Identification of the murine cytomegalovirus glycoprotein B gene and its expression by recombinant vaccinia virus

The gene encoding glycoprotein B (gB) of murine cytomegalovirus (MCMV) strain Smith was identified, sequenced, and expressed by recombinant vaccinia virus. The gB gene was found adjacent to the polymerase gene, as it is in the genome of human cytomegalovirus (HCMV). The open reading frame consists of 2,784 nucleotides capable of encoding a protein of 928 amino acids. Comparison with gB homologs of other herpesviruses revealed a high degree of homology. The similarity between the MCMV gB and the HCMV gB is most prominent, since 45% of the amino acids are identical. In addition, all cysteine residues are at homologous positions, indicating a similar tertiary structure of the two proteins. In contrast to HCMV, the MCMV gB mRNA is a true late transcript. A recombinant vaccinia virus expressing the MCMV gB gene has been constructed (Vac-gB). Antibodies raised against the Vac-gB recombinant precipitated proteins of 130, 105, and 52 kDa from MCMV-infected cells. The identity of the MCMV gB with the major envelope glycoprotein of MCMV described by Loh et al. was shown (L. C. Loh, N. Balachandran, and L. F. Qualtiere, Virology 166:206-216, 1988). Immunization of mice with the Vac-gB recombinant gave rise to neutralizing antibodies.

Structural organization, expression, and functional characterization of the murine cytomegalovirus immediate-early gene 3

We have previously defined ie3 as a coding region located downstream of the ie1 gene which gives rise to a 2.75-kb immediate-early (IE) transcript. Here we describe the structural organization of the ie3 gene, the amino acid sequence of the gene product, and some of the functional properties of the protein. The 2.75-kb ie3 mRNA is generated by splicing and is composed of four exons. The first three exons, of 300, 111, and 191 nucleotides (nt), are shared with the ie1 mRNA and are spliced to exon 5, which is located downstream of the fourth exon used by the ie1 mRNA. Exon 5 starts 28 nt downstream of the 3' end of the ie1 mRNA and has a length of 1,701 nt. The IE3 protein contains 611 amino acids, the first 99 of which are shared with the ie1 product pp89. The IE3 protein expressed at IE times has a relative mobility of 88 kDa in gels, and a mobility shift to 90 kDa during the early phase is indicative of posttranslational modification. Sequence comparison reveals significant homology of the exon 5-encoded amino acid sequence with the respective sequence of UL 122, a component of the IE1-IE2 complex of human cytomegalovirus (HCMV). This homology is also apparent at the functional level. The IE3 protein is a strong transcriptional activator of the murine cytomegalovirus (MCMV) e1 promoter and shows an autoregulatory function by repression of the MCMV ie1/ie3 promoter. The high degree of conservation between the MCMV ie3 and HCMV IE2 genes and their products with regard to gene structure, amino acid sequence, and protein functions suggests that these genes play a comparable role in the transcriptional control of the two cytomegaloviruses.

Molecular requirements for the mu-induced light chain gene rearrangement in pre-B cells

During B cell differentiation rearrangement of immunoglobulin (Ig) genes is partially regulated by the Ig proteins. Rearrangement of heavy (H) chain genes is inhibited, whilst that of light (L) chain genes is induced by the membrane form of the mu H chain. In order to analyse additional structural requirements of mu induced L chain gene rearrangement we transfected wild-type mu and mutant mu constructs lacking functional exons encoding the first or second constant domains into Abelson murine leukemia virus (AMuLV) transformed pre-B cells. All mu chains are expressed on the surface of the pre-B cell and all associate with omega and iota, two proteins forming a surrogate light chain, necessary for mu membrane expression. Nevertheless, only wild-type mu and not the mutant mu proteins promote L gene rearrangement. A heterodimer of proteins with Mr of 33 kd and 36 kd was found associated with wild-type but not with the mutant mu proteins. Continuous presence of mu is required for L chain gene recombination since loss of mu stopped and readdition of mu started L gene rearrangement. We propose that the protein complex composed of mu and the 33 kd/36 kd protein heterodimer is responsible for the activation of the L chain gene locus and its rearrangement.

The core histone-binding region of the murine cytomegalovirus 89K immediate early protein

The gene regulatory immediate early protein, pp89, of murine cytomegalovirus interacts with both DNA-associated and isolated histones in vitro. We characterized the histone-binding region of pp89 and its cellular localization during cell division to examine the possible interaction between pp89 and chromatin. pp89 expressed constitutively in cell line BALB/c 3T3 IE1 does not interact with condensed chromatin. As observed in infected cells, pp89 is localized within the nucleus of cells during interphase but spreads throughout the cell plasma following degradation of the nuclear membrane during early mitosis. In late telophase, pp89 is reorganized within the nucleus. Analysis of pp89 deletion mutants and of fragments generated by cleavage at pH 2.5 revealed that the regions responsible for association with histone are located between amino acids 71 and 415, and are not identical with the domain that shows homology to histone H2B or the highly acidic carboxy-terminal region. A potential gene-activating role of the high affinity of pp89 for isolated histones and the low affinity for DNA-associated histones is discussed.

