Bianca Bruzzone

Novel Approach To Reduce the Hepatitis C Virus (HCV) Window Period: Clinical Evaluation of a New Enzyme-Linked Immunosorbent Assay for HCV Core Antigen

ABSTRACT The window period in hepatitis C virus (HCV) infection is still a major problem in ensuring blood safety. HCV RNA detection by nucleic acid amplification technology-based tests has contributed to reduce the infectivity of blood products, but it is expensive, time-consuming and affected by a high prevalence of false-positive results. The aim of this study was to assess the performance of a newly developed enzyme immunoassay for the detection of HCV core antigen and its suitability for use in the screening of blood units in order to identify infecting samples that do not contain specific antibodies. For evaluation of laboratory performance, different samples were selected: to evaluate specificity, we tested 2,586 sera from blood donors, 500 general population samples, and 58 “difficult sera”. All samples were tested by two screening assays, and results were negative. To estimate clinical sensitivity, 103 HCV RNA-positive, anti-HCV-negative samples, 6 natural seroconversion panels, and 9 commercial seroconversion panels were tested. Intra- and interassay precision were determined on two HCV-RNA-positive, anti-HCV-negative sera. Seventeen (0.66%) blood donor samples, 2 (0.4%) general population samples, and 2 (3.44%) difficult sera were initially reactive; 3 sera were positive on repetition. These 21 samples tested by reverse transcription-PCR were negative. The clinical sensitivity calculated with seroconversion panels and seroconverted patient samples was very similar to PCR sensitivity: 95% of PCR-positive, antibody-negative samples contained detectable HCV antigen. Data on intra- and interassay precision showed dispersion indices with values of less than 10%. In conclusion, the HCV antigen assay showed high sensitivity and specificity and could become a useful means of improving the safety of blood and blood products.

A novel methodology for large-scale phylogeny partition

Phylogenetic analysis is used to identify transmission chains, but no software is available for the automated partition of large phylogenies. Prosperiet al. apply a new search algorithm to identify transmission clusters within the phylogeny of HIV-1gene sequences linking molecular and epidemiological data. Supplementary information The online version of this article (doi:10.1038/ncomms1325) contains supplementary material, which is available to authorized users.

Hepatitis C virus in the new era: Perspectives in epidemiology, prevention, diagnostics and predictors of response to therapy

Despite the great successes achieved in the fields of virology and diagnostics, several difficulties affect improvements in hepatitis C virus (HCV) infection control and eradication in the new era. New HCV infections still occur, especially in some of the poorest regions of the world, where HCV is endemic and long-term sequelae have a growing economic and health burden. An HCV vaccine is still no available, despite years of researches and discoveries about the natural history of infection and host-virus interactions: several HCV vaccine candidates have been developed in the last years, targeting different HCV antigens or using alternative delivery systems, but viral variability and adaption ability constitute major challenges for vaccine development. Many new antiviral drugs for HCV therapy are in preclinical or early clinical development, but different limitations affect treatment validity. Treatment predictors are important tools, as they provide some guidance for the management of therapy in patients with chronic HCV infection: in particular, the role of host genomics in HCV infection outcomes in the new era of direct-acting antivirals may evolve for new therapeutic targets, representing a chance for modulated and personalized treatment management, when also very potent therapies will be available. In the present review we discuss the most recent data about HCV epidemiology, the new perspectives for the prevention of HCV infection and the most recent evidence regarding HCV diagnosis, therapy and predictors of response to it.

Safety and immunogenicity of two influenza virus subunit vaccines, with or without MF59 adjuvant, administered to human immunodeficiency virus type 1-seropositive and -seronegative adults.

ABSTRACT The objective of this study was to evaluate and compare both the safety and tolerability and the humoral and cell-mediated immune responses for two influenza virus subunit vaccines, one with MF59 adjuvant (Fluad) and one without an adjuvant (Agrippal), in healthy and in human immunodeficiency virus type 1 (HIV-1)-infected adult individuals. To achieve this aim, an open, randomized, comparative clinical trial was performed during the 2005-2006 season. A total of 256 subjects were enrolled to receive one dose of vaccine intramuscularly. Blood samples were taken at the time of vaccination and at 1 and 3 months postvaccination. A good humoral antibody response was detected for both vaccines, meeting all the criteria of the Committee for Medical Products for Human Use. After Beyers correction for prevaccination status, Fluad exhibited better immunogenicity than Agrippal, as shown from the analysis of the geometric mean titers, with significant differences for some virus strains; however, no definitive conclusions on the clinical significance of such results can be drawn, because the method used to estimate antibody response is currently nonstandard for influenza virus vaccines. Significant induction of an antigen-specific CD4+ T-lymphocyte proliferative response was detected at all time points after immunization, for both the vaccines, among HIV-1-seronegative subjects. This was different from what was observed for HIV-1-infected individuals. In this group, significance was not reached at 30 days postvaccination (T30) for those immunized with Agrippal. Also when data were compared between treatment groups, a clear difference in the response at T30 was observed in favor of Fluad (P = 0.0002). The safety profiles of both vaccines were excellent. For HIV-1-infected individuals, no significant changes either in viremia or in the CD4+ cell count were observed at any time point. The results showed good safety and immunogenicity for both vaccines under study for both uninfected and HIV-1-infected adults, confirming current recommendations for immunization of this high-risk category.

