Raiees Andrabi

All India Institute of Medical Sciences, New Dilli, NCT, India

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Publications (24)80.5 Total impact

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    ABSTRACT: Little is known about the neutralizing antibodies induced in HIV-1 patients on antiretroviral treatment, which constitute an interesting group of individuals with improved B cell profile. Plasma samples from 34 HIV-1 seropositive antiretroviral drug treated (ART) patients were tested for neutralization against a panel of 14 subtype-A, B and C tier 1 and tier 2 viruses in TZM-bl assay. Of the 34 plasma samples, remarkably all the plasma samples were able to neutralize at least one virus while 32 (94 %) were found to neutralize ≥50 % viruses tested. In terms of overall neutralization frequency, approximately 86 %, 68 % and 17 % of the virus/plasma combinations showed 50 % neutralizing activity at 1 > 60, 1 ≥ 200 and 1 ≥ 2000 dilutions respectively. The improvement in neutralizing activity was shown to be associated with ART in two follow up patients. The neutralization of viruses by two representative plasma samples, AIIMS221 and AIIMS265, was exclusively mediated by immunoglobulin G fractions independent of ART drugs and IgG retained cross-reactive binding to recombinant gp120 proteins. We observed a positive trend of neutralization with duration of ART (p = 0.06), however no such correlation was found with clinical and immunological variables like CD4 count (p = 0.35), viral load (p = 0.09) and plasma total IgG (p = 0.46). Our study suggests that the plasma antibodies from ART patients display high neutralizing activity most likely due to an improved B cell function induced by ART despite low antigenic stimulation.
    Journal of Clinical Immunology 03/2014; · 3.38 Impact Factor
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    ABSTRACT: A region in the conserved 5' long terminal repeat (LTR) promoter of the integrated HIV-1C provirus was identified for effective targeting by a short double-stranded RNA (dsRNA) to cause heterochromatization leading to a long-lasting decrease in viral transcription, replication and subsequent productive infection in human host cells. Small interfering RNAs (siRNAs) were transfected into siHa cells containing integrated LTR-luciferase reporter constructs and screened for efficiency of inducing transcriptional gene silencing (TGS). TGS was assessed by a dual luciferase assay and real-time PCR. Chromatin modification at the targeted region was also studied. The efficacy of potent siRNA was then checked for effectiveness in TZM-bl cells and human peripheral blood mononuclear cells (PBMCs) infected with HIV-1C virus. Viral Gag-p24 antigen levels were determined by ELISA. One HIV-1C LTR-specific siRNA significantly decreased luciferase activity and its mRNA expression with no such effect on HIV-1B LTR. This siRNA-mediated TGS was induced by histone methylation, which leads to heterochromatization of the targeted LTR region. The same siRNA also substantially suppressed viral replication in TZM-bl cells and human PBMCs infected with various HIV-1C clinical isolates for ≥3 weeks after a single transfection, even of a strain that had a mismatch in the target region. We have identified a potent dsRNA that causes long-term suppression of HIV-1C virus production in vitro and ex vivo by heritable epigenetic modification at the targeted C-LTR region. This dsRNA has promising therapeutic potential in HIV-1C infection, the clade responsible for more than half of AIDS cases worldwide.
    Journal of Antimicrobial Chemotherapy 09/2013; · 5.34 Impact Factor
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    ABSTRACT: One approach to the development of an HIV vaccine is to design a protein template which can present gp120 epitopes inducing cross-neutralizing antibodies. To select a V3 sequence for immunogen design, we compared the neutralizing activities of 18 anti-V3 monoclonal antibodies (mAbs) derived from Cameroonian and Indian individuals infected with clade AG and C, respectively. It was found that V3 mAbs from the Cameroonian patients were significantly more cross-neutralizing than those from India. Interestingly, superior neutralizing activity of Cameroonian mAbs was also observed among the nine VH5-51/VL lambda genes encoding V3 mAbs which mediate a similar mode of recognition. This correlated with higher relative binding affinity to a variety of gp120s and increased mutation rates in V3 mAbs from Cameroon. These results suggest that clade C V3 is probably weakly immunogenic and that the V3 sequence of CRF02_AG viruses can serve as a plausible template for vaccine immunogen design.
