpanzees with pathogenic infections.

Immunologic and biologic factors associated with the progression to AIDS in HIV-1-infected chimpanzees were investigated. Chimpanzee C499 was euthanized in 1996 as a result of the development of AIDS approximately 11 years after infection with HIV-1. At the time of initial disease development (September 1995), blood from this animal was transfused to an uninfected chimpanzee, C455, resulting in a rapid loss of CD4(+) T cells. Virus isolates were derived from both animals and termed HIV-1(JC) (derived from C499 at the time of disease development; JC isolate) and HIV-1(NC) (derived from C455 1 month posttransfusion; NC isolate). In vitro studies demonstrate that the parental viruses used to inoculate C499 were susceptible to neutralization by serum from that animal. In contrast, serum from C499 at any time was unable to neutralize the JC or NC isolates. Similarly, the JC and NC isolates were highly resistant to neutralization by serum from C455. However, serum from C455 was also unable to neutralize either of the parental viruses or any of the normally neutralization sensitive isolates tested. Serum samples from the two additional chimpanzees that were inoculated with the NC isolate were also unable to neutralize these isolates. Coreceptor usage of the uncloned JC and NC isolates was somewhat expanded when compared with that of LAV1b and SF2. However, molecular clones derived from the JC and NC isolates (JC16 and NC7) displayed only a limited coreceptor repertoire despite having unique V3 loop sequences. The results suggest that the JC and NC isolates are neutralization escape mutants and display a different phenotype than the parental strains LAV1b and SF2.

Determinants for the syncytium-inducing phenotype of HIV-1 subtype F isolates are located in the V3 region.

The HIV-1 syncytium-inducing phenotype is determined by virus replication and the presence of cytopathic effects in MT-2 cells. There is a strong correlation between the syncytium-inducing/MT-2-tropic phenotype and positively charged amino acids at positions 306 and 320 in the V3 loop for HIV-1 subtypes A, B, D, and E. In contrast, a lack of correlation between signature amino acids and syncytium formation in MT-2 cells for subtype F viruses from Romania has been reported. Virus phenotype and V3 loop amino acid sequences from Romanian HIV-1 subtype F isolates were further investigated in the present study. While the determinants of MT-2 tropism are clearly harbored in the V3 loop of subtype F isolates from Romania, the induction of syncytium formation occurs in the presence or absence of positively charged amino acids at positions 306, 320, and/or 324. However, the net positive charge of V3 loop sequences derived from syncytium-inducing viruses was higher than that of the nonsyncytium-inducing isolate.

Variable sensitivity of CCR5-tropic human immunodeficiency virus type 1 isolates to inhibition by RANTES analogs.

Aminooxypentane (AOP)-RANTES efficiently and specifically blocks entry of non-syncytium-inducing (NSI), CCR5-tropic (R5) human immunodeficiency virus type 1 (HIV-1) into host cells. Inhibition appears to be mediated by increased intracellular retention of the CCR5 coreceptor- AOP-RANTES complex and/or competitive binding of AOP-RANTES with NSI R5 HIV-1 isolates for CCR5. Although AOP-RANTES and other beta-chemokine analogs are potent inhibitors, the extreme heterogeneity of the HIV-1 envelope glycoproteins (gp120 and gp41) and variable coreceptor usage may affect the susceptibility of variant HIV-1 strains to these drugs. Using the same peripheral blood mononuclear cells (PBMC) with all isolates, we observed a significant variation in AOP-RANTES inhibition of 13 primary NSI R5 isolates; 50% inhibitory concentrations (IC(50)) ranged from 0.04 nM with HIV-1(A-92RW009) to 1.3 nM with HIV-1(B-BaL). Experiments performed on the same isolate (HIV-1(B-BaL)) with PBMC from different donors revealed no isolate-specific variation in AOP-RANTES IC(50) values but did show a considerable difference in virus replication efficiency. Exclusive entry via the CCR5 coreceptor by these NSI R5 isolates suggests that variable inhibition by AOP-RANTES is not due to alternative coreceptor usage but rather differential CCR5 binding. Analysis of the envelope V3 loop sequence linked a threonine or arginine at position 319 (numbering based on the HXB2 genome) with AOP-RANTES resistance. With the exception of one isolate, A319 was associated with increased sensitivity to AOP-RANTES inhibition. Distribution of AOP-RANTES IC(50) values with these isolates has promoted ongoing screens for new CCR5 agonists that show broad inhibition of HIV-1 variants.

