Seroepidemiology of varicella zoster virus infection in Vojvodina, Serbia.

The present cross-sectional serosurvey constitutes the first effort to describe the varicella zoster virus (VZV) seroepidemiology in Serbia. An age-stratified serum bank of 3570 residual samples collected between 2015 and 2016 in each of the seven districts of the Vojvodina Province was tested for IgG anti-VZV antibodies with an enzyme immunoassay. Results were standardised into common units according to the European Sero-Epidemiology Network (ESEN2) methodology. Univariable and multivariable analyses were used to examine the relationships between standardised anti-VZV positivity or logarithmically transformed antibody titres and demographic features of study subjects. Seropositivity (85% overall) increased with age, in parallel with geometric mean titres. By the time of school entry, 68% of children were immune. The slower subsequent acquisition of immunity leaves epidemiologically relevant proportions of adolescents (7%), young adults (6%) and especially females of reproductive age (6%) prone to more severe forms of varicella. In the ongoing pre-vaccine era, natural infection provides a high level of collective immunity, with the highest VZV transmission in children of preschool age. The detected gaps in VZV immunity of the Serbian population support the adoption of the official recommendations for varicella immunisation of non-immune adolescents and young adults, including non-pregnant women of childbearing age.

Estimating seroprevalence of vaccine-preventable infections: is it worth standardizing the serological outcomes to adjust for different assays and laboratories?

The aim of the European Sero-Epidemiology Network 2 (ESEN2) project was to estimate age-specific seroprevalence for a number of vaccine-preventable diseases in Europe. To achieve this serosurveys were collected by 22 national laboratories. To adjust for a variety of laboratory methods and assays, all quantitative results were transformed to a reference laboratory's units and were then classified as positive or negative to obtain age-specific seroprevalence. The aim of this study was to assess the value of standardization by comparing the crude and standardized seroprevalence estimates. Seroprevalence was estimated for measles, mumps, rubella, diphtheria, varicella zoster and hepatitis A virus (HAV) and compared before and after serological results had been standardized. The results showed that if no such adjustment had taken place, seroprevalence would have differed by an average of 3·2% (95% bootstrap interval 2·9-3·6) although this percentage varied substantially by antigen. These differences were as high as 16% for some serosurveys (HAV) which means that standardization could have a considerable impact on seroprevalence estimates and should be considered when comparing serosurveys performed in different laboratories using different assay methods.

Comparative hepatitis A seroepidemiology in 10 European countries.

The WHO recommends hepatitis A virus (HAV) immunization according to level of transmission and disease burden. We aimed to identify susceptible age groups by standardized serosurveys to inform HAV vaccination policy in participating countries: Belgium, Czech Republic, England, Finland, Germany, Italy, Lithuania, Malta, Romania, and Slovakia. Each country tested national serum banks (n = 1854-6748), collected during 1996-2004, for anti-HAV antibodies. Local laboratory results were standardized to common units. Forty-one per cent of those aged <30 years and 6% of those aged ≥30 years were susceptible to HAV in Romania; compared to 70-94% and 26-71%, respectively, elsewhere. Romania reported high HAV incidence in children and young adults. Other countries reported HAV disease primarily in older risk groups. The results suggest low level of HAV transmission in most of Europe. Romania, however, appeared as an area with intermediate transmission. Vaccination of risk groups in countries with high susceptibility of young and middle-aged adults needs to be continued.

The European Sero-Epidemiology Network 2 (ESEN2): standardization of assay results for hepatitis A virus (HAV) to enable comparisons of seroprevalence data across 15 countries.

The European Sero-Epidemiology Network 2 (ESEN2) aimed to compare serological results of vaccine-preventable diseases across Europe. To ensure direct inter-country comparability of hepatitis A virus antibody (anti-HAV) measurements, a standardization panel of 150 sera was developed by a designated reference laboratory and tested by participating national laboratories using assays of choice; each country's results were subsequently regressed against those of the reference laboratory. Quantitatively, the assays were generally highly correlated (R2>0.90). Nevertheless, qualitative comparisons indicated that results obtained with different assays may differ despite the usage of well-established international and local standards. To a great extent standardization successfully alleviated such differences. The generated standardization equations will be used to convert national serological results into common units to enable direct international comparisons of HAV seroprevalence data. The results of this study are expected to contribute to the evaluation and potential improvement of the currently employed immunization strategies for hepatitis in Europe.

