Browsing by Author "Ochsenbauer, Christina"

Now showing 1 - 8 of 8
  • Thumbnail Image
    ItemOpen Access
    Association of HIV-1 Envelope-Specific Breast Milk IgA Responses with Reduced Risk of Postnatal Mother-to-Child Transmission of HIV-1.
    (J Virol, 2015-10) Pollara, Justin; McGuire, Erin; Fouda, Genevieve G; Rountree, Wes; Eudailey, Josh; Overman, R Glenn; Seaton, Kelly E; Deal, Aaron; Edwards, R Whitney; Tegha, Gerald; Kamwendo, Deborah; Kumwenda, Jacob; Nelson, Julie AE; Liao, Hua-Xin; Brinkley, Christie; Denny, Thomas N; Ochsenbauer, Christina; Ellington, Sascha; King, Caroline C; Jamieson, Denise J; van der Horst, Charles; Kourtis, Athena P; Tomaras, Georgia D; Ferrari, Guido; Permar, Sallie R
    UNLABELLED: Infants born to HIV-1-infected mothers in resource-limited areas where replacement feeding is unsafe and impractical are repeatedly exposed to HIV-1 throughout breastfeeding. Despite this, the majority of infants do not contract HIV-1 postnatally, even in the absence of maternal antiretroviral therapy. This suggests that immune factors in breast milk of HIV-1-infected mothers help to limit vertical transmission. We compared the HIV-1 envelope-specific breast milk and plasma antibody responses of clade C HIV-1-infected postnatally transmitting and nontransmitting mothers in the control arm of the Malawi-based Breastfeeding Antiretrovirals and Nutrition Study using multivariable logistic regression modeling. We found no association between milk or plasma neutralization activity, antibody-dependent cell-mediated cytotoxicity, or HIV-1 envelope-specific IgG responses and postnatal transmission risk. While the envelope-specific breast milk and plasma IgA responses also did not reach significance in predicting postnatal transmission risk in the primary model after correction for multiple comparisons, subsequent exploratory analysis using two distinct assay methodologies demonstrated that the magnitudes of breast milk total and secretory IgA responses against a consensus HIV-1 envelope gp140 (B.con env03) were associated with reduced postnatal transmission risk. These results suggest a protective role for mucosal HIV-1 envelope-specific IgA responses in the context of postnatal virus transmission. This finding supports further investigations into the mechanisms by which mucosal IgA reduces risk of HIV-1 transmission via breast milk and into immune interventions aimed at enhancing this response. IMPORTANCE: Infants born to HIV-1-infected mothers are repeatedly exposed to the virus in breast milk. Remarkably, the transmission rate is low, suggesting that immune factors in the breast milk of HIV-1-infected mothers help to limit transmission. We compared the antibody responses in plasma and breast milk of HIV-1-transmitting and -nontransmitting mothers to identify responses that correlated with reduced risk of postnatal HIV-1 transmission. We found that neither plasma nor breast milk IgG antibody responses were associated with risk of HIV-1 transmission. In contrast, the magnitudes of the breast milk IgA and secretory IgA responses against HIV-1 envelope proteins were associated with reduced risk of postnatal HIV-1 transmission. The results of this study support further investigations of the mechanisms by which mucosal IgA may reduce the risk of HIV-1 transmission via breastfeeding and the development of strategies to enhance milk envelope-specific IgA responses to reduce mother-to-child HIV transmission and promote an HIV-free generation.
  • Thumbnail Image
    ItemOpen Access
    Differential inhibition of human immunodeficiency virus type 1 in peripheral blood mononuclear cells and TZM-bl cells by endotoxin-mediated chemokine and gamma interferon production.
