Shiv j

Laboratory of Molecular Microbiology, Virology Laboratory, Vaccine Research Center, and Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892. Laboratory of Molecular Microbiology, Virology Laboratory, Vaccine Research Center, and Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892. Howard Hughes Medical Institute, Chevy Chase, MD 20815. Division of Biology, California Institute of Technology, Pasadena, CA 91125. Department of Immunology and Microbial Science, IAVI Neutralizing Antibody Center, and Center for HIV/AIDS Vaccine immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037. Department of Immunology and Microbial Science, IAVI Neutralizing Antibody Center, and Center for HIV/AIDS Vaccine immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037. Howard Hughes Medical Institute, Chevy Chase, MD 20815. Pre-exposure passive transfer of five mAbs to rhesus macaques and challenge with two different R5 SHIVs Although in vitro neutralization assays can provide important information about antibody potency and breadth, and guide the development of new mAbs with improved entry inhibiting properties, a more relevant test of antiviral efficacy is protection against an in vivo challenge in passive transfer experiments. As noted earlier, the critical goal of vaccination, in the case of primate lentiviruses, is sterilizing protection. Based on the results shown in Fig. 2, five neutralizing mAbs were selected for a preexposure passive transfer study: VRC01, because it was the first CD4bs NAb of the newly isolated broadly acting NAbs to be characterized; the CD4bs mAbs 45-46m2 and 3BNC117, both of which exhibited strong neutralizing activity against both SHIV AD8EO and SHIV DH12-V3AD8; and the gp120 N332 glycan-dependent mAbs PGT121 and 10–1074. Comparable but higher IC 50 values for these five mAbs were obtained in a 14-d PBMC-based neutralization assay, using replication-competent SHIV AD8EO or SHIV DH12-V3AD8 ( Table S1 ). The protocol used for passive transfer experiments was to administer decreasing amounts of neutralizing mAbs intravenously and challenge animals intrarectally 24 h later. Because our goal was to block virus acquisition, coupled with the knowledge that repeated administrations of human anti-HIV mAbs to individual macaques could reduce their potency and/or possibly induce anaphylactic responses, we elected to use a SHIV challenge dose of sufficient size to establish an in vivo infection after a single virus inoculation. In this regard, we had previously conducted intrarectal (IR) titrations of SHIV AD8 in rhesus monkeys and reported that the inoculation of 10 3 TCID 50, determined by endpoint dilution in rhesus macaque PBMC, was equivalent to administering∼3–5 animal infectious doses 50 (AID 50; Gautam et al., 2012 ). In fact, single IR inoculations of 3 to 5 AID 50 have resulted in the successful establis. Department of Immunology and Microbial Science, IAVI Neutralizing Antibody Center, and Center for HIV/AIDS Vaccine immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037. Masashi Shingai, Olivia K. Donau, Ronald J. Plishka, Alicia Buckler-White, John R. Mascola, Gary J. Nabel, Martha C. Nason, David Montefiori, Brian Moldt, Pascal Poignard, Ron Diskin, Pamela J. Bjorkman, Michael A. Eckhaus, Florian Klein, Hugo Mouquet, Julio Cesar Cetrulo Lorenzi, Anna Gazumyan, Dennis R. Burton, Michel C. Nussenzweig, Malcolm A. Martin, Yoshiaki Nishimura. In vitro characterization of 11 broadly reactive anti-HIV NAbs against two R5-tropic SHIVs The neutralization sensitivities of two different R5-tropic SHIVs, to be subsequently used as challenge viruses in the preexposure passive antibody experiments described below, were assessed using the TZM-bl cell neutralization assay. One of the R5 SHIVs evaluated, SHIV AD8EO ( Shingai et al., 2012 ), is a molecularly cloned derivative of SHIV AD8 ( Nishimura et al., 2010 ), replicates to high levels in rhesus macaque PBMCs, exhibits a Tier 2 neutralization sensitivity phenotype ( Gautam et al., 2012 ), and generates sustained levels of plasma viremia and depletion of CD4 + T cells leading to symptomatic immunodeficiency in inoculated monkeys. The second R5-tropic SHIV, SHIV DH12-V3AD8, was newly constructed by inserting the entire 33 amino acid gp120 V3 coding region of SHIV AD8EO, which confers the capacity to use the CCR5 coreceptor for cell entry, into the genetic background of the previously described X4-tropic SHIV DH12-CL-7 ( Fig. 1 A; Sadjadpour et al., 2004 ). SHIV DH12-V3AD8 exhibits robust replication kinetics during infection of rhesus monkey PBMC and exclusively utilizes CCR5 to enter these cells ( Fig. 1, B and C ). The gp120s of SHIV DH12-V3AD8 and SHIV AD8EO differ by 10% at the nucleotide level. Their sensitivities to a panel of sera from HIV-1–infected individuals exhibiting a wide range of neutralizing activity indicates that both possess a Tier 2 anti–HIV-1 neutralization phenotype ( Table 1 ). Rhesus macaques inoculated intravenously or intrarectally with SHIV DH12-V3AD8 exhibited peak levels of plasma viremia ranging from 10 5 to 10 7 viral RNA copes/ml of plasma at weeks 2 to 3 post infection (PI; Fig. 1, D and E ). Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065. Laboratory of Molecular Microbiology, Virology Laboratory, Vaccine Research Center, and Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892. jem Home " 2014 Archive " 22 September " 211 (10): 2061. Department of Immunology and Microbial Science, IAVI Neutralizing Antibody Center, and Center for HIV/AIDS Vaccine immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037. The neutralization sensitivity of SHIV AD8EO to 11 recently reported broadly reactive anti–HIV-1 mAbs was initially determined in the TZM-bl assay system. Eight of these antibodies (VRC01 [ Zhou et al., 2010 ], NIH45-46 [ Diskin et al., 2011 ], 45–46 G54W [ Diskin et al., 2011 ], 45-46m2 [ Diskin et al., 2013 ], 3BNC117 [ Scheid et al., 2011 ], 12A12 [ Scheid et al., 2011 ], 1NC9 [ Scheid et al., 2011 ], and 8ANC195 [ Scheid et al., 2011 ]) target the gp120 CD4bs and three (10–1074, PGT121, and PGT126; Walker et al., 2011a; Mouquet et al., 2012 ) are dependent on the presence of the HIV-1 gp120 N332 glycan, located immediately downstream of the V3 loop. When tested against SHIV AD8EO, all three glycan-dependent mAbs exhibited greater potency than the CD4bs mAbs ( Fig. 2 A ). The IC 50 values for the three mAbs targeting the gp120 N332 glycan ranged from 0.09 to 0.15 µg/ml ( Fig. 2 B ). The CD4bs mAbs exhibited a much broader range (0.14 to 6.36 µg/ml) of IC 50 neutralizing activities with 3BNC117 being the most potent. A similar hierarchy (glycan dependent > CD4bs dependent) of neutralizing mAb potency was also observed against SHIV DH12-V3AD8 ( Fig. 2 C ), but the neutralizing activity was distributed across a much wider (>800-fold) range compared with the IC 50 values observed for SHIV AD8EO ( Fig. 2 D ). SHIV DH12-V3AD8 was somewhat more sensitive to the glycan-targeting mAbs and more resistant to the CD4bs neutralizing mAbs than SHIV AD8EO. Passive transfer of modest titers of potent and broadly neutralizing anti-HIV monoclonal antibodies block SHIV infection in macaques. A major challenge in HIV research since the onset of the AIDS epidemic more than 30 years ago has been the development of an effective prophylactic vaccine. Most effective prophylactic vaccines directed against human pathogens elicit neutralizing antibodies (NAbs; Amanna and Slifka, 2011 ). Historically, monoclonal and polyclonal NAbs have been passively administered to susceptible humans and animals to prevent virus-induced disease ( Keller and Stiehm, 2000; Buchwald and Pirofski, 2003 ). However, because HIV-1 infections, once established, nearly invariably lead to fatal outcomes, effective passively transferred antibodies must block virus acquisition to prevent disease. The passive transfer of early generations of anti–HIV-1 mAbs demonstrated that they could confer sterilizing protection in macaques against challenges with SHIVs ( Mascola et al., 1999; Baba et al., 2000; Parren et al., 2001 ). However, the amounts of antibody required to prevent virus acquisition were so high that it was believed that this type of protection was not achievable by vaccination. During the past four to five years, a new generation of potent, broadly acting, neutralizing mAbs have been isolated from HIV-1–infected individuals ( Burton et al., 2012; Kwong and Mascola, 2012; Klein et al., 2013b ). These mAbs target the CD4 binding site (CD4bs), protein-glycan epitopes associated with the gp120 V1/V2, V3, and V4 regions, and the membrane proximal external region of gp41 ( Walker et al., 2009, 2010, 2011a; Wu et al., 2010; McLellan et al., 2011; Scheid et al., 2011; Huang et al., 2012; Kong et al., 2013 ) and typically exhibit great breadth and potency against heterologous HIV-1 isolates when assayed for neutralization in vitro. In this study, five of the new neutralizing mAbs were individually administered to groups of rhesus macaques, which were subsequently separately challenged intrarectally with either of two different R5 SHIVs. Levels of HIV-1 NAbs in the blood and tissues were measured at the time of virus challenge. By combini. Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard, Boston, MA 021142. Department of Surgery, Duke University Medical Center, Durham, NC 27710. Passive transfer of VRC01 or PGT121 mAbs and subsequent challenge with two different R5-tropic SHIVs. (A and B) Plasma viral loads in rhesus monkeys, administered VRC01 or PGT121 and challenged by the IR route 24 h later with SHIV AD8EO ( n = 14; A) or SHIV DH12-V3AD8 ( n = 14; B), were determined by RT-PCR. The amounts of mAb injected Abstract It is widely appreciated that effective human vaccines directed against viral pathogens elicit neutralizing antibodies (NAbs). The passive transfer of anti–HIV-1 NAbs conferring sterilizing immunity to macaques has been used to determine the plasma neutralization titers, which must be present at the time of exposure, to prevent acquisition of SIV/HIV chimeric virus (SHIV) infections. We administered five recently isolated potent and broadly acting anti-HIV neutralizing monoclonal antibodies (mAbs) to rhesus macaques and challenged them intrarectally 24 h later with either of two different R5-tropic SHIVs. By combining the results obtained from 60 challenged animals, we determined that the protective neutralization titer in plasma preventing virus infection in 50% of the exposed monkeys was relatively modest (∼1:100) and potentially achievable by vaccination.