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Ronald S Veazey

Publications and source records attributed to Ronald S Veazey.

At least 19 recordsLinked to original sources
PubMed2007

Current concepts in AIDS pathogenesis: insights from the SIV/macaque model.

The pathogenesis of AIDS has proven to be quite complex and dynamic, with most of the critical events (e.g., transmission, CD4(+) T cell destruction) occurring in tissues that are not easily accessible for analysis. In addition, although the disease can progress over years, many critical events happen within the first few weeks of infection, when most patients are unaware that they are infected. The nonhuman primate model of AIDS has been used extensively to fill these gaps in our understanding of AIDS pathogenesis.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Massive infection and loss of CD4+ T cells occurs in the intestinal tract of neonatal rhesus macaques in acute SIV infection.

Rapid, profound, and selective depletion of memory CD4+ T cells has now been confirmed to occur in simian immunodeficiency virus (SIV)-infected adult macaques and human immunodeficiency virus (HIV)-infected humans. Within days of infection, marked depletion of memory CD4+ T cells occurs primarily in mucosal tissues, the major reservoir for memory CD4+ T cells in adults. However, HIV infection in neonates often results in higher viral loads and rapid disease progression, despite the paucity of memory CD4+ T cells in the peripheral blood. Here, we examined the immunophenotype of CD4+ T cells in normal and SIV-infected neonatal macaques to determine the distribution of naive and memory T-cell subsets in tissues. We demonstrate that, similar to adults, neonates have abundant memory CD4+ T cells in the intestinal tract and spleen and that these are selectively infected and depleted in primary SIV infection. Within 12 days of SIV infection, activated (CD69+), central memory (CD95+CD28+) CD4+ T cells are marked and persistently depleted in the intestine and other tissues of neonates compared with controls. The results in dicate that "activated" central memory CD4+ T cells are the major target for early SIV infection and CD4+ T cell depletion in neonatal macaques.

Acute Disease↗
PubMed2006

Paucity of CD4+CCR5+ T cells is a typical feature of natural SIV hosts.

In contrast to lentiviral infections of humans and macaques, simian immunodeficiency virus (SIV) infection of natural hosts is nonpathogenic despite high levels of viral replication. However, the mechanisms underlying this absence of disease are unknown. Here we report that natural hosts for SIV infection express remarkably low levels of CCR5 on CD4+ T cells isolated from blood, lymph nodes, and mucosal tissues. Given that this immunologic feature is found in 5 different species of natural SIV hosts (sooty mangabeys, African green monkeys, mandrills, sun-tailed monkeys, and chimpanzees) but is absent in 5 nonnatural/recent hosts (humans, rhesus, pigtail, cynomolgus macaques, and baboons), it may represent a key feature of the coevolution between the virus and its natural hosts that led to a nonpathogenic infection. Beneficial effects of low CCR5 expression on CD4+ T cells may include the reduction of target cells for viral replication and a decreased homing of activated CD4+ T cells to inflamed tissue.

Animals↗
PubMed2006

Distribution of simian immunodeficiency virus target cells in vaginal tissues of normal rhesus macaques: implications for virus transmission.

Most new cases of HIV-1 infection occur as the result of vaginal transmission. Identifying the phenotype and distribution of potential viral target cells in the vagina is important for understanding events in viral transmission and for developing effective prevention strategies. For example, compounds that prevent CD4 or CCR5 binding have been demonstrated recently to prevent vaginal transmission in rhesus macaques, but the expression and distribution of CCR5 has not been examined in the macaque vagina. The objective of this study was to examine the distribution and phenotype of cells and molecules in the vagina of rhesus macaques that may be involved in HIV transmission, including CCR5, CD3, CD4, CD8, CD1a, CD28, CD95, CD123 and HLA-DR. Normal juvenile and adult female rhesus macaques were examined by multicolor immunohistochemistry and flow cytometry. Although both CD4 and CCR5 were observed in the lamina propria, essentially no CD4 or CCR5 expression was detected within the squamous or keratinized layers of the vaginal epithelium. CCR5 expression was higher in the vaginal lamina propria of mature macaques compared to 1-3-year-old juveniles. The vast majority of CD4(+)CCR5(+) lymphocytes in the vagina had a central memory (CD95(+)CD28(+)) phenotype. Numerous CCR5-expressing dendritic cells (CD123(+)) or macrophages (CD68(+)) were observed in the lamina propria, but no CCR5, CD4 or DC-SIGN expression was detectable in the epithelium. Thus, the multiple layers of squamous epithelium normally covering the vaginal mucosa may provide an effective barrier against vaginal HIV-1 transmission. Microbicides that block CD4 or CCR5 expression may act within the deeper layers of the vaginal epithelium rather than on the epithelial surface.

