Molecular Epidemiology of HIV-1 Subtype B Reveals Heterogeneous Transmission Risk: Implications for Intervention and Control.

Background: The impact of HIV pre-exposure prophylaxis (PrEP) depends on infections averted by protecting vulnerable individuals as well as infections averted by preventing transmission by those who would have been infected if not receiving PrEP. Analysis of HIV phylogenies reveals risk factors for transmission, which we examine as potential criteria for allocating PrEP. Methods: We analyzed 6912 HIV-1 partial pol sequences from men who have sex with men (MSM) in the United Kingdom combined with global reference sequences and patient-level metadata. Population genetic models were developed that adjust for stage of infection, global migration of HIV lineages, and changing incidence of infection through time. Models were extended to simulate the effects of providing susceptible MSM with PrEP. Results: We found that young age <25 years confers higher risk of HIV transmission (relative risk = 2.52 [95% confidence interval, 2.32-2.73]) and that young MSM are more likely to transmit to one another than expected by chance. Simulated interventions indicate that 4-fold more infections can be averted over 5 years by focusing PrEP on young MSM. Conclusions: Concentrating PrEP doses on young individuals can avert more infections than random allocation.

European Multicenter Study on Analytical Performance of Veris HIV-1 Assay.

The analytical performance of the Veris HIV-1 assay for use on the new, fully automated Beckman Coulter DxN Veris molecular diagnostics system was evaluated at 10 European virology laboratories. The precision, analytical sensitivity, performance with negative samples, linearity, and performance with HIV-1 groups/subtypes were evaluated. The precision for the 1-ml assay showed a standard deviation (SD) of 0.14 log10 copies/ml or less and a coefficient of variation (CV) of ≤6.1% for each level tested. The 0.175-ml assay showed an SD of 0.17 log10 copies/ml or less and a CV of ≤5.2% for each level tested. The analytical sensitivities determined by probit analysis were 19.3 copies/ml for the 1-ml assay and 126 copies/ml for the 0.175-ml assay. The performance with 1,357 negative samples demonstrated 99.2% with not detected results. Linearity using patient samples was shown from 1.54 to 6.93 log10 copies/ml. The assay performed well, detecting and showing linearity with all HIV-1 genotypes tested. The Veris HIV-1 assay demonstrated analytical performance comparable to that of currently marketed HIV-1 assays. (DxN Veris products are Conformité Européenne [CE]-marked in vitro diagnostic products. The DxN Veris product line has not been submitted to the U.S. FDA and is not available in the U.S. market. The DxN Veris molecular diagnostics system is also known as the Veris MDx molecular diagnostics system and the Veris MDx system.).

European Multicenter Study on Analytical Performance of DxN Veris System HCV Assay.

The analytical performance of the Veris HCV Assay for use on the new and fully automated Beckman Coulter DxN Veris Molecular Diagnostics System (DxN Veris System) was evaluated at 10 European virology laboratories. Precision, analytical sensitivity, specificity, and performance with negative samples, linearity, and performance with hepatitis C virus (HCV) genotypes were evaluated. Precision for all sites showed a standard deviation (SD) of 0.22 log10 IU/ml or lower for each level tested. Analytical sensitivity determined by probit analysis was between 6.2 and 9.0 IU/ml. Specificity on 94 unique patient samples was 100%, and performance with 1,089 negative samples demonstrated 100% not-detected results. Linearity using patient samples was shown from 1.34 to 6.94 log10 IU/ml. The assay demonstrated linearity upon dilution with all HCV genotypes. The Veris HCV Assay demonstrated an analytical performance comparable to that of currently marketed HCV assays when tested across multiple European sites.

Diagnosing acute HIV infection at point of care: a retrospective analysis of the sensitivity and specificity of a fourth-generation point-of-care test for detection of HIV core protein p24.

OBJECTIVES: Detection of acute HIV infection is vital in preventing onward transmission. HIV point-of-care testing (POCT) has improved uptake of HIV testing but has been limited to third-generation assays, which only detect chronic HIV infection. Previous evaluation of the fourth-generation Alere Determine HIV-1/2 Ag/Ab Combo POCT showed only 50% sensitivity for HIV core protein p24 (p24 antigen) detection, which is suboptimal for diagnosis of acute HIV infection with limited advantage over third-generation POCT. We aimed to assess the sensitivity of the new Alere HIV Combo POCT to detect acute HIV infection. METHODS: Stored samples in samples already identified as p24-positive using standard-of-care fourth-generation assays were randomly selected alongside groups of antibody-positive samples and HIV-negative samples. Each sample was tested using the new Alere POCT according to manufacturer's instructions. Sensitivity and specificity were then calculated. RESULTS: The Alere HIV Combo POCT test demonstrated 88% sensitivity 95% CI (78% to 98%) and 100% specificity 95% CI (99.7% to 100%) for detection of p24 antigen. CONCLUSIONS: This new POCT shows improved sensitivity for detection of p24 antigen and may be of value for clinical use in detecting acute HIV infection. Further evaluation of its use in a clinical setting is still required.