Study of Genotypic and Phenotypic HIV-1 Dynamics of Integrase Mutations During Raltegravir Treatment: A Refined Analysis by Ultra-Deep 454 Pyrosequencing

BACKGROUND The dynamics of raltegravir-resistant variants and their impact on virologic response in 23 HIV-1-infected patients, who started a salvage raltegravir-containing regimen, were investigated. METHODS Integrase population sequencing and Ultra-Deep-454 Pyrosequencing (UDPS) were performed on plasma samples at baseline and at raltegravir failure. All integrase mutations detected at a frequency ≥1% were considered to be reliable for the UDPS analyses. Phylogenetic and phenotypic resistance analyses were also performed. RESULTS At baseline, primary resistance mutations were not detected by both population and UDPS genotypic assays; few secondary mutations (T97A-V151I-G163R) were rarely detected and did not show any statistically association either with virologic response at 24-weeks or with the development of resistant variants at failure. At UDPS, not all resistant variants appearing early during treatment evolved as major populations during failure; only specific resistance pathways (Y143R-Q148H/R-N155H) associated with an increased rate of fitness and phenotypic resistance were selected. CONCLUSIONS Resistance to raltegravir in integrase strand transfer inhibitor-naive patients remains today a rare event, which might be changed by future extensive use of such drugs. In our study, pathways of resistance at failure were not predicted by baseline mutations, suggesting that evolution plus stochastic selection plays a major role in the appearance of integrase-resistance mutations, whereas fitness and resistance are dominant factors acting for the late selection of resistant quasispecies.

A comparison of hepatitis B seroepidemiology in ten European countries

To inform current and future vaccination strategies, we describe the seroepidemiology of hepatitis B virus (HBV) infection in ten representative European countries using standardized serology that allowed international comparisons. Between 1996 and 2003, national serum banks were compiled by collecting residual sera or by community sampling; sera were then tested by each country using its preferred enzyme immunoassays and testing algorithm, and assay results were standardized. Information on current and past HBV vaccination programmes in each country was also collected. Of the ten countries, six reported low levels (<3%) of antibodies against HBV core antigen (anti-HBc). Of the eight countries testing for HBV surface antigen (HBsAg), the highest prevalence was reported in Romania (5.6%) and in the remaining seven countries prevalence was <1%. Universal HBV vaccination programmes had been established in seven countries as recommended by the World Health Organization, but the seroprevalence of antibodies against HBsAg (anti-HBs) was lower than the reported vaccine coverage in three countries. Regular serological surveys to ascertain HBV status within a population, such as reported here, provide important data to assess the need for and to evaluate universal HBV vaccination programmes.

Epidemiology of measles, mumps and rubella in Italy

A serosurvey for measles, mumps and rubella was conducted in Italy; incidence based on statutory notifications over the last three decades was also calculated. In Italy the diseases followed an endemic-epidemic pattern, with an incidence peak every 2-4 years, and had a limited reduction of incidence attributable to childhood immunization. Lower notification rates were observed in the Southern regions. This is possibly related to greater under notification in the South and is confirmed by our seroprevalence data. Incidence of measles and rubella and proportion of cases among young adults increased significantly in the three decades considered, but not for mumps. Serological data confirmed that these infections are still very frequent in Italy, without significant geographic variation in the country. In the age groups 2-4 and 5-9 years the percentage of individuals still susceptible to each virus was higher than 30%. The proportion of susceptible subjects older than 15 years was similar for the three infections (6.1, 11.7 and 8.8% for measles, mumps and rubella, respectively). The low vaccine coverage for rubella and measles in Italy has so far only partially affected the occurrence of the diseases. No impact of mumps vaccination is visible. The average number of deaths, for each disease, has decreased during the three study periods. Today the priority in Italy is to halt the progressive increase of the mean age of acquisition of the three infections, to eliminate differences in coverage among regions and to conform to European standards. This will be achieved through a combination of increasing MMR vaccine coverage before 2 years of age, implementing vaccination campaigns for low seroprevalence age groups, and/or introducing a second dose of MMR, depending on the level of current MMR coverage.