Animals↗
PubMed2006

Single epitope mucosal vaccine delivered via immuno-stimulating complexes induces low level of immunity against simian-HIV.

The difficulty in developing an effective vaccine to contain the HIV/AIDS epidemic coupled with the fact that primary HIV-1 infection typically occurs via mucosal sites has increased emphasis on vaccine approaches that protect at mucosal surfaces. In this study we employed HIV and simian-HIV (SHIV)-derived T helper (Th) and cytotoxic T lymphocyte (CTL) single epitopes incorporated into immuno-stimulating complexes (ISCOM) as a candidate immunogens. Immunized rhesus macaques (Macaca mulatta) were challenged with CCR5-tropic SHIV(SF162p4). On the day of challenge, low levels of virus-neutralizing antibodies (Ab) and CTLs were detected in ISCOM-immunized macaques. Greater than 10(5) viral RNA copies per ml of plasma in 2/5 immunized and 3/4 control macaques were detected within 3 weeks post-challenge. Depletion of CD4+ T cells from gut-associated lymphoid tissues (GALT) was observed by post-challenge day (PCD) 14 in all macaques regardless immunization. Nonetheless, lower viral loads and relatively better preservation of peripheral CD4+ T cells following the SHIV infection was observed in ISCOM-immunized macaques. We predict that if coadministered with additional epitopes and/or more efficacious mucosal delivery system or route, HIV/SIV-derived peptide vaccines may have potential to elicit heterologous protection.

Adjuvants, Immunologic↗
PubMed2006

Intestinal lymphocyte subsets and turnover are affected by chronic alcohol consumption: implications for SIV/HIV infection.

We recently demonstrated that simian immunodeficiency virus (SIV) viral loads were significantly higher in the plasma of rhesus macaques consuming alcohol compared with controls following intrarectal SIV infection. To understand the possible reasons behind increased viral replication, here we assessed the effects of chronic alcohol consumption on distribution and cycling of various lymphocyte subsets in the intestine. Macaques were administered alcohol (n = 11) or sucrose (n = 12), and percentages of memory and naive and activated lymphocyte subsets were compared in the blood, lymph nodes, and intestines. Although minimal differences were detected in blood or lymph nodes, there were significantly higher percentages of central memory (CD95+CD28+) CD4+ lymphocytes in the intestines from alcohol-receiving animals before infection compared with controls. In addition, higher percentages of naive (CD45RA+CD95-) as well as CXCR4+CD4 cells were detected in intestines of alcohol-treated macaques. Moreover, alcohol consumption resulted in significantly lower percentages of effector memory (CD95+CD28-) CD8 lymphocytes as well as activated Ki67+CD8 cells in the intestines. A subset (7 receiving alcohol and 8 receiving sucrose) were then intrarectally inoculated with SIV(mac251). Viral RNA was compared in different tissues using real-time PCR and in situ hybridization. Higher levels of SIV replication were observed in tissues from alcohol-consuming macaques compared with controls. Central memory CD4 lymphocytes were significantly depleted in intestines and mesenteric lymph nodes from all alcohol animals at 8 weeks postinfection. Thus, changes in the mucosal immune compartment (intestines) in response to alcohol are likely the major reasons behind higher replication of SIV observed in these animals.

Alcohol Drinking↗
PubMed2006

Immunodomination in the evolution of dominant epitope-specific CD8+ T lymphocyte responses in simian immunodeficiency virus-infected rhesus monkeys.

