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SIV Infection (siv + infection)
Selected AbstractsExpression of CD8, identifies a distinct subset of effector memory CD4+ T lymphocytesIMMUNOLOGY, Issue 2 2006Iole Macchia Summary Circulating CD4+ CD8+ T lymphocytes have been described in the peripheral blood of humans and several animal species. However, the origin and functional properties of these cells remain poorly understood. In the present study, we evaluated the frequency, phenotype and function of peripheral CD4+ CD8+ T cells in rhesus macaques. Two distinct populations of CD4+ CD8+ T cells were identified: the dominant one was CD4hi CD8lo and expressed the CD8,, homodimer, while the minor population was CD4lo CD8hi and expressed the CD8,, heterodimer. The majority of CD4hi CD8,lo T cells exhibited an activated effector/memory phenotype (CCR5lo CD7, CD28, HLA-DR+) and expressed relatively high levels of granzyme B. Intracellular cytokine staining assays demonstrated that the frequency of cytomegalovirus-specific T cells was enriched five-fold in CD4hi CD8,lo T cells compared to single-positive CD4+ T cells, whereas no consistent enrichment was observed for simian immunodeficiency virus (SIV)-specific T cells. Cross-sectional studies of SIV-infected animals demonstrated that the frequency of CD4hi CD8,lo T cells was lower in wild-type SIV-infected animals compared to uninfected controls, although prospective studies of SIV-infected animals demonstrated depletion of CD4hi CD8,lo lymphocytes only in a subset of animals. Taken together, these data suggest that CD4+ T cells expressing CD8, represent an effector/memory subset of CD4+ T cells and that this cell population can be depleted during the course of SIV infection. [source] Rhesus macaque antibody molecules: sequences and heterogeneity of alpha and gamma constant regionsIMMUNOLOGY, Issue 1 2004Franco Scinicariello Summary Rhesus macaques (Macaca mulatta) are extensively used in vaccine development. Macaques infected with simian immunodeficiency viruses (SIV) or simian-human immunodeficiency viruses (SHIV) are the best animal model currently available for acquired-immune-deficiency-syndrome-related studies. Recent results emphasize the importance of antibody responses in controlling HIV and SIV infection. Despite the increasing attention placed on humoral immunity in these models, very limited information is available on rhesus macaque antibody molecules. Therefore, we sequenced, cloned and characterized immunoglobulin gamma (IGHG) and alpha (IGHA) chain constant region genes from rhesus macaques of Indian and Chinese origin. Although it is currently thought that rhesus macaques express three IgG subclasses, we identified four IGHG genes, which were designated IGHG1, IGHG2, IGHG3 and IGHG4 on the basis of sequence similarities with the four human genes encoding the IgG1, IgG2, IgG3 and IgG4 subclasses. The four genes were expressed at least at the messenger RNA level, as demonstrated by real-time reverse transcription polymerase chain reaction (RT-PCR). The level of intraspecies heterogeneity was very high for IGHA genes, whereas IGHG genes were remarkably similar in all animals examined. However, single amino acid substitutions were present in IGHG2 and IGHG4 genes, indicating the presence of IgG polymorphism possibly resulting in the expression of different allotypes. Two IgA alleles were identified in several animals and RT-PCR showed that both alleles may be expressed. Presence of immunoglobulin gene polymorphism appears to reflect the unusually high levels of intraspecies heterogeneity already demonstrated for major histocompatibility complex genes in this non-human primate species. [source] Antibody convergence along a common idiotypic axis in immunodeficiency virus and hepatitis C virus infectionsJOURNAL OF MEDICAL VIROLOGY, Issue 1 2002Michael D. GrantArticle first published online: 29 NOV 200 Abstract The anti-idiotypic antibody 1F7 selectively binds antibodies against human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) gag, pol, and env proteins. We tested anti-hepatitis C virus (HCV) antibodies to investigate selection of the 1F7 idiotype on antibodies against other chronic pathogens. Twelve of 15 HCV-seropositive individuals co-infected with HIV had detectable antibodies against recombinant HCV core, 4 against HCV NS4 protein, and 3 against HCV NS3 protein. All four HCV-seropositive, non-HIV-infected individuals had antibodies against HCV core and NS4, while 3 had antibodies against NS3. The 1F7 idiotype was frequently present on antibodies against each of the HCV antigens in the HIV co-infected and non-HIV-infected groups. Antibodies against HCV, including antibodies recognizing the putative principal neutralizing determinant of HCV E2 protein, displayed skewed ,/, light chain usage consistent with clonal dominance. These observations extend the association between expression of the 1F7 idiotype and abnormal B cell clonal dominance in HIV and SIV infection to HCV infection and suggest that early establishment of an oligoclonal antibody response against HCV may freeze the B cell repertoire, impair adaptation to emergent HCV variants, and favor escape from neutralizing antibodies. We also demonstrated that expression of the 1F7 idiotype extends beyond antibodies against multiple antigens of AIDS-causing retroviruses to include antibodies against multiple antigens of an unrelated chronic hepatitis virus. Thus, distinct pathogens establishing chronic infection in the face of strong humoral immune responses select antibodies along a common idiotypic axis of the immune network. J. Med. Virol. 66:13,21, 2002. © 2002 Wiley-Liss, Inc. [source] HIV and SIV infection: the role of cellular restriction and immune responses in viral replication and pathogenesisAPMIS, Issue 5-6 2009KENNETH C. WILLIAMS The human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) have a long biological history. Both viruses evolved from Africa and remnants of them can be found in the ,fossil record' of several species in which they are not endemic. SIV remains endemic in several species of monkeys in Africa where it does not cause immune deficiency. HIV and SIV actively replicate within humans and Asian non-human primates, despite cellular and genetic viral restriction factors and genes, and at times robust innate and adaptive immune responses. While Lentiviruses are considered ,slow viruses' it is clear in humans and susceptible Asian monkeys that virus production is rapid and highly active. This results in a massive loss of CD4+ memory effector T cells early after infection and a continued race between viral evolution, cytotoxic lymphocytes, and failed neutralizing antibody responses. Concurrently, HIV and SIV can infect monocyte/macrophage populations in blood and more importantly in tissues, including the central nervous system, where the virus can remain sequestered and not cleared by anti-retroviral therapy, and hide for years. This review will discuss species and cellular barriers to infection, and the role of innate and acquired immunity with infection and pathogenesis of HIV and SIV in select species. 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