Quantification of HIV-DNA and residual viremia in patients starting ART by droplet digital PCR: Their dynamic decay and correlations with immunological parameters and virological success

The transactivation of human endogenous retroviruses is associated with HIV-1 reservoir, lymphocyte activation and low CD4 count in virologically suppressed PLWH

In the context of long-term therapy in virologically suppressed people living with HIV-1 (PLWH), the identification of new biomarkers associated with immuno-virological discordance, and the risk of disease progression is needed. Herein we investigated HERVs expression in association with immuno-virological discordance parameters for the identification of novel markers for the clinical monitoring of virologically suppressed PLWH. It is known the human endogenous retroviruses (HERVs), relics of ancestral exogenous retroviral infections comprising 8 % of human genome, could be reactivated by exogenous viruses including HIV-1. The study included 31 virologically suppressed PLWH and 10 healthy donors; blood HIV-DNA levels and residual plasma viremia were quantified by droplet digital-PCR, the expression of HERVs by RT-Real time PCR, and immunophenotyping by flow cytometry. The results revealed a dynamic association of HERVs with several virological and immunological parameters such as the HIV-1 reservoir, CD4 cell count, CD4 nadir and with CD8 and CD19 lymphocyte activation. In an era of searching innovative biomarkers for people living with HIV-1, the interconnection of HERVs with the HIV-1 reservoir and lymphocyte activation opens to further investigation on HERVs role in persistent immune activation in virologically suppressed PLWH, proposing them as potential new markers for clinical monitoring.

Use of next-generation sequencing on HIV-1 DNA to assess archived resistance in highly treatment-experienced people with multidrug-resistant HIV under virological control: data from the PRESTIGIO Registry

BACKGROUND

To clarify whether next-generation sequencing (NGS) can be useful for resistance assessment in virologically suppressed highly treatment-experienced (HTE) individuals with MDR HIV.

METHODS

Ninety-one participants from the PRESTIGIO Registry were included. NGS was performed on HIV-DNA at 1%, 5% and 20% cut-offs; major drug resistance mutations (DRMs) were evaluated and compared with those detected in historical plasma genotypic resistance testing (h-GRT). APOBEC editing was also characterized.

RESULTS

Participants had a complex and long treatment history [median 23 (IQR 21-25) years of ART exposure) and had been virologically suppressed since a median of 3 (IQR 2-5) years. Among all major DRMs detected by HIV-DNA NGS and/or h-GRT, 30% were exclusively found through NGS. The highest detection rate of historical major DRMs was reached with NGS set at 1%, but unusual substitutions and extensive APOBEC hypermutations suggest technical issues and poor clinical relevance in the 1%-5% interval. At NGS set at 5%, 67.2% of historical major DRMs were detected. The number of major DRMs detected exclusively by DNA-NGS as minority variants (frequency 5%-20%) was significantly higher in individuals who later experienced virological rebound compared with those who maintained virological control [median 2 (IQR 1-3) versus 1 (0-2), P = 0.030] and positively correlated with viraemia levels at rebound (rho = 0.474, P = 0.030).

CONCLUSIONS

In non-viraemic people with an MDR virus, HIV-1 DNA NGS set at 5% is an acceptable technical cut-off that might help to reveal mutations with a potential clinical relevance. Moreover, the number of minority resistance mutations additionally detected by NGS might be associated with loss of virological control.

Plasma, intracellular and lymph node antiretroviral concentrations and HIV DNA change during primary HIV infection: Results from the INACTION P25 study

Despite its effectiveness, combination antiretroviral treatment (cART) has a limited effect on HIV DNA reservoir, which establishes early during primary HIV infection (PHI) and is maintained by latency, homeostatic T-cells proliferation, and residual replication. This limited effect can be associated with low drug exposure in lymphoid tissues and/or suboptimal adherence to antiretroviral drugs (ARVs). The aim of this study was to assess ARV concentrations in plasma, peripheral blood mononuclear cells (PBMCs) and lymph nodes (LNs), and their association to HIV RNA and HIV DNA decay during PHI. Participants were randomised to receive standard doses of darunavir/cobicistat (Arm I), dolutegravir (Arm II) or both (Arm III), with a backbone of tenofovir alafenamide and emtricitabine. Total HIV DNA was measured using digital-droplet PCR in PBMCs at baseline, 12 and 48 weeks. Drug concentrations in plasma and PBMCs were determined at 2, 12 and 48 weeks (LNs at 12 weeks) by UHPLC-MS/MS. Seventy-two participants were enrolled, mostly male (n=68), with a median age of 34 years and variable Fiebig stages (V-VI 57.7%, I-II 23.9%, and III-IV 18.3%). Twenty-six patients were assigned to Arm I, 27 to Arm II and 19 to Arm III. After 48 weeks, most patients had undetectable viremia, with minor differences in HIV RNA decay between arms. Patients with Fiebig I-II showed faster HIV RNA and HIV DNA decay. Intracellular tissue penetration was high for nucleoside analogues and low-moderate for darunavir and dolutegravir. Only tenofovir diphosphate concentrations in PBMCs showed correlation with HIV DNA decay. Overall, these results indicate that the timing of treatment initiation and intracellular tenofovir penetration are primary and secondary factors, respectively, affecting HIV reservoir.