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.

The European Sero-Epidemiology Network 2: standardization of assay results for hepatitis B virus.

The aim of the European Sero-Epidemiology Network 2 was to coordinate and standardize the serological surveillance of vaccine-preventable diseases in Europe. In this study, the standardization of hepatitis B virus (HBV) results is described. The 15 participating national laboratories tested a unique panel of 172 sera established by the Greek reference centre for HBV surface antigen (HBsAg), antibodies to HBsAg (anti-HBs) and/or to the HBV core antigen (anti-HBc) by assay methods of their choice. Country-specific quantitative measurements for anti-HBs and anti-HBc were transformed into common units using standardization equations derived by regressing each country's panel results against the reference centre's results, thus adjusting for interassay and interlaboratory variability. For HBsAg, a qualitative analysis (positive/negative) showed at least 99% agreement with the reference laboratory for all countries. By combining these standardized and qualitative results for the markers mentioned earlier, it was possible to achieve comparable estimates of the proportion of the population susceptible to HBV, vaccinated against HBV, with a past HBV infection, and with a current infection or chronic carrier state. Standardization is a very important tool that allows for international serological comparisons to assess the current vaccination policies and the progress of HBV control in Europe.

Low-dose IFN-alpha monotherapy in treatment-naive individuals with HIV-1 infection: evidence of potent suppression of viral replication.

To evaluate the safety and antiviral action of interferon-alpha (IFN-alpha) in HIV-1 infection, we undertook a proof of concept study in 27 treatment-naive patients. Eligible patients comprised two groups: the IFN-alphaT group (n = 17), which received 5 MIU IFN-alpha s.c. daily for 32 consecutive days, and the IFN-alphaNT group (n = 10), which did not receive IFN-alpha prior to highly active antiretroviral therapy (HAART), which was commenced on day 28 in both groups. IFN-alphaTreatment was well tolerated in 14 of the 17 patients of the IFN-alphaT group who completed the study. The mean HIV RNA reduction in the IFN-alphaT group on day 14 was 1.1 log(10). Viral load suppression was inversely associated with baseline viral load (p = 0.031). Four weeks after initiation of HAART, IFN-alphaT and IFN-alphaNT group patients had 2.40 and 1.82 log(10) HIV RNA reduction from baseline, respectively (p < 0.001). There was no evidence of cross-resistance with existing antiretrovirals in patients with HIV-RNA rebound after initial plasma viral load decline > or = 1 log(10) during IFN-alpha monotherapy. Thus, low daily IFN-alpha exhibits potent anti-HIV-1 activity in vivo without serious adverse effects. These properties render IFN-alpha an attractive candidate for further assessment as a constituent of HAART.

Prevalence and genotypic distribution of TT virus in Athens, Greece.

The prevalence of TT virus (TTV) infection in various population groups from Athens, Greece, was assessed by the polymerase chain reaction (PCR) using two primer sets from distinct regions of the genome: the conventional set derived from the open reading frame-1 (ORF-1) and the new, highly sensitive set targeting the region that includes the TATA signal localized upstream of ORF-2. Based on both primer sets, TTV DNA was detected in 42/50 (84.0%) healthy individuals, 42/50 (84.0%) chronic hepatitis C patients, 31/39 (79.5%) acute non-A-E hepatitis patients (group I), 14/16 (87.5%) renal failure patients with acute non-A-E hepatitis (group II), 47/50 (94.0%) intravenous drug users (IVDU), 36/50 (72.0%) hemophiliacs, and 21/31 (67.7%) hemodialysis patients. The presence of TTV was not associated with any particular risk group, and no differences were observed in relation to demographic, biochemical and virological characteristics between TTV DNA-positive and -negative patients. TTV did not seem to have a profound effect on the course of chronic C or acute non-A-E hepatitis either. Phylogenetic analysis revealed that TTV strains circulating in the greater metropolitan area of Athens belong not only to the G1 and G2 genotypes that are encountered worldwide, but also to G3 and to G5 that are found mainly in Europe and Asia, respectively. Further studies will shed light on the role of this highly prevalent virus.

