Overview of revised measures to prevent malaria transmission by blood transfusion in France.

Plasmodial transmission by blood donation is rare in non-endemic countries, but a very serious complication of blood transfusion. The French national blood service (Etablissement Français du Sang and Centre de Transfusion sanguine des Armees) intended to revise the measures to strengthen blood safety with regard to Plasmodiae as transmissible pathogens. To limit the risk of transmission during infusion, serious additive measures have been taken for more than a decade in France, which is the European country with the highest rate of exposure to imported plasmodial infections or malaria. These measures were revised and strengthened after the occurrence of a lethal transfusion-transmitted infection in 2002, but did not prevent another occurrence in 2006. This report examines the weaknesses of the systems and aims at emphasizing the safety measures already taken and addresses issues to best respond to that risk.

[Anelloviruses (TTV and variants): state of the art 10years after their discovery]. / Les anellovirus (TTV et variants): données actuelles dix ans après leur découverte.

Ten years after their discovery, anelloviruses combine some characteristics making them particularly intriguing. In support of their extreme genetic diversity and high prevalence in various populations, their natural history is still poorly understood along with their implication in human health. These viruses have been identified in blood and blood-derived products, and are probably remarkable examples of co-existence and co-evolution in their various hosts. This article presents epidemiological and molecular characterizing this new viral family.

Use of the PSA enhancer core element to modulate the expression of prostate- and non-prostate-specific basal promoters in a lentiviral vector context.

Composite promoters combining the prostate-specific antigen (PSA) enhancer core element with promoter elements derived from gene coding for human prostate-specific transglutaminase gene, prostate-specific membrane antigen gene, prostate-specific antigen, rat probasin or phosphoglycerate kinase were characterized for their ability to specifically express the enhanced green fluorescent protein (EGFP) gene in prostate versus non-prostate cancer cell lines when transferred with a human immunodeficiency virus-1-based lentiviral vector. By themselves minimal proximal promoter elements were found to inefficiently promote relevant tissue-specific expression; in all the vectors tested, addition of the PSA enhancer core element markedly improved EGFP expression in LnCaP, a cancer prostate cell line used as a model for prostate cancer. The composite promoter was inactive in HuH7, a hepatocarcinoma cell line used as a model of neighboring non-prostate cancer cells. Among the promoters tested, the combination of the PSA enhancer and the rat probasin promoter showed both high specificity and a strong EGFP expression. Neither a high viral input nor the presence of the cPPT/CTS sequence affected composite promoter behavior. Our data suggest that composite prostate-specific promoters constructed by combining key elements from various promoters can improve and/or confer tissue specific expression in a lentiviral vector context.

[West Nile virus (WNV): generalities and implications for blood transfusion]. / Le virus West Nile: généralités et implications en transfusion sanguine.

West Nile virus (WNV) is an arbovirus (genus Flavivirus, Family Flaviviridae, transmitted to humans by mosquito bite. In most cases (80%), human infection remains asymptomatic. Severe central nervous system complications (encephalitis and meningoencephalitis) are rare. In the Old World, the virus circulation has been demonstrated in Asia, Australia, Africa, Middle East and Europe. Several outbreaks in humans have been described. Following its introduction into North America in 1999, WN virus has been responsible of a large number of human cases in USA and Canada. For the first time, viral transmission by blood products was clearly demonstrated in USA in 2002. In France, the presence of virus has been reported in the Southeastern departments since 1962. In 2003, the occurrence of humans cases at specific geographical foci urged the French National Blood Agency (etablissement francais du sang) to take preventive measures for evaluating the virus transmission risks.

Comparison of viral burden and phenotype of HIV-1 isolates from lymph nodes and blood.