HIV-DNA decrease during treatment in primary HIV-1 infection with three different drug regimens: Italian Network of Acute HIV Infection (INACTION) clinical trial

As the introduction of antiretroviral therapy (ART) during primary HIV-1 infection (PHI) could restrict the establishment of HIV reservoirs, we aimed to assess the effect of three different ART regimens on HIV-DNA load in people living with HIV (PLWH), who started ART in PHI. Randomized, open-label, multicentric study, including subjects in PHI (defined as an incomplete HIV-1 Western blot and detectable plasma HIV-RNA) in the Italian Network of Acute HIV Infection cohort. Participants were randomly assigned (10:10:8) to a fixed-dose combination of tenofovir alafenamide fumarate (TAF) 10 mg plus emtricitabine (FTC) 200 mg, darunavir 800 mg, and cobicistat 150 mg once daily (group A), or TAF 25 mg plus FTC 200 mg, dolutegravir 50 mg once daily (group B), or an intensified four-drug regimen (TAF 10 mg plus FTC 200 mg, dolutegravir 50 mg, darunavir 800 mg, and cobicistat 150 mg once daily) (group C). The primary endpoint was the decrease of HIV-DNA copies/106 peripheral blood mononuclear cells (PBMCs) at weeks (W) 12 and 48. Secondary endpoints were increased in CD4+ cells and in CD4+/CD8+ ratio and percentage of PLWH reaching undetectable HIV-RNA. HIV-DNA was quantified by Droplet Digital PCR (Biorad QX100) and normalized to RPP30 reference gene. This study was registered in ClinicalTrials.gov (number NCT04225325). Among 78 participants enrolled, 30 were randomized to group 1, 28 to group 2, and 20 to group 3. At baseline, median CD4+ count was 658/µL (476-790), HIV-RNA 5.37 (4.38, 6.12) log10  copies/mL, without statistical difference in their change among groups at weeks 12 and 48 (p = 0.432 and 0.234, respectively). The trial was prematurely discontinued for slow accrual and for COVID-19 pandemic-associated restrictions. In the per-protocol analysis, PLWH (n = 72) with undetectable viral load was 54.3% at W12 and 86.4% at W48. Interestingly, the CD4/CD8 ratio progressively increased over time, up to normalization in almost half of the cohort by week 48, despite a deflection in group 3; no difference was observed by the Fiebig stage (I-III vs. IV-VI). HIV-DNA decreased from 4.46 (4.08, 4.81) log10  copies/106 PBMCs to 4.22 (3.79, 4.49) at week 12, and 3.87 (3.46, 4.34) at week 48, without difference among groups. At multivariable analysis, HIV-DNA delta at W48 was associated only with the increase of CD4+ count by 100 cells/mm3 but not with the Fiebig stage, the CD4+/CD8+ ratio, and treatment arm, despite a higher decrease in group 3. Six adverse events were recorded during our study, which did not cause any withdrawal from the study. We observed a decrease in HIV-DNA from baseline to W48 in PLWH treated during PHI, associated with an increase in CD4+ count, unrelated to the treatment arm.

Combination Antiretroviral Therapy and Immunophenotype of Feline Immunodeficiency Virus

Feline Immunodeficiency Virus (FIV) causes progressive immune dysfunction in cats similar to human immunodeficiency virus (HIV) in humans. Although combination antiretroviral therapy (cART) is effective against HIV, there is no definitive therapy to improve clinical outcomes in cats with FIV. This study therefore evaluated pharmacokinetics and clinical outcomes of cART (2.5 mg/kg Dolutegravir; 20 mg/kg Tenofovir; 40 mg/kg Emtricitabine) in FIV-infected domestic cats. Specific pathogen free cats were experimentally infected with FIV and administered either cART or placebo treatments (n = 6 each) for 18 weeks, while n = 6 naïve uninfected cats served as controls. Blood, saliva, and fine needle aspirates from mandibular lymph nodes were collected to quantify viral and proviral loads via digital droplet PCR and to assess lymphocyte immunophenotypes by flow cytometry. cART improved blood dyscrasias in FIV-infected cats, which normalized by week 16, while placebo cats remained neutropenic, although no significant difference in viremia was observed in the blood or saliva. cART-treated cats exhibited a Th2 immunophenotype with increasing proportions of CD4+CCR4+ cells compared to placebo cats, and cART restored Th17 cells compared to placebo-treated cats. Of the cART drugs, dolutegravir was the most stable and long-lasting. These findings provide a critical insight into novel cART formulations in FIV-infected cats and highlight their role as a potential animal model to evaluate the impact of cART on lentiviral infection and immune dysregulation.

Evaluation of HIV-DNA and residual viremia levels through week 96 in HIV-infected individuals who continue a two-drug or switch to a three-drug integrase strand transfer inhibitor based regimen

OBJECTIVES

To investigate HIV-DNA and residual viremia (RV) levels over 96 weeks (W96) in virologically suppressed HIV-1 infected individuals enrolled in the Be-OnE Study. Individuals were randomized to continue a two-drug regimen with dolutegravir (DTG) plus one RTI or to switch to elvitegravir/cobicistat/emtricitabine/tenofovir-alafenamide (E/C/F/TAF).

STUDY DESIGN

Total HIV-DNA and RV were evaluated at baseline, W48 and W96 with ddPCR technique. Potential relationships between viro-immunological parameters and between/within arms were also assessed.

