scholarly journals Development of a reverse transcription droplet digital PCR (RT-ddPCR) assay for sensitive detection of simian immunodeficiency virus (SIV)

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Samuel Long ◽  
Brian Berkemeier
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Reverse Transcription ◽  
Rhesus Macaques ◽  
Digital Pcr ◽  
Droplet Digital Pcr ◽  
Sensitive Detection ◽  
Similar Reaction ◽  
Tissue Samples ◽  
Low Level ◽  
Immunodeficiency Virus

Abstract Background Simian immunodeficiency virus (SIV)-infected rhesus macaques constitute an excellent model of human HIV infection. Sensitive detection of SIV RNA in cell and tissue samples from infected animals subjected to treatment regimens becomes especially critical in determining which therapeutic attempts are successful, and consequently, which interventions should be prioritized in HIV cure research. Results In this report, we describe the design and testing of a Raindance ddPCR platform-based, sensitive SIV reverse transcription droplet digital PCR (RT-ddPCR) assay by exploring the combinations of various priming conditions and reverse transcriptases, and testing one-step vs. two-step procedures, to eliminate background signal(s) and enable detection and quantification of low level target signals. Conclusions Similar reaction conditions and assay validation procedures can be explored for potential development of additional assays for other applications that require sensitive detection of low-level targets in RNA samples.

Development of a novel reverse transcription droplet digital PCR assay for the sensitive detection of Senecavirus A

2018 ◽  
Vol 66 (1) ◽  
pp. 517-525 ◽  
Author(s):  
Zhou Zhang ◽  
Yongning Zhang ◽  
Xiangmei Lin ◽  
Zhenhai Chen ◽  
Shaoqiang Wu
Keyword(s):  
Reverse Transcription ◽  
Digital Pcr ◽  
Droplet Digital Pcr ◽  
Sensitive Detection ◽  
Pcr Assay

scholarly journals Occult Systemic Infection and Persistent Simian Immunodeficiency Virus (SIV)-Specific CD4+-T-Cell Proliferative Responses in Rhesus Macaques That Were Transiently Viremic after Intravaginal Inoculation of SIV

1998 ◽  
Vol 72 (12) ◽  
pp. 10029-10035 ◽  
Author(s):  
Michael B. McChesney ◽  
Jennifer R. Collins ◽  
Ding Lu ◽  
Xusheng Lu ◽  
Judith Torten ◽  
...  
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Sexual Transmission ◽  
Systemic Infection ◽  
Lymphoid Tissues ◽  
Vaginal Mucosa ◽  
Tissue Samples ◽  
Immunodeficiency Virus ◽  
Culture Negative ◽  
Ctl Responses

ABSTRACT The intact cervicovaginal mucosa is a relative barrier to the sexual transmission of human immunodeficiency virus type 1 (HIV-1). In the simian immunodeficiency virus (SIV) macaque model of HIV infection, seronegative transient viremia (STV; virus isolation positive followed by repeated negative cultures) occurs after intravaginal inoculation of a low dose of pathogenic SIVmac251 (C. J. Miller, M. Marthas, J. Torten, N. Alexander, J. Moore, G. Doncel, and A. Hendrickx, J. Virol. 68:6391–6400, 1994). Thirty-one adult female macaques that had been inoculated intravaginally with pathogenic SIVmac251 became transiently viremic. One monkey that had been culture negative for a year after SIV inoculation became persistently viremic and developed simian AIDS. No other STV monkey developed persistent viremia or disease. Results of very sensitive assays showed that 6 of 31 monkeys had weak SIV-specific antibody responses. SIV-specific antibodies were not detected in the cervicovaginal secretions of 10 STV monkeys examined. Twenty of 26 monkeys had lymphocyte proliferative responses to p55 gag and/or gp130 env antigens; 3 of 6 animals, including the monkey that became persistently viremic, had detectable cytotoxic T-lymphocyte (CTL) responses to SIV. At necropsy, lymphoid tissues and vaginal mucosa were virus culture negative, but in 10 of 10 animals, SIV provirus was detected by PCR using gag-specific primer pairs. Fifty percent of the PCR-positive tissue samples were also positive for SIV gag RNA by reverse transcriptase PCR. Thus, transient viremia following intravaginal inoculation of pathogenic SIV is associated with persistent, systemic infection, either latent or very low level productive. Atypical immune responses, characterized by lymphocyte proliferation and some CTL responses in the absence of conventionally detectable antibodies, develop in transiently viremic monkeys.

scholarly journals Enhanced Intestinal TGF-β/SMAD-Dependent Signaling in Simian Immunodeficiency Virus Infected Rhesus Macaques

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 806
Author(s):  
Nongthombam Boby ◽  
Alyssa Ransom ◽  
Barcley T. Pace ◽  
Kelsey M. Williams ◽  
Christopher Mabee ◽  
...  
Keyword(s):  
Gene Expression ◽  
Simian Immunodeficiency Virus ◽  
Transforming Growth Factor ◽  
Rhesus Macaques ◽  
Transforming Growth Factor Β ◽  
Immunodeficiency Virus ◽  
Cellular Source ◽  
Siv Infection ◽  
Β Receptor ◽  
Differentiation And Proliferation

