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  • 1
    In: Blood, American Society of Hematology, Vol. 113, No. 18 ( 2009-04-30), p. 4250-4261
    Abstract: We investigated the impact of rhesus macaque (RM) B-cell depletion before inoculation with the isolate SIVsmmD215. Seven RMs were treated every 3 weeks with 50 mg/kg of an anti-CD20 antibody (rituximab) starting 7 days before inoculation for 2 (n = 4) and 5 (n = 3) months. Four control animals received no antibody. Three animals were completely depleted of CD20+ B cells, but 4 were only partially depleted of CD20 cells in the LNs and intestine. The decrease in antibody production was consistent with the efficacy of tissue CD20 depletion. Seroconversion and neutralizing antibody production was significantly delayed in animals showing complete tissue CD20 depletion and remained at low titers in all CD20-depleted RMs. Surprisingly, there was no significant difference in acute or chronic viral loads between CD20-depleted and control animal groups. There was a tendency for lower viral set points in CD20-depleted animals. At 6 weeks after inoculation, cellular immune responses were significantly stronger in CD20-depleted animals than in controls. There was no significant difference in survival between CD20-depleted and control animals. Our data suggest that a deficiency of Ab responses did not markedly affect viral replication or disease progression and that they may be compensated by more robust cellular responses.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2009
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
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  • 2
    In: Journal of Virology, American Society for Microbiology, Vol. 92, No. 17 ( 2018-09)
    Abstract: Current approaches do not eliminate all human immunodeficiency virus type 1 (HIV-1) maternal-to-infant transmissions (MTIT); new prevention paradigms might help avert new infections. We administered maraviroc (MVC) to rhesus macaques (RMs) to block CCR5-mediated entry, followed by repeated oral exposure of a CCR5-dependent clone of simian immunodeficiency virus (SIV) mac251 (SIVmac766). MVC significantly blocked the CCR5 coreceptor in peripheral blood mononuclear cells and tissue cells. All control animals and 60% of MVC-treated infant RMs became infected by the 6th challenge, with no significant difference between the number of exposures ( P = 0.15). At the time of viral exposures, MVC plasma and tissue (including tonsil) concentrations were within the range seen in humans receiving MVC as a therapeutic. Both treated and control RMs were infected with only a single transmitted/founder variant, consistent with the dose of virus typical of HIV-1 infection. The uninfected RMs expressed the lowest levels of CCR5 on the CD4 + T cells. Ramp-up viremia was significantly delayed ( P = 0.05) in the MVC-treated RMs, yet peak and postpeak viral loads were similar in treated and control RMs. In conclusion, in spite of apparent effective CCR5 blockade in infant RMs, MVC had a marginal impact on acquisition and only a minimal impact on the postinfection delay of viremia following oral SIV infection. Newly developed, more effective CCR5 blockers may have a more dramatic impact on oral SIV transmission than MVC. IMPORTANCE We have previously suggested that the very low levels of simian immunodeficiency virus (SIV) maternal-to-infant transmissions (MTIT) in African nonhuman primates that are natural hosts of SIVs are due to a low availability of target cells (CCR5 + CD4 + T cells) in the oral mucosa of the infants, rather than maternal and milk factors. To confirm this new MTIT paradigm, we performed a proof-of-concept study in which we therapeutically blocked CCR5 with maraviroc (MVC) and orally exposed MVC-treated and naive infant rhesus macaques to SIV. MVC had only a marginal effect on oral SIV transmission. However, the observation that the infant RMs that remained uninfected at the completion of the study, after 6 repeated viral challenges, had the lowest CCR5 expression on the CD4 + T cells prior to the MVC treatment appears to confirm our hypothesis, also suggesting that the partial effect of MVC is due to a limited efficacy of the drug. New, more effective CCR5 inhibitors may have a better effect in preventing SIV and HIV transmission.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1495529-5
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  • 3
    In: Journal of Virology, American Society for Microbiology, Vol. 95, No. 11 ( 2021-05-10)
