Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Dec 21;96(24):e0160522.
doi: 10.1128/jvi.01605-22. Epub 2022 Nov 30.

New Assay Reveals Vast Excess of Defective over Intact HIV-1 Transcripts in Antiretroviral Therapy-Suppressed Individuals

Affiliations

New Assay Reveals Vast Excess of Defective over Intact HIV-1 Transcripts in Antiretroviral Therapy-Suppressed Individuals

Holly Anne Martin et al. J Virol. .

Abstract

Most of the HIV DNA in infected individuals is noninfectious because of deleterious mutations. However, it is unclear how much of the transcribed HIV RNA is potentially infectious or defective. To address this question, we developed and validated a novel intact viral RNA assay (IVRA) that uses droplet digital reverse transcriptase PCR (dd-RT-PCR) for the commonly mutated packaging signal (Psi) and Rev response element (RRE) regions (from the intact proviral DNA assay [IPDA]) to quantify likely intact (Psi+ RRE+), 3' defective (Psi+ RRE-), and 5' defective (Psi- RRE+) HIV RNA. We then applied the IPDA and IVRA to quantify intact and defective HIV DNA and RNA from peripheral CD4+ T cells from 9 antiretroviral therapy (ART)-suppressed individuals. Levels of 3' defective HIV DNA were not significantly different from those of 5' defective HIV DNA, and both were higher than intact HIV DNA. In contrast, 3' defective HIV RNA (median 86 copies/106 cells; 94% of HIV RNA) was much more abundant than 5' defective (2.1 copies/106 cells; 5.6%) or intact (0.6 copies/106 cells; <1%) HIV RNA. Likewise, the frequency of CD4+ T cells with 3' defective HIV RNA was greater than the frequency with 5' defective or intact HIV RNA. Intact HIV RNA was transcribed by a median of 0.018% of all proviruses and 2.2% of intact proviruses. The vast excess of 3' defective RNA over 5' defective or intact HIV RNA, which was not observed for HIV DNA, suggests that HIV transcription is completely blocked prior to the RRE in most cells with intact proviruses and/or that cells transcribing intact HIV RNA are cleared at very high rates. IMPORTANCE We developed a new assay that can distinguish and quantify intact (potentially infectious) as well as defective HIV RNA. In ART-treated individuals, we found that the vast majority of all HIV RNA is defective at the 3' end, possibly due to incomplete transcriptional processivity. Only a very small percentage of all HIV RNA is intact, and very few total or intact proviruses transcribe intact HIV RNA. Though rare, this intact HIV RNA is tremendously important because it is necessary to serve as the genome of infectious virions that allow transmission and spread, including rebound after stopping ART. Moreover, intact viral RNA may contribute disproportionately to the immune activation, inflammation, and organ damage observed with untreated and treated HIV infection. The intact viral RNA assay can be applied to many future studies aimed at better understanding HIV pathogenesis and barriers to HIV cure.

Keywords: HIV DNA; HIV RNA; HIV provirus; HIV-1; defective; infectious; intact; intact proviral DNA assay (IPDA); latent infection; transcription; transcriptional regulation; viral replication.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

FIG 1
FIG 1
Linearity, efficiency, and detection limit of IVRA on supernatant HIV RNA standards. HIV RNA standards were prepared from the supernatant of in vitro infections and independently quantified using the Abbott clinical assay. The HIV RNA standards were diluted to achieve predicted inputs of 1 to 104 copies (x axis), and the copies of Psi (A and D), RRE (B and D), and Psi+ RRE+ (intact) (C and D) HIV RNA were measured by dd-RT-PCR (IVRA). Slopes and R2 values were determined by linear regression analysis.
FIG 2
FIG 2
Levels and proportions of defective and intact HIV DNA and RNA. RNA and DNA were extracted in parallel from replicate dilutions of peripheral CD4+ T cells from 9 ART-suppressed individuals. Average levels (A) and proportions (B) of defective and intact HIV DNA were measured by ddPCR using the IPDA. Defective and intact HIV RNA levels (C) and proportions (D) were measured by dd-RT-PCR using the IVRA. Each color represents a different individual. Samples in which intact HIV DNA or RNA was not detected were assigned a maximum value (inverted triangles) based on 1 copy divided by the total cell equivalents analyzed across all cell replicates. Bars indicate the medians. ** indicates P < 0.005 (Wilcoxon signed-rank test).
FIG 3
FIG 3
Ratios of intact and defective HIV RNA to DNA. The copies/106 cells of intact and defective HIV RNA were divided by the copies/106 cells of total (containing Psi and/or RRE) HIV DNA (A) or the corresponding type of HIV DNA (B) to express the HIV RNA/DNA ratio (y axis). Each color represents a different individual. Samples in which either intact HIV RNA or DNA was not detected were assigned a maximum value (set to 1 copy divided by the total cell equivalents analyzed) in order to calculate the maximum (inverted triangle) or minimum (triangle) HIV RNA/DNA levels. Bars represent the medians. ** indicates P < 0.005 (Wilcoxon signed-rank test).
FIG 4
FIG 4
Frequencies of peripheral CD4+ T cells harboring defective and intact HIV RNA. Using the proportion of cell replicates in which each type of HIV RNA was detected, along with the total number of cells per replicate (starting cell counts), we calculated the frequencies (y axes) of CD4+ T cells that contain each type of HIV RNA (A) and intact HIV RNA (B) according to the method of extreme limiting dilution analysis (ELDA). Each color represents a different individual. Circles indicate estimated frequencies; triangles indicate minimums; inverted triangles represent maximums. Bars represent medians. * indicates P < 0.05 (Wilcoxon signed-rank test). PID, patient identifier.

Similar articles

Cited by

References

    1. Chun TW, Stuyver L, Mizell SB, Ehler LA, Mican JA, Baseler M, Lloyd AL, Nowak MA, Fauci AS. 1997. Presence of an inducible HIV-1 latent reservoir during highly active antiretroviral therapy. Proc Natl Acad Sci USA 94:13193–13197. 10.1073/pnas.94.24.13193. - DOI - PMC - PubMed
    1. Wong JK, Hezareh M, Gunthard HF, Havlir DV, Ignacio CC, Spina CA, Richman DD. 1997. Recovery of replication-competent HIV despite prolonged suppression of plasma viremia. Science 278:1291–1295. 10.1126/science.278.5341.1291. - DOI - PubMed
    1. Finzi D, Hermankova M, Pierson T, Carruth LM, Buck C, Chaisson RE, Quinn TC, Chadwick K, Margolick J, Brookmeyer R, Gallant J, Markowitz M, Ho DD, Richman DD, Siliciano RF. 1997. Identification of a reservoir for HIV-1 in patients on highly active antiretroviral therapy. Science 278:1295–1300. 10.1126/science.278.5341.1295. - DOI - PubMed
    1. Phillips AN, Neaton J, Lundgren JD. 2008. The role of HIV in serious diseases other than AIDS. AIDS 22:2409–2418. 10.1097/QAD.0b013e3283174636. - DOI - PMC - PubMed
    1. Kuller LH, Tracy R, Belloso W, De Wit S, Drummond F, Lane HC, Ledergerber B, Lundgren J, Neuhaus J, Nixon D, Paton NI, Neaton JD, INSIGHT SMART Study Group . 2008. Inflammatory and coagulation biomarkers and mortality in patients with HIV infection. PLoS Med 5:e203. 10.1371/journal.pmed.0050203. - DOI - PMC - PubMed

Publication types