A practical guide to research for nurses and midwives.

Research is a key way for nurses and midwives to develop their knowledge and skills. An understanding of the research process and accessing resources is essential if more nurses are to become active in research. This article summarises Conducting Research: A Handbook for Nurses and Midwives (McEwen et al, 2006), which provides information on tools, techniques and contacts.

The genome of Epstein-Barr virus type 2 strain AG876.

Two Epstein-Barr virus (EBV) types are known, EBV1 and EBV2, which possess substantially diverged alleles for latency genes EBNA-2, EBNA-3A, EBNA-3B and EBNA-3C but are thought to be otherwise similar. We report the first complete EBV2 genome sequence, for strain AG876, as 172,764 bp. The sequence was interpreted as containing at least 80 protein coding genes. Comparison with the published EBV1 sequence demonstrated that the two sequences are collinear and, outside the known diverged alleles, generally very close. The EBNA-1 gene was identified as another diverged locus, although its variation is believed not to correlate with EBV type. Patterns of substitution between the two genomes presented a wide spectrum of classes of change. No evidence was seen for involvement of B-cell-specific hypermutation systems in generation of the diverged alleles. Overall, genomic comparisons indicated that the two EBV types should be regarded as belonging to the same virus species.

Genetic content of wild-type human cytomegalovirus.

The genetic content of wild-type human cytomegalovirus was investigated by sequencing the 235 645 bp genome of a low passage strain (Merlin). Substantial regions of the genome (genes RL1-UL11, UL105-UL112 and UL120-UL150) were also sequenced in several other strains, including two that had not been passaged in cell culture. Comparative analyses, which employed the published genome sequence of a high passage strain (AD169), indicated that Merlin accurately reflects the wild-type complement of 165 genes, containing no obvious mutations other than a single nucleotide substitution that truncates gene UL128. A sizeable subset of genes exhibits unusually high variation between strains, and comprises many, but not all, of those that encode proteins known or predicted to be secreted or membrane-associated. In contrast to unpassaged strains, all of the passaged strains analysed have visibly disabling mutations in one or both of two groups of genes that may influence cell tropism. One comprises UL128, UL130 and UL131A, which putatively encode secreted proteins, and the other contains RL5A, RL13 and UL9, which are members of the RL11 glycoprotein gene family. The case in support of a lack of protein-coding potential in the region between UL105 and UL111A was also strengthened.

Two novel spliced genes in human cytomegalovirus.

Two novel spliced genes (UL131A and UL128) flanking UL130 were predicted from sequence comparisons between human cytomegalovirus (HCMV) and its closest known relative, chimpanzee cytomegalovirus (CCMV), and the splicing patterns were confirmed by mRNA mapping experiments. Both genes were transcribed with late kinetics and shared a polyadenylation site. Comparisons with wild-type HCMV in infected human tissues showed that three of five isolates passaged in cell culture contained disruptions of UL128, one was frameshifted in UL131A and one exhibited a deletion affecting UL131A and UL130. CCMV and the Colburn strain of simian cytomegalovirus, which have been passaged in cell culture, also exhibit disruptions of UL128. These observations indicate that expression of either one of UL128 and UL131A is deleterious to growth of primate cytomegaloviruses in cell culture. Although the functions of these genes are unknown, sequence comparisons suggest that UL128 encodes a beta-chemokine.

Homology between the human cytomegalovirus RL11 gene family and human adenovirus E3 genes.

A significant proportion of the human cytomegalovirus (HCMV) genome comprises 12 multigene families that probably arose by gene duplication. One, the RL11 family, contains 12 members, most of which are predicted to encode membrane glycoproteins. Comparisons of sequences near the left end of the genome in several HCMV strains revealed two adjacent open reading frames that potentially encode related proteins: RL6, which is hypervariable, and RL5A, which has not been recognized previously. These genes potentially encode a domain that is the hallmark of proteins encoded by the RL11 family, and thus constitute two new members. A homologous domain is also present in a subset of human adenovirus E3 membrane glycoproteins. Evolution of genes specifying the shared domain in cytomegaloviruses and adenoviruses is characterized by extensive divergence, gene duplication and selective sequence loss. These features prompt speculation about the roles of these genes in the two virus families.

The human cytomegalovirus genome revisited: comparison with the chimpanzee cytomegalovirus genome.

The gene complement of wild-type human cytomegalovirus (HCMV) is incompletely understood, on account of the size and complexity of the viral genome and because laboratory strains have undergone deletions and rearrangements during adaptation to growth in culture. We have determined the sequence (241 087 bp) of chimpanzee cytomegalovirus (CCMV) and have compared it with published HCMV sequences from the laboratory strains AD169 and Toledo, with the aim of clarifying the gene content of wild-type HCMV. The HCMV and CCMV genomes are moderately diverged and essentially collinear. On the basis of conservation of potential protein-coding regions and other sequence features, we have discounted 51 previously proposed HCMV ORFs, modified the interpretations for 24 (including assignments of multiple exons) and proposed ten novel genes. Several errors were detected in the published HCMV sequences. We presently recognize 165 genes in CCMV and 145 in AD169; this compares with an estimate of 189 unique genes for AD169 made in 1990. Our best estimate for the complement of wild-type HCMV is 164 to 167 genes.