Genetic diversity of noroviruses from outbreaks, sporadic cases and wastewater in Luxembourg 2008-2009.

The genetic diversity of norovirus strains obtained from gastroenteritis outbreaks, sporadic case surveillance and wastewater plants was compared in Luxembourg from October 2008 until June 2009. Except for GI.6 and GIV.1 strains detected exclusively in wastewater, all other genotypes were also found in human samples. Of the nine NoV genotypes detected, only three (GII.4, GIIb/II.3 and GIIc/II.12) were associated with institutional outbreaks. The majority of sequences from all sources belonged to genotype GII.4, including two potentially new sub-variants. Strains collected in the context of outbreaks may significantly under-represent the overall genetic diversity of NoVs circulating in a country.

Genetic variability of wild-type measles viruses, circulating in the Russian Federation during the implementation of the National Measles Elimination Program, 2003-2007.

Genetic characterization of wild-type measles viruses (MVs) is an important component of laboratory surveillance of measles. In this study, a phylogenetic analysis was performed of the nucleoprotein gene sequences of 228 MVs isolated in the Russian Federation between 2003 and 2007. Five genotypes, D4, D5, D6, D8, and H1, were detected. From 1999 through the first 6 months of 2003, the most prevalent genotype in the European part of Russia was D4. All genotype D4-type viruses were closely related to each other (with overall sequence diversity of

Genetic variability and mRNA editing frequencies of the phosphoprotein genes of wild-type measles viruses.

The sequences of the nucleoprotein (N) and hemagglutinin (H) genes are routinely used for molecular epidemiologic studies of measles virus (MV). However, the amount of genetic diversity contained in other genes of MV has not been thoroughly evaluated. In this report, the nucleotide sequences of the phosphoprotein (P) genes from 34 wild-type strains representing 15 genotypes of MV were analyzed and found to be almost as variable as the H genes but less variable than the N genes. Deduced amino acid sequences of the three proteins encoded by the P gene, P, V and C, demonstrated considerably higher variability than the H proteins. Phylogenetic analysis showed the same tree topography for the P gene sequences as previously seen for the N and H genes. RNA editing of P gene transcripts affects the relative ratios of P and V proteins, which may have consequences for pathogenicity. Wild-type isolates produced more transcripts with more than one G insertion; however, there was no significant difference in the use of P and V open reading frames, suggesting that the relative amounts of P and V proteins in infected cells would be similar for both vaccine and wild-type strains.

Computer visualization of three-dimensional image data using IMOD.

We have developed a computer software package, IMOD, as a tool for analyzing and viewing three-dimensional biological image data. IMOD is useful for studying and modeling data from tomographic, serial section, and optical section reconstructions. The software allows image data to be visualized by several different methods. Models of the image data can be visualized by volume or contour surface rendering and can yield quantitative information.

HVEM tomography of the trans-Golgi network: structural insights and identification of a lace-like vesicle coat.

High voltage electron microscopy and computer axial tomography have been used to study the 3-D structure of trans-Golgi cisternae and trans-Golgi networks (TGNs) in NRK cells. Both structures were specifically labeled by photoconversion of a fluorescent analogue of ceramide using a modification of the techique of Pagano et al. (J. Cell Biol. 1991. 113: 1267-1279). Regions of the Golgi ribbon in fixed, stained cells were cut in 250-nm sections and analyzed by tilt series microscopy and subsequent tomographic reconstruction. Resolution of the reconstructions ranged from 6 to 10 nm. The size and structure of the TGN varied considerably throughout the Golgi ribbon; all reconstructions were made from regions with pronounced TGN. Most regions analyzed contained multiple (2-4) Golgi cisternae that stain with ceramide. These "peel off" from the closely stacked cisternae and are continuous at their ends with tubules that contribute to the TGN. Most vesicular profiles visualized in the TGN are connected to TGN tubules. The budding of vesicles appears to occur synchronously along the length of a TGN tubule. Two distinct coats were visualized on budding vesicles: clathrin cages and a novel, lace-like structure. Individual TGN tubules produce vesicles of only one coat type. These observations lead to the following predictions: (a) sorting of molecules must occur prior to the formation of TGN tubules; (b) vesicle formation takes place almost synchronously along a given TGN tubule; and (c) lace-like coats form an exocytic vesicles.