    (AIDS Res Hum Retroviruses, 2010-03) Geonnotti, Anthony R; Bilska, Miroslawa; Yuan, Xing; Ochsenbauer, Christina; Edmonds, Tara G; Kappes, John C; Liao, Hua-Xin; Haynes, Barton F; Montefiori, David C
    Bacterial lipopolysaccharide (endotoxin) is a frequent contaminant of biological specimens and is also known to be a potent inducer of beta-chemokines and other soluble factors that inhibit HIV-1 infection in vitro. Though lipopolysaccharide (LPS) has been shown to stimulate the production of soluble HIV-1 inhibitors in cultures of monocyte-derived macrophages, the ability of LPS to induce similar inhibitors in other cell types is poorly characterized. Here we show that LPS exhibits potent anti-HIV activity in phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs) but has no detectable anti-HIV-1 activity in TZM-bl cells. The anti-HIV-1 activity of LPS in PBMCs was strongly associated with the production of beta-chemokines from CD14-positive monocytes. Culture supernatants from LPS-stimulated PBMCs exhibited potent anti-HIV-1 activity when added to TZM-bl cells but, in this case, the antiviral activity appeared to be related to IFN-gamma rather than to beta-chemokines. These observations indicate that LPS stimulates PBMCs to produce a complex array of soluble HIV-1 inhibitors, including beta-chemokines and IFN-gamma, that differentially inhibit HIV-1 depending on the target cell type. The results also highlight the need to use endotoxin-free specimens to avoid artifacts when assessing HIV-1-specific neutralizing antibodies in PBMC-based assays.
  • Thumbnail Image
    ItemOpen Access
    Infectious virion capture by HIV-1 gp120-specific IgG from RV144 vaccinees.
    (J Virol, 2013-07) Liu, Pinghuang; Yates, Nicole L; Shen, Xiaoying; Bonsignori, Mattia; Moody, M Anthony; Liao, Hua-Xin; Fong, Youyi; Alam, S Munir; Overman, R Glenn; Denny, Thomas; Ferrari, Guido; Ochsenbauer, Christina; Kappes, John C; Polonis, Victoria R; Pitisuttithum, Punnee; Kaewkungwal, Jaranit; Nitayaphan, Sorachai; Rerks-Ngarm, Supachai; Montefiori, David C; Gilbert, Peter; Michael, Nelson L; Kim, Jerome H; Haynes, Barton F; Tomaras, Georgia D
    The detailed examination of the antibody repertoire from RV144 provides a unique template for understanding potentially protective antibody functions. Some potential immune correlates of protection were untested in the correlates analyses due to inherent assay limitations, as well as the need to keep the correlates analysis focused on a limited number of endpoints to achieve statistical power. In an RV144 pilot study, we determined that RV144 vaccination elicited antibodies that could bind infectious virions (including the vaccine strains HIV-1 CM244 and HIV-1 MN and an HIV-1 strain expressing transmitted/founder Env, B.WITO.c). Among vaccinees with the highest IgG binding antibody profile, the majority (78%) captured the infectious vaccine strain virus (CM244), while a smaller proportion of vaccinees (26%) captured HIV-1 transmitted/founder Env virus. We demonstrated that vaccine-elicited HIV-1 gp120 antibodies of multiple specificities (V3, V2, conformational C1, and gp120 conformational) mediated capture of infectious virions. Although capture of infectious HIV-1 correlated with other humoral immune responses, the extent of variation between these humoral responses and virion capture indicates that virion capture antibodies occupy unique immunological space.
  • Thumbnail Image
    ItemOpen Access
    Neutralization Takes Precedence Over IgG or IgA Isotype-related Functions in Mucosal HIV-1 Antibody-mediated Protection.
    (EBioMedicine) Astronomo, Rena D; Santra, Sampa; Ballweber-Fleming, Lamar; Westerberg, Katharine G; Mach, Linh; Hensley-McBain, Tiffany; Sutherland, Laura; Mildenberg, Benjamin; Morton, Georgeanna; Yates, Nicole L; Mize, Gregory J; Pollara, Justin; Hladik, Florian; Ochsenbauer, Christina; Denny, Thomas N; Warrier, Ranjit; Rerks-Ngarm, Supachai; Pitisuttithum, Punnee; Nitayapan, Sorachai; Kaewkungwal, Jaranit; Ferrari, Guido; Shaw, George M; Xia, Shi-Mao; Liao, Hua-Xin; Montefiori, David C; Tomaras, Georgia D; Haynes, Barton F; McElrath, Juliana M
    HIV-1 infection occurs primarily through mucosal transmission. Application of biologically relevant mucosal models can advance understanding of the functional properties of antibodies that mediate HIV protection, thereby guiding antibody-based vaccine development. Here, we employed a human ex vivo vaginal HIV-1 infection model and a rhesus macaque in vivo intrarectal SHIV challenge model to probe the protective capacity of monoclonal broadly-neutralizing (bnAb) and non-neutralizing Abs (nnAbs) that were functionally modified by isotype switching. For human vaginal explants, we developed a replication-competent, secreted NanoLuc reporter virus system and showed that CD4 binding site bnAbs b12 IgG1 and CH31 IgG1 and IgA2 isoforms potently blocked HIV-1JR-CSF and HIV-1Bal26 infection. However, IgG1 and IgA nnAbs, either alone or together, did not inhibit infection despite the presence of FcR-expressing effector cells in the tissue. In macaques, the CH31 IgG1 and IgA2 isoforms infused before high-dose SHIV challenge were completely to partially protective, respectively, while nnAbs (CH54 IgG1 and CH38 mIgA2) were non-protective. Importantly, in both mucosal models IgG1 isotype bnAbs were more protective than the IgA2 isotypes, attributable in part to greater neutralization activity of the IgG1 variants. These findings underscore the importance of potent bnAb induction as a primary goal of HIV-1 vaccine development.