The contribution of viral genotype to plasma viral set-point in HIV infection.

Disease progression in HIV-infected individuals varies greatly, and while the environmental and host factors influencing this variation have been widely investigated, the viral contribution to variation in set-point viral load, a predictor of disease progression, is less clear. Previous studies, using transmission-pairs and analysis of phylogenetic signal in small numbers of individuals, have produced a wide range of viral genetic effect estimates. Here we present a novel application of a population-scale method based in quantitative genetics to estimate the viral genetic effect on set-point viral load in the UK subtype B HIV-1 epidemic, based on a very large data set. Analyzing the initial viral load and associated pol sequence, both taken before anti-retroviral therapy, of 8,483 patients, we estimate the proportion of variance in viral load explained by viral genetic effects to be 5.7% (CI 2.8-8.6%). We also estimated the change in viral load over time due to selection on the virus and environmental effects to be a decline of 0.05 log10 copies/mL/year, in contrast to recent studies which suggested a reported small increase in viral load over the last 20 years might be due to evolutionary changes in the virus. Our results suggest that in the UK epidemic, subtype B has a small but significant viral genetic effect on viral load. By allowing the analysis of large sample sizes, we expect our approach to be applicable to the estimation of the genetic contribution to traits in many organisms.

Deep Sequencing of HIV-1 in Cerebrospinal Fluid.

Using deep sequencing, human immunodeficiency virus (HIV) resistance-associated mutations were detected as minority species in the cerebrospinal fluid (CSF) of 4 patients with higher HIV type 1 RNA load in CSF than in plasma, but not in 2 patients with higher plasma viral load. Deep sequencing could help our understanding of viral escape in the central nervous system.

A European multicenter study on the analytical performance of the VERIS HBV assay.

BACKGROUND: Hepatitis B viral load monitoring is an essential part of managing patients with chronic Hepatits B infection. Beckman Coulter has developed the VERIS HBV Assay for use on the fully automated Beckman Coulter DxN VERIS Molecular Diagnostics System.1 OBJECTIVES: To evaluate the analytical performance of the VERIS HBV Assay at multiple European virology laboratories. STUDY DESIGN: Precision, analytical sensitivity, negative sample performance, linearity and performance with major HBV genotypes/subtypes for the VERIS HBV Assay was evaluated. RESULTS: Precision showed an SD of 0.15 log10 IU/mL or less for each level tested. Analytical sensitivity determined by probit analysis was between 6.8-8.0 IU/mL. Clinical specificity on 90 unique patient samples was 100.0%. Performance with 754 negative samples demonstrated 100.0% not detected results, and a carryover study showed no cross contamination. Linearity using clinical samples was shown from 1.23-8.23 log10 IU/mL and the assay detected and showed linearity with major HBV genotypes/subtypes. CONCLUSIONS: The VERIS HBV Assay demonstrated comparable analytical performance to other currently marketed assays for HBV DNA monitoring.

Impact of rectal gonorrhoea and chlamydia on HIV viral load in the rectum: potential significance for onward transmission.

The aim of this study was to investigate the effect of asymptomatic rectal bacterial sexually transmitted infections (STIs) on rectal HIV viral load (VL). A prospective cohort study of HIV-positive men who have sex with men attending a tertiary centre in London, UK, for their routine HIV care was performed. Forty-two HIV-positive men who have sex with men were recruited between January and August 2014. In participants on antiretroviral therapy (ART), there was no significant difference in rectal VL in those with and without STI ( p = 0.4). All rectal HIV VLs were below the limit of detection (<100 copies/µg of total RNA) whether an STI was present or not. In those not on ART, rectal HIV VL was on average 0.6log10 lower post STI treatment. The presence of asymptomatic rectal chlamydia and gonorrhoea was not associated with increased rectal HIV VL in those fully suppressed on ART. In the context of effective ART, the presence of rectal gonorrhoea or chlamydia does not appear to increase rectal HIV VL and the risk of increased viral infectivity.

A European multicientre study on the comparison of HBV viral loads between VERIS HBV assay and Roche COBAS® TAQMAN® HBV test, Abbott RealTime HBV assay, Siemens VERSANT HBV assay, and Qiagen artus HBV RG kit.

