Acquired Immunodeficiency Syndrome: Ibuki K

Fukazawa Y, Miyake A, Ibuki K, Inaba K, Saito N, Motohara M, Horiuchi R, Himeno A, Matsuda K, Matsuyama M, Takahashi H, Hayami M, Igarashi T, Miura T. · Laboratory of Primate Model, Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, 53 Shogoinkawaramachi, Sakyo-ku, Kyoto 606-8507, Japan. · J Virol. · Pubmed #18400862 links to  free full text

Abstract: To analyze the relationship between acute virus-induced injury and the subsequent disease phenotype, we compared the virus replication and CD4(+) T-cell profiles for monkeys infected with isogenic highly pathogenic (KS661) and moderately pathogenic (#64) simian-human immunodeficiency viruses (SHIVs). Intrarectal infusion of SHIV-KS661 resulted in rapid, systemic, and massive virus replication, while SHIV-#64 replicated more slowly and reached lower titers. Whereas KS661 systemically depleted CD4(+) T cells, #64 caused significant CD4(+) T-cell depletion only in the small intestine. We conclude that SHIV, regardless of pathogenicity, can cause injury to the small intestine and leads to CD4(+) T-cell depletion in infected animals during acute infection.

Shimizu Y, Inaba K, Kaneyasu K, Ibuki K, Himeno A, Okoba M, Goto Y, Hayami M, Miura T, Haga T. · Department of Veterinary Microbiology, University of Miyazaki, Miyazaki 889-2192, Japan. · Virology. · Pubmed #17157892 No free full text.

Abstract: Regulated-on-activation-normal-T-cell-expressed-and-secreted (RANTES), a CC-chemokine, enhances antigen-specific T helper (Th) type-1 responses against HIV-1. To evaluate the adjuvant effects of RANTES against HIV vaccine candidate in SHIV-macaque models, we genetically engineered a live-attenuated SHIV to express the RANTES gene (SHIV-RANTES) and characterized the virus's properties in vivo. After the vaccination, the plasma viral loads were same in the SHIV-RANTES-inoculated monkeys and the parental nef-deleted SHIV (SHIV-NI)-inoculated monkeys. SHIV-RANTES provided some immunity in monkeys by remarkably increasing the antigen-specific CD4+ Th cell-proliferative response and by inducing an antigen-specific IFN-gamma ELISpot response. The magnitude of the immunity in SHIV-RANTES-immunized animals, however, failed to afford greater protection against a heterologous pathogenic SHIV (SHIV-C2/1) challenge compared to control SHIV-NI-immunized animals. SHIV-RANTES immunized monkeys, elicited robust cellular CD4+ Th responses and IFN-gamma ELISpot responses after SHIV-C2/1 challenge. These findings suggest that the chemokine RANTES can augment vaccine-elicited, HIV-specific CD4+ T cell responses.

Motohara M, Ibuki K, Miyake A, Fukazawa Y, Inaba K, Suzuki H, Masuda K, Minato N, Kawamoto H, Nakasone T, Honda M, Hayami M, Miura T. · Laboratory of Primate Model, Experimental Research Center for Infectious Diseases, Institute for Virus Research, Kyoto University, 53 Shogoinkawara-Machi, Sakyo-Ku, Kyoto 606-8507, Japan. · Microbes Infect. · Pubmed #16702011 No free full text.

Abstract: One of the mechanisms by which HIV infection induces the depletion of CD4+ T cells has been suggested to be impairment of T-cell development in the thymus, although there is no direct evidence that this occurs. To examine this possibility, we compared T-cell maturation in the intrathymic progenitors between macaques infected with an acute pathogenic chimeric simian-human immunodeficiency virus (SHIV), which causes profound and irreversible CD4+ T-cell depletion, and macaques infected with a less pathogenic SHIV, which causes only a transient CD4+ T-cell decline. Within 27 days post-inoculation (dpi), the two virus infections caused similar increases in plasma viral loads and similar decreases in CD4+ T-cell counts. However, in the thymus, the acute pathogenic SHIV resulted in increased thymic involution, atrophy and the depletion of immature T cells including CD4(+)CD8(+) double-positive (DP) cells, whereas the less pathogenic SHIV did not have these effects. Ex vivo differentiation of CD3(-)CD4(-)CD8(-) triple-negative (TN) intrathymic progenitors to DP cells was assessed by a monkey-mouse xenogenic fetal thymus organ culture system. Differentiation was impaired in the TN intrathymic progenitors of the acute pathogenic SHIV-infected monkeys, while differentiation was not impaired in the TN intrathymic progenitors of the less pathogenic SHIV-infected monkeys. These differences suggest that dysfunction of thymic maturation makes an important contribution to the irreversible depletion of circulating CD4+ T cells in vivo.