  • Thumbnail Image
    ItemOpen Access
    Optimization and validation of a neutralizing antibody assay for HIV-1 in A3R5 cells.
    (Journal of immunological methods, 2014-07) Sarzotti-Kelsoe, Marcella; Daniell, Xiaoju; Todd, Christopher A; Bilska, Miroslawa; Martelli, Amanda; LaBranche, Celia; Perez, Lautaro G; Ochsenbauer, Christina; Kappes, John C; Rountree, Wes; Denny, Thomas N; Montefiori, David C
    A3R5 is a human CD4(+) lymphoblastoid cell line that was engineered to express CCR5 and is useful for the detection of weak neutralizing antibody responses against tier 2 strains of HIV-1. Here we describe the optimization and validation of the HIV-1 neutralizing antibody assay that utilizes A3R5 cells, performed in compliance with Good Clinical Laboratory Practice (GCLP) guidelines. The assay utilizes Renilla luciferase-expressing replication competent infectious molecular clones (IMC) encoding heterologous env genes from different HIV-1 clades. Key assay validation parameters tested included specificity, accuracy, precision, limit of detection and quantitation, specificity, linearity and range, and robustness. Plasma samples demonstrated higher non-specific activity than serum samples in the A3R5 assay. This assay can tolerate a wide range of virus input but is more sensitive to cell concentration. The higher sensitivity of the A3R5 assay in neutralization responses to tier 2 strains of HIV-1 makes it complementary to, but not a substitute for the TZM-bl assay. The validated A3R5 assay is employed as an endpoint immunogenicity test for vaccine-elicited neutralizing antibodies against tier 2 strains of HIV-1, and to identify correlates of protection in HIV-1 vaccine trials conducted globally.
  • Thumbnail Image
    ItemOpen Access
    Phenotypic properties of transmitted founder HIV-1.
    (Proc Natl Acad Sci U S A, 2013-04-23) Parrish, Nicholas F; Gao, Feng; Li, Hui; Giorgi, Elena E; Barbian, Hannah J; Parrish, Erica H; Zajic, Lara; Iyer, Shilpa S; Decker, Julie M; Kumar, Amit; Hora, Bhavna; Berg, Anna; Cai, Fangping; Hopper, Jennifer; Denny, Thomas N; Ding, Haitao; Ochsenbauer, Christina; Kappes, John C; Galimidi, Rachel P; West, Anthony P; Bjorkman, Pamela J; Wilen, Craig B; Doms, Robert W; O'Brien, Meagan; Bhardwaj, Nina; Borrow, Persephone; Haynes, Barton F; Muldoon, Mark; Theiler, James P; Korber, Bette; Shaw, George M; Hahn, Beatrice H
    Defining the virus-host interactions responsible for HIV-1 transmission, including the phenotypic requirements of viruses capable of establishing de novo infections, could be important for AIDS vaccine development. Previous analyses have failed to identify phenotypic properties other than chemokine receptor 5 (CCR5) and CD4+ T-cell tropism that are preferentially associated with viral transmission. However, most of these studies were limited to examining envelope (Env) function in the context of pseudoviruses. Here, we generated infectious molecular clones of transmitted founder (TF; n = 27) and chronic control (CC; n = 14) viruses of subtypes B (n = 18) and C (n = 23) and compared their phenotypic properties in assays specifically designed to probe the earliest stages of HIV-1 infection. We found that TF virions were 1.7-fold more infectious (P = 0.049) and contained 1.9-fold more Env per particle (P = 0.048) compared with CC viruses. TF viruses were also captured by monocyte-derived dendritic cells 1.7-fold more efficiently (P = 0.035) and more readily transferred to CD4+ T cells (P = 0.025). In primary CD4+ T cells, TF and CC viruses replicated with comparable kinetics; however, when propagated in the presence of IFN-α, TF viruses replicated to higher titers than CC viruses. This difference was significant for subtype B (P = 0.000013) but not subtype C (P = 0.53) viruses, possibly reflecting demographic differences of the respective patient cohorts. Together, these data indicate that TF viruses are enriched for higher Env content, enhanced cell-free infectivity, improved dendritic cell interaction, and relative IFN-α resistance. These viral properties, which likely act in concert, should be considered in the development and testing of AIDS vaccines.