    Abstract: Previously, we showed that substitution of HIV-1 envelope (Env) residue 375-Ser by bulky aromatic residues enhances binding to rhesus CD4 and enables primary HIV-1 Envs to support efficient replication as simian-human immunodeficiency virus (SHIV) chimeras in rhesus macaques (RMs). Here, we test this design strategy more broadly by constructing SHIVs containing 10 primary Envs corresponding to HIV-1 subtypes A, B, C, AE, and AG. All 10 SHIVs bearing wild-type Env375 residues replicated efficiently in human CD4 + T cells, but only one replicated efficiently in primary rhesus cells. This was a subtype AE SHIV that naturally contained His at Env375. Replacement of wild-type Env375 residues by Trp, Tyr, Phe, or His in the other nine SHIVs led to efficient replication in rhesus CD4 + T cells in vitro and in vivo . Nine SHIVs containing optimized Env375 alleles were grown large-scale in primary rhesus CD4 + T cells to serve as challenge stocks in preclinical prevention trials. These virus stocks were genetically homogeneous, native-like in Env antigenicity and tier 2 neutralization sensitivity, and transmissible by rectal, vaginal, penile, oral, or intravenous routes. To facilitate future SHIV constructions, we engineered a simplified second-generation design scheme and validated it in RMs. Overall, our findings demonstrate that SHIVs bearing primary Envs with bulky aromatic substitutions at Env375 consistently replicate in RMs, recapitulating many features of HIV-1 infection in humans. Such SHIVs are efficiently transmitted by mucosal routes common to HIV-1 infection and can be used to test vaccine efficacy in preclinical monkey trials. IMPORTANCE SHIV infection of Indian rhesus macaques is an important animal model for studying HIV-1 transmission, prevention, immunopathogenesis, and cure. Such research is timely, given recent progress with active and passive immunization and novel approaches to HIV-1 cure. Given the multifaceted roles of HIV-1 Env in cell tropism and virus entry, and as a target for neutralizing and nonneutralizing antibodies, Envs selected for SHIV construction are of paramount importance. Until recently, it has been impossible to strategically design SHIVs bearing clinically relevant Envs that replicate consistently in monkeys. This changed with the discovery that bulky aromatic substitutions at residue Env375 confer enhanced affinity to rhesus CD4. Here, we show that 10 new SHIVs bearing primary HIV-1 Envs with residue 375 substitutions replicated efficiently in RMs and could be transmitted efficiently across rectal, vaginal, penile, and oral mucosa. These findings suggest an expanded role for SHIVs as a model of HIV-1 infection.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
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  • 4
    In: Journal of Virology, American Society for Microbiology, Vol. 82, No. 11 ( 2008-06), p. 5501-5509
    Abstract: Simian immunodeficiency virus (SIV) persistence in wild populations of African nonhuman primates (NHPs) may occur through horizontal and vertical transmission. However, the mechanism(s) and timing of the latter type of transmission have not been investigated to date. Here we present the first study of SIV transmissibility by breast-feeding in an African NHP host. Six mandrill dames were infected with plasma containing 300 50% tissue culture infective doses of SIVmnd-1 on the day after delivery. All female mandrills became infected, as demonstrated by both plasma viral loads (VLs) and anti-SIVmnd-1 seroconversion. Neither fever nor lymphadenopathy was observed. At the peak of SIVmnd-1 viral replication (days 7 to 10 postinoculation), plasma VLs were high (8 × 10 6 to 8 × 10 8 RNA copies/ml) and paralleled the high VLs in milk (4.7 × 10 4 to 5.6 × 10 5 RNA/ml). However, at the end of the breast-feeding period, after 6 months of follow-up, no sign of infection was observed for the offspring. Later on, during a 4-year follow-up examination, two of the offspring showed virological evidence of SIVmnd-1 infection. Both animals seroconverted at least 6 months after the interruption of lactation. In conclusion, despite extensive viral replication in mandrill mothers and high levels of free virus in milk, no SIVmnd-1 transmission was detectable at the time of breast-feeding or during the following months. Since we observed a markedly lower expression of CCR5 on the CD4 + T cells of young mandrills and African green monkeys than on those of adults, we propose that low levels of this viral coreceptor on CD4 + T cells may be involved in the lack of breast-feeding transmission in natural hosts of SIVs.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
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  • 5
    In: Journal of Virology, American Society for Microbiology, Vol. 80, No. 10 ( 2006-05-15), p. 4858-4867
    Abstract: 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 × 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.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
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  • 6