RESULTS

Median (IQR) HIV-DNA was 2247 (767;4268), 1587 (556;3543) and 1076 (512;2345) copies/10⁶ CD4+T-cells at baseline, W48 and at W96, respectively, while RV was 3 (1;5), 4 (1;9) and 2 (2;4) copies/mL, without significant differences between arms. A significant reduction in HIV-DNA and in RV from baseline to W96 was observed in the E/C/F/TAF-arm (HIV-DNA: -285 [-2257;-45], p=0.010; RV: (-1 [-3;0], p=0.007). In the DTG+1RTI-arm, HIV-DNA and RV levels remained stable (HIV-DNA: -549 [-2269;+307], p=0.182; RV: (-1 [-3;+1], p=0.280). For both HIV-DNA and RV, no significant changes were found overtime between the arms. A positive correlation was found between baseline HIV-DNA and HIV-DNA at W96 (E/C/F/TAF: rs=0.726, p=0.0004; DTG+1RTI: rs=0.589, p=0.010). In general, no significant correlations were found between HIV-DNA, RV and immunological parameters overtime.

CONCLUSIONS

In virologically suppressed individuals, a small reduction in the HIV-DNA and HIV-RNA levels was found from baseline to W96 in individuals who switched to the E/C/F/TAF arm compared to those who remained under DTG+1RTI. However, no significant differences were found in the changes of HIV-DNA and HIV-RNA between the two arms over time.

Diagnostic performance of molecular and serological tests of SARS-CoV-2 on well-characterised specimens from COVID-19 individuals: The EDCTP "PERFECT-study" protocol (RIA2020EF-3000)

BACKGROUND

The SARS-CoV-2 pandemic is a global threat affecting 210 countries, with 2,177,469 confirmed cases and 6.67% case fatality rate as of April 16, 2020. In Africa, 17,243 cases have been confirmed, but many remain undiagnosed due to limited laboratory-capacity, suboptimal performance of used molecular-assays (~30% false negative, Yu et al. and Zhao et al., 2020) and limited WHO-recommended rapid-tests.

OBJECTIVES

We aim to implement measures to minimize risks for COVID-19 in Cameroon, putting together multidisciplinary highly-experienced virologists, immunologists, bioinformaticians and clinicians, to achieve the following objectives: (a) to integrate/improve available-infrastructure, methodologies, and expertise on COVID-19. For this purpose, we will create a platform enabling researchers/clinicians to better integrate and translate evidence into the COVID-19 clinical-practice; (b) to enhance capacities in Cameroon for screening/detecting individuals with high-risks of COVID-19, by setting-up effective core-facilities on-site; (c) to validate point-of-care SARS-CoV-2 molecular assays allowing same-day result delivery, thus permitting timely diagnosis, treatment, and retention in care of COVID-19 patients; (d) to implement SARS-CoV-2 diagnosis with innovative/highly sensitive ddPCR-based assays and viral genetic characterization; (e) to validate serological assays to identify COVID-19-exposed persons and follow-up of convalescents.

METHODS

This is a prospective, observational study conducted among COVID-19 suspects/contacts during 24 months in Cameroon. Following consecutive sampling of 1,536 individuals, oro/nasopharyngeal swabs and sera will be collected. Well characterised biorepositories will be established locally; molecular testing will be performed on conventional real-time qPCR, point-of-care GeneXpert, antigen-tests and digital droplet PCR (ddPCR); SARS-CoV2 amplicons will be sequenced; serological testing will be performed using ELISA, and antibody-based kits. Sensitivity, specificity, positive- and negative-predictive values will be evaluated.

EXPECTED OUTCOMES

These efforts will contribute in creating the technical and clinical environment to facilitate earlier detection of Sars-CoV-2 in Africa in general and in Cameroon in particular. Specifically, the goals will be: (a) to implement technology transfer for capacity-building on conventional and point-of-care molecular assays, achieving a desirable performance for clinical diagnosis of SARS-CoV2; (b) to integrate/improve the available infrastructure, methodologies, and expertise on Sars-CoV2 detection; (c) to improve the turn-around-time for diagnosing COVID-19 infection with obvious advantage for patients/clinical management thanks to low-cost assays, thus permitting timely treatment and retention in care; (d) to assess the epidemiology of COVID-19 and circulating-variants in Cameroon as compared to strains found in other countries.

Quantitative Evaluation of Very Low Levels of HIV-1 Reverse Transcriptase by a Novel Highly Sensitive RT-qPCR Assay

Based on previous experience in our laboratory, we developed a real-time reverse transcriptase (RT) quantitative PCR (RT-qPCR) assay for the assessment of very low levels of HIV-1 RT activity. The RNA, acting as a template for reverse transcription into cDNA by HIV-1 RT, consisted of a synthetic RNA ad hoc generated by in vitro transcription and included a coding sequence for HSV-1 gD (gD-RNA-synt). Different conditions of variables involved in the RT-qPCR reaction, notably different amounts of gD-RNA-synt, different mixes of the reaction buffer, and different dNTP concentrations, were tested to optimize the assay. The results indicated that the gD-RNA-synt-based RT assay, in its optimized formulation, could detect a specific cDNA reverse transcription even in the presence of 1 × 10^-9 U of HIV RT. This achievement greatly improved the sensitivity of the assay over previous versions. In summary, this constructed RT-qPCR assay may be considered a promising tool for providing accurate information on very low HIV-1 RT activity.