    Virology 03/2013; · 3.35 Impact Factor
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    ABSTRACT: BACKGROUND: Production of human monoclonal antibodies that exhibit broadly neutralizing activity isneeded for preventing HIV-1 infection, however only a few such antibodies have beengenerated till date. Isolation of antibodies by the hybridoma technology is a cumbersomeprocess with fewer yields. Further, the loss of unstable or slowly growing clones which mayhave unique binding specificities often occurs during cloning and propagation and thestrongly positive clones are often lost. This has been avoided by the process described in thispaper, wherein, by combining the strategy of EBV transformation and recombinant DNAtechnology, we constructed human single chain variable fragments (scFvs) against the thirdvariable region (V3) of the clade C HIV-1 envelope. RESULTS: An antigen specific phage library of 7000 clones was constructed from the enriched V3-positive antibody secreting EBV transformed cells. By ligation of the digested scFv DNAinto phagemid vector and bio panning against the HIV-1 consensus C and B V3 peptidesfollowed by random selection of 40 clones, we identified 15 clones that showed V3 reactivityin phage ELISA. DNA fingerprinting analysis and sequencing showed that 13 out of the 15clones were distinct. Expression of the positive clones was tested by SDS-PAGE and Westernblot. All the 13 anti-V3 scFvs showed cross-reactivity against both the clade C and B V3peptides and did not show any reactivity against other unrelated peptides in ELISA.Preliminary neutralization assays indicated varying degrees of neutralization of clade C and Bviruses. EBV transformation, followed by antigen selection of lines to identify specificbinders, enabled the selection of phage from un-cloned lines for scFv generation, thusavoiding the problems of hybridoma technology. Moreover, as the clones were pretested forantigen binding, a comparatively small library sufficed for the selection of a considerablenumber of unique antigen binding phage. After selection, the phage clones were propagatedin a clonal manner. CONCLUSIONS: This strategy can be efficiently used and is cost effective for the generation of diverserecombinant antibodies. This is the first study to generate anti-V3 scFvs against HIV-1 CladeC.
    BMC Biotechnology 11/2012; 12(1):87. · 2.17 Impact Factor
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    ABSTRACT: Subtypes of human immunodeficiency virus type 1 circulating in 21 north Indian patients were characterized based on the partial sequence of the gp120 envelope protein. A majority of viruses (85.7%, 18/21) were subtype C, while 14.3% (3/21) were subtype A. Sequence analysis revealed that the V3 region was highly conserved compared with V4 and V5. The predicted use of co-receptors indicated exclusive usage of R5, except for two subtype A viruses (AIIMS279 and AIIMS281). Our results demonstrate conservation within the V3 loop of subtype C viruses, and suggest the emergence of non-clade C viruses in the north Indian population.
    The Journal of Microbiology 10/2012; 50(5):869-73. · 1.28 Impact Factor
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    ABSTRACT: Highly efficient neutralization of human immunodeficiency viruses by plasma from antiretroviral drug treated patients is mediated by IgG fractions R Andrabi, M Makhdoomi, R Kumar, M Bala, T Velpandian, K Luthra* From AIDS Vaccine 2012 Boston, MA, USA. 9-12 September 2012 Background Little is known about the neutralizing activity in patients on antiretroviral therapy (ART), as most recent studies have focused on drug naïve individuals. ART may lead to a significant increase in B cell numbers and normalization of B cell subpopulations, providing a possible explanation for improved B cell responses after ART. Methods Thirty-four HIV-1 seropositive patients on ART (25 males and 9 females) within the age range of 20-55 years were recruited in this study. The patients had a median CD4 count and viral load of 283 cells and 178 RNA copies respectively, and were on treatment for a few days up to two years. Heat inactivated plasma samples were tested for neutralization against a panel of 14 subtype-A, B and C tier 1 and tier 2 viruses in TZM-bl assay. Results Of the 34 plasma samples, remarkably all the plasma samples were able to neutralize at least one virus while 32 (94%) samples were found to neutralize ≥50% viruses tested. Clustering analysis revealed that AIIMS253 (a clade-C virus) was the most sensitive while RHPA4259.7 (a clade-B isolate) was most resistant to antibody neutralization. The Immunoglobulin-G fractions from two representative samples AIIMS221 and AIIMS265 were shown to mediate neutralization exclusively. The IgG fractions retained binding to subtype-A, B and C recombinant gp120 proteins. We did not find any association of mean reciprocal ID50 neutralization titers with the plasma levels of ART drugs and clinical and immunological variables like CD4 count (p=0.35), viral load (p=0.37) and plasma total IgG (p=0.46). However we observed a positive association of neutralization with duration of ART (p=0.02) with a similar trend in two follow up patient samples. Conclusion Plasma antibodies from patients on ART display high neutralizing activity most likely due to an improved B cell function induced by ART despite low antigenic stimulation.