Because the control of HIV-1 replication is largely dependent on CD8+ T lymphocyte responses specific for immunodominant viral epitopes, vaccine strategies that increase the breadth of dominant epitope-specific responses should contribute to containing HIV-1 spread. Developing strategies to elicit such broad immune responses will require an understanding of the mechanisms responsible for focusing CD8+ T lymphocyte recognition on a limited number of epitopes. To explore this biology, we identified cohorts of rhesus monkeys that expressed the MHC class I molecules Mamu-A*01, Mamu-A*02, or both, and assessed the evolution of their dominant epitope-specific CD8+ T lymphocyte responses (Gag p11C- and Tat TL8-specific in the Mamu-A*01+ and Nef p199RY-specific in the Mamu-A*02+ monkeys) following acute SIV infection. The Mamu-A*02+ monkeys that also expressed Mamu-A*01 exhibited a significant delay in the evolution of the CD8+ T lymphocyte responses specific for the dominant Mamu-A*02-restricted SIV epitope, Nef p199RY. This delay in kinetics was not due to differences in viral load kinetics or magnitude or in viral escape mutations, but was associated with the evolution of the Mamu-A*01-restricted CD8+ T lymphocyte responses to the highly dominant SIV epitopes Gag p11C and Tat TL8. Thus, the evolution of dominant epitope-specific CD8+ T lymphocyte responses can be suppressed by other dominant epitope-specific responses, and this immunodomination is important in determining the kinetics of dominant epitope-specific responses.

Amino Acid Sequence↗
PubMed2006

Intestinal double-positive CD4+CD8+ T cells are highly activated memory cells with an increased capacity to produce cytokines.

Peripheral blood and intestinal CD4+CD8+ double-positive (DP) T cells have been described in several species including humans, but their function and immunophenotypic characteristics are still not clearly understood. Here we demonstrate that DP T cells are abundant in the intestinal lamina propria of normal rhesus macaques (Macaca mulatta). Moreover, DP T cells have a memory phenotype and are capable of producing different and/or higher levels of cytokines and chemokines in response to mitogen stimulation compared to CD4+ single-positive T cells. Intestinal DP T cells are also highly activated and have higher expression of CCR5, which makes them preferred targets for simian immunodeficiency virus/HIV infection. Increased levels of CD69, CD25 and HLA-DR, and lower CD62L expression were found on intestinal DP T cells populations compared to CD4+ single-positive T cells. Collectively, these findings demonstrate that intestinal and peripheral blood DP T cells are effector cells and may be important in regulating immune responses, which distinguishes them from the immature DP cells found in the thymus. Finally, these intestinal DP T cells may be important target cells for HIV infection and replication due to their activation, memory phenotype and high expression of CCR5.

Animals↗
PubMed2006

Chronic alcohol consumption results in higher simian immunodeficiency virus replication in mucosally inoculated rhesus macaques.

The influence of alcohol consumption on HIV pathogenesis is not well understood. In this study we used the SIV/macaque model of HIV infection to study the influence of chronic binge alcohol consumption on simian immunodeficiency virus (SIV) infection. Rhesus macaques were fed alcohol or isocaloric amounts of sucrose via indwelling intragastric catheters and then inoculated with SIVmac251 by the rectal route. Real-time RTPCR for SIV gag mRNA showed significantly higher plasma viral copies in alcohol-consuming macaques at 4 and 6 weeks pi, compared with sucrose controls. The viral copies were 1 to 2 logs higher in these animals. The percentage of CD8+ lymphocytes in the duodenum of alcohol-consuming macaques was significantly lower than in sucrose-consuming macaques both before infection as well as at different time points postinfection. Also, the percentage of CD4+CD3+ lymphocytes in the intestines was significantly higher in alcohol-consuming macaques before infection. These findings suggest that a higher percentage of SIV target cells (CD4) in the gut coupled with lower percentages of CD8 cells, which could be important in controlling virus replication, may be responsible for the higher SIV loads observed in alcohol-consuming macaques.

Administration, Rectal↗
PubMed2006

Simian immunodeficiency viruses replication dynamics in African non-human primate hosts: common patterns and species-specific differences.