Assessing the Variability of Cell-Associated HIV DNA Quantification through a Multicenter Collaborative Study

Reliable and accurate quantification of cell-associated HIV DNA (CA HIV DNA) is critical for early infant diagnosis, clinical management of patients under therapy, and to inform new therapeutics efficacy. The present study assessed the variability of CA HIV DNA quantification obtained from various assays and the value of using reference materials to help harmonize the measurements. Using a common set of reagents, our multicenter collaborative study highlights significant variability of CA HIV DNA quantification and lower limit of quantification across assays. The quantification of CA HIV DNA from a panel of infected PBMCs can be harmonized through cross-subtype normalization but assay calibration with the commonly used 8E5 cell line failed to reduce quantification variability between assays, demonstrating the requirement to thoroughly evaluate reference material candidates to help improve the comparability of CA HIV DNA diagnostic assay performance. IMPORTANCE Despite a global effort, HIV remains a major public health burden with an estimated 1.5 million new infections occurring in 2020. HIV DNA is an important viral marker, and its monitoring plays a critical role in the fight against HIV: supporting diagnosis in infants and underpinning clinical management of patients under therapy. Our study demonstrates that HIV DNA measurement of the same samples can vary significantly from one laboratory to another, due to heterogeneity in the assay, protocol, and reagents used. We show that when carefully selected, reference materials can reduce measurement variability and harmonize HIV DNA quantification across laboratories, which will help contribute to improved diagnosis and clinical management of patients living with HIV.

Phosphatidylcholine Liposomes Down-Modulate CD4 Expression Reducing HIV Entry in Human Type-1 Macrophages

A strategy adopted to combat human immunodeficiency virus type-1 (HIV-1) infection is based on interfering with virus entry into target cells. In this study, we found that phosphatidylcholine (PC) liposomes reduced the expression of the CD4 receptor in human primary type-1 macrophages but not in CD4⁺ T cells. The down-regulation was specific to CD4, as any effect was not observed in CCR5 membrane expression. Moreover, the reduction of membrane CD4 expression required the Ca²⁺-independent protein kinase C (PKC), which in turn mediated serine phosphorylation in the intracytoplasmic tail of the CD4 receptor. Serine phosphorylation of CD4 was also associated with its internalization and degradation in acidic compartments. Finally, the observed CD4 downregulation induced by PC liposomes in human primary macrophages reduced the entry of both single-cycle replication and replication competent R5 tropic HIV-1. Altogether, these results show that PC liposomes reduce HIV entry in human macrophages and may impact HIV pathogenesis by lowering the viral reservoir.

Accuracy of real-time PCR and digital PCR for the monitoring of total HIV DNA under prolonged antiretroviral therapy

Total HIV DNA is a standard marker to monitor the HIV reservoir in people living with HIV. We investigated HIV DNA quantification accuracy by a real-time PCR kit (qPCR) and digital PCR (dPCR) method within the same set of primers and probes. Among 48 aviremic patients followed for up to 7 years with qPCR, the mean coefficient of variation of total HIV DNA between two successive measurements was 77% (± 0.42log₁₀ HIVDNA copies/10⁶ PBMC). The total HIV DNA quantified by the two PCR methods has a high correlation (0.99 and 0.83, for 8E5 and PLHIV samples, respectively), but we observed better repeatability and reproducibility of the dPCR compared to the qPCR (CV of 11.9% vs. 24.7% for qPCR, p-value = 0.024). Furthermore, we highlighted a decay of the number of HIV copies in the 8E5 cell line qPCR standard over time (from 0.73 to 0.43 copies per cell), contributing to variations of HIV DNA results in patients whose HIV reservoir should be theoretically stabilized. Our study highlighted that absolute quantification of total HIV DNA by dPCR allows more accurate monitoring of the HIV reservoir than qPCR in patients under prolonged antiretroviral therapy.

miRNA Expression Profiling in Subcutaneous Adipose Tissue of Monozygotic Twins Discordant for HIV Infection: Validation of Differentially Expressed miRNA and Bioinformatic Analysis

Combined AntiRetroviral Treatments (cARTs) used for HIV infection may result in varied metabolic complications, which in some cases, may be related to patient genetic factors, particularly microRNAs. The use of monozygotic twins, differing only for HIV infection, presents a unique and powerful model for the controlled analysis of potential alterations of miRNAs regulation consequent to cART treatment. Profiling of 2578 mature miRNA in the subcutaneous (SC) adipose tissue and plasma of monozygotic twins was investigated by the GeneChip® miRNA 4.1 array. Real-time PCR and ddPCR experiments were performed in order to validate differentially expressed miRNAs. Target genes of deregulated miRNAs were predicted by the miRDB database (prediction score > 70) and enrichment analysis was carried out with g:Profiler. Processes in SC adipose tissue most greatly affected by miRNA up-regulation included (i) macromolecular metabolic processes, (ii) regulation of neurogenesis, and (iii) protein phosphorylation. Furthermore, KEGG analysis revealed miRNA up-regulation involvement in (i) insulin signaling pathways, (ii) neurotrophin signaling pathways, and (iii) pancreatic cancer. By contrast, miRNA up-regulation in plasma was involved in (i) melanoma, (ii) p53 signaling pathways, and (iii) focal adhesion. Our findings suggest a mechanism that may increase the predisposition of HIV+ patients to insulin resistance and cancer.

