Detection of TT virus by single-primer sequence-independent amplification in multiple samples collected from an outbreak of gastroenteritis

Culture and identification of TTV virus associated with human chronic gastritis

AIM: To develop a suitable proliferative cell culture system for chronic gastritis-related tiny virus, and to identify the type of this virus.

METHODS: The gastric adenocarcinoma cell line SGC-7901 was used to culture the tiny virus, and cells were observed by inverted microscopy and transmission electron microscopy (TEM). The primers for transfusion transmitted virus (TTV) and human parvovirus B19 were used to amplify DNA from the tiny virus.

RESULTS: After three blind passages in SGC-7901 cells, the tiny virus could proliferate in vitro and produce obvious CPE. TEM analysis showed that TTV was distributed in the nucleus and cytoplasm. The virions were globular, approximately 20 nm in size. PCR analysis showed that the tiny virus specimens were TTV DNA amplification-positive.

CONCLUSION: SGC-7901 cells can be used as a proliferation system for tiny virus. The tiny virus and TTV virus belong to the same genus.

Torque teno virus in fecal samples of patients with gastroenteritis: prevalence, genogroups distribution, and viral load

Torque teno virus (TTV, genus Alphatorquevirus, family Anelloviridae) is a DNA virus, highly prevalent in populations from around the world. TTV isolates have been classified into five main phylogenetic groups (1-5) showing a large genetic distance between them. The presence of TTV has been detected in feces. However, whether all five TTV genogroups are excreted in feces and the frequency of these events are presently unknown. The presence of TTV DNA was assessed in feces from 135 Brazilian (0-90 years old) patients with gastroenteritis by using three PCR methods, including real-time PCR. One hundred twenty one (91.1%) samples were positive with at least one method. Using a genogroup-specific assay, it was shown that all genogroups were present. Thirty-seven (27.4%), 27 (20.0%), 57 (42.2%), 29 (21.5%), and 33 (24.4%) fecal samples contained TTV isolates belonging to genogroups 1-5, respectively. Coinfections with two, three, four, and five TTV genogroups were found in 23 (17.0%), 15 (11.1%), 7 (5.2%), and 7 (5.2%) fecal samples, respectively. Thus, 52 (38.5%) samples contained more than one TTV genogroup. Viral loads ranged from 2.6 to 6.5 log genome equivalents per gram of feces. However, only moderate variations of viral load were noted depending on genogroup and number of coinfecting TTV genogroups. These results show a high prevalence and a diversity of TTV isolates in feces.

Molecular detection and characterization of Aichi viruses in sewage-polluted waters of Venezuela

The circulation of Aichi virus in a major urban area was demonstrated using molecular detection with samples recovered from a major river polluted with sewage discharges in Caracas, Venezuela. Five out of 11 water samples studied were positive, being classified by phylogenetic analysis as genotype B. Analysis of sewage waters appears to be a useful methodology to uncover the presence of a hitherto undetected fecal pathogen in a given geographical area.

Emerging molecular assays for detection and characterization of respiratory viruses

This article describes several emerging molecular assays that have potential applications in the diagnosis and monitoring of respiratory viral infections. These techniques include direct nucleic acid detection by quantum dots, loop-mediated isothermal amplification, multiplex ligation-dependent probe amplification, amplification using arbitrary primers, target-enriched multiplexing amplification, pyrosequencing, padlock probes, solid and suspension microarrays, and mass spectrometry. Several of these systems already are commercially available to provide multiplex amplification and high-throughput detection and identification of a panel of respiratory viral pathogens. Further validation and implementation of such emerging molecular assays in routine clinical virology services will enhance the rapid diagnosis of respiratory viral infections and improve patient care.