A rapid and sensitive assay for detection of replication-competent adenoviruses by a combination of microcarrier cell culture and quantitative PCR

The development of a rapid and sensitive assay for detection of replication-competent adenoviruses (RCAs) is described. This RCA assay consists of an incubation step of 4 days of adenoviral vectors on A549 cells in a microcarrier cell culture system followed by detection of amplified RCAs by E1-specific quantitative PCR. The detection limit of this assay is 3 RCAs in 1 x 10(10) vector particles per 70 ml of microcarrier cell culture. The main advantage of the combination of cell culture and PCR detection is that replicated virus can be detected long before cytopathic effects become visible and therefore, it is much faster than conventional cell culture-based assays. This assay was validated by spiking replication-incompetent adenoviral vectors with wild-type adenovirus serotype 5 (wt Ad5) as a positive control for RCA. It was found that the replication of wt Ad5 is hampered above a vector particle per cell ratio of 50. However, if microcarrier beads are used, many cells can be grown in a small suspension culture and consequently a large number of vector particles can be tested for contamination with RCA. (c) 2007 Elsevier B.V. All rights reserved

Presence and persistence of viable, clinically relevant Legionella pneumophila bacteria in garden soil in the Netherlands

Garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. Legionella bacteria were detected in 22 of 177 garden soil samples (12%) by amoebal coculture. Of these 22 Legionella-positive soil samples, seven contained L. pneumophila Several other species were found including the pathogenic L. Longbeachae (4 gardens) and L. sainthelensi (9 gardens). The L. pneumophila isolates comprised 15 different sequence types (STs) and eight of these STs were previously isolated from patients, according to the EWGLI database. Six gardens that were found positive for L. pneumophila were resampled after several months and in three gardens, L. pneumophila was again isolated. One of these gardens was re-sampled four times throughout the year and found positive for L. pneumophila on all occasions. IMPORTANCE: Tracking the source of infection for sporadic cases of Legionnaires' disease (LD) has proven to be hard. L. pneumophila ST47, the sequence type that is most frequently isolated from LD patients in the Netherlands, is rarely found in potential environmental sources. As L. pneumophila ST47 was previously isolated from a garden soil sample during an outbreak investigation, garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. The detection of viable, clinically relevant Legionella strains indicates that garden soil is a potential source of Legionella bacteria and future research should assess the public health implication of the presence of L. pneumophila in garden soil

Preclinical and clinical safety studies on DNA vaccines.

DNA vaccines are based on the transfer of genetic material, encoding an antigen, to the cells of the vaccine recipient. Despite high expectations of DNA vaccines as a result of promising preclinical data their clinical utility remains unproven. However, much data is gathered in preclinical and clinical studies about the safety of DNA vaccines. Here we review current knowledge about the safety of DNA vaccines. Safety concerns of DNA vaccines relate to genetic, immunologic, toxic, and environmental effects. In this review we provide an overview of findings related to the safety of DNA vaccines, obtained so far. We conclude that the potential risks of DNA vaccines are minimal. However, their safety issues may differ case-by-case, and they should be treated accordingly

Confirmed and Potential Sources of Legionella Reviewed

Legionella bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires' disease. This review provides an overview of reservoirs of Legionella reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of Legionella. A total of 17 systems and matrices could be classified as confirmed sources of Legionella. Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious Legionella bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of Legionella. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden

Confirmed and Potential Sources of Legionella Reviewed

Legionella bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires' disease. This review provides an overview of reservoirs of Legionella reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of Legionella. A total of 17 systems and matrices could be classified as confirmed sources of Legionella. Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious Legionella bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of Legionella. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden

Confirmed and Potential Sources of <i>Legionella</i> Reviewed

<i>Legionella</i> bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires’ disease. This review provides an overview of reservoirs of <i>Legionella</i> reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of <i>Legionella</i>. A total of 17 systems and matrices could be classified as confirmed sources of <i>Legionella.</i> Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious <i>Legionella</i> bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of <i>Legionella</i>. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden

Confirmed and Potential Sources of <i>Legionella</i> Reviewed

<i>Legionella</i> bacteria are ubiquitous in natural matrices and man-made systems. However, it is not always clear if these reservoirs can act as source of infection resulting in cases of Legionnaires’ disease. This review provides an overview of reservoirs of <i>Legionella</i> reported in the literature, other than drinking water distribution systems. Levels of evidence were developed to discriminate between potential and confirmed sources of <i>Legionella</i>. A total of 17 systems and matrices could be classified as confirmed sources of <i>Legionella.</i> Many other man-made systems or natural matrices were not classified as a confirmed source, since either no patients were linked to these reservoirs or the supporting evidence was weak. However, these systems or matrices could play an important role in the transmission of infectious <i>Legionella</i> bacteria; they might not yet be considered in source investigations, resulting in an underestimation of their importance. To optimize source investigations it is important to have knowledge about all the (potential) sources of <i>Legionella</i>. Further research is needed to unravel what the contribution is of each confirmed source, and possibly also potential sources, to the LD disease burden

Presence and persistence of viable, clinically relevant Legionella pneumophila bacteria in garden soil in the Netherlands

Garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. Legionella bacteria were detected in 22 of 177 garden soil samples (12%) by amoebal coculture. Of these 22 Legionella-positive soil samples, seven contained L. pneumophila Several other species were found including the pathogenic L. Longbeachae (4 gardens) and L. sainthelensi (9 gardens). The L. pneumophila isolates comprised 15 different sequence types (STs) and eight of these STs were previously isolated from patients, according to the EWGLI database. Six gardens that were found positive for L. pneumophila were resampled after several months and in three gardens, L. pneumophila was again isolated. One of these gardens was re-sampled four times throughout the year and found positive for L. pneumophila on all occasions. IMPORTANCE: Tracking the source of infection for sporadic cases of Legionnaires' disease (LD) has proven to be hard. L. pneumophila ST47, the sequence type that is most frequently isolated from LD patients in the Netherlands, is rarely found in potential environmental sources. As L. pneumophila ST47 was previously isolated from a garden soil sample during an outbreak investigation, garden soils were investigated as reservoirs and potential sources of pathogenic Legionella bacteria. The detection of viable, clinically relevant Legionella strains indicates that garden soil is a potential source of Legionella bacteria and future research should assess the public health implication of the presence of L. pneumophila in garden soil