Miyake A, Ibuki K, Enose Y, Suzuki H, Horiuchi R, Motohara M, Saito N, Nakasone T, Honda M, Watanabe T, Miura T, Hayami M. · Institute for Virus Research, Laboratory of Primate Model, Experimental Research Center for Infectious Disease, Kyoto University, Sakyo-ku, Japan. · J Gen Virol. · Pubmed #16603534 links to  free full text

Abstract: A better understanding of virological events during the early phase of human immunodeficiency virus 1 (HIV-1) infection is important for development of effective antiviral vaccines. In this study, by using quantitative PCR and an infectious plaque assay, virus distribution and replication were examined in various internal organs of rhesus macaques for almost 1 month after intrarectal inoculation of a pathogenic simian immunodeficiency virus/HIV chimeric virus (SHIV-C2/1-KS661c). At 3 days post-inoculation (p.i.), proviral DNA was detected in the rectum, thymus and axillary lymph node. In lymphoid tissues, infectious virus was first detected at 6 days p.i. and a high level of proviral DNA and infectious virus were both detected at 13 days p.i. By 27 days p.i., levels of infectious virus decreased dramatically, although proviral DNA load remained unaltered. In the intestinal tract, levels of infectious virus detected were much lower than in lymphoid tissues, whereas proviral DNA was detected at the same level as in lymphoid tissues throughout the infection. In the thymus and jejunum, CD4CD8 double-positive T cells were depleted earlier than CD4 single-positive cells. These results show that the virus spread quickly to systemic tissues after mucosal transmission. Thereafter, infectious virus was actively produced in the lymphoid tissues, but levels decreased significantly after the peak of viraemia. In contrast, in the intestinal tract, infectious virus was produced at low levels from the beginning of infection. Moreover, virus pathogenesis differed in CD4 single-positive and CD4CD8 double-positive T cells.

Kaneyasu K, Kita M, Ohkura S, Yamamoto T, Ibuki K, Enose Y, Sato A, Kodama M, Miura T, Hayami M. · Institute for Virus Research, Kyoto University, Kyoto, Kyoto 606-8507, Japan. · Microbiol Immunol. · Pubmed #16365534 links to  free full text

Abstract: We previously reported that a nef-deleted SHIV (SHIV-NI) is nonpathogenic and gave macaques protection from challenge infection with pathogenic SHIV-C2/1. To investigate whether IFN-gamma augments the immune response induced by this vaccination, we examined the antiviral and adjuvant effect of recombinant human IFN-gamma (rIFN-gamma) in vaccinated and unvaccinated monkeys. Nine monkeys were vaccinated with nef-deleted nonpathogenic SHIV-NI. Four of them were administered with rIFN-gamma and the other five monkeys were administered with placebo. After the challenge with pathogenic SHIV-C2/1, CD4(+) T-cell counts were maintained similarly in monkeys of both groups, while those of the unvaccinated monkeys decreased dramatically at 2 weeks after challenge. However, the peaks of plasma viral load were reduced to 100-fold in SHIV-NI vaccinated monkeys combined with rIFN-gamma compared with those in SHIV-NI vaccinated monkeys without rIFN-gamma. The peaks of plasma viral load were inversely correlated with the number of SIV Gag-specific IFN-gamma-producing cells. In SHIV-NI-vaccinated monkeys with rIFN-gamma, the number of SIV Gag-specific IFN-gamma-producing cells of PBMCs increased 2-fold compared with those in SHIV-NI-vaccinated monkeys without rIFN-gamma, and the NK activity and MIP-1alpha production of PBMCs were also enhanced. Thus, vaccination of SHIV-NI in combination with rIFN-gamma was more effective in modulating the antiviral immune system into a Th1 type response than SHIV-NI vaccination alone. These results suggest that IFN-gamma augmented the anti-viral effect by enhancing innate immunity and shifting the immune response to Th1.