    Retrovirology 09/2012; · 5.66 Impact Factor
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    ABSTRACT: BACKGROUND: Analysis of human monoclonal antibodies (mAbs) developed from HIV-1 infected donors have enormously contributed to the identification of neutralization sensitive epitopes on the HIV-1 envelope glycoprotein. The third variable region (V3) is a crucial target on gp120, primarily due to its involvement in co-receptor (CXCR4 or CCR5) binding and presence of epitopes recognized by broadly neutralizing antibodies. METHODS: Thirty-three HIV-1 seropositive drug naive patients (18 males and 15 females) within the age range of 20--57 years (median = 33 years) were recruited in this study for mAb production. The mAbs were selected from EBV transformed cultures with conformationally constrained Cholera-toxin-B containing V3C (V3C-CTB) fusion protein. We tested the mAbs for their binding with HIV-1 derived proteins and peptides by ELISA and for neutralization against HIV-1 viruses by TZM-bl assays. RESULTS: We isolated three anti-V3 mAbs, 277, 903 and 904 from the cells of different individuals. The ELISA binding revealed a subtype-C and subtype-A specific binding of antibody 277 and 903 while mAb 904 exhibited cross reactivity also with subtype-B V3. Epitope mapping of mAbs with overlapping V3 peptides showed exclusive binding to V3 crown. The antibodies displayed high and low neutralizing activity against 2/5 tier 1 and 1/6 tier 2 viruses respectively. Overall, we observed a resistance of the tier 2 viruses to neutralization by the anti-V3 mAbs, despite the exposure of the epitopes recognized by these antibodies on two representative native viruses (Du156.12 and JRFL), suggesting that the affinity of mAb might equally be crucial for neutralization, as the epitope recognition. CONCLUSIONS: Our study suggests that the anti-V3 antibodies derived from subtype-C infected Indian patients display neutralization potential against tier 1 viruses while such activity may be limited against more resistant tier 2 viruses. Defining the fine epitope specificities of these mAbs and further experimental manipulations will be helpful in identification of epitopes, unique to clade C or shared with non-clade C viruses, in context of V3 region.
    Virology Journal 09/2012; 9(1):196. · 2.09 Impact Factor
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    ABSTRACT: Purpose/Objective: HIV1-the causative agent of AIDS, is the most infectious and epidemic virus worldwide. Till now there is no permanent cure for HIV1 infection and Current therapy reduces viral gene expression and its infection through inhibition of viral proteins (proteases, integrase and reverse transcriptase), blockade of gp120 and CD4 interaction and degradation of RNA, however targeting at the transcription level of the integrated provirus has been less explored. 5’ LTR promoter of HIV1 regulates the expression of all downstream viral genes and shows variation in sequences and transcription factor binding sites in a clade specific manner. Indian AIDS patients are commonly infected with HIV-1C compared to HIV-1B in developed countries. In our study, we have targeted the HIV-1C LTR promoter using dsRNA to induce transcriptional gene silencing (TGS) and decrease viral gene transcription. Materials and methods: In this study, SiHa cell line stably expressing the luciferase reporter under the HIV-1C LTR promoter was used in the presence of Tat protein. Luciferase expression (mRNA) and activity was measured by Real-Time PCR and dual luciferase assay respectively. The chromatin status after dsRNA transfection was studied using CHART-PCR and histone modifications at the targeted region of LTR were analyzed by ChIP assay. HIV-1C infected cells were transfected with siRNA and p24 assay was done at different time intervals after transfection. Results: Multiple siRNAs targeting the U3 region of HIV-1C 5’ LTR were screened using dual luciferase assay and Real-time PCR. One siRNA (S4) showed significant decrease in luciferase activity and mRNA expression 72 h post transfection. The S4 mediated TGS was caused by heterochromatization as seen by the reduced accessibility of MNAse in CHART PCR assay. Histone methylation of the targeted region was checked after siRNA transfection by ChIP assay. Our results showed that the heterochromatization of the HIV1-C LTR promoter was mediated by histone methylation. We also observed that S4 siRNA reduces HIV-1 gene transcription and their productive infection in HIV-1C infected cells after transfection. Conclusions: Heterochromatization of HIV-1C 5’ LTR by dsRNA can suppress downstream viral gene expression and thereby productive HIV1 infection. Thus dsRNA mediated TGS can be used as a therapeutic modality for HIV-1C infection in future.