Epidemic transmission of human immunodeficiency virus in renal dialysis centers in Egypt.

In 1993 an epidemic of human immunodeficiency virus (HIV) infection occurred among 39 patients at 2 renal dialysis centers in Egypt. The centers, private center A (PCA) and university center A (UCA) were visited, HIV-infected patients were interviewed, seroconversion rates at UCA were calculated, and relatedness of HIV strains was determined by sequence analysis; 34 (62%) of 55 patients from UCA and 5 (42%) of 12 patients from PCA were HIV-infected. The HIV seroconversion risk at UCA varied significantly with day and shift of dialysis session. Practices that resulted in sharing of syringes among patients were observed at both centers. The analyzed V3 loop sequences of the HIV strain of 12 outbreak patients were >96% related to each other. V3 loop sequences from each of 8 HIV-infected Egyptians unrelated to the 1993 epidemic were only 76%-89% related to those from outbreak strains. Dialysis patients may be at risk for HIV infection if infection control guidelines are not followed.

Analysis of the V3 loop sequences from 12 HIV type 1-infected patients from Colombia, South America.

AIDS Research and Human RetrovirusesVol. 15, No. 12 Analysis of the V3 Loop Sequences from 12 HIV Type 1-Infected Patients from Colombia, South AmericaMaria-Cristina Navas, Franck Letourneur, Emmanuel Gomas, Jorge Boshell, and Sentob SaragostiMaria-Cristina NavasSearch for more papers by this author, Franck LetourneurSearch for more papers by this author, Emmanuel GomasSearch for more papers by this author, Jorge BoshellSearch for more papers by this author, and Sentob SaragostiSearch for more papers by this authorPublished Online:5 Jul 2004https://doi.org/10.1089/088922299310430AboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byCharacterization of HIV Type 1 Envelope Sequence Among Viral Isolates Circulating in the Northern Region of Colombia, South America José-Luis Villarreal, Jaime Gutiérrez, Lucy Palacio, Martha Peñuela, Robin Hernández, Guy Lemay, and Guillermo Cervantes-Acosta21 November 2012 | AIDS Research and Human Retroviruses, Vol. 28, No. 12Antiretroviral drug resistance in HIV-infected patients in ColombiaInternational Journal of Infectious Diseases, Vol. 14, No. 4Neutralizing inter-clade cross-reactivity of HIV-1 V1/V2-specific secretory immunoglobulin A in Colombian and French cohortsAIDS, Vol. 23, No. 16Molecular Epidemiology of HIV Type 1 in Northern Brazil: Identification of Subtypes C and D and the Introduction of CRF02_AG in the Amazon Region of Brazil Luiz F.A. Machado, Marluísa O.G. Ishak, Antonio C.R. Vallinoto, José Alexandre R. Lemos, Vania N. Azevedo, Marcio R.C. Moreira, Maria I.M. Souza, Luciana M. Fernandes, Lia L.B. Souza, and Ricardo Ishak20 October 2009 | AIDS Research and Human Retroviruses, Vol. 25, No. 10Molecular Epidemiology of HIV-1 in Venezuela: High Prevalence of HIV-1 Subtype B and Identification of a B/F Recombinant InfectionJAIDS Journal of Acquired Immune Deficiency Syndromes, Vol. 32, No. 3HIV-1 Polymorphism: a Challenge for Vaccine Development - A ReviewMemórias do Instituto Oswaldo Cruz, Vol. 97, No. 2Molecular Characterization of Human Immunodeficiency Virus Type 1-Infected Individuals from Bolivia Reveals the Presence of Two Distinct Genetic Subtypes B and F K. G. Velarde-Dunois, M. L. Guimarães, C. La Fuente, R. Andrade, R. Arévalo, S. Pantoja, R. Mariscal, R. Sandoval, F. Iriarte, V. Chamón, M. L. Melgar, R. Carvajal, and M. G. Morgado5 July 2004 | AIDS Research and Human Retroviruses, Vol. 16, No. 17Emerging genetic diversity of HIV-1 in South AmericaAIDS, Vol. 14, No. 12 Volume 15Issue 12Aug 1999 To cite this article:Maria-Cristina Navas, Franck Letourneur, Emmanuel Gomas, Jorge Boshell, and Sentob Saragosti.Analysis of the V3 Loop Sequences from 12 HIV Type 1-Infected Patients from Colombia, South America.AIDS Research and Human Retroviruses.Aug 1999.1141-1144.http://doi.org/10.1089/088922299310430Published in Volume: 15 Issue 12: July 5, 2004PDF download

Similar HIV-1 subtype A V3 loop sequences are found in dual HIV-1/HIV-2 and HIV-1-only seropositives in Ghana.