OBJECTIVE: To compare the viral burden and the biological phenotype of HIV-1 isolates obtained from lymphoid node mononuclear cells (LNMC) and peripheral blood mononuclear cells (PBMC) in 11 HIV-infected patients. METHODS: Viral burden was quantified by cocultivating LNMC and PBMC from HIV-infected patients with PBMC from seronegative donors. For each patient, LNMC and PBMC isolates were characterized in terms of susceptibility to neutralizing antibodies, syncytium-inducing capacity and sensitivity to zidovudine. RESULTS: Our data show that: (1) viral burden was 1.73 log higher in LNMC than PBMC in patients with persistent generalized lymphadenopathy and only 0.37 log higher in patients with AIDS-related complex; (2) five out of 11 LNMC bulk isolates were phenotypically distinct from autologous PBMC isolates; (3) in three patients, the autologous serum neutralized the PBMC isolates but not the LNMC isolates. CONCLUSIONS: These results suggest that the relatively high level of HIV-1 replication in lymph nodes may favour the emergence of viruses exhibiting specific phenotypes, including neutralization escape variants. The existence of viral variants in lymphoid tissue at all stages of HIV infection may elucidate certain aspects of the pathogenesis of HIV-1 infection.

Correlation between surrogate markers, viral load, and disease progression in HIV-1 infection.

Surrogate markers generally used for observation of patients infected with human immunodeficiency virus (HIV) and their plasma and cellular viral load were assayed in a series of 40 patients before initiation of zidovudine therapy. Plasma viremia was positive in 62.5% of patients and was statistically correlated with clinical stage, CD4+ T cell count, CD8+ T cell count, beta 2-microglobulin level, neopterin level, and immunoglobulin A level. Cellular viremia was positive in 95% of patients and was correlated with clinical stage, CD4+ T cell count, beta 2-microglobulin, neopterin levels, and disease progression during the following months. A discordance was found between p24 antigenemia, even after acid dissociation of immune complexes, and plasma viremia. In fact, p24 antigenemia was correlated with only biological markers of immune activation as beta 2-microglobulin and neopterin levels. The measurement of anti-p24 antibodies did not appear discriminative in our staging. Plasma viremia, like CD4+ T cell count, reflects the patient's status at the time of assessment. Cellular viremia could be more informative for the prediction of future clinical progression.

Prevalence of hepatitis G virus infection in kidney transplant recipients.

BACKGROUND: We investigated the prevalence, risk factors, and consequences of hepatitis G virus (HGV) infection in 87 kidney transplant recipients. METHODS: Infection was diagnosed with reverse transcriptase polymerase chain reaction using primers in the NS3 region of the viral genoma. RESULTS: Twenty-four patients (27.5%) were HGV RNA positive (HGV+ group) and 63 patients (72.5%) were HGV RNA negative (HGV- group). No statistically significant differences were found between the two groups for age, sex, transplantation and hemodialysis duration, number of kidney transplantations, serum creatinine, history of transfusions, hepatitis B and C virus infections, and percentage of patients having suffered from acute rejection. Acute and chronic hepatitis were not more prevalent in the HGV+ group than in the HGV- group. CONCLUSIONS: HGV infection is highly prevalent in kidney transplant recipients but does not alter liver or kidney functions. HGV contamination may be linked to nosocomial transmission during long-term hemodialysis.

Identification and strain differentiation of Mycobacterium species on the basis of DNA 16S-23S spacer region polymorphism.

Amplification of the region separating the genes coding for the two rRNA species 16S and 23S was performed to identify 56 mycobacterial strains, belonging to eleven species: Mycobacterium tuberculosis, M. avium, M. kansasii, M. gordonae, M. abscessus, M. fortuitum, M. xenopi, M. bovis, M. bovis/BCG, M. africanum and M. intracellulare. Reproducible amplification patterns were obtained with most species with the exception of M. kansasii which showed heterogeneity, confirming the existence of a genetically distinct subspecies within this species. In addition, we used the amplified products as target DNA for restriction endonuclease digestion and RAPD (randomly amplified polymorphic DNA) analysis to compare strains of M. abscessus, M. tuberculosis and M. avium. The discriminatory power of these two typing methods was higher than when whole genomic DNA is used as target. Our results demonstrate that the two-step approach to identification and typing on the basis of the hypervariability of 16S-23S spacer region is reliable, rapid and simple, and consequently could be an epidemiological tool in clinical laboratories.