METHODS: To define potential common features of simian immunodeficiency virus (SIV) infections in different naturally infected host species, we compared the dynamics of viral replication in 31 African green monkeys (10 sabeus, 15 vervets and seven Caribbean AGMs), 14 mandrills and three sooty mangabeys (SMs) that were experimentally infected with their species-specific viruses. RESULTS: After infection, these SIVs replicated rapidly reaching viral loads (VLs) of 10(5)-10(9) copies/ml of plasma between days 9-14 post-infection (p.i). Set point viremia was established between days 42 and 60 p.i., with levels of approximately 10(5)-10(6) copies/ml in SM and mandrills, and lower levels (10(3)-10(5) copies/ml) in AGMs. VL during the chronic phase did not correlate with viral genome structure: SIVmnd-2 (a vpx-containing virus) and SIVmnd-1 (which does not contain vpu or vpx) replicated to similar levels in mandrills. VL was dependent on virus strain: vervets infected with three different viral strains showed different patterns of viral replication. The pattern of viral replication of SIVagm.sab, which uses both CCR5 and CXCR4 co-receptors was similar to those of the other viruses. CONCLUSIONS: Our results show a common pattern of SIV replication in naturally and experimentally infected hosts. This is similar overall to that observed in pathogenic SIV infection of macaques. This result indicates that differences in clinical outcome between pathogenic and non-pathogenic infections rely on host responses rather than the characteristics of the virus itself.

Animals↗
PubMed2006

Simian immunodeficiency virus SIVagm.sab infection of Caribbean African green monkeys: a new model for the study of SIV pathogenesis in natural hosts.

Caribbean-born African green monkeys (AGMs) were classified as Chlorocebus sabaeus by cytochrome b sequencing. Guided by these phylogenetic analyses, we developed a new model for the study of simian immunodeficiency virus (SIV) infection in natural hosts by inoculating Caribbean AGMs with their species-specific SIVagm.sab. SIVagm.sab replicated efficiently in Caribbean AGM peripheral blood mononuclear cells in vitro. During SIVagm.sab primary infection of six Caribbean AGMs, the virus replicated at high levels, with peak viral loads (VLs) of 10(7) to 10(8) copies/ml occurring by day 8 to 10 postinfection (p.i.). Set-point values of up to 2 x 10(5) copies/ml were reached by day 42 p.i. and maintained throughout follow-up (through day 450 p.i.). CD4(+) T-cell counts in the blood showed a transient depletion at the peak of VL, and then returned to near preinfection values by day 28 p.i. and remained relatively stable during the chronic infection. Preservation of CD4 T cells was also found in lymph nodes (LNs) of chronic SIVagm.sab-infected Caribbean AGMs. No activation of CD4(+) T cells was detected in the periphery in SIV-infected Caribbean AGMs. These virological and immunological profiles from peripheral blood and LNs were identical to those previously reported in African-born AGMs infected with the same viral strain (SIVagm.sab92018). Due to these similarities, we conclude that Caribbean AGMs are a useful alternative to AGMs of African origin as a model for the study of SIV infection in natural African hosts.

Animals↗
PubMed2005

Protection of macaques from vaginal SHIV challenge by an orally delivered CCR5 inhibitor.

Pre-exposure oral prophylaxis with antiviral drugs is a potential method for preventing transmission of human immunodeficiency virus type 1 (HIV-1). We show that oral delivery of CMPD167, a small molecule that binds to the CCR5 coreceptor, for 10-14 d can protect a substantial proportion of macaques from vaginal infection with a CCR5-using virus (SHIV-162P3). The macaques that became infected despite receiving CMPD167 had reduced plasma viremia levels during the earliest stages of infection.

Administration, Oral↗
PubMed2005

Protection of macaques from vaginal SHIV challenge by vaginally delivered inhibitors of virus-cell fusion.