775 G H AN A A N D IV ORY COAS T are situated between the two major initial foci of the African HIV-1 and HIV-2 epidemics. It is in such countries that dual HIV-1/HIV-2 serological reactivity (dual seropositivity) is most common. The proportion of dual seropositivity has increased in West Africa countries, where HIV-2 was initially the main cause of the epidemic. The diagnosis of dual HIV-1/HIV-2 infections may be complicated, as HIV-2 DNA cannot always be detected and the levels of HIV-2 DNA in dual seropositives may decrease with progression to AIDS. Also, even low levels of HIV-2 antibodies can imply dual infection. 4 The lack of HIV-2 DNA and/or low HIV2 antibody level may thus be related not only to the diagnostic methods used, but possibly to suppression of HIV-2 by HIV-1. HIV-2 infection may protect against HIV-1 superinfection, which could have impact on the development of protective vaccines. It has been suggested that the HIV-2 protection from subsequent HIV-1 infection is mediated by b -chemokines and CD8 1 cells, and is restricted to HIV-1 strains using the CCR5 receptor. Furthermore, conflicting reports on cross-neutralization of HIV-1 isolates by HIV-2 sera exist. Since the V3 loops of the viruses are important for chemokine receptor usage and neutralization, a critical look at this region is of interest for understanding the interaction between HIV-1 and HIV-2 in vivo. We therefore determined the V3 sequences of HIV-1 strains obtained from epidemiologicall y matched patients seropositive for both types or HIV-1 only. Peripheral blood mononuclear cells (PBMCs) were obtained from patients who were HIV seropositive by World Health Organization (WHO) criteria (Table 1), attending semi rural or urban AIDS clinics in the southern part of Ghana during 1996. Ethical permission was obtained from the Ministry of Health (Accra, Ghana), the University of Ghana Medical School (Accra, Ghana), and the Huddinge Hospital (Huddinge/ Stockholm, Sweden). Lymphocyte subset determination was performed by a flow cytometric method and the patients classfied as asymptomatic or symptomatic on the basis of the WHO expanded clinical definition of AIDS. Two commercial kits were used for analysis of anti-HIV reactivity. In brief, a dot immunobinding assay (Target HIV1-HIV2; V-Tech, Pomona, CA), which is based on homologous synthetic peptides in the HIV-1 and HIV2 transmembrane proteins, was used for screening. Confirmatory tests with a line immunoassay including recombinant proteins and peptides for HIV-1, and a peptide for HIV-2 (Innolia; NV Innogenetics, Antwerp, Belgium), were done according to the manufacturer instructions. Samples that reacted with HIV1 gp41 (and other bands) with a rating of 1 1 or above were considered HIV-1 seropositive, and those having additional reactivities of at least 11 with the HIV-2 gp36 band were classified as dual seropositive. Two million PBMCs were lysed and DNA was extracted by phenol±chloroform and ethanol precipitation. To amplify an env fragment encoding the V3 loop, the following outer primers were used: JA 167 [5 9 TAT C(C/T)T TTG AGC CAA TTC C(C/T)A TAC A] and JA 170 [5 9 GTG ATG TAT T(A/G)C A(A/G)T AGA AAA ATT C], with conditions previously described. For the nested step, primers V3-3 (59 biotin-AATGGCAGTCTAGCAGAA) and V3-4-M13 (5 9 M13-CTGGGTCCCCTCCTGAGG) were used. Direct sequencing was performed using magnetic beads with covalently coupled streptavidin (Dynabeads, M280-streptivid in; Dynal A.S., Oslo, Norway), an AutoRead sequencing kit (Pharmacia Biotech, Uppsala, Sweden), and an automated laser fluorescence sequencer (ALFexpress; Pharmacia Biotech). Sequences approximately 252 or 249 nucleotides long were manually aligned. The phylogenetic analysis was done with the TREEDON package and 1000 bootstrap resamplings. Distance calculations were derived by neighbor joining, using the Jin and Nei method ( g distribu-

Role of the HIV type 1 glycoprotein 120 V3 loop in determining coreceptor usage.