Shimizu Y, Miyazaki Y, Ibuki K, Suzuki H, Kaneyasu K, Goto Y, Hayami M, Miura T, Haga T. · Department of Veterinary Microbiology, University of Miyazaki, Miyazaki 889-2192, Japan. · Virology. · Pubmed #16169034 No free full text.

Abstract: TNF-alpha has been implicated in the pathogenesis of, and the immune response against, HIV-1 infection. To clarify the roles of TNF-alpha against HIV-1-related virus infection in an SHIV-macaque model, we genetically engineered an SHIV to express the TNF-alpha gene (SHIV-TNF) and characterized the virus's properties in vivo. After the acute viremic stage, the plasma viral loads declined earlier in the SHIV-TNF-inoculated monkeys than in the parental SHIV (SHIV-NI)-inoculated monkeys. SHIV-TNF induced cell death in the lymph nodes without depletion of circulating CD4(+) T cells. SHIV-TNF provided some immunity in monkeys by increasing the production of the chemokine RANTES and by inducing an antigen-specific proliferation of lymphocytes. The monkeys immunized with SHIV-TNF were partly protected against a pathogenic SHIV (SHIV-C2/1) challenge. These findings suggest that TNF-alpha contributes to the induction of an effective immune response against HIV-1 rather than to the progression of disease at the early stage of infection.

Miyake A, Ibuki K, Suzuki H, Horiuchi R, Saito N, Motohara M, Hayami M, Miura T. · Institute for Virus Research, Kyoto University, Kyoto, Japan. · J Med Primatol. · Pubmed #16128924 No free full text.

Abstract: Children infected with human immunodeficiency virus type 1 often have higher viral loads and progress to acquired immunodeficiency syndrome more rapidly than adults. In our previous study of simian-human immunodeficiency virus (SHIV)-infected adult monkeys, immature CD4CD8 double-positive T cells in the thymus and jejunum decreased faster than mature CD4 single-positive T cells. Here, we examined the effect of virus replication on immature T cells from the same SHIV-inoculated newborn monkeys having more immature T cells than adults. The infectious viruses were more abundantly detected in the thymus than in other tissues at both 13 and 26 days post-infection (dpi). However, mature CD4(+) T cells in the thymus declined after 13 dpi and immature CD3(-) CD4 single-positive T cells remained at 26 dpi. These results suggested that many immature CD4(+) T cells in the thymus of newborns support the production of infectious viruses even after the depletion of mature CD4(+) T cells.

Suzuki H, Motohara M, Miyake A, Ibuki K, Fukazawa Y, Inaba K, Masuda K, Minato N, Kawamoto H, Hayami M, Miura T. · Laboratory of Primate Model, Institute for Virus Research, Kyoto University, Japan. · Microbiol Immunol. · Pubmed #16034211 links to  free full text

Abstract: We intrarectally infected newborn macaques with a pathogenic simian/human immunodeficiency virus (SHIV) that induced rapid and profound CD4 (+) T cell depletion, and examined the early effects of this SHIV on the thymus. After intrarectal infection, viral loads were much higher in the thymus than in other lymphoid tissues in newborns. In contrast, no clear difference was seen in the viral loads of different tissues in adults. Histological and immunohistochemical observations showed severe thymic involution. Depletion of CD4 (+) thymocytes began in the medulla at 2 weeks post infection and spread over the whole thymus. After in vivo infection, the CD2 (+) subpopulation, which represents a relatively later stage of T cell progenitors, was selectively reduced and development of thymocytes from CD3 (-) CD4 (-) CD8 (-) cells to CD4 (+) CD8 (+) cells was impaired. These results suggest that profound and irreversible loss of CD4 (+) cells that are observed in the peripheral blood of SHIV-infected monkeys are due to destruction of the thymus and impaired thymopoiesis as a result of SHIV infection in the thymus.

Takahashi M, Ido E, Uesaka H, Fukushima T, Ibuki K, Miura T, Hayami M, Takahashi H. · Department of Microbiology and Immunology, Nippon Medical School, Tokyo, Japan. · Arch Virol. · Pubmed #15841338 No free full text.