    Immunology 09/2012; 137:114. · 3.71 Impact Factor
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    R Andrabi, A Gupta, M Bala, K Luthra
    Retrovirology 09/2012; 9(2). · 5.66 Impact Factor
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    Retrovirology 09/2012; 9(2). · 5.66 Impact Factor
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    R Andrabi, M Bala, R Kumar, K Luthra
    Retrovirology 09/2012; 9(2). · 5.66 Impact Factor
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    ABSTRACT: In this cross-sectional study, we evaluated the efficiency of the plasma of 38 antiretroviral-naïve HIV-1-infected children from northern India against a standard panel of pseudoviruses (3 clade C and 3 clade B) by TZM-bl assay. Neutralization potential was observed to a variable extent, with a potency ranging up to reciprocal ID(50) titers of 1967. Cross-neutralization was observed in 28.9 % (11/38) of the children. There was a significant positive correlation between viremia and neutralization efficiency against two of the viruses studied (Du172 r = 0.49; p = 0.007 and RHPA r = 0.47; p = 0.01), suggesting that persistent antigenic stimulation is necessary for the generation of broadly neutralizing antibody responses in these children. Further mapping of the epitope specificities of the neutralization determinants in the polyclonal plasma would provide important information for immunogen design.
    Archives of Virology 06/2012; 157(9):1797-801. · 2.03 Impact Factor
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    ABSTRACT: We assessed the anti-V3 antibody content and viral neutralization potential of the plasma of 63 HIV-1-infected patients (antiretroviral naïve=39, treated=24) against four primary isolates (PIs) of clade C and a tier 1 clade B isolate SF162. Depletion and inhibition of anti-V3 antibodies in the plasma of five patients with high titers of anti-V3 antibodies led to modest change in the neutralization percentage against two PIs (range 0–21%). The plasma of antiretroviral-treated patients exhibited higher neutralization potential than that of the drug-naïve plasmas against the four PIs tested which was further evidenced by a follow-up study.
    The Journal of Microbiology 04/2012; 50(2):363. · 1.28 Impact Factor
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    ABSTRACT: We assessed the anti-V3 antibody content and viral neutralization potential of the plasma of 63 HIV-1-infected patients (antiretroviral naïve=39, treated=24) against four primary isolates (PIs) of clade C and a tier 1 clade B isolate SF162. Depletion and inhibition of anti-V3 antibodies in the plasma of five patients with high titers of anti-V3 antibodies led to modest change in the neutralization percentage against two PIs (range 0-21%). The plasma of antiretroviral-treated patients exhibited higher neutralization potential than that of the drug-naïve plasmas against the four PIs tested which was further evidenced by a follow-up study.
    The Journal of Microbiology 02/2012; 50(1):149-54. · 1.28 Impact Factor
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    ABSTRACT: Broadly cross neutralizing antibodies (NAbs) are generated in a group of HIV-1 infected individuals during the natural infection, but little is known about their prevalence in patients infected with viral subtypes from different geographical regions. We tested here the neutralizing efficiency of plasma antibodies from 80 HIV-1 infected antiretroviral drug naive patients against a panel of subtype-B and C tier 2 viruses. We detected cross-neutralizing antibodies in approximately 19-27% of the plasma, however the subtype-C specific neutralization efficiency predominated (p = 0.004). The neutralizing activity was shown to be exclusively mediated by the immunoglobulin G (IgG) fraction in the representative plasma samples. Epitope mapping of three, the most cross-neutralizing plasma (CNP) AIIMS206, AIIMS239 and AIIMS249 with consensus-C overlapping envelope peptides revealed ten different binding specificities with only V3 and IDR being common. The V3 and IDR were highly antigenic regions but no correlation between their reciprocal Max50 binding titers and neutralization was observed. In addition, the neutralizing activity of CNP was not substantially reduced by V3 and gp41 peptides except a modest contribution of MPER peptide. The MPER was rarely recognized by plasma antibodies though antibody depletion and competition experiments demonstrated MPER dependent neutralization in two out of three CNP. Interestingly, the binding specificity of one of the CNP (AIIMS206) overlapped with broadly neutralizing mAb 2F5 epitope. Overall, the data suggest that, despite the low immunogenicity of HIV-1 MPER, the antibodies directed to this region may serve as crucial reagents for HIV-1 vaccine design.