Macrophage (M)-tropic HIV-1 isolates use the beta-chemokine receptor CCR5 as a coreceptor for entry, while T cell line-adapted (TCLA) strains use CXCR4 and dual-tropic strains can use either CCR5 or CXCR4. To investigate the viral determinants involved in choice of coreceptor, we used a fusion assay based on the infection of CD4+ HeLa cells that express one or both coreceptors with Semliki Forest virus (SFV) recombinants expressing the native HIV-1 gp160 of a primary M-tropic isolate (HIV-1BX08), a TCLA isolate (HIV-1LAI), or a dual-tropic strain (HIV-1MN). We examined whether the V3 region of these glycoproteins interacts directly with the corresponding coreceptors by assaying coreceptor-dependent cell-to-cell fusion mediated by the different recombinants in the presence of various synthetic linear peptides. Synthetic peptides corresponding to different V3 loop sequences blocked syncytium formation in a coreceptor-specific manner. Synthetic V2 peptides were also inhibitory for syncytium formation, but showed no apparent coreceptor specificity. A BX08 V3 peptide with a D320 --> R substitution retained no inhibitory capacity for BX08 Env-mediated cell-to-cell fusion, but inhibited LAI Env-mediated fusion as efficiently as the homologous LAI V3 peptide. The same mutation engineered in the BX08 env gene rendered it able to form syncytia on CD4+CXCR4+CCR5-HeLa cells and susceptible to inhibition by SDF-1alpha and MIP-1beta. Other substitutions tested (D320 --> Q/D324 --> N or S306 --> R) exhibited intermediate effects on coreceptor usage. These results underscore the importance of the V3 loop in modulating coreceptor choice and show that single amino acid modifications in V3 can dramatically modify coreceptor usage. Moreover, they provide evidence that linear V3 loop peptides can compete with intact cell surface-expressed gp120/gp41 for CCR5 or CXCR4 interaction.

Characterization of V3 loop sequences from HIV type 1 subtype B in South Korea: predominance of the GPGS motif.

AIDS Research and Human RetrovirusesVol. 15, No. 7 Characterization of V3 Loop Sequences from HIV Type 1 Subtype B in South Korea: Predominance of the GPGS MotifEun-Young Kim, Yeon-Sook Cho, Sung-Ho Maeng, Chun Kang, Jeong-Gu Nam, and Joo-Shil LeeEun-Young KimSearch for more papers by this author, Yeon-Sook ChoSearch for more papers by this author, Sung-Ho MaengSearch for more papers by this author, Chun KangSearch for more papers by this author, Jeong-Gu NamSearch for more papers by this author, and Joo-Shil LeeSearch for more papers by this authorPublished Online:5 Jul 2004https://doi.org/10.1089/088922299310999AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail FiguresReferencesRelatedDetailsCited byEpidemiology, detection of resistance and tropism of HIV-1: updateRevista de Medicina de LaboratorioHIV-1 subtype B: Traces of a pandemicVirology, Vol. 495Detection of the B"-GWGR variant in the southernmost region of Brazil: unveiling the complexity of the human immunodeficiency virus-1 subtype B epidemicMemórias do Instituto Oswaldo Cruz, Vol. 108, No. 6Timing and evolution of the most recent common ancestor of the Korean clade HIV subtype B based on Nef and Vif sequences20 February 2009 | The Journal of Microbiology, Vol. 47, No. 1Characterization and signature pattern analysis of Korean clade HIV-1 using nef gene sequences11 March 2008 | The Journal of Microbiology, Vol. 46, No. 1Full Sequence of HIV Type 1 Korean Subtype B in an AIDS Case with Atypical Seroconversion: TAAAA at TATA Box Young K. Cho, Heungsup Sung, In G. Bae, Heung B. Oh, Nam J. Kim, Jun H. Woo, and Young B. Kim5 December 2005 | AIDS Research and Human Retroviruses, Vol. 21, No. 11Molecular Epidemiology of HIV in Asia and the PacificThe History of HIV and Other Infectious Diseases in the Republic of KoreaAn HIV Type 1 Subtype B Founder Effect in Korea: gp160 Signature Patterns Infer Circulation of CTL-Escape Strains at the Population Level Rod S. Daniels, Chun Kang, Dina Patel, Zheng Xiang, Nigel W. Douglas, Natalie N. Zheng, Hae-Wol Cho, and Joo-Shil Lee5 July 2004 | AIDS Research and Human Retroviruses, Vol. 19, No. 8Determination of Genetic Subtypes of HIV Type 1 Isolated from Korean AIDS Patients Myoung-Don Oh, Sang Won Park, Uiseok Kim, Hong Bin Kim, Young Ju Choe, Euijong Kim, and Kangwon Choe5 July 2004 | AIDS Research and Human Retroviruses, Vol. 18, No. 16Sequence Note: Introduction of HIV Type 1 Subtype E Virus into South Korea Joo-Shil Lee, Jeong-Gu Nam, Eun-Young Kim, Chun Kang, Bon-Ki Koo, and Hae-Wol Cho5 July 2004 | AIDS Research and Human Retroviruses, Vol. 16, No. 11 Volume 15Issue 7May 1999 To cite this article:Eun-Young Kim, Yeon-Sook Cho, Sung-Ho Maeng, Chun Kang, Jeong-Gu Nam, and Joo-Shil Lee.Characterization of V3 Loop Sequences from HIV Type 1 Subtype B in South Korea: Predominance of the GPGS Motif.AIDS Research and Human Retroviruses.May 1999.681-686.http://doi.org/10.1089/088922299310999Published in Volume: 15 Issue 7: July 5, 2004PDF download