Molecular characterization of a complex, recombinant human immunodeficiency virus type 1 (HIV-1) isolate (A/G/J/K/?): evidence to support the existence of a novel HIV-1 subtype.

Recombination is one of several factors that contribute to the great genetic diversity of human immunodeficiency virus type 1 (HIV-1). In the current study, analysis of the full-length genome of a novel complex mosaic HIV-1 isolate (99GR303) from a Greek sailor who was possibly infected in Sierra Leone, Africa is presented. The 99GR303 isolate was found to comprise genomic regions belonging to subtypes A, G, J and K as well as of regions of a subtype that remains unclassified. For a partial region of env as well as vpr, no apparent similarity to the known HIV-1 subtypes or to any of the circulating recombinant forms was found. In fact, in the partial env gene, including the C2-V3 region, the 99GR303 isolate formed a new clade, suggesting the existence of an additional HIV-1 subtype. Thus, novel recombinants embody partial genomic regions which may have originated either from subtypes that existed in the past and became extinct or from contemporary subtypes that are extremely rare.

Comparative evaluation of the QUANTIPLEX HIV-1 RNA 2.0 and 3.0 (bDNA) assays and the AMPLICOR HIV-1 MONITOR v1.5 test for the quantitation of human immunodeficiency virus type 1 RNA in plasma.

HIV-1 RNA measurements from 84 plasma specimens obtained with the QUANTIPLEX HIV-1 RNA 2.0 and 3.0 (bDNA) assays (Chiron Diagnostics, Emeryville, CA) and with the AMPLICOR HIV-1 MONITOR Test, version 1.5 with ultra-sensitive specimen preparation (Roche Diagnostic Systems, Inc., Branchburg, NJ) were compared. The absolute RNA values of tested specimens differed significantly between bDNA 2.0 and bDNA 3.0 or Monitor v1.5 measurements (Wilcoxon signed-rank test P<0.001). Results generated with bDNA 3.0 or with Monitor v1.5 were approximately twofold greater than those generated with bDNA 2.0, with smaller differences at higher HIV-1 RNA levels and greater differences at RNA levels below 1000 copies per ml. Although highly correlated (r=0.92 and 0.86, respectively), viral load data generated with bDNA 2.0 and either bDNA 3.0 or Monitor v1.5 were in poor agreement. Concordant results (difference in log(10) copies per ml <0.5) were found at frequencies of 80% for bDNA 2.0 and bDNA 3.0 and only at 58.5% for bDNA 2.0 and Monitor v1.5. In contrast, bDNA 3.0 and Monitor v1.5 measurements were highly correlated (r=0.96) and in good agreement (92.7%).

Molecular epidemiology of GB virus C/hepatitis G virus in Athens, Greece.

The relevance of GB virus C/hepatitis G virus (GBV-C/HGV) infections in liver pathology remains unclear. To investigate the epidemiology of GBV-C/HGV in Athens, Greece, sera from 512 subjects were screened for present and past markers of GBV-C/HGV infection using a reverse transcription-polymerase chain reaction (RT-PCR) and a serological assay, respectively. GBV-C/HGV RNA was detected in 18/56 (32.1%), 12/42 (28.6%), and 16/55 (29.1%) patients with acute hepatitis B, C, or non-A-E, and in 5/58 (8.6%) and 18/68 (26.5%) patients with chronic hepatitis B or C, respectively, as well as in 50/133 (37.6%) hemodialysis patients and 10/100 (10%) healthy individuals. The data indicated that GBV-C/HGV seroprevalence is age-dependent; thus, GBV-C/HGV RNA and anti-E2 positivity were shown to be associated with younger age [odds ratio 0.98, 95% confidence interval (CI) 0. 97-1.00, P = 0.017] and older age (odds ratio 1.03, 95% CI 1.01-1.05, P = 0.002), respectively. No significant associations were identified between GBV-C/HGV RNA status and alanine aminotransferase (ALT) levels in either hepatitis or hemodialysis patients. Nevertheless, GBV-C/HGV RNA-positive acute non-A-E hepatitis patients were more likely to manifest a more severe clinical form of acute hepatitis (P = 0.024). Phylogenetic analysis of partial 5'-untranslated region sequences isolated from 18 viremic individuals showed that most GBV-C/HGV strains circulating in the greater metropolitan area of Athens belong to the 2a subgroup. A genetically diverse type 2 sequence that may represent a novel subtype within group 2 was also characterized.