Abstract: CD4-bearing T cells are the primary targets for human immunodeficiency virus type 1(HIV-1)/simian immunodeficiency virus (SIV) infection. However, it is unclear whether the susceptibility of CD4-bearing T cells including CD4 single positive and CD4/8 double positive T cells to HIV/SIV infection is the same or not. In this study, we compared the susceptibility to SIV infection between CD4(+) and CD4(+)8(+) T cells, using Herpesvirus saimiri (HVS)-transformed CD4(+) and CD4(+)8(+) T cells established from peripheral blood mononuclear cells (PBMC) of rhesus macaques. Although there was little difference between the two CD4-bearing T cell population in the expression level of CD4 molecules and chemokine receptors such as CXCR4 and CCR5, SIV replicated more efficiently in CD4(+)8(+) T cells than in CD4(+) T cells. Moreover, we found that reverse transcription initiated more efficiently in CD4(+)8(+) T cells than in CD4(+) T cells and that the cell lysates from CD4(+) T cells impaired the RT activity more strongly than that from CD4(+)8(+) T cells. These findings suggest that intracellular environment in CD4(+) 8(+) T cells is better for reverse transcription and that the infection of those CD4(+)8(+) T cells might play critical and different roles in HIV-1/SIV infection and dissemination.

Enose Y, Kita M, Yamamoto T, Suzuki H, Miyake A, Horiuchi R, Ibuki K, Kaneyasu K, Kuwata T, Takahashi E, Sakai K, Shinohara K, Miura T, Hayami M. · Institute for Virus Research, Kyoto University, Kyoto, Japan. · Arch Virol. · Pubmed #15593414 No free full text.

Abstract: To clarify the involvement of primitive non-specific immune responses in the protective effects of a live, attenuated virus, each two rhesus macaques were intravenously immunized with an attenuated chimeric simian and human immunodeficiency virus (SHIV) in which the nef gene was deleted (SHIV-NI) or a SHIV having human IFN-gamma inserted into the deleted nef region (SHIV IFN-gamma). These immunized monkeys were intravenously challenged with a heterologous pathogenic SHIV (SHIV-C2/1) at four weeks post immunization (wpi). After vaccination, one of each SHIV-NI- or SHIV IFN-gamma-immunized monkeys showed a low level of SIV Gag-specific lymphocyte proliferative response but did not have neutralizing antibodies to both the parental and challenge viruses. After the challenge, the plasma viral RNA loads of the challenge virus were suppressed in all the immunized monkeys and the severe CD4+ T cell loss observed in the unimmunized monkeys was not found. Thus, both SHIV IFN-gamma and SHIV-NI infections could prevent from disease progression by a pathogenic virus early after immunization, suggesting that primitive non-specific immune response elicited by attenuated virus infection, in addition to highly acquired virus-specific immunity, contributes to the protective effect against a pathogenic virus.

Iida T, Kuwata T, Ui M, Suzuki H, Miura T, Ibuki K, Takahashi H, Yamamoto T, Imanishi J, Hayami M, Kita M. · Department of Microbiology, Kyoto Prefectural University of Medicine, Kyoto, Japan. · Arch Virol. · Pubmed #15045561 No free full text.

Abstract: A nef-deleted SHIV-NM-3rN (SHIV-NI) was previously shown to be nonpathogenic and to induce protective immunity. In the present study, a SHIV-NI expressing human interferon-gamma (SHIV-IFN-gamma) was constructed and the effect of co-expression of IFN-gamma on virus replication and immunopotentiation was investigated in macaques that were vaccinated with both viruses, by comparing cytokine responses during the first 4 weeks after vaccination. Peripheral blood mononuclear cells (PBMC) isolated from vaccinated macaques were stimulated with inactivated viral particles for 24 h, and the production of IL-2, IL-4, IL-6, IL-10, IL-12, TNF-alpha and IFN-gamma was determined by ELISA and flow cytometry. All of the vaccinated macaques showed increases in cytokine production. However, the production of IFN-gamma (Th1-type cytokine) was more rapidly induced by SHIV-IFN-gamma vaccination, and IFN-gamma-producing cells appeared to be still increasing at 4 weeks after vaccination, although the difference of virus replication during the time was not significant in contrast to in vitro replication in cultured PBMC. These results suggest that co-expression of IFN-gamma with SHIV can modulate the antiviral immune responses into the Th1 type response, which would probably provide more protective immunity.

