Sergio Carmona

Controlling HBV Replication in Vivo by Intravenous Administration of Triggered PEGylated siRNA-Nanoparticles

Harnessing RNA interference (RNAi) to inhibit hepatitis B virus (HBV) gene expression has promising application to therapy. Here we describe a new hepatotropic nontoxic lipid-based vector system that is used to deliver chemically unmodified small interfering RNA (siRNA) sequences to the liver. Anti HBV formulations were generated by condensation of siRNA (A component) with cationic liposomes (B component) to form AB core particles. These core particles incorporate an aminoxy cholesteryl lipid for convenient surface postcoupling of polyethylene glycol (PEG; C component, stealth/biocompatibility polymer) to give triggered PEGylated siRNA-nanoparticles (also known as siRNA-ABC nanoparticles) with uniform small sizes of 80-100 nm in diameter. The oxime linkage that results from PEG coupling is pH sensitive and was included to facilitate acidic pH-triggered release of nucleic acids from endosomes. Nanoparticle-mediated siRNA delivery results in HBV replication knockdown in cell culture and in murine hydrodynamic injection models in vivo. Furthermore repeated systemic administration of triggered PEGylated siRNA-nanoparticles to HBV transgenic mice results in the suppression of markers of HBV replication by up to 3-fold relative to controls over a 28 day period. This compares favorably to silencing effects seen during lamivudine treatment. Collectively these observations indicate that our PEGylated siRNA-nanoparticles may have valuable applications in RNAi-based HBV therapy.

Early diagnosis of in utero and intrapartum HIV infection in infants prior to 6-weeks of age

ABSTRACT Early initiation of antiretroviral therapy reduces HIV-related infant mortality. The early peak of pediatric HIV-related deaths in South Africa occurs at 3 months of age, coinciding with the earliest age at which treatment is initiated following PCR testing at 6 weeks of age. Earlier diagnosis is necessary to reduce infant mortality. The performances of the Amplicor DNA PCR, COBAS AmpliPrep/COBAS TaqMan (CAP/CTM), and Aptima assays for detecting early HIV infection (acquired in utero and intrapartum) up to 6 weeks of age were compared. Dried blood spots (DBS) were collected at birth and at 2, 4, and 6 weeks from HIV-exposed infants enrolled in an observational cohort study in Johannesburg, South Africa. HIV status was determined at 6 weeks by DNA PCR on whole blood. Serial DBS samples from all HIV-infected infants and two HIV-uninfected, age-matched controls were tested with the 3 assays. Of 710 infants of known HIV status, 38 (5.4%) had in utero (n = 29) or intrapartum (n = 9) infections. By 14 weeks, when treatment should have been initiated, 13 (45%) in utero-infected and 2 (22%) intrapartum-infected infants had died or were lost to follow-up. The CAP/CTM and Aptima assays identified 76.3% of all infants with early HIV infections at birth and by 4 weeks were 96% sensitive. DNA PCR demonstrated lower sensitivities at birth and 4 weeks of 68.4% and 87.5%, respectively. All assays had the lowest sensitivity at 2 weeks of age. CAP/CTM was the only assay with 100% specificity at all ages. Testing at birth versus 6 weeks of age identifies a higher total number of HIV-infected infants, irrespective of the assay.

Performance of the New Roche Cobas AmpliPrep-Cobas TaqMan Version 2.0 Human Immunodeficiency Virus Type 1 Assay

The Cobas TaqMan human immunodeficiency virus type 1 (HIV-1) assay (Roche Molecular Systems, Branchburg, NJ) technology combines the extraction of total nucleic acids on the Cobas AmpliPrep (CAP) with real-time PCR on the Cobas TaqMan analyzer (CTM), using hydrolysis probe technology ([5][1], [6][2

HIV-1 Drug Resistance Mutations: Potential Applications for Point-of-Care Genotypic Resistance Testing

The increasing prevalence of acquired and transmitted HIV-1 drug resistance is an obstacle to successful antiretroviral therapy (ART) in the low- and middle-income countries (LMICs) hardest hit by the HIV-1 pandemic. Genotypic drug resistance testing could facilitate the choice of initial ART in areas with rising transmitted drug resistance (TDR) and enable care-providers to determine which individuals with virological failure (VF) on a first- or second-line ART regimen require a change in treatment. An inexpensive near point-of-care (POC) genotypic resistance test would be useful in settings where the resources, capacity, and infrastructure to perform standard genotypic drug resistance testing are limited. Such a test would be particularly useful in conjunction with the POC HIV-1 viral load tests that are currently being introduced in LMICs. A POC genotypic resistance test is likely to involve the use of allele-specific point mutation assays for detecting drug-resistance mutations (DRMs). This study proposes that two major nucleoside reverse transcriptase inhibitor (NRTI)-associated DRMs (M184V and K65R) and four major NNRTI-associated DRMs (K103N, Y181C, G190A, and V106M) would be the most useful for POC genotypic resistance testing in LMIC settings. One or more of these six DRMs was present in 61.2% of analyzed virus sequences from ART-naïve individuals with intermediate or high-level TDR and 98.8% of analyzed virus sequences from individuals on a first-line NRTI/NNRTI-containing regimen with intermediate or high-level acquired drug resistance. The detection of one or more of these DRMs in an ART-naïve individual or in a individual with VF on a first-line NRTI/NNRTI-containing regimen may be considered an indication for a protease inhibitor (PI)-containing regimen or closer virological monitoring based on cost-effectiveness or country policy.