A one-step microbial DNA extraction method using "Chelex 100" suitable for gene amplification.

"Chelex 100" chelating resin has been previously proposed for the rapid extraction of human DNA for polymerase chain reaction. Protocols are given for the rapid extraction of bacterial and viral DNA from cultures or clinical samples. The DNA samples obtained were suitable for use in polymerase chain reaction.

Variations in DNA concentrations significantly affect the reproducibility of RAPD fingerprint patterns.

The influence of the DNA concentration was tested using two different primers and nine DNA samples. Major modifications in the DNA banding pattern were apparent between successive dilutions. Such differences could be explained by concomitant changes in three different molecular conditions: the presence of perfect priming sites, the amplification of rare sites and the existence of mismatch annealing events. At low DNA concentrations (less than 1 pg/microliter), molecular events occurred at random and had a direct consequence on the reproducibility of RAPD profiles. At the appropriate DNA concentration (between 100 ng/microliters and 10 pg/microliters), reproducibility was adequate at a given concentration, but RAPD profiles differed from one dilution to another. These observations demonstrate the usefulness of the bis-benzimide method for quantification of DNA extracts.

Comparison of systems performance for TT virus detection using PCR primer sets located in non-coding and coding regions of the viral genome.

BACKGROUND: the heterogeneity of the TT virus (TTV) DNA prevalence values reported from comparable human cohorts suggests that diagnostic PCR protocols still require to be optimized. OBJECTIVES: to design TTV PCR primer sets with low genotype restriction and to compare their performances with commonly used amplification systems. STUDY DESIGN: we compared full length TTV genomic sequences and identified conserved nucleotide patterns in the 5' and 3' non-coding regions of the viral genome. This permitted to design two new primer sets usable for the PCR amplification of the most divergent human isolates of TTV described to date. The performances of these amplification systems were compared with those of three other PCR systems earlier used for prevalence studies. RESULTS: the primer systems P5Bx and P3Bx exhibited higher PCR scores than the other systems tested; 14 to 34% improvement values were obtained, and divergent positive results of earlier described PCR systems were confirmed systematically by our new detection assays. CONCLUSIONS: an optimized detection of TT virus DNA is a pre-requisite for the accurate epidemiological survey of viral infection and for the realization of phylogenetic studies. Such PCR systems with low genotype restriction will be helpful in the future for a better knowledge of natural history of TT virus infection.

TT virus infection: prevalence of elevated viraemia and arguments for the immune control of viral load.

BACKGROUND: The most recent polymerase chain reaction (PCR) detection protocols for the TT virus (TTV) permit one to identify the presence of viral DNA in the serum of a majority of healthy individuals, in the absence of any particular risk factor. This is in contrast with previous epidemiological studies that reported a higher prevalence of TTV infection in populations such as haemodialysis patients (HD), haemophiliacs, intravenous drug users or diabetics. OBJECTIVES: To show that these discrepant results were due to the different sensitivity (number of viral copies detected) of the detection protocols used in initial and more recent epidemiological studies. STUDY DESIGN AND RESULTS: We designed a standardised primary PCR assay that detects only viraemia >5x10(3) to 5x10(4) copies/ml for genotypes 1, 2 and 3, and compared the results of this test with those of a nested PCR assay which is 100-fold more sensitive. Viraemia >5x10(3) to 5x10(4) copies/ml were statistically more frequent in HD patients (54.3%), diabetics (54.7%), and HIV-infected patients with CD4 cells <200/mm(3) (69%) than in blood donors (37%) or HIV-infected patients with CD4 cells >500/mm(3) (33%). CONCLUSIONS: These data suggest a possible relationship between the prevalence of elevated viral loads and the level of immunocompetence of the populations studied, and therefore that of an immune control of TTV viraemia. This corroborates previous findings showing that the stimulation of the immune system by an interferon treatment was able to clear TTV viraemia.