    PLoS ONE 01/2012; 7(8):e43704. · 3.73 Impact Factor
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    ABSTRACT: Limited information exists on the antibody responses elicited against the viral envelope in HIV-1-infected children. In this cross-sectional study, we assessed the antibody responses against three different immunogenic regions of HIV-1 envelope, namely V3 region of gp120, membrane proximal external region (MPER), and immunodominant loop (IDL) of gp41 in HIV-1-infected children from north India. We recruited 75 HIV-1-infected (40 antiretroviral naive and 35 treated) children, with age ranging from 1.5 to 16 y. Antibodies to V3 and the IDL region were found in a majority of the infected children, whereas antibodies to MPER were found in approximately one-third of the children studied. Higher antibody titers to the immunogenic regions corresponded to the symptomatic stages of HIV-1 infection in both naive and antiretroviral therapy (ART)-treated children. High titers of anti-V3C and anti-IDL antibodies were observed in a subset of antiretroviral-naive patients with suppressed viremia (<47 RNA copies/mL), suggesting that antibodies to these immunogenic regions are present regardless of their viremic status. Further, the antibody titers were significantly lower in the plasma of treated patients compared to naive patients, regardless of whether they were virologically suppressed or not. This is the first report on the antibody responses elicited in HIV-1-infected children in India. The study may help to understand the humoral antibody responses directed against viral envelope in HIV-1-infected children.
    Viral immunology 12/2011; 24(6):463-9. · 1.78 Impact Factor
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    ABSTRACT: Antibodies to two crucial regions, the third variable loop (V3) of gp120 and the membrane-proximal external region (MPER) of gp41 are important for HIV-1 neutralization. We here evaluated the relative binding of polyclonal plasma antibodies from 99 HIV-1-infected individuals from India to the consensus-C V3 and MPER peptides and observed immunodominance of V3 over MPER (p < 0.0001). We further examined the V3- and MPER-specific antibody correlates with clinical parameters. Our results revealed that anti-V3 antibody titers are significantly lower in patients on ART compared to drug-naive individuals (p < 0.0001), most likely due to a decrease in plasma viral load, irrespective of their CD4 counts and total IgG. No such association was observed for MPER, with a similar trend in four follow-up patients. These findings strongly suggest that high titers of V3-specific antibodies are dependent on persistence of virus in circulation, while antibodies to MPER are probably not.
    Archives of Virology 07/2011; 156(10):1787-94. · 2.03 Impact Factor
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    ABSTRACT: The viral reverse transcriptase gene was amplified from the plasma of 27 drug-naïve and five drug-experienced HIV patients in Northern India. Follow-up samples of naïve patients after antiretroviral therapy initiation were collected in six patients at 3 months and three patients at 6 months. Phylogenetic analysis revealed two new recombinant forms, CRF_CH and CRF_CK, and an accessory non-nucleoside reverse transcriptase inhibitor mutation E138A, not previously reported from India. The major DRMs found in two 6-month follow-up samples were absent in their baseline blood samples. This is the first follow-up study to determine anti-retroviral drug resistance mutations in Indian HIV patients.
    Archives of Virology 02/2010; 155(4):563-9. · 2.03 Impact Factor
  • JAIDS Journal of Acquired Immune Deficiency Syndromes 01/2009; 51. · 4.65 Impact Factor
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    BMC Infectious Diseases 12(1). · 3.03 Impact Factor

Publication Stats

22 Citations
80.50 Total Impact Points

Institutions

  • 2010–2013
    • All India Institute of Medical Sciences
      • Department of Biochemistry
      New Dilli, NCT, India
  • 2010–2012
    • AIIMS Bhopal All India Institute of Medical Sciences
      Bhopal, Madhya Pradesh, India