Effect of recent thymic emigrants on progression of HIV-1 disease.

BACKGROUND: The concentration of T-cell receptor-rearrangement excision DNA circles (TREC) in peripheral-blood T cells is a marker of recent thymic emigrant alphabeta T cells. We studied the predictive ability of measurements of TREC for clinical outcome in HIV-1-infected individuals. METHODS: We measured TREC in peripheral-blood mononuclear cells with a real-time PCR assay. We studied 131 Greek participants in the Multicenter Hemophilia Cohort Study who had known HIV-1 seroconversion dates. The prognostic value of baseline TREC, CD4 T-cell count, and HIV-1 RNA concentration was assessed by Kaplan-Meier and Cox's regression analysis. FINDINGS: Four participants had progressed to AIDS by first blood sampling. Among the remaining 127 individuals, the median value of TREC per 10(6) cells was 6900 (IQR 2370-15604). Baseline TREC values were lower in the 53 who progressed to AIDS than in those who did not (geometric mean 2843 [95% CI 1468-5504] vs 6560 [4723-9113] per 10(6) cells; p=0.017). The relative hazard of AIDS, adjusted for plasma viral load, CD4 T-cell count, and age at seroconversion was 1.44 (95% CI 1.04-2.01; p=0.031) per ten-fold increase in TREC; that for death was 1.52 (1.12-2.06; p=0.007). The adjusted relative hazards of death were 2.91 (1.91-4.44; p<0.001) per ten-fold increase in plasma HIV-1 RNA load and 1.20 (1.04-1.38; p=0.014) per 100-cell decrease in CD4 T-cell count. INTERPRETATION: The concentration of TREC in the peripheral T-cell pool complements HIV-1 RNA load and CD4 T-cell count in predicting the rate of HIV-1 disease progression. Recent thymic emigrants have a role in the pathogenesis of HIV-1 disease.

Prevalence patterns and genotypes of GB virus C/hepatitis G virus among imprisoned intravenous drug users.

An RT-PCR assay using primers from the 5'-UTR of the GBV-C/HGV genome was used to detect viremia, and a serological assay was used to detect past exposure to GBV-C/HGV, in sera from 106 imprisoned Greek intravenous drug users. High seroprevalence rates indicative of the parenteral route of transmission of the virus were found (32.1% for GBV-C RNA and 46.2% for anti-GBV-C E2). These rates were nonetheless lower in comparison to the corresponding rates of HCV infection markers (64.2% for HCV RNA and 77.4% for anti-HCV). Statistically significant univariate associations were observed between GBV-C-RNA positivity and younger age (P=0.006) and HCV-RNA positivity (P=0.024), as well as with higher serum alanine aminotransferase levels (P< 0.001); this latter association was shown to be independent of coinfection with HCV and of age by a multiple logistic regression model. Apparently, GBV-C/HGV had spread readily by needle-sharing in prison, while causing acute subclinical hepatitis in infected inmates. Phylogenetic analysis of the partial 5'-UTR of the GBV-C/HGV genome from 16 seropositive individuals, which delineated their grouping within genotype 2, also revealed a close genetic relationship between two sets of sequences from 4 drug addicts, 3 of whom admitted to sharing needles while imprisoned.