External quality assessment of HIV-1 DNA quantification assays used in the clinical setting in Italy

Total cell-associated HIV-1 DNA is a surrogate marker of the HIV-1 reservoir, however, certified systems for its quantification are not available. The Italian HIV DNA Network was launched to validate HIV-1 DNA quantification methods in use at University and Hospital labs. A quality control panel including HIV-1 DNA standards, reconstructed blood samples (RBSs) and DNA from different HIV-1 subtypes was blindly tested by 12 participating labs by quantitative real-time PCR (n = 6), droplet digital PCR (n = 3) or both (n = 3). The median 95% hit rate was 4.6 (3.7–5.5) copies per test and linearity in the tested range was excellent (R2 = 1.000 [1.000–1.000]). The median values obtained across labs were 3,370 (2,287–4,245), 445 (299–498), 59 (40–81) and 7 (6–11) HIV-1 DNA copies, for the 3,584, 448, 56 and 7-copy standards, respectively. With RBSs, measured values were within twofold with respect to the median in two thirds of cases. HIV-1 subtypes were missed (CRF01_AE by 3 labs) or underestimated by > 1 log (subtypes A, C, D, F by one lab; CRF01_AE by one lab; CRF02_AG by one lab). The overall performance was excellent with HIV-1 DNA standards, however detection of different HIV-1 subtypes must be improved.

Quantification of Total HIV DNA as a Marker to Measure Viral Reservoir: Methods and Potential Implications for Clinical Practice

The focus of this review is to examine the importance of quantifying total HIV DNA to target the HIV reservoir and the clinical implications and challenges involved in its future application in clinical practice. Despite intrinsic limitations, the quantification of total HIV DNA is currently the most widely used marker for exploring the HIV reservoir. As it allows estimating all forms of HIV DNA in the infected cells, total HIV DNA load is the biomarker of the HIV reservoir that provides most of the insights into HIV pathogenesis. The clinical role of total HIV-DNA in both untreated and treated patients is extensively supported by important lines of evidence. Thus, predictive models that include total HIV DNA load together with other variables could constitute a prognostic tool for use in clinical practice. To date, however, this marker has been primarily used in experimental evaluations. The main challenge is technical. Although the implementation of droplet digital PCR could improve analytical performance over real-time PCR, the lack of standardization has made cross-comparisons of the data difficult. An effort by investigators to compare protocols is needed. Furthermore, the main effort now should be to involve the biomedical industry in the development of certified assays for in vitro diagnostics use.

Viral resistance burden and APOBEC editing correlate with virological response in heavily treatment-experienced people living with multi-drug resistant HIV

BACKGROUND

The impact of drug resistance mutational load and APOBEC editing in heavily treatment-experienced (HTE) people living with multidrug-resistant HIV has not been investigated.

MATERIAL AND METHODS

This study explored the HIV-DNA and HIV-RNA mutational load of drug resistance and APOBEC-related mutations through next-generation sequencing (NGS, Illumina MiSeq) in 20 failing HTE participants enrolled in the PRESTIGIO registry.

RESULTS

The patients showed high levels of both HIV-DNA (4.5 [4.0-5.2] log₁₀ copies/10⁶ T-CD4+ cell) and HIV-RNA (4.5 [4.1-5.0] log₁₀ copies/mL) with complex resistance patterns in both compartments. Among the 255 drug-resistant mutations found, 66.3% were concordantly detected in both HIV-DNA and HIV-RNA; 71.3% of mutations were already present in historical Sanger genotypes. At an intra-patient frequency > 5%, a considerable proportion of mutations detected through DNA-NGS were found in historical genotypes but not through RNA-NGS, and few patients had APOBEC-related mutations. Of 14 patients who switched therapy, the five who failed treatment had DNA resistance with higher intra-patient frequency and higher DNA/RNA mutational load in a context of tendentially less pronounced APOBEC editing compared with those who responded.

CONCLUSIONS

Using NGS in HIV-DNA and HIV-RNA together with APOBEC editing evaluation might help to identify HTE individuals with MDR who are more prone to experience virological failure.

Prevalence and risk of residual viremia after ART in low- and middle-income countries: A cross-sectional study