  • Thumbnail Image
    ItemOpen Access
    Postnatally-transmitted HIV-1 Envelope variants have similar neutralization-sensitivity and function to that of nontransmitted breast milk variants.
    (Retrovirology, 2013-01-10) Fouda, Genevieve G; Mahlokozera, Tatenda; Salazar-Gonzalez, Jesus F; Salazar, Maria G; Learn, Gerald; Kumar, Surender B; Dennison, S Moses; Russell, Elizabeth; Rizzolo, Katherine; Jaeger, Frederick; Cai, Fangping; Vandergrift, Nathan A; Gao, Feng; Hahn, Beatrice; Shaw, George M; Ochsenbauer, Christina; Swanstrom, Ronald; Meshnick, Steve; Mwapasa, Victor; Kalilani, Linda; Fiscus, Susan; Montefiori, David; Haynes, Barton; Kwiek, Jesse; Alam, S Munir; Permar, Sallie R
    BACKGROUND: Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n = 13 viruses), five clinically-matched nontransmitting mothers (n = 16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses). RESULTS: There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants. CONCLUSION: Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.
  • Thumbnail Image
    ItemOpen Access
    Potent functional antibody responses elicited by HIV-I DNA priming and boosting with heterologous HIV-1 recombinant MVA in healthy Tanzanian adults.
    (PLoS One, 2015) Joachim, Agricola; Nilsson, Charlotta; Aboud, Said; Bakari, Muhammad; Lyamuya, Eligius F; Robb, Merlin L; Marovich, Mary A; Earl, Patricia; Moss, Bernard; Ochsenbauer, Christina; Wahren, Britta; Mhalu, Fred; Sandström, Eric; Biberfeld, Gunnel; Ferrari, Guido; Polonis, Victoria R
    UNLABELLED: Vaccine-induced HIV antibodies were evaluated in serum samples collected from healthy Tanzanian volunteers participating in a phase I/II placebo-controlled double blind trial using multi-clade, multigene HIV-DNA priming and recombinant modified vaccinia Ankara (HIV-MVA) virus boosting (HIVIS03). The HIV-DNA vaccine contained plasmids expressing HIV-1 gp160 subtypes A, B, C, Rev B, Gag A, B and RTmut B, and the recombinant HIV-MVA boost expressed CRF01_AE HIV-1 Env subtype E and Gag-Pol subtype A. While no neutralizing antibodies were detected using pseudoviruses in the TZM-bl cell assay, this prime-boost vaccination induced neutralizing antibodies in 83% of HIVIS03 vaccinees when a peripheral blood mononuclear cell (PBMC) assay using luciferase reporter-infectious molecular clones (LucR-IMC) was employed. The serum neutralizing activity was significantly (but not completely) reduced upon depletion of natural killer (NK) cells from PBMC (p=0.006), indicating a role for antibody-mediated Fcγ-receptor function. High levels of antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies against CRF01_AE and/or subtype B were subsequently demonstrated in 97% of the sera of vaccinees. The magnitude of ADCC-mediating antibodies against CM235 CRF01_AE IMC-infected cells correlated with neutralizing antibodies against CM235 in the IMC/PBMC assay. In conclusion, HIV-DNA priming, followed by two HIV-MVA boosts elicited potent ADCC responses in a high proportion of Tanzanian vaccinees. Our findings highlight the potential of HIV-DNA prime HIV-MVA boost vaccines for induction of functional antibody responses and suggest this vaccine regimen and ADCC studies as potentially important new avenues in HIV vaccine development. TRIAL REGISTRATION: Controlled-Trials ISRCTN90053831 The Pan African Clinical Trials Registry ATMR2009040001075080 (currently PACTR2009040001075080).