Human immunodeficiency virus type 1 (HIV-1) continues to spread, principally by heterosexual sex, but no vaccine is available. Hence, alternative prevention methods are needed to supplement educational and behavioural-modification programmes. One such approach is a vaginal microbicide: the application of inhibitory compounds before intercourse. Here, we have evaluated the microbicide concept using the rhesus macaque 'high dose' vaginal transmission model with a CCR5-receptor-using simian-human immunodeficiency virus (SHIV-162P3) and three compounds that inhibit different stages of the virus-cell attachment and entry process. These compounds are BMS-378806, a small molecule that binds the viral gp120 glycoprotein and prevents its attachment to the CD4 and CCR5 receptors, CMPD167, a small molecule that binds to CCR5 to inhibit gp120 association, and C52L, a bacterially expressed peptide inhibitor of gp41-mediated fusion. In vitro, all three compounds inhibit infection of T cells and cervical tissue explants, and C52L acts synergistically with CMPD167 or BMS-378806 to inhibit infection of cell lines. In vivo, significant protection was achieved using each compound alone and in combinations. CMPD167 and BMS-378806 were protective even when applied 6 h before challenge.

Administration, Intravaginal↗
PubMed2005

Serial electrophysiologic studies in rhesus monkeys with Krabbe disease.

Krabbe disease is a progressive leukodystrophy that results in demyelination in the central and peripheral nervous systems in humans. It has been described in a number of mammalian species including the rhesus monkey. We performed serial nerve conduction studies beginning within the first 2 months of life in four homozygous, two heterozygous, and two normal rhesus monkeys (Macaca mulatta) to characterize the peripheral neuropathy. Mean conduction velocities of the median, ulnar, and tibial nerves were significantly slower in the affected than unaffected monkeys at all ages (P < 0.0001). The conduction velocity differences became more apparent between the affected and unaffected as the monkeys aged. When compared to the unaffected monkeys, the serial conduction velocities suggested occurrence of dysmyelination followed by demyelination in the affected monkeys. These observations provide further insight into the disease process and suggest an early window of opportunity for treating Krabbe disease.

Action Potentials↗
PubMed2005

Chronic alcohol consumption results in higher simian immunodeficiency virus replication in mucosally inoculated rhesus macaques.

The influence of alcohol consumption on HIV pathogenesis is not well understood. In this study we used the simian immunodeficiency virus (SIV)/macaque model of HIV infection to study the influence of chronic binge alcohol consumption on SIV infection. Rhesus macaques were fed alcohol or isocaloric amounts of sucrose via indwelling intragastric catheters and then inoculated with SIVmac251 by the rectal route. Real-time RT-PCR for SIV gag mRNA showed significantly higher plasma viral copies in alcohol-consuming macaques at 4 and 6 weeks pi, compared with sucrose controls. The viral copies were 1 to 2 logs higher in these animals. The percentage of CD8+ lymphocytes in the duodenum of alcohol-consuming macaques was significantly lower than in sucrose-consuming macaques both before infection as well as at different time points postinfection. Also, the percentage of CD4(+)CD3+ lymphocytes in the intestines was significantly higher in alcohol-consuming macaques before infection. These findings suggest that a higher percentage of SIV target cells (CD4) in the gut coupled with lower percentages of CD8 cells, which could be important in controlling virus replication, may be responsible for the higher SIV loads observed in alcohol-consuming macaques.

Administration, Rectal↗
PubMed2005

Hematologic and lymphocyte immunophenotypic reference values for normal rhesus monkey (Macaca mulatta) umbilical cord blood; gravidity may play a role in study design.

Hematology and flow cytometry reference values for rhesus umbilical cord blood (UCB) were established in 17 healthy infant rhesus monkeys delivered by elective cesarean section 10 days preterm. The infants were born to age matched, singly caged primigravid or secundigravid dams. The hematology and flow cytometry values were determined by automated cell counter and by FACS. No significant differences were observed with respect to infant gender. With respect to gravida, the primigravid infants had a significantly higher percentage (P= 0.05) of CD20(+) B lymphocytes in UCB. These results provide useful reference values for future studies of maternal - fetal disease transmission, vaccine and drug evaluation in non-human primate pregnancy, as well as fetal programming and immune modulation, gene therapy and the use of UCB as a source of stem cells for research and transplantation. Importantly, our results suggest that maternal gravidity may be an important variable to consider.

Animals↗