ABSTRACT

In order to design effective strategies to eradicate the HIV, an understanding of persistent viral reservoirs is needed. Many studies have demonstrated HIV residual viremia prevalence in high income countries, data from low- and middle-income countries (LMIC) are limited. We assessed the prevalence, and factors associated with residual viremia in people with HIV (PWH), who were virally-suppressed on antiretroviral therapy (ART) in LMIC. We also compared residual viremia prevalence between the LMIC and US.This is a cross-sectional, retrospective study that utilized stored specimen samples from the AIDS clinical trials group (ACTG) studies A5175 and A5208. The last available sample among participants with plasma HIV RNA < 400 copies/mL for ≥3 years were tested by the HIV molecular and monitoring core gag (HMMCgag) single copy assay (SCA). Residual viremia was defined as detectable if ≥1 copy/mL. Spearman's correlation and multivariable stepwise logistic regression were used to assess associations of various factors with SCA.A total of 320 participants, 246 (77%) from LMIC and 74 (23%) from US, were analyzed. Median (IQR) age was 33 (2840) years; baseline CD4 166 (88,230) cells/mm3; HIV RNA 5.0 (4.5, 5.3) log10 copies/mL; duration of viral suppression 3.4 (3.1, 4.0) years and 48% were male. In 85 participants with information available, 53% were subtype C, 42% subtype B and 5% other subtypes. Overall prevalence of residual viremia was 57% [95% CI, 52-63] with 51% [40-63] in US and 59% [53-65] in LMIC. Among participants with detectable SCA, the median (IQR) HIV RNA was 3.8 (2.2, 8.1) copies/mL. The multivariable model conducted in LMIC participants showed that higher baseline HIV RNA was associated with detectable residual RNA (OR 2.9, 95% CI 1.8, 4.6 for every log10 increase, P < .001). After including both US and LMIC in the final model, baseline HIV RNA remained significant. No difference in SCA detestability was found between US and LMIC sites (OR 1.1 [0.6, 2.0], P = .72) after adjusting for baseline RNA and parent study.The prevalence of residual viremia between both groups were not different and more than half of the participants had detectable viremia. Higher baseline HIV RNA was independently associated with residual viremia.

Impact of Analytical Treatment Interruption on Burden and Diversification of HIV Peripheral Reservoir: A Pilot Study

BACKGROUND

If analytical antiretroviral-treatment (ART) interruption (ATI) might significantly impact quantitative or qualitative peripheral-total HIV-DNA is still debated.

METHODS

Six chronically HIV-1 infected patients enrolled in APACHE-study were analysed for peripheral-total HIV-DNA and residual viremia, major-resistance-mutations (MRMs) and C2-V3-C3 evolution at pre-ATI (T1), during ATI (T2) and at achievement of virological success after ART-resumption (post-ATI, T3). These data were obtained at three comparable time-points in five chronically HIV-1 infected patients on suppressive ART for ≥1 year, enrolled in MODAt-study.

RESULTS

At T1, APACHE and MODAt individuals had similar peripheral-total HIV-DNA and residual viremia (p = 0.792 and 0.662, respectively), and no significant changes for these parameters were observed between T1 and T3 in both groups. At T1, 4/6 APACHE and 2/5 MODAt carried HIV-DNA MRMs. MRMs disappeared at T3 in 3/4 APACHE. All disappearing MRMs were characterized by T1 intra-patient prevalence <80%, and mainly occurred in APOBEC3-related sites. All MRMs persisted over-time in the 2 MODAt. C2-V3-C3 genetic-distance significantly changed from T1 to T3 in APACHE individuals (+0.36[0.11-0.41], p = 0.04), while no significant changes were found in MODAt. Accordingly, maximum likelihood trees (bootstrap > 70%) and genealogical sorting indices (GSI > 0.50 with p-value < 0.05) showed that T1 C2-V3-C3 DNA sequences were distinct from T2 and T3 viruses in 4/6 APACHE. Virus populations at all three time-points were highly interspersed in MODAt.

CONCLUSIONS

This pilot study indicates that short ATI does not alter peripheral-total HIV-DNA burden and residual viremia, but in some cases could cause a genetic diversification of peripheral viral reservoir in term of both MRMs rearrangement and viral evolution.

Sensitive quantitative detection of SARS-CoV-2 in clinical samples using digital warm-start CRISPR assay

Quantifying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in clinical samples is crucial for early diagnosis and timely medical treatment of coronavirus disease 2019. Here, we describe a digital warm-start CRISPR (dWS-CRISPR) assay for sensitive quantitative detection of SARS-CoV-2 in clinical samples. The dWS-CRISPR assay is initiated at above 50 °C and overcomes undesired premature target amplification at room temperature, enabling accurate and reliable digital quantification of SARS-CoV-2. By targeting SARS-CoV-2's nucleoprotein gene, the dWS-CRISPR assay is able to detect down to 5 copies/μl SARS-CoV-2 RNA in the chip. It is clinically validated by quantitatively determining 32 clinical swab samples and three clinical saliva samples. Moreover, it has been demonstrated to directly detect SARS-CoV-2 in heat-treated saliva samples without RNA extraction. Thus, the dWS-CRISPR method, as a sensitive and reliable CRISPR assay, facilitates accurate SARS-CoV-2 detection toward digitized quantification.

Droplet digital PCR of viral ‎DNA/RNA, current progress, challenges, and future perspectives

High-throughput droplet-based digital PCR (ddPCR) is a refinement of the conventional polymerase chain reaction (PCR)‎ methods. In ddPCR, DNA/RNA is encapsulated stochastically inside the microdroplets as reaction chambers. A small percentage of the reaction chamber contains one or fewer copies of the DNA or RNA. After PCR amplification, concentrations are determined based on the proportion of nonfluorescent partitions through the Poisson distribution. Some of the main features of ddPCR include high sensitivity and specificity, absolute quantification without a standard curve, high reproducibility, good tolerance to PCR inhibitor, and high efficacy compared to conventional molecular methods. These advantages make ddPCR a valuable addition to the virologist's toolbox. The following review outlines the recent technological advances in ddPCR methods and their applications in viral identification.