BACKGROUND: Hepatitis B viral load testing is essential to treatment and monitoring decisions in patients with chronic Hepatitis B. Beckman Coulter has developed the VERIS HBV Assay (Veris) for use on the fully automated DxN VERIS Molecular Diagnostics System.1 OBJECTIVES: To evaluate the clinical performance of the Veris HBV Assay at multiple EU laboratories STUDY DESIGN: Method comparison was performed with a total of 344 plasma specimens from HBV infected patients tested with Veris and COBAS® TaqMan® HBV Test (Cobas), 207 specimens tested with Veris and RealTime HBV Assay (RealTime), 86 specimens tested with Veris and VERSANT® HBV Assay (Versant), and 74 specimens tested with Veris and artus® HBV RG PCR kit (artus). RESULTS: Bland-Altman analysis showed average bias of -0.46 log10 IU/mL between Veris and Cobas, -0.46 log10IU/mL between Veris and RealTime, -0.36 log10IU/mL between Veris and Versant, and -0.12 log10IU/mL between Veris and artus. Bias was consistent across the assay range. Patient monitoring results using Veris demonstrated similar viral load trends over time to Cobas, RealTime, and artus. CONCLUSIONS: The VERIS HBV Assay demonstrated comparable clinical performance, with varying degrees of negative bias, compared to other currently marketed assays for HBV DNA monitoring. This negative bias should be taken into consideration if switching monitoring methods to Veris.

A European multicientre study on the comparison of HIV-1 viral loads between VERIS HIV-1 Assay and Roche COBAS® TAQMAN® HIV-1 test, Abbott RealTime HIV-1 Assay, and Siemens VERSANT HIV-1 Assay.

BACKGROUND: Viral load monitoring is essential for patients under treatment for HIV. Beckman Coulter has developed the VERIS HIV-1 Assay for use on the novel, automated DxN VERIS Molecular Diagnostics System.¥ OBJECTIVES: Evaluation of the clinical performance of the new quantitative VERIS HIV-1 Assay at multiple EU laboratories. STUDY DESIGN: Method comparison with the VERIS HIV-1 Assay was performed with 415 specimens at 5 sites tested with COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Test, v2.0, 169 specimens at 3 sites tested with RealTime HIV-1 Assay, and 202 specimens from 2 sites tested with VERSANT HIV-1 Assay. Patient monitoring sample results from 4 sites were also compared. RESULTS: Bland-Altman analysis showed the average bias between VERIS HIV-1 Assay and COBAS HIV-1 Test, RealTime HIV-1 Assay, and VERSANT HIV-1 Assay to be 0.28, 0.39, and 0.61 log10 cp/mL, respectively. Bias at low end levels below 1000cp/mL showed predicted bias to be <0.3 log10 cp/mL for VERIS HIV-1 Assay versus COBAS HIV-1 Test and RealTime HIV-1 Assay, and <0.5 log10cp/mL versus VERSANT HIV-1 Assay. Analysis on 174 specimens tested with the 0.175mL volume VERIS HIV-1 Assay and COBAS HIV-1 Test showed average bias of 0.39 log10cp/mL. Patient monitoring results using VERIS HIV-1 Assay demonstrated similar viral load trends over time to all comparators. CONCLUSIONS: The VERIS HIV-1 Assay for use on the DxN VERIS System demonstrated comparable clinical performance to COBAS® HIV-1 Test, RealTime HIV-1 Assay, and VERSANT HIV-1 Assay.

K65R and Y181C are less prevalent in HAART-experienced HIV-1 subtype A patients.

The vast majority of HIV-1 infections globally are caused by subtype A or C, although little is known about their drug resistance profiles. We found that HAART-experienced patients infected with subtype A had a lower prevalence of K65R and Y181C than those with subtypes B or C, despite similar exposure to antiretroviral agents that select for these mutations. If confirmed, this information may be important in the planning of antiretroviral regimens in patients infected with HIV-1 subtype A.

The natural history and clinical significance of intermittent viraemia in patients with initial viral suppression to < 400 copies/ml.