Characterization of Lymphomas in a high prevalence HIV setting.

Background:HIV infection has been associated with an increased risk of malignancy, both AIDS defining and non-AIDS defining. Methods:This study presents a detailed pathological description of newly diagnosed lymphomas in Johannesburg, South Africa (January 2004 and December 2006). The review coincides with introduction of combination antiretroviral therapy. Results:One thousand eight hundred and ninety-seven new lymphoproliferative disorders were referred to the Charlotte Maxeke Johannesburg Academic Hospital. B-cell non-Hodgkin lymphoma accounted for 83%, T-cell non-Hodgkin lymphoma 3.5%, and Hodgkin lymphoma 7% of cases. The overall prevalence of HIV infection was 37% (n = 709). Diffuse large B-cell lymphoma (21%; n = 401) was the most common lymphoma. HIV prevalence ranged from an absence in follicular or mantle cell lymphoma to a low prevalence in diseases like small lymphocytic lymphoma/chronic lymphocytic leukemia (4%) and pre-B/common ALL (5%) to a high prevalence in diffuse large B-cell lymphoma (80%), Burkitt lymphoma/leukemia (86%), and primary effusion lymphoma (100%). Conclusions:This study provides a baseline for monitoring the impact of HIV and management thereof on lymphoma trends. The high prevalence of HIV in certain lymphoma categories emphasizes the need for capacity to diagnose and manage dual conditions. This study highlights the need for strengthening of cancer registries within South Africa and the region.

Exploiting the RNA interference pathway to counter hepatitis B virus replication

Abstract: Chronic infection with hepatitis B virus (HBV) is endemic to sub‐Saharan Africa and parts of Asia where persistence of the virus is commonly associated with complicating cirrhosis and hepatocellular carcinoma (HCC). Licensed therapies for HBV are partially effective in selected patients and development of novel treatments remains an important global medical objective. HBV has an unusually compact genome that restricts the ability of the virus to evade potentially therapeutic nucleic acid hybridization. Thus, exploiting the RNA interference (RNAi) pathway, which enables sequence‐specific target RNA degradation using small interfering RNA (siRNA), is well suited to developing novel treatment for HBV infection. Several studies, both in vitro and in vivo, have demonstrated that HBV replication can be inhibited in transfected cells by synthetic siRNA duplexes and also Pol III‐derived short hairpin RNA (shRNA) sequences. The effectiveness of anti‐HBV sequences varies considerably, and is likely to result from differences in activation of the RNAi pathway by individual siRNA species. Exclusion of potentially toxic off‐target effects and also development of efficient methods of hepatotropic nucleic acid delivery are important prerequisites before RNAi can be used successfully for anti‐HBV treatment.

Laboratory evaluation of the Liat HIV Quant (IQuum) whole-blood and plasma HIV-1 viral load assays for point-of-care testing in South Africa.

ABSTRACT Point-of-care (POC) HIV viral load (VL) testing offers the potential to reduce turnaround times for antiretroviral therapy monitoring, offer near-patient acute HIV diagnosis in adults, extend existing centralized VL services, screen women in labor, and prompt pediatrics to early treatment. The Liat HIV Quant plasma and whole-blood assays, prerelease version, were evaluated in South Africa. The precision, accuracy, linearity, and agreement of the Liat HIV Quant whole-blood and plasma assays were compared to those of reference technologies (Roche CAP CTMv2.0 and Abbott RealTime HIV-1) on an HIV verification plasma panel (n = 42) and HIV clinical specimens (n = 163). HIV Quant plasma assay showed good performance, with a 2.7% similarity coefficient of variation (CV) compared to the Abbott assay and a 1.8% similarity CV compared to the Roche test on the verification panel, and 100% specificity. HIV Quant plasma had substantial agreement (pc [concordance correlation] = 0.96) with Roche on clinical specimens and increased variability (pc = 0.73) in the range of <3.0 log copies/ml range with the HIV Quant whole-blood assay. HIV Quant plasma assay had good linearity (2.0 to 5.0 log copies/ml; R 2 = 0.99). Clinical sensitivity at a viral load of 1,000 copies/ml of the HIV Quant plasma and whole-blood assays compared to that of the Roche assay (n = 94) was 100% (confidence interval [CI], 95.3% to 100%). The specificity of HIV Quant plasma was 88.2% (CI, 63.6% to 98.5%), and that for whole blood was 41.2% (CI, 18.4% to 67.1%). No virological failure (downward misclassification) was missed. Liat HIV Quant plasma assay can be interchanged with existing VL technology in South Africa. Liat HIV Quant whole-blood assay would be advantageous for POC early infant diagnosis at birth and adult adherence monitoring and needs to be evaluated further in this clinical context. LIAT cartridges currently require cold storage, but the technology is user-friendly and robust. Clinical cost and implementation modeling is required.