Evaluation of a new hepatitis C virus sequencing assay as a routine method for genotyping

The determination of HCV genotypes, subtypes and isolates has been helpful in understanding the evolution and the epidemiology of the virus, and is an important factor in the pre‐treatment evaluation. A new simpler and automated sequencing based system has been developed recently, the Visible Genetics TruGene™ Hepatitis C Assay. The aim of the study was to compare this new genotyping assay with reverse hybridization based Innogenetics INNO‐LiPA HCV II assay that is used most commonly. Eighty‐eight HCV‐RNA positive patients were enrolled and divided in four groups: 26 hemodialysed patients, 30 untreated patients with chronic HCV hepatitis, 12 IFN non‐responder patients with chronic HCV hepatitis, 20 asymptomatic HCV positive subjects. The 5′‐UTR region was amplified by RT‐PCR and the nucleotide sequences determined by the TruGene™ assay. In parallel, the amplicons were also tested by INNO‐LiPA. Concordant results were obtained in 80 out of 88 cases (90.9%). The new assay allowed to genotype 2 samples not typed by LiPA as 1b and 2a/c. The new system also allowed the subtyping of 3 untypable samples, classified as genotype 1 by INNO‐LiPA, as genotype 1b (1 sample) and, as genotype 4 (2 samples). The difference between these genotype 4 isolates and the closest genotype 1 isolate was 6 nucleotides. One LiPA genotype 1a sample was typed as 1b and 2 genotype 1b samples were all typed as 1a by the sequence analysis. In conclusion, the new assay is a sensitive and rapid method that is suitable for accurate large‐scale genotyping. J. Med. Virol. 63:17–21, 2001.

Combination hepatitis C virus antigen and antibody immunoassay as a new tool for early diagnosis of infection.

Summary.  Reduction of the window period of hepatitis C virus (HCV) infection represents an important goal in the transfusional and diagnostic setting. A prototype assay designed to simultaneously detect circulating HCV antigen and anti‐HCV, has been developed. Aim of this study was to evaluate the performance of this new assay in terms of specificity and sensitivity and to compare its efficacy with commercial assays. To evaluate the specificity of the assay, 400 samples from the general population and 100 ‘difficult’ sera, negative for anti‐HCV, were tested. To assess sensitivity, the new test was used on 76 PCR‐positive and anti‐HCV negative sera, seven natural or commercial seroconversion panels that included 17 RNA‐positive and anti‐HCV negative sera and 31 anti‐HCV positive sera, 20 weak anti‐HCV positive sera, 80 viraemic and anti‐HCV‐positive sera from patients infected with different subtypes and 10 sera from patients with HBV–HCV or HIV–HCV co‐infections. Of 500 anti‐HCV negative samples, 499 (99.8%) were negative with a cut‐off index <0.5, while one sample was within the grey zone. Of the 93 HCV‐RNA positive and anti‐HCV negative sera from patients and panels, 85 (91.4%) resulted positive, and one had the cut‐off index in the grey zone. The reduction in the diagnostic window period observed with the new test and HCV‐RNA assays were equal, on average, to 24 and 34.4 days respectively. All anti‐HCV positive sera were positive. The new assay shows high sensitivity and specificity and could be a useful tool not only in the diagnostic setting, where procedures to reduce the window period, such as antigen or HCV‐RNA detection, are not currently recommended, but also in the screening of blood donations, when nucleic acid technologies is not feasible because of costs, organization, emergency and/or logistic difficulties.

Emerging mutations at virological failure of HAART combinations containing tenofovir and lamivudine or emtricitabine.

Objective:To compare the emergence of drug-resistant HIV variants at failure of lamivudine (3TC)/tenofovir (TDF)-containing or emtricitabine (FTC)/TDF-containing HAART as a consequence of the different 3TC and FTC intracellular half-lives. Design:Retrospective evaluation of 859 patients selected from an Italian HIV resistance database (Antiretroviral Resistance Cohort Analysis). Methods:Patients were selected for analysis if treated with a HAART whose nucleoside/nucleotide reverse transcriptase inhibitor backbone was either 3TC/TDF or FTC/TDF; if they experienced a virological failure after at least 6 months of plasma HIV-RNA undetectability; and if HIV genotypes before treatment and at failure were available. Univariate and multivariate logistic regression analyses were done to detect predictors of resistance mutations emerging at failure. Results:Of 714 patients failing with 3TC/TDF and 145 with FTC/TDF, 35.8 and 21.1% were in Centers for Disease Control and Prevention stage C, and 8.8 and 15.2% were on first-line HAART, respectively. At multivariate analysis, the emergence of K70R (P = 0.002), M184V (P = 0.031), T215F (P = 0.020) and Y181C (P = 0.005) was significantly more common in 3TC-treated than in FTC-treated patients, with an odds ratio of 4, 1.56, 1.89 and 3.84, respectively. Conclusion:Despite their close structural similarity, 3TC and FTC are associated with a significantly different rate of drug resistance at treatment failure when combined with TDF in HAART regimens independently of the third drug used.