Evolution of cellular HIV DNA levels in virologically suppressed patients switching to dolutegravir/lamivudine versus maintaining a triple regimen: a prospective, longitudinal, matched, controlled study

OBJECTIVES

To assess the impact of switching to dolutegravir plus lamivudine maintenance therapy on the HIV cellular reservoir size.

PATIENTS AND METHODS

This was a prospective, longitudinal, matched, controlled study. We enrolled virologically suppressed patients on stable three-drug ART who switched at baseline (BL) to dolutegravir/lamivudine (DT group) or maintained triple therapy (TT group); subjects in the TT group were matched 1:1 with those in the DT group according to age, gender, years since HIV diagnosis, years on ART and anchor drug. Total blood-associated HIV DNA levels were assessed by droplet digital PCR at BL and after 48 weeks (T48). Results were expressed as log10 HIV DNA copies/106 leucocytes.

RESULTS

We enrolled 40 patients in the DT group and 40 in the TT group; the two groups were homogeneous for all main characteristics except nadir CD4 cell count. At BL, HIV DNA levels were comparable between the DT and TT groups: 2.27 (IQR 1.97-2.47) and 2.26 (IQR 2.05-2.61) log10 HIV DNA copies/106 leucocytes, respectively. Change in HIV DNA load from BL to T48 was -0.105 (IQR -0.384 to 0.121, P = 0.041) in the DT group and -0.132 (IQR -0.362 to 0.046, P = 0.005) in the TT group, with a comparable decline observed between the two groups (P = 0.821). A higher HIV DNA decline was associated with higher BL CD4/CD8 ratio.

CONCLUSIONS

Maintenance therapy with dolutegravir/lamivudine had the same impact as the triple regimen on HIV DNA levels after 48 weeks of treatment. These data seem to support the effectiveness of a dolutegravir/lamivudine dual regimen in controlling the magnitude of the cellular reservoir (www.clinicaltrials.gov, number NCT02836782).

Droplet digital PCR assay as an innovative and promising highly sensitive assay to unveil residual and cryptic HBV replication in peripheral compartment

Droplet digital PCR is an innovative and promising approach for highly sensitive quantification of nucleic acids that is being increasingly used in the field of clinical virology, including the setting of hepatitis B virus (HBV). Here, we comprehensively report a robust and reproducible ddPCR assay for the highly sensitive quantification of serum HBV-DNA. The assay showed a limit of detection of 4 copies/ml (<1IU/ml) by Probit analysis, showed a good linearity (R² = 0.94) and a high intra- and inter-run reproducibility with differences between the values obtained in the same run or in two independent runs never exceeding 0.14logcopies/mL and 0.21logcopies/mL, respectively. By analysing serum samples from chronically HBV infected patients (mostly under antiviral treatment), ddPCR successfully quantified serum HBV-DNA in 89.8% of patients with detectable serum HBV-DNA < 20 IU/mL [equivalent to <112copies/ml] by classical Real-Time PCR assay, with a median (IQR) of 8(5-14)IU/mL [45(28-78)copies/ml], and in 66.7% of patients with undetectable serum HBV-DNA, with a median (IQR) of 5(4-9)IU/mL [28(20-50)copies/ml]. Similarly, by analysing serum samples from patients with a serological profile compatible with occult HBV infection (anti-HBc+/HBsAg-), ddPCR successfully quantified serum HBV-DNA in 40% of patients with a median (IQR) value of 1(1-2)IU/mL [5(5-11)copies/ml], in line with the extremely limited viral replication typically observed in occult HBV infection. Overall, the availability of assays for the highly sensitive quantification of serum HBV-DNA can provide an added value in optimizing the diagnosis of occult hepatitis B infection, improving the therapeutic management of chronically HBV infected patients, also in the light of innovative drugs (upcoming in clinical practise) aimed at achieving HBV functional cure.

ASSURED-SQVM diagnostics for COVID-19: addressing the why, when, where, who, what and how of testing

Introduction: SARS-CoV-2, the new coronavirus that originated in 2019, continues to impact every aspect of society in a profound manner. Testing will remain an important tool to mitigate the effects of this pandemic as early and accurate diagnosis can lead to appropriate countermeasures to reduce mortality and morbidity. However, testing isn't a simple yes/no answer as the target and host are complex, the virus is a moving target, there is a plethora of tests that identify different parts of the virus and have their own limits and range of detection, and when prevalence is low, false positives and negatives can be very high.Areas covered: This article covers all the major questions related to COVID-19 diagnostics, the why, when, where, who, what and how of testing, the different types of tests, interpretation of results and the ideal ASSURED-SQVM diagnostic. A comprehensive literature review using all the publicly available databases and government websites and reports was performed.Expert opinion: Diagnostics that meet the 'ASSURED-SQVM' (Affordable, Selective and Sensitive, User-friendly, Rapid and Robust, Equipment-free, Deliverable to end-users and additionally, allows for Self-testing, Quantifiable, detects if pathogens are Viable and can detect Multiple pathogens) would make a major impact in our fight against the current pandemic. While a significant majority of researchers focus on developing novel diagnostics that are highly selective and sensitive, it is the opinion of these authors that other aspects of the ASSURED-SQVM principles also be considered early in the development process for widespread use.

