In vitro stimulation with a non-peptidic alkylphosphate expands cells expressing Vgamma2-Jgamma1.2/Vdelta2 T-cell receptors.

The majority of peripheral blood gammadelta T cells in healthy adult humans express the Vgamma2/Vdelta2 T-cell receptor (TCR) and generate TCR-mediated, major histocompatibility complex (MHC)-unrestricted proliferative responses to low molecular weight alkylphosphates. Vgamma2/Vdelta2 populations after antigen proliferation maintained diversity in the CDR3s of Vgamma2 mRNA, indicating that the response was polyclonal or oligoclonal, and were enriched for Vgamma2 TCR chains containing the Jgamma1.2 segment. Alkylphosphate stimulation further skewed an already biased peripheral blood gammadelta T-cell population and increased the abundance of Vgamma2-Jgamma1.2/Vdelta2 T cell receptors, suggesting similarities between the alkylphosphate response and peripheral selection mechanisms shaping this repertoire in human beings.

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7.

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E. coli O157:H7 (ref. 4). Here we have sequenced the genome of E. coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E. coli, through comparison with the genome of the non-pathogenic laboratory strain E. coli K-12 (ref. 5). We find that lateral gene transfer is far more extensive than previously anticipated. In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7. These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Identification and sequence analysis of the core protein genes of bovine adenovirus 2.

The DNA sequence of the genome of bovine adenovirus type 2 (BAdV-2) was determined between map units 42.5 and 50. By sequence analysis and homology search, the genes of five structural proteins were identified within this region: the penton base protein (III; partial sequence), the major core protein precursor (pVII), the minor core protein (V), the mu core protein precursor (pX) and the hexon associated protein precursor (pVI; partial sequence). The putative polypeptides were compared to their known counterparts from other adenoviruses. The existence of protein V and the presence and structure of certain protease cleavage recognition sites confirmed BAdV-2 as a member of the genus Mastadenovirus.

Gammadelta T cell receptor repertoire in blood and colonic mucosa of rhesus macaques.

Although their precise roles are not well defined, gammadelta T lymphocytes are recognized as regular components of immune responses. These cells express a limited T cell receptor repertoire and they can be stimulated by soluble ligands without conventional processing and presentation by major histocompatibility antigens. Progress in this area has been limited by the substantial differences between murine and human gammadelta T cells and the lack of knowledge about these cells in nonhuman primates. We used molecular analysis of T cell receptor diversity to characterize gammadelta T cell populations from peripheral blood and colon of rhesus macaques (Macaca mulatta). The gammadelta T cell receptor diversity was limited and distinct for these tissue compartments, particularly in the TCRGV2 family. Furthermore, the TCRDV1 + subset of peripheral blood gammadelta T cells showed signs of progressive oligoclonalization as a function of age. Similar observations have been reported for human tissue samples and our results validate rhesus macaques as an appropriate animal model for studying primate gammadelta T cell populations.

Sequence, transcriptional analysis, and deletion of the bovine adenovirus type 1 E3 region.

The early 3 (E3) transcriptional unit of human adenoviruses (HAV) encodes proteins that modulate host antiviral immune defenses. HAV E3 sequences are highly variable; different HAV groups encode phylogenetically unrelated proteins. The role of the E3 region of many human and animal adenoviruses is unknown because the sequences are unrelated to previously characterized viruses and the functions of proteins encoded by these regions have not been studied. We sequenced a portion of the bovine adenovirus serotype 1 (BAV-1) genome corresponding to the putative E3 region. This sequence was substantially different from other adenoviral E3 sequences, including those of two other bovine adenoviruses. However, two regions of putative sequence conservation were identified. BAV-1 E3 sequences were identified in early and late transcripts, but, unlike HAV, introns were not detected in the E3 region transcripts. Like HAV E3, a majority of the BAV-1 E3 region was not essential for growth in cell culture, as demonstrated by the construction of a recombinant BAV-1 lacking 60% of the putative E3 region.