HIV type 1 V3 domain serotyping and genotyping in Gauteng, Mpumalanga, KwaZulu-Natal, and Western Cape Provinces of South Africa.

More than 20.8 million people are living with HIV/AIDS in sub-Saharan Africa, with southern Africa the worst affected area and accounting for one of the fastest growing AIDS epidemics worldwide. Samples from 81 patients, including 25 from KwaZulu-Natal, 26 from Gauteng, 5 from Mpumalanga, and 25 from Western Cape Province, were serotyped using a competitive V3 peptide enzyme immunoassay (cPEIA). Viral RNA was also isolated from serum and the V3 region amplified by reverse transcriptase polymerase chain reaction (RT-PCR) to obtain a 240-bp product for direct sequencing of 29 samples. CLUSTAL W was used to make multiple sequence alignments. Distance calculation, tree construction methods, and bootstrap analysis were done using TREECON. Subtype C-like V3 loop sequences predominate in all provinces tested in South Africa. Discordant sero- and genotype results were observed in one patient only. The correlation between sero- and genotyping was 96% (24 of 25) in KwaZulu-Natal and 100% in Gauteng and Mpumalanga. In Western Cape Province 18% of patients were identified as sero/genotype B and 82% as sero/genotype C. Our data show that results of the second-generation V3 cPEIA correlated well with V3 sequencing and would be a rapid and affordable screening test to monitor the explosive southern African HIV-1 epidemic.

Mucosal administration of a chimera composed of Pseudomonas exotoxin and the gp120 V3 loop sequence of HIV-1 induces both salivary and serum antibody responses

We have used a mouse immunization model to evaluate the potential for a chimera protein composed of a nontoxic form of Pseudomonas exotoxin (ntPE) to incite and sustain a mucosal immune response against an integrated antigen. The chimera, termed ntPE-V3MN26, contained 26 amino acids of the gp120 V3 loop region sequence of the MN strain of HIV-1 integrated in place of the Ib region of ntPE. Following either vaginal, rectal, oral or subcutaneous administration and boosting, anti-gp120-specific IgA and IgG levels in serum and saliva samples were assessed by ELISA. All dosing regimens stimulated significant and comparable salivary IgA and serum IgG responses at 1, 2 and 3 months after the initial inoculation. Following a boost at 16 months with ntPE-V3MN26, a strong memory response to the antigen was observed. Isotyping of serum antibodies at this time suggested that both a Th1 and a Th2 response had been induced. Responses to ntPE-V3MN26 following subcutaneous injection in the presence or absence of Freund's adjuvant demonstrated that Freund's adjuvant resulted in a three-fold greater enhancement of immune response compared to administration of chimera alone. These results demonstrate that mucosal presentation of a chimera composed of a nontoxic form of Pseudomonas exotoxin can result in a strong mucosal and systemic antigen-specific immune response to an integrated antigen. The profound memory responses induced by this chimera may be particularly useful for practical vaccine applications.