COVID-19: Virology, biology and novel laboratory diagnosis

BACKGROUND

At the end of December 2019, a novel coronavirus tentatively named SARS-CoV-2 in Wuhan, a central city in China, was announced by the World Health Organization. SARS-CoV-2 is an RNA virus that has become a major public health concern after the outbreak of the Middle East Respiratory Syndrome-CoV (MERS-CoV) and Severe Acute Respiratory Syndrome-CoV (SARS-CoV) in 2002 and 2012, respectively. As of 29 October 2020, the total number of COVID-19 cases had reached over 44 million worldwide, with more than 1.17 million confirmed deaths.

DISCUSSION

SARS-CoV-2 infected patients usually present with severe viral pneumonia. Similar to SARS-CoV, the virus enters respiratory tract cells via the angiotensin-converting enzyme receptor 2. The structural proteins play an essential role in budding the virus particles released from different host cells. To date, an approved vaccine or treatment option of a preventive character to avoid severe courses of COVID-19 is still not available.

CONCLUSIONS

In the present study, we provide a brief review of the general biological features of CoVs and explain the pathogenesis, clinical symptoms and diagnostic approaches regarding monitoring future infectivity and prevent emerging COVID-19 infections.

Detection and quantification of SARS-CoV-2 by droplet digital PCR in real-time PCR negative nasopharyngeal swabs from suspected COVID-19 patients

Since SARS-CoV-2-based disease (COVID-19) spreads as a pandemic, the necessity of a highly sensitive molecular diagnosis that can drastically reduce false negatives reverse transcription PCR (rtPCR) results, raises as a major clinical need. Here we evaluated the performance of a ddPCR-based assay to quantify SARS-CoV-2 titer in 55 suspected COVID-19 cases with negative rtPCR results thanks to in-house ddPCR assay (targeting RdRp and host RNaseP). Samples were collected at ASST-GOM Niguarda between February and May 2020 at hospital admission. Clinical and imaging data were obtained for clinical staging and definition of disease severity. Patients were mainly female (45.5%) with a median age of 73 (57–84) years. ddPCR-based assay detected SARS-CoV-2 genome in nasopharyngeal samples of 19 (34.5%) patients (median viral-load: 128 copies/mL, IQR: 72–345). In 15 of them (78.9%), chest CT showed a classical COVID-19 bilateral interstitial pneumonia; 14 patients (73.7%) showed severe COVID-19 manifestations. ddPCR did not identify any trace of SARS-CoV-2 genome in the respiratory samples of the remaining 36 patients. The serological assay performed in a subgroup of 34 patients at the later stage of illness (from 3 days to 90 days after) confirmed the presence of SARS-CoV-2 antibodies in all patients tested positive for SARS-CoV-2 in ddPCR (100%). Contrariwise, negative tests were observed in 95.0% ddPCR negative patients (P<0.001). Thanks to a ddPCR-based assay, we achieved a rapid and accurate SARS-CoV-2 diagnosis in rtPCR-negative respiratory samples of individuals with COVID-19 suspect, allowing the rapid taking care and correct management of these patients.

Impact of Raltegravir or Efavirenz on Cell-Associated Human Immunodeficiency Virus-1 (HIV-1) Deoxyribonucleic Acid and Systemic Inflammation in HIV-1/Tuberculosis Coinfected Adults Initiating Antiretroviral Therapy

Background

In view of the fast viremia decline obtained with integrase inhibitors, we studied the respective effects of initiating efavirenz (EFV) or raltegravir (RAL)-based antiretroviral therapy (ART) regimens on human immunodeficiency virus (HIV)-1 deoxyribonucleic acid (DNA) levels and inflammation biomarkers in the highly inflammatory setting of advanced HIV-1 disease with tuberculosis (TB) coinfection.

Methods

We followed cell-associated HIV-1 DNA, high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), soluble CD14 and D-Dimer levels for 48 weeks after ART initiation in the participants to the ANRS12-180 REFLATE-TB study. This phase II open-label randomized study included ART-naive people with HIV and TB treated with rifampicin to receive RAL 400 mg twice daily (RAL400), RAL 800 mg twice daily (RAL800) or EFV 600 mg QD with tenofovir and lamivudine.

Results

In 146 participants, the median (interquartile range [IQR]) week (W)0 HIV-1 DNA level was 4.7 (IQR, 4.3–5.1) log₁₀ copies/10⁶ CD4⁺, and the reduction by W48 was −0.8 log₁₀ copies/10⁶ CD4⁺ on EFV, −0.9 on RAL400, and −1.0 on RAL800 (P = .74). Baseline median (IQR) hsCRP, IL-6, sCD14, and D-Dimer levels were 6.9 (IQR, 3.3–15.6) mg/L, 7.3 (IQR, 3.5–12.3) pg/mL, 3221 (IQR, 2383–4130) ng/mL, and 975 (IQR, 535–1970) ng/mL. All biomarker levels decreased over the study: the overall W0–W48 mean (95% confidence interval) fold-change on ART was 0.37 (IQR, 0.28–0.48) for hsCRP, 0.42 (IQR, 0.35–0.51) for IL-6, 0.51 (IQR, 0.47–0.56) for sCD14, and 0.39 (IQR, 0.32–0.47) for D-Dimers. There were no differences in biomarker reduction across treatment arms.

Conclusions

In participants with HIV and TB, EFV, RAL400, or RAL800 effectively and equally reduced inflammation and HIV-1 DNA levels.