OBJECTIVES: To determine the prevalence and prognostic significance of intermittent viraemia (IV) in patients who attained an undetectable viral load (VL) < 400 copies/ml within 6 months on highly active antiretroviral therapy (HAART). METHODS: Retrospective analysis of viral load rebound > or = 400 copies/ml and CD4 cell counts rise for 765 patients followed for > or = 12 months following initial VL undetectability, comparing the 226 (29.5%) who maintained an undetectable VL for > 1 year from initiation of HAART and 122 (15.9%) who had one or more episodes of IV. Genotypic resistance was evaluated at the time of the first episode of IV > or = 2000 copies/ml. RESULTS: Patients with IV had a threefold higher rate of sustained virological rebound [hazards ratio (HR), 3.15; 95% confidence interval (CI), 1.72-5.77; P < 0.001). For patients with and without IV, the Kaplan-Meier estimates at 24 and 36 months after initiation of HAART were 19.3% (95% CI, 8.9-21.5) versus 7.7% (95% CI, 4.5-13.0) and 31.6% (95% CI, 21.8-44.2) versus 12.9% (95% CI, 7.5-21.5), respectively (P < 0.001). The median CD4 cell count rise at 18 and 24 months was significantly lower in those with IV than in those without: 138 [interquartile range (IQR), 58-221] versus 224 x 10(6) cells/l (IQR, 119-357) (P = 0.0001) and 200 (IQR, 89-294) versus 260 x 10(6) cells/l (IQR, 125-384) (P = 0.003), respectively. In a subgroup of 16 patients, genotypic resistance mutations were found in the reverse transcriptase gene for five (31%) and in the protease gene in one. A probable contributing factor/event was identified for most patients with IV, such as poor adherence (42.6%), intercurrent infection (26.2%) or drug interaction (6.8%). CONCLUSIONS: Patients with IV > 400 copies/ml are three times more likely to experience sustained viral rebound and to have an impaired CD4 cell rise relative to those who maintain undetectable VL. This supports the adoption of a more pro-active approach to treatment intensification and the need for caution with structured treatment interruptions.

Drug resistance is uncommon in pregnant women with low viral loads taking zidovudine monotherapy to prevent perinatal HIV transmission.

Zidovudine monotherapy is used to reduce perinatal HIV transmission in women with low viral loads. There are few data on the risk of drug resistance in this select cohort of women. We determined the prevalence of newly acquired mutations conferring reduced sensitivity to zidovudine after exposure during pregnancy, and found that the development of mutations was uncommon and was restricted to women treated before 1998 who had higher baseline viral loads than those currently recommended monotherapy.

Is the addition of a standard HIV educational comment to virology laboratory reports effective in changing requesting behaviour?

BACKGROUND: It is not known whether the addition of general educational comments to virology laboratory reports can influence the requesting behaviour of practitioners. OBJECTIVES: To establish if there is any change in requesting behaviour after the addition of a standard comment to virology laboratory reports highlighting the need to include HIV testing when investigating patients presenting with a glandular fever (GF)-like illness. STUDY DESIGN: A standard comment to encourage inclusion of HIV testing was added to all GF screening reports from April 2010. The proportion of GF screening samples with concomitant HIV test requests before and after the introduction of the standard comment were compared over a 1 year period. RESULTS: A significant increase in concomitant HIV requests from 9.5% to 19.6% on GF screening samples from primary care practitioners was observed after the addition of the standard comment (p<0.0000001). This effect peaked at 5 months and although it waned, requests at one year were still higher than at baseline. CONCLUSIONS: Addition of a general HIV educational comment to virology laboratory reports is effective in changing requesting behaviour.

Impact of HIV-1 viral subtype on disease progression and response to antiretroviral therapy.

BACKGROUND: Our intention was to compare the rate of immunological progression prior to antiretroviral therapy (ART) and the virological response to ART in patients infected with subtype B and four non-B HIV-1 subtypes (A, C, D and the circulating recombinant form, CRF02-AG) in an ethnically diverse population of HIV-1-infected patients in south London. METHODS: A random sample of 861 HIV-1-infected patients attending HIV clinics at King's and St Thomas' hospitals' were subtyped using an in-house enzyme-linked immunoassay and env sequencing. Subtypes were compared on the rate of CD4 cell decline using a multi-level random effects model. Virological response to ART was compared using the time to virological suppression (< 400 copies/ml) and rate of virological rebound (> 400 copies/ml) following initial suppression. RESULTS: Complete subtype and epidemiological data were available for 679 patients, of whom 357 (52.6%) were white and 230 (33.9%) were black African. Subtype B (n = 394) accounted for the majority of infections, followed by subtypes C (n = 125), A (n = 84), D (n = 51) and CRF02-AG (n = 25). There were no significant differences in rate of CD4 cell decline, initial response to highly active antiretroviral therapy and subsequent rate of virological rebound for subtypes B, A, C and CRF02-AG. However, a statistically significant four-fold faster rate of CD4 decline (after adjustment for gender, ethnicity and baseline CD4 count) was observed for subtype D. In addition, subtype D infections showed a higher rate of virological rebound at six months (70%) compared with subtypes B (45%, p = 0.02), A (35%, p = 0.004) and C (34%, p = 0.01) CONCLUSIONS: This is the first study from an industrialized country to show a faster CD4 cell decline and higher rate of subsequent virological failure with subtype D infection. Further studies are needed to identify the molecular mechanisms responsible for the greater virulence of subtype D.