High prevalence of the K65R mutation in HIV-1 subtype C infected patients failing tenofovir-based first-line regimens in South Africa.

Background Tenofovir (TDF) has replaced stavudine (d4T) as the preferred nucleoside reverse transcriptase inhibitor (NRTI) in first-line regimens in South Africa, but limited information is available on the resistance patterns that develop after the introduction of TDF. This study investigated the antiretroviral drug resistance patterns in South African HIV-1 subtype C-infected patients failing stavudine- (d4T) and tenofovir- (TDF) based first-line regimens and assess the suitability of TDF as the preferred first-line nucleotide reverse transcriptase inhibitor (NRTI). Methods Resistance patterns of HIV-1 from 160 adult patients virologically failing TDF- (n = 80) and d4T- (n = 80) based first-line regimens were retrospectively analyzed. The pol gene was sequenced using an in-house protocol and mutations were analysed using the IAS-USA 2014 Drug Resistance Mutation list. Results Compared to d4T-exposed patients (n = 7), patients failing on a TDF-containing regimen (n = 43) were almost 5 times more likely to present with a K65R mutation (aRR 4.86 95% CI 2.29 – 10.34). Y115F was absent in the d4T group, and detected in 13.8% (n = 11) of TDF-exposed patients, p = 0.0007. Virus from 9 of the 11 patients (82.0%) who developed the Y115F mutation also developed K65R. Intermediate or high-level resistance to most NRTIs was common in the TDF-treatment group, but these patients twice more likely to remain susceptible to AZT as compared to those exposed to d4T (aRR 2.09 95% CI 1.13 – 3.90). Conclusion The frequency of the TDF induced K65R mutation was higher in our setting compared to non-subtype C dominated countries. However, despite the higher frequency of cross-resistance to NRTIs, most patients remained susceptible to AZT, which is reflected in the South African treatment guidelines that recommend AZT as an essential component of second-line regimens.

Adult antiretroviral therapy guidelines 2017

These guidelines are intended as an update to those published in the Southern African Journal of HIV Medicine in 2014 and the update on when to initiate antiretroviral therapy in 2015. Since the release of the previous guidelines, the scale-up of antiretroviral therapy (ART) in southern Africa has continued. New antiretroviral drugs have become available with improved efficacy, safety and robustness. The guidelines are intended for countries in the southern African region, which vary between lower and middle income.

Scale-up of Early Infant HIV Diagnosis and Improving Access to Pediatric HIV Care in Global Plan Countries: Past and Future Perspectives

Abstract: Investment to scale-up early infant diagnosis (EID) of HIV has increased substantially in the last decade. This investment includes physical infrastructure, equipment, human resources, and specimen transportation systems as well as specialized mechanisms to deliver laboratory results to clinics. The Global Plan Towards the Elimination of New HIV Infections Among Children by 2015 and Keeping Their Mothers Alive, as well as related international initiatives to prevent mother-to-child transmission of HIV and treat children living with HIV have been important drivers of this scale-up by mobilizing resources, creating advocacy, developing normative recommendations, and providing direct technical support to countries through the global community of international stakeholders. As a result, the number of early infant diagnosis tests performed annually has increased 10-fold between 2005 and 2015, and many thousands of infants are now receiving life-saving antiretroviral therapy because of this improved access. Despite these efforts and many success stories, timely infant diagnosis remains a challenge in many Global Plan countries. The most recent data (from the end of 2015) suggest a large variation in access. Some countries report that almost 90% of HIV-exposed infants are being tested; others report that the level of access has stagnated at 30%. Still, just over half of all exposed infants in Global Plan countries receive a test in the first 2 months of life. We discuss the key factors that are responsible for this scale-up of diagnostic capacity, highlight some of the challenges that have hampered progress, and describe priorities for the future that can help maintain momentum to achieve true universal access to HIV testing for children.