Shimada T, Suzuki H, Motohara M, Kuwata T, Ibuki K, Ui M, Iida T, Fukumoto M, Miura T, Hayami M. · Department of Pathology, Kyoto City Hospital, 604-8845, Kyoto, Japan. · Virology. · Pubmed #12642106 No free full text.

Abstract: To clarify the early pathological events in simian and human immunodeficiency chimeric virus (SHIV)-infected lymphoid organs, we examined rhesus macaques infected with an acute pathogenic SHIV (SHIV89.6P) or a nonpathogenic SHIV (NM-3rN) by sequential biopsies and serial necropsies. In the SHIV89.6P-infected monkeys, acute thymic involution as shown by increased cortical tingible-body macrophages and by neutrophilic infiltrates without follicular aggregation in the medulla began within 14 days postinoculation (dpi). Cells that were strongly positive for the virus were identified in the thymic medulla. SHIV89.6P-infected lymph nodes showed severe paracortical lymphadenitis with scattered virus-positive cells at 14 dpi and they developed paracortical depletion without the obvious follicular involution. In contrast, NM-3rN-infected monkeys showed no signs of thymic dysinvolution and the lymph nodes exhibited only follicular hyperplasia. NM-3rN-infected monkeys showed much fewer virus-positive cells in these lymphoid tissues than did SHIV89.6P-infected monkeys during the same period. These differences clearly reflect the difference in the virulence of these SHIVs.

Kwofie TB, Miura T, Ibuki K, Enose Y, Suzuki H, Ui M, Kuwata T, Hayami M. · Laboratory of Viral Pathogenesis, Research Center for AIDS, Institute for Virus Research, Kyoto University, Japan. · Arch Virol. · Pubmed #12111421 No free full text.

Abstract: Monkeys that have been vaccinated with nef-deleted SHIVs were either fully or partially protected against challenge with acute pathogenic SHIV-89.6 P. Viruses isolated from these vaccinated monkeys were all found to be the 89.6 P challenge virus using PCR amplification and restriction enzyme analysis of the env region of the viruses. Analysis of the 3'-end of the env region and 5'-half of the nef region using a heteroduplex mobility assay revealed that the parental 89.6 P and re-isolated viruses from unvaccinated 89.6 P-infected monkeys had quite an abundant and similar heterogeneous quasispecies population. In contrast, the viruses isolated from the vaccinated monkeys had different and fewer quasispecies indicating a selective immune pressure in the vaccinated monkeys. The in vitro replication of the viruses isolated from the vaccinated monkeys in human and macaque peripheral blood mononucular cells (PBMCs) as well as in established cell lines such as M8166 and HSC-F cells, were slow and delayed when compared to the parental 89.6 P and re-isolated viruses from unvaccinated 89.6 P-infected monkeys. Further comparison revealed that in HSC-F cells the viruses from vaccinated monkeys again showed delayed and weak CD4(+) cell down-modulation as well as having little or no effect on cell growth or cell viability on HSC-F cells and monkey PBMC. Thus we noticed that these re-isolated 89.6 P viruses from the vaccinated monkeys had changed or had been selected for low pathogenic viruses in the monkeys. This suggests that though the vaccination did not completely prevent the replication of the challenge virus in the monkeys it did contain the challenge virus by suppressing the pathogenic variants. This further enhances the prospects of this nef-deleted SHIV as the bases for effective anti-HIV vaccine candidates.

Takehisa J, Harada Y, Ndembi N, Mboudjeka I, Taniguchi Y, Ngansop C, Kuate S, Zekeng L, Ibuki K, Shimada T, Bikandou B, Yamaguchi-Kabata Y, Miura T, Ikeda M, Ichimura H, Kaptué L, Hayami M. · Department of Viral Infection and International Health, Graduate School of Medical Science, Kanazawa University, Kanazawa 920-8640, Japan. · AIDS Res Hum Retroviruses. · Pubmed #11522184 No free full text.