TT virus: a study of molecular epidemiology and transmission of genotypes 1, 2 and 3.

BACKGROUND: TT virus (TTV) is a recently discovered virus, which is not related to any other known virus infecting humans. OBJECTIVES: To investigate: (i) the world-wide distribution of the three major TTV genotypes; and (ii) the possible routes of viral transmission. STUDY DESIGN: (i) The phylogenetic distribution of 494 TTV isolates originating from 31 countries was analysed, using partial ORF1 sequences. (ii) Faeces samples (n=22) and saliva samples (n=72) from French individuals were tested for the presence of TTV DNA. (iii) Viral titres in paired serum and saliva samples were compared. RESULTS: (i) Genotypes 1, 2 and 3 were distributed world-wide, with a high proportion of type 1 in Asia (71%) and no type 3 identified in Africa to date. In the USA, 77% of isolates were grouped in four clusters only (genetic distances <10%). This was also the case of 76% of French isolates, 76% of Japanese isolates, and 89% of Hong Kong isolates. (ii) TTV DNA was detected in 18% of faeces samples and 68% of saliva samples tested. (iii) Viral titre in saliva samples was 100-1000 times higher than that of the corresponding serum. CONCLUSIONS: (i) The observed epidemiological distribution of TTV isolates is compatible with an ancient dissemination of viral ancestors belonging to the different genotypes and a slow genetic evolution in sedentary populations. (ii) Besides the possible transmission of TTV by the parental and oral-faecal routes, the high titre of TTV DNA observed in saliva raises the hypothesis of the viral transmission by saliva droplets. This route of transmission could explain the high degree of exposure to viral infection observed in the general population.

Evaluation of a disinfection procedure for hysteroscopes contaminated by hepatitis C virus.

We assessed the ability of a standard disinfection procedure to eliminate hepatitis C virus (HCV) from the air-water channel of hysteroscopes. The residual HCV RNA remaining after the disinfection procedure was measured by polymerase chain reaction. When correctly applied to hysteroscopes, the standard disinfection procedure was sufficient to eliminate the risk of HCV transmission.

Serologic and molecular diagnosis of Colorado tick fever viral infections.

Molecular and serologic methods usable for the biological diagnosis of Coltivirus infection are reported. We designed a multiplex reverse transcription-polymerase chain reaction system that allowed the simultaneous and specific amplification of three genomic segments from as little as 0.01 plaque-forming units. Another system in the S2 viral segment permitted the differential diagnosis of American and European viral isolates. We also discuss some improvements of previous ELISAs, and the results obtained with paired sera from Colorado tick fever (CTF) virus-infected individuals. Western blot analysis was developed that allowed the detection of antibodies to a 38-kD viral protein in all tested sera. It also enabled the detection of anti-CTF virus antibodies in ELISA-negative sera. Specific IgM antibodies against a synthetic viral peptide could be detected in sera at the acute stage of the infection. Together, these results should permit the diagnosis of Coltivirus infection at any stage of the pathology.

Demonstration of Mycobacterium kansasii species heterogeneity by the amplification of the 16S-23S spacer region.

Amplification of the region separating the genes coding for the two rRNA species 16S and 23S was performed with 56 strains of several mycobacterial species, including 21 clinical isolates of Mycobacterium kansasii and the M. kansasii type strain ATCC 12478. On the basis of PCR product profiles, the previously suggested heterogeneity of M. kansasii species was confirmed. Three subgroups were identified; members of the first subgroup showed the same PCR profile as the reference strain. Different profiles were obtained for the two other subgroups. Amplification of the 16S-23S spacer is rapid and simple and, consequently, may be a helpful tool for identification and characterisation of M. kansasii isolates in epidemiological analysis.