    In: Journal of Virology, American Society for Microbiology, Vol. 88, No. 12 ( 2014-06-15), p. 6778-6792
    Abstract: While simian immunodeficiency viruses (SIVs) are generally nonpathogenic in their natural hosts, dramatic increases in pathogenicity may occur upon cross-species transmission to new hosts. Deciphering the drivers of these increases in virulence is of major interest for understanding the emergence of new human immunodeficiency viruses (HIVs). We transmitted SIVsab from the sabaeus species of African green monkeys (AGMs) to pigtailed macaques (PTMs). High acute viral replication occurred in all SIVsab-infected PTMs, yet the outcome of chronic infection was highly variable, ranging from rapid progression to controlled infection, which was independent of the dynamics of acute viral replication, CD4 + T cell depletion, or preinfection levels of microbial translocation. Infection of seven PTMs with plasma collected at necropsy from a rapid-progressor PTM was consistently highly pathogenic, with high acute and chronic viral replication, massive depletion of memory CD4 + T cells, and disease progression in all PTMs. The plasma inoculum used for the serial passage did not contain adventitious bacterial or viral contaminants. Single-genome amplification showed that this inoculum was significantly more homogenous than the inoculum directly derived from AGMs, pointing to a strain selection in PTMs. In spite of similar peak plasma viral loads between the monkeys in the two passages, immune activation/inflammation levels dramatically increased in PTMs infected with the passaged virus. These results suggest that strain selection and a massive cytokine storm are major factors behind increased pathogenicity of SIV upon serial passage and adaptation of SIVs to new hosts following cross-species transmission. IMPORTANCE We report here that upon cross-species transmission and serial passage of SIVsab from its natural host, the sabaeus African green monkey (AGM), to a new host, the pigtailed macaque (PTM), viral adaptation and increased pathogenicity involve strain selection and a massive cytokine storm. These results permit the design of strategies aimed at preventing cross-species transmission from natural hosts of SIVs to humans in areas of endemicity. Furthermore, our study describes a new animal model for SIV infection. As the outcomes of SIVsab infection in PTMs, African green monkeys, and rhesus macaques are different, the use of these systems enables comparative studies between pathogenic, nonpathogenic, and elite-controlled infections, to gain insight into the mechanisms of SIV immunodeficiency and comorbidities.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
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  • 7
    In: Journal of Virology, American Society for Microbiology, Vol. 79, No. 9 ( 2005-05), p. 5278-5287
    Abstract: The outcome of feline leukemia virus (FeLV) infection in nature is variable, including malignant, proliferative, and degenerative disorders. The determinants of disease outcome are not well understood but are thought to include viral, host, and environmental factors. In particular, genetic variations in the FeLV long terminal repeat (LTR) and SU gene have been linked to disease outcome. FeLV-945 was previously identified as a natural isolate predominant in non-T-cell neoplastic and nonneoplastic diseases in a geographic cohort. The FeLV-945 LTR was shown to contain unique repeat elements, including a 21-bp triplication downstream of the enhancer. The FeLV-945 SU gene was shown to encode mutational changes in functional domains of the protein. The present study details the outcomes of infection with recombinant FeLVs in which the LTR and envelope ( env ) gene of FeLV-945, or the LTR only, was substituted for homologous sequences in a horizontally transmissible prototype isolate, FeLV-A/61E. The results showed that the FeLV-945 LTR determined the kinetics of disease. Substitution of the FeLV-945 LTR into FeLV-A/61E resulted in a significantly more rapid disease onset but did not alter the tumorigenic spectrum. In contrast, substitution of both the FeLV-945 LTR and env gene changed the disease outcome entirely. Further, the impact of FeLV-945 env on the disease outcome was dependent on the route of inoculation. Since the TM genes of FeLV-945 and FeLV-A/61E are nearly identical but the SU genes differ significantly, FeLV-945 SU is implicated in the outcome. These findings identify the FeLV-945 LTR and SU gene as determinants of disease.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2005
    detail.hit.zdb_id: 1495529-5
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  • 8
    Online Resource
    Online Resource
    American Society for Microbiology ; 2003
    In:  Journal of Virology Vol. 77, No. 16 ( 2003-08-15), p. 8783-8792