Transforming growth factor-β signaling (TGF-β) maintains a balanced physiological function including cell growth, differentiation, and proliferation and regulation of immune system by modulating either SMAD2/3 and SMAD7 (SMAD-dependent) or SMAD-independent signaling pathways under normal conditions. Increased production of TGF-β promotes immunosuppression in Human Immunodeficiency Virus (HIV)/Simian Immunodeficiency Virus (SIV) infection. However, the cellular source and downstream events of increased TGF-β production that attributes to its pathological manifestations remain unknown. Here, we have shown increased production of TGF-β in a majority of intestinal CD3−CD20−CD68+ cells from acute and chronically SIV infected rhesus macaques, which negatively correlated with the frequency of jejunum CD4+ T cells. No significant changes in intestinal TGF-β receptor II expression were observed but increased production of the pSMAD2/3 protein and SMAD3 gene expression in jejunum tissues that were accompanied by a downregulation of SMAD7 protein and gene expression. Enhanced TGF-β production by intestinal CD3−CD20−CD68+ cells and increased TGF-β/SMAD-dependent signaling might be due to a disruption of a negative feedback loop mediated by SMAD7. This suggests that SIV infection impacts the SMAD-dependent signaling pathway of TGF-β and provides a potential framework for further study to understand the role of viral factor(s) in modulating TGF-β production and downregulating SMAD7 expression in SIV. Regulation of mucosal TGF-β expression by therapeutic TGF-β blockers may help to create effective antiviral mucosal immune responses.

scholarly journals A Truncated Form of Nef Selected during Pathogenic Reversion of Simian Immunodeficiency Virus SIVmac239Δnef Increases Viral Replication

2003 ◽  
Vol 77 (2) ◽  
pp. 1245-1256 ◽  
Author(s):  
Lisa A. Chakrabarti ◽  
Karin J. Metzner ◽  
Tijana Ivanovic ◽  
Hua Cheng ◽  
Jean Louis-Virelizier ◽  
...  
Keyword(s):  
T Cell ◽  
Viral Replication ◽  
Simian Immunodeficiency Virus ◽  
Rhesus Macaques ◽  
Premature Stop Codon ◽  
Cell Depletion ◽  
Partial Recovery ◽  
Wild Type ◽  
T Cell Depletion ◽  
Immunodeficiency Virus

ABSTRACT The live, attenuated vaccine simian immunodeficiency virus SIVmac239Δnef efficiently protects rhesus macaques against infection with wild-type SIVmac but occasionally causes CD4+ T-cell depletion and progression to simian AIDS (SAIDS). Virus recovered from a vaccinated macaque (Rh1490) that progressed to SAIDS had acquired an additional deletion in the nef gene, resulting in a frameshift that restored the original nef open reading frame (R. I. Connor, D. C. Montefiori, J. M. Binley, J. P. Moore, S. Bonhoeffer, A. Gettie, E. A. Fenamore, K. E. Sheridan, D. D. Ho, P. J. Dailey, and P. A. Marx, J. Virol. 72:7501-7509, 1998). Intravenous inoculation of the Rh1490 viral isolate into four naive rhesus macaques induced CD4+ T-cell depletion and disease in three out of four animals within 2 years, indicating a restoration of virulence. A DNA fragment encompassing the truncated nef gene amplified from the Rh1490 isolate was inserted into the genetic backbone of SIVmac239. The resulting clone, SIVmac239-Δ2nef, expressed a Nef protein of approximately 23 kDa, while the original SIVmac239Δnef clone expressed a shorter protein of 8 kDa. The revertant form of Nef did not cause downregulation of CD4, CD3, or major histocompatibility complex class I. The infectivity of SIVmac239-Δ2nef was similar to that of SIVmac239Δnef in single-cycle assays using indicator cell lines. In contrast, SIVmac239-Δ2nef replicated more efficiently than SIVmac239Δnef in peripheral blood mononuclear cell (PBMC) cultures infected under unstimulated conditions. The p27 Gag antigen levels in SIVmac239-Δ2nef-infected cultures were still lower than those obtained with wild-type SIVmac239, consistent with a partial recovery of Nef function. The transcriptional activity of long terminal repeat (LTR)-luciferase constructs containing the nef deletions did not differ markedly from that of wild-type LTR. Introduction of a premature stop codon within Nef-Δ2 abolished the replicative advantage in PBMCs, demonstrating that the Nef-Δ2 protein, rather than the structure of the U3 region of the LTR, was responsible for the increase in viral replication. Taken together, these results show that SIV with a deletion in the nef gene can revert to virulence and that expression of a form of nef with multiple deletions may contribute to this process by increasing viral replication.

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