Generation of the Pathogenic R5-Tropic SHIVAd8 by Serial Passaging in Rhesus Macaques.

Laboratory of Molecular Microbiology, National Institutes of Health, Bethesda, MD 20892-0460, USA.
Journal of Virology (Impact Factor: 4.44). 02/2010; 84(9):4769-81. DOI: 10.1128/JVI.02279-09
Source: PubMed


A new pathogenic R5-tropic simian/human immunodeficiency virus (SHIV) was generated following serial passaging in rhesus macaques.
All 13 animals inoculated with SHIVAD8 passaged lineages experienced marked depletions of CD4+ T cells. Ten of these infected monkeys became normal progressors (NPs) and had gradual losses of both memory and naïve CD4+ T lymphocytes, generated antiviral CD4+ and CD8+ T cell responses, and sustained chronic immune activation while maintaining variable levels of plasma viremia (102 to 105 RNA copies/ml for up to 3 years postinfection [p.i.]). To date, five NPs developed AIDS associated with opportunistic infections
caused by Pneumocystis carinii, Mycobacterium avium, and Campylobacter coli that required euthanasia between weeks 100 and 199 p.i. Three other NPs have experienced marked depletions of circulating
CD4+ T lymphocytes (92 to 154 cells/μl) following 1 to 2 years of infection. When tested for coreceptor usage, the viruses isolated
from four NPs at the time of their euthanasia remained R5 tropic. Three of the 13 SHIVAD8-inoculated macaques experienced a rapid-progressor syndrome characterized by sustained plasma viremia of >1 × 107 RNA copies/ml and rapid irreversible loss of memory CD4+ T cells that required euthanasia between weeks 19 and 23 postinfection. The sustained viremia, associated depletion of CD4+ T lymphocytes, and induction of AIDS make the SHIVAD8 lineage of viruses a potentially valuable reagent for vaccine studies.

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Available from: Tatsuhiko Igarashi
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    • "Peripheral lymph nodes were found to be the preferred sites of X4 emergence and expansion in macaques infected with R5 SHIVs [42,51,52]. Because longitudinal samples (w8, 46, 54, 84) from the inguinal lymph node (Ing LN) of FF94 were available, we analyzed this tissue compartment as well as the PBMC and serum samples collected at the corresponding time points for X4 emergence in this animal. "
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    ABSTRACT: Background Mucosally transmissible and pathogenic CCR5 (R5)-tropic simian-human immunodeficiency virus (SHIV) molecular clones are useful reagents to identity neutralization escape in HIV-1 vaccine experiments and to study the envelope evolutionary process and mechanistic basis for coreceptor switch during the course of natural infection. Results We observed progression to AIDS in rhesus macaques infected intrarectally with molecular clones of the pathogenic R5 SHIVSF162P3N isolate. Expansion to CXCR4 usage was documented in one diseased macaque that mounted a neutralizing antibody response and in another that failed to do so, with the latter displaying a rapid progressor phenotype. V3 loop envelop glycoprotein gp120 sequence changes that are predictive of a CXCR4 (X4)-using phenotype in HIV-1 subtype B primary isolates, specifically basic amino acid substations at positions 11 (S11R), 24 (G24R) and 25 (D25K) of the loop were detected in the two infected macaques. Functional assays showed that envelopes with V3 S11R or D25K mutation were dual-tropic, infecting CD4+ target cells that expressed either the CCR5 or CXCR4 coreceptor. And, consistent with findings of coreceptor switching in macaques infected with the pathogenic isolate, CXCR4-using variant was first detected in the lymph node of the chronically infected rhesus monkey several weeks prior to its presence in peripheral blood. Moreover, X4 emergence in this macaque coincided with persistent peripheral CD4+ T cell loss and a decline in neutralizing antibody titer that are suggestive of immune deterioration, with macrophages as the major virus-producing cells at the end-stage of disease. Conclusions The data showed that molecular clones derived from the R5 SHIVSF162P3N isolate are mucosally transmissible and induced disease in a manner similar to that observed in HIV-1 infected individuals, providing a relevant and useful animal infection model for in-depth analyses of host selection pressures and the env evolutionary changes that influence disease outcome, coreceptor switching and vaccine escape.
    Full-text · Article · Jan 2013 · Retrovirology
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    • "However, one would argue that IHR-mediated generation of SHIV does not allow for a detailed genetic analysis, such as mutagenesis of particular gene(s), because of the virus being ''swarm.'' While this is undeniable, the vast majority of currently available replicationcompetent SHIVs are resultants of evolution through animal-toanimal passage and exist as quasispecies (Joag et al., 1996 #49; Reimann et al., 1996a #52; Igarashi et al., 1999 #156; Harouse et al., 2001 #154; Song et al., 2006 #158; Nishimura et al., 2010 #157}. A molecular-cloned virus representing the properties of the swarm is attainable by introduction of consensus sequences to a molecular clone, if necessary. "
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    ABSTRACT: A new simian-human immunodeficiency virus (SHIV), carrying env from an uncloned HIV-1 subtype C clinical isolate (97ZA012), was generated through intracellular homologous recombination, a DNA repair mechanism of the host cell. PCR fragments amplified from an existing SHIV plasmid (a 7-kb fragment from the 5' end and a 1.5-kb fragment from the 3' end) and a 4-kb fragment amplified from 97ZA012 cDNA containing env were co-transfected to human lymphoid cells. The resulting recombinant was subjected to serial passage in rhesus peripheral blood mononuclear cells (RhPBMCs). The resulting SHIV 97ZA012 was replication competent in RhPBMCs and monkey alveolar macrophages, and possessed CCR5 preference as an entry co-receptor. Experimental infection of rhesus macaques with SHIV 97ZA012 caused high titers of plasma viremia and a transient but profound depletion of CD4(+) T lymphocytes in the lung. Animal-to-animal passage was shown to be a promising measure for further adaptation of the virus in monkeys.
    Preview · Article · Dec 2012 · Virology
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    • "Infection with X4-tropic SHIVs such as SHIV89.6P results in acute CD4+ T cell depletion, while R5-tropic SHIVs such as SHIV162P3 induce persistent infection leading to chronic disease progression (Tsai et al., 2007; Nishimura et al., 2010; Zhuang et al., 2011). These SHIVs are useful especially for the analysis of Env-specific antibody responses (Ng et al., 2010; Watkins et al., 2011). "
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    ABSTRACT: Virus-specific cytotoxic T lymphocytes (CTLs) are major effectors in acquired immune responses against viral infection. Virus-specific CTLs recognize specific viral peptides presented by major histocompatibility complex class-I (MHC-I) on the surface of virus-infected target cells via their T cell receptor (TCR) and eliminate target cells by both direct and indirect mechanisms. In human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections, host immune responses fail to contain the virus and allow persistent viral replication, leading to AIDS progression. CTL responses exert strong suppressive pressure on HIV/SIV replication and cumulative studies have indicated association of HLA/MHC-I genotypes with rapid or slow AIDS progression.
    Preview · Article · Jun 2012 · Frontiers in Microbiology
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