    In: Journal of Virology, American Society for Microbiology, Vol. 77, No. 16 ( 2003-08-15), p. 8783-8792
    Abstract: Children with human immunodeficiency virus infection often have higher viral loads and progress to AIDS more rapidly than adults. Since the intestinal tract is a major site of early viral replication and CD4 + T-cell depletion in adults, we examined the effects of simian immunodeficiency virus (SIV) on both peripheral and intestinal lymphocytes from 13 neonatal macaques infected with SIVmac239. Normal neonates had more CD4 + T cells and fewer CD8 + T cells in all tissues than adults. Surprisingly, neonates had substantial percentages of CD4 + T cells with an activated, memory phenotype (effector CD4 + T cells) in the lamina propria of the intestine compared to peripheral lymphoid tissues, even when examined on the day of birth. Moreover, profound and selective depletion of jejunum lamina propria CD4 + T cells occurred in neonatal macaques within 21 days of infection, which was preceded by large numbers of SIV-infected cells in this compartment. Furthermore, neonates with less CD4 + T-cell depletion in tissues tended to have higher viral loads. The persistence of intestinal lamina propria CD4 + T cells in some neonates with high viral loads suggests that increased turnover and/or resistance to CD4 + T-cell loss may contribute to the higher viral loads and increased severity of disease in neonatal hosts.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
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  • 9
    In: Journal of Virology, American Society for Microbiology, Vol. 85, No. 17 ( 2011-09), p. 8702-8708
    Abstract: Many species of African nonhuman primates are natural hosts for individual strains of simian immunodeficiency virus (SIV). These infected animals do not, however, develop AIDS. Here we show that multiple species of African nonhuman primate species characteristically have low frequencies of CD4 + T cells and high frequencies of both T cells that express only the alpha-chain of CD8 and double-negative T cells. These subsets of T cells are capable of eliciting functions generally associated with CD4 + T cells, yet these cells lack surface expression of the CD4 protein and are, therefore, poor targets for SIV in vivo . These data demonstrate that coevolution with SIV has, in several cases, involved downregulation of receptors for the virus by otherwise-susceptible host target cells. Understanding the genetic factors that lead to downregulation of these receptors may lead to therapeutic interventions that mimic this modulation in progressive infections.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
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  • 10
    In: Journal of Virology, American Society for Microbiology, Vol. 83, No. 20 ( 2009-10-15), p. 10347-10357
    Abstract: Simian immunodeficiency virus (SIV)-infected African nonhuman primates do not progress to AIDS in spite of high and persistent viral loads (VLs). Some authors consider the high viral replication observed in chronic natural SIV infections to be due to lower anti-SIV antibody titers than those in rhesus macaques, suggesting a role of antibodies in controlling viral replication. We therefore investigated the impact of antibody responses on the outcome of acute and chronic SIVagm replication in African green monkeys (AGMs). Nine AGMs were infected with SIVagm.sab. Four AGMs were infused with 50 mg/kg of body weight anti-CD20 (rituximab; a gift from Genentech) every 21 days, starting from day −7 postinfection up to 184 days. The remaining AGMs were used as controls and received SIVagm only. Rituximab-treated AGMs were successfully depleted of CD20 cells in peripheral blood, lymph nodes (LNs), and intestine, as shown by the dynamics of CD20 + and CD79a + cells. There was no significant difference in VLs between CD20-depleted AGMs and control monkeys: peak VLs ranged from 10 7 to 10 8 copies/ml; set-point values were 10 4 to 10 5 SIV RNA copies/ml. Levels of acute mucosal CD4 + T-cell depletion were similar for treated and nontreated animals. SIVagm seroconversion was delayed for the CD20-depleted AGMs compared to results for the controls. There was a significant difference in both the timing and magnitude of neutralizing antibody responses for CD20-depleted AGMs compared to results for controls. CD20 depletion significantly altered the histological structure of the germinal centers in the LNs and Peyer's patches. Our results, although obtained with a limited number of animals, suggest that humoral immune responses play only a minor role in the control of SIV viral replication during acute and chronic SIV infection in natural hosts.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
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