Abstract: We found a novel primate lentivirus in mandrill (Mandrillus sphinx). To clarify the evolutionary relationships and transmission patterns of human/simian immunodeficiency virus (HIV/SIV), we screened blood samples from 30 wild-born healthy Cameroonian mandrills. Five (16.7%) of them were seropositive for SIV. Three SIV strains were isolated from the five seropositive mandrills by cocultivation of their peripheral blood mononuclear cells (PBMCs) with PBMCs of rhesus macaques, a human T cell line (M8166), and/or a cynomolgus macaque T cell line (HSC-F). One of the newly isolated SIV strains was intravenously inoculated into two rhesus macaques and resulted in chronic infection. In the SIV-infected macaques at 45 weeks after inoculation, we observed a mild decline in the number of peripheral CD4(+) lymphocytes, lymphadenopathy, and blastic follicular dendritic cells with mild follicular hyperplasia in the peripheral lymph nodes. A phylogenetic analysis based on the pol sequence showed that the newly found SIVs from Cameroonian mandrills did not cluster with SIVmndGB1, which is the former representative strain of SIVmnd. The SIVmnds from Cameroon formed a new, independent lineage that branched before the root of the HIV-1/SIVcpz lineage with 996 of 1000 bootstrap replications. They clustered host specifically, and exhibited about 16.9% diversity at the level of nucleotide sequence among Cameroonian SIVmnd strains. These results indicate that the SIVmnds isolated in Cameroon are a novel type of SIVmnd and have infected Cameroonian mandrills for a long time. We therefore designated the Cameroonian SIVmnd as SIVmnd type 2 and redesignated SIVmndGB1 as SIVmnd type 1. To date, M. sphinx is the only primate species other than humans that is naturally infected with two different types of SIV.

Kozyrev IL, Ibuki K, Shimada T, Kuwata T, Takemura T, Hayami M, Miura T. · Laboratory of Viral Pathogenesis, Graduate School of Medicine, Kyoto University, 606-8507, Japan. · Virology. · Pubmed #11259185 No free full text.

Abstract: For a better understanding of the acute pathogenicity of SHIV-89.6P stock virus, which induces prominent CD4 cell loss within a month after inoculation in monkeys, we have constructed four infectious molecular clones (cl 18, cl 64, cl 69, and cl 71). Cl 64, cl 69, and cl 71, like the parental virus, showed a high in vitro replication ability and a pathogenic-like effect (CD4 downmodulation) in a monkey CD4(+) cell line, whereas cl 18 showed a lower replication ability and could not downmodulate CD4. Cl 64, which has characteristics similar to those of the parental virus in vitro, was inoculated into four rhesus monkeys. All monkeys showed a plasma viral load similar to that of the parental virus with a peak at 2 weeks after inoculation. However, the viral load gradually decreased and the virus failed to cause an AIDS-like disease in infected monkeys, but it induced a strong antiviral antibody response. These results demonstrate the polyclonal nature of the parental SHIV-89.6P virus stock and demonstrate that cl 64, aside from its high replicability, may differ qualitatively from the parental virus.

Iida T, Ichimura H, Shimada T, Ibuki K, Ui M, Tamaru K, Kuwata T, Yonehara S, Imanishi J, Hayami M. · Department of Microbiology, Kyoto Prefectural University of Medicine, Japan. · AIDS Res Hum Retroviruses. · Pubmed #10628812 No free full text.

Abstract: To investigate the role of apoptosis in the progressive loss of CD4+ lymphocytes in HIV infection, we have used macaques infected with SHIV, a hybrid virus of HIV and simian immunodeficiency virus (SIV). In the present study, we sequentially analyzed apoptosis induction in the acute phase of SHIV infection. Four macaques infected with a pathogenic SHIV, SHIV89.6P, and four macaques infected with a nonpathogenic SHIV, NM-3rN, were analyzed during the first 2 or 4 weeks postinfection. In the 89.6P-infected macaques the number of peripheral CD4+ cells sharply decreased at 2 weeks postinfection and was maintained below 50/microl until 4 weeks postinfection, while in the NM-3rN-infected macques the number of the CD4+ cells did not change significantly. Plasma viral loads peaked at 2 and 2-3 weeks postinfection, and the peak values were about 1 x 10(9) and 10(6)-10(7) copies/ml in the 89.6P- and the NM-3rN-infected macaques, respectively. In the 89.6P-infected macaques, Fas antigen expression and the extent of apoptosis in PBMCs and peripheral lymph nodes increased at 1-2 weeks postinfection. A high number of apoptotic cells was also observed in thymus sections 2 and 4 weeks postinfection. On the other hand, apoptosis was scarcely induced in the NM-3rN-infected macaques. These results suggest that the extent of apoptosis induction is closely correlated with the pathogenicity of SHIV and that the apoptosis induction in peripheral lymphoid tissues and thymus, where T cell maturation occurs, may play an important role in the depletion of CD4+ lymphocytes in 89.6P infection.