Investigation of outbreaks of Enterobacter aerogenes colonisation and infection in intensive care units by random amplification of polymorphic DNA.

During a 4-month period, 41 isolates of Enterobactor aerogenes were cultured from different specimens from a 14-bed intensive care unit (ICU1). These were obtained from 12 patients out of a total of 187 patients admitted to the ICU. Sixteen E. aerogenes isolates were cultured from another ICU (ICU2) 6 months later. Six non-outbreaks associated strains were included as controls and all the isolates were compared by random amplification of polymorphic DNA (RAPD), with three different 10-mer oligonucleotide primers. RAPD fingerprinting with primer AP12h was as discriminatory as the combined results from all three primers and defined 22 different patterns for the 41 isolates from the ICU1. In nine instances, isolates with indistinguishable RAPD patterns were detected in two-to-five patients over a 3-15-day period, suggesting patient-to-patient transmission. During their stay in ICU1, patients harboured one-to-12 distinguishable isolates. Isolates from ICU2 were indistinguishable by RAPD analysis with the three different primers. These findings suggest that the cluster of colonisations and infections in ICU1 was a 'false outbreak', consisting of successive patient-to-patient transmission of different E. aerogenes strains. In contrast, the outbreak on ICU2 probably involved the extensive spread of a single strain.

Strategies for the sequence determination of viral dsRNA genomes.

The genetic study of viruses having dsRNA genomes is hampered by the technical difficulty of complete sequence determination of dsRNA. Optimised methods are described here for sequencing dsRNAs, which meet three different situations: (1) genomes that can be obtained in fairly high amounts (>20 ng per separated segment); (2) genomes with limited amounts of RNA that can be detected by electrophoretic gel separation and staining; (3) genomes that cannot be detected by electrophoretic gel separation and staining. These methods include improved Single Primer Amplification Technique protocols, an adaptation of the SMART methodology, and a new method permitting the selective enzymatic removal of dsRNA segments. Strategies permitting adaptation of these protocols to the full-length determination of dsRNA viral genomes are described. Each of the protocols is described for sequence determination of a chosen dsRNA virus.

Molecular diagnosis of group B coltiviruses infections.

The group-B of genus Coltivirus encompasses isolates from humans, ticks or mosquitoes collected in Indonesia and China. Subgroup-B1 includes the strain JKT/dsR-7075 and subgroup-B2 strains JKT/dsR-6423, JKT/dsR-6969, JKT/dsR-7043 and the Banna virus. Data are described for the PCR-based diagnosis of infection by group B coltiviruses. Sets of primers were designed from the sequences of the 7th, 9th and 12th viral segments and RT PCR assays were developed. Consensus primers permitted the detection of all known isolates of subgroup 1 or 2. Viral strains could be characterised further using primers specific for type B2a or B2b, or based on the length of the amplification products. All primers gave negative results when using RNAs from Orbiviruses or Group-A coltiviruses. These primers permitted the detection of Group-B coltiviruses-RNA in infected mouse blood at the acute stage of the disease. Accordingly, they could be used for the diagnosis of infection in humans.

Evaluation of four PCR systems amplifying different genomic regions for molecular diagnosis of GB virus C infections.

Diagnosis of GB virus C (GBV-C) infection is based on RT-PCR methodology that detects genomic viral RNA. Four sets of primers located in different genomic regions were compared. These primers were used to amplify a reference panel of sera used by the French blood banks, including five positive sera, five negative sera and 10-fold serial dilutions of one positive serum. Three sets of primers located in the 5'UTR, NS3 and NS5a genomic regions gave comparable results with undiluted sera. When diluted sera were tested, the most sensitive protocol was that using a set of primers and a probe selected within the 5'UTR, together with a colorimetric detection based on DNA enzyme immunoassay.