Ui M, Kuwata T, Igarashi T, Ibuki K, Miyazaki Y, Kozyrev IL, Enose Y, Shimada T, Uesaka H, Yamamoto H, Miura T, Hayami M. · Institute for Virus Research, Kyoto University, Kyoto, 606-8507, Japan. · Virology. · Pubmed #10600597 No free full text.

Abstract: To evaluate the potential of SHIVs as anti-HIV-1 live vaccines, we constructed two gene-deleted SHIVs, designated SHIV-drn and SHIV-dxrn. The former lacks vpr/nef and the latter lacks vpx/vpr/nef. Four macaques that had been vaccinated with SHIV-drn were challenged with SHIV-NM-3rN, which has an HIV-1 Env that is the same as that of SHIV-drn. No challenge virus was detected by DNA PCR in, or recovered from, two of the macaques. In the other two, challenge virus was detected once and twice, respectively. Plasma viral loads were much lower than those in unvaccinated controls. Another four macaques were vaccinated with SHIV-dxrn. These macaques showed resistance but less than that of SHIV-drn-vaccinated macaques. When the two SHIV-drn-vaccinated macaques were challenged with pathogenic SHIV-89.6P, which has an HIV-1 Env that is antigenically different from that of SHIV-drn, replication of the challenge virus was restricted, and the usual decrease in the number of CD4(+) cells was prevented. In this protection, it is noteworthy that protection involved not only neutralizing antibodies and killer cell activity, but also other unknown specific and nonspecific immunity elicited by the infection.

Ibuki K, Ido E, Funahashi S, Miura T, Hayami M, Shida H. · Department of Cell Biology, Institute for Virus Research, Kyoto University, Shogoin Kawahara-cho, Sakyo-ku, Kyoto, Japan. · Vaccine. · Pubmed #10519941 No free full text.

Abstract: Protective immunity induced by a recombinant vaccinia virus expressing the envelope (Env) protein of a simian immunodeficiency virus strain, SIVagm, (SEN-RVV), was evaluated in cynomolgus monkeys (Macaca fascicularis). Three monkeys were immunized twice with SEN-RVV and boostered with the purified SIVagm Env protein. These monkeys developed high titers of anti-SIVagm Env antibody, especially after boostering. After challenge with polyclonal SIVagm, no virus was recovered from two of the monkeys and no provirus DNA was detected in one of these two. After autopsy, however, proviral DNA was detected in the spleen of this monkey. These results suggest that this immunization regimen could not completely protect the monkeys from SIV infection but that it did reduce the replicability of the challenged virus.

Enose Y, Ibuki K, Tamaru K, Ui M, Kuwata T, Shimada T, Hayami M. · Institute for Virus Research, Laboratory of Viral Pathogenesis, Kyoto University, Japan. · J Gen Virol. · Pubmed #10211952 links to  free full text

Abstract: In order to test the hypothesis that macrophages and dendritic cells (DCs) in mucosal tissue play an important role in heterosexual transmission of human immunodeficiency virus, the replication capacities of two simian immunodeficiency viruses (SIVs) were examined in cultured macrophages and DCs as well as in cultured PBMCs in vitro. The virus strains were a T cell-tropic SIV, SIVmac239, and a T cell- and macrophage-tropic (dual-tropic) SIV, SIVmac239/316E. The infectivities of these viruses to cynomolgus macaques by intravaginal inoculation were also compared. Although both virus strains replicated well in cultured PBMCs, SIVmac239 did not replicate in cultured macrophages, whereas SIVmac239/316E did. Both strains showed little replication in cultured DCs, but a high virus yield could be obtained when SIVmac239/316E-infected DCs were co-cultured with uninfected PBMCs. A mixture of these SIVs was inoculated intravaginally to three monkeys and the virus strain that first appeared through the vaginal mucosa was determined. The virus clones detected first in PBMCs, inguinal lymph nodes and vaginal wash cells (VWCs) after the virus inoculation were of SIVmac239 in all cases, except for one clone of SIVmac239/316E in VWCs of one monkey at one time-point. These results show that the infectivity of the virus in intravaginal transmission did not depend on the cell tropism in vitro of the virus.