Clinical characteristics of patients with repeated systemic reactions during specific immunotherapy with hymenoptera venoms. A retrospective study

In general, specific immunotherapy with hymenoptera venoms can be considered as safe, but occasionally there are patients who cannot reach the maintenance dose due to repeated systemic reactions (RSR) or who suffer from RSR during maintenance therapy. In a multicenter retrospective study comprising seven departments in Germany, Austria and Switzerland 23 patients with RSR were reported from approximately 3000 patients treated with hymenoptera venoms (bee and wasp venom to approximately equivalent frequency). From these, 22 were allergic to bee venom and only one to vespid venom. In general the clinical symptoms of RSR were milder than the initial reaction. But 4/23 (18%) exhibited cardiovascular reactions up to full shock. Neither anamnestic details, reactivity in skin tests or in vitro tests revealed a special pattern of patients with RSR. In some patients, however, an extremely high reactivity in the skin test was found and may indicate the possibility of further RSR.

Prevalence of acute mountain sickness in the Swiss Alps

OBJECTIVE

To assess the prevalence of symptoms and signs of acute mountain sickness of the Swiss Alps.

DESIGN

A study using an interview and clinical examination in a representative population of mountaineers. Positive symptoms and signs were assigned scores to quantify the severity of acute mountain sickness.

SETTING

Four huts in the Swiss Alps at 2850 m, 3050 m, 3650 m, and 4559 m.

SUBJECTS

466 Climbers, mostly recreational: 47 at 2850 m, 128 at 3050 m, 82 at 3650, and 209 at 4559 m.

RESULTS

In all, 117 of the subjects were entirely free of symptoms and clinical signs of acute mountain sickness; 191 had one or two symptoms and signs; and 158 had more than two. Those with more than two symptoms and signs were defined as suffering from acute mountain sickness. At 4559 m 11 climbers presented with high altitude pulmonary oedema or cerebral oedema, or both. Men and women were equally affected. The prevalence of acute mountain sickness correlated with altitude: it was 9% at 2850 m, 13% at 3050 m, 34% at 3650 m, and 53% at 4559 m. The most frequent symptoms and signs were insomnia, headache, peripheral oedema, and scanty pulmonary rales. Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales were associated with other symptoms and signs and therefore characteristic of acute mountain sickness.

CONCLUSION

Acute mountain sickness is not an uncommon disease at moderately high altitude--that is, above 2800 m. Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales indicate severe acute mountain sickness, and subjects who suffer these should immediately descend to lower altitudes.

Characterization of the murine cytomegalovirus early transcription unit e1 that is induced by immediate-early proteins

The regulation of murine cytomegalovirus early (E) gene expression was studied in the cell line B25, which is stably transfected with the immediate-early ie1/ie3 gene complex. Infection of B25 cells in the presence of the protein synthesis inhibitor cycloheximide resulted in the expression of some E genes, whereas for the expression of other E genes prior protein synthesis was still mandatory, thus showing differences in the expression requirements of individual E genes. Transcription unit e1, a member of the E genes induced by immediate-early products of the ie1/ie3 gene complex, was characterized. It is located between map units 0.709 and 0.721 of the genome of murine cytomegalovirus strain Smith. A 2.6-kilobase RNA specified in this region is spliced from three exons of 912, 177, and 1,007 or 1,020 nucleotides, which are separated by introns of 93 and 326 nucleotides. The second AUG located in the first exon 119 nucleotides downstream of the 5' cap site is followed by an open reading frame of 990 nucleotides. The predicted polypeptide of 330 amino acids has a calculated molecular mass of 36.4 kilodaltons. Transfection with e1 revealed three antigenically related proteins of 36, 37, and 38 kilodaltons; these proteins probably represent differently modified forms of the predicted protein. These three proteins are phosphorylated and are associated with intranuclear inclusion bodies. A 33-kilodalton protein also derived from e1 was identified as a product of nonspliced transcripts. Comparison of amino acid sequences revealed homology between the murine cytomegalovirus transcription unit e1 and a human cytomegalovirus E transcription unit.

CT findings in subarachnoidal haemorrhage (SAH). A retrospective study of 138 patients

In a retrospective study the CT scans of 138 patients with the clinical diagnosis of SAH were reviewed. CT was highly sensitive in detecting blood in the CSF spaces during the 3 days following SAH, with decreasing accuracy correlated to the time interval between SAH and CT examination. Clinical state on admission and CT findings were closely related, as were the localisation of detectable blood and the site of source of bleeding. Whereas blood clots in the basal cisterns, above the convexities, and intracerebrally, as well as the finding of a brain oedema, were significantly correlated to the time of survival, hydrocephalus and ventricular haemorrhage had no bearing on the survival time.

Molecular analysis of herpesviral gene products recognized by protective cytolytic T lymphocytes

The infection of the mouse with murine cytomegalovirus (MCMV) served as a model system to understand the biology of human CMV infection. The contribution of cytolytic T lymphocytes (CTL) to the recovery from infection was studied. Protection against lethal MCMV disease could be conferred on immunodepleted hosts by adoptive transfer of lymphocytes. The antiviral effect was mediated by specifically sensitized T lymphocytes of the CD8+ subset. These cells limited viral spread, prevented tissue destruction by viral cytopathic effects, and protected from lethal disease. Transferred cells have protective therapeutic function even when the virus has already colonized host tissues. CD8+ cells do not require the contribution of CD4+ cells for in vivo function. Selective expression of immediate-early (IE) phase genes in target cells allowed the detection of the immunodominant IE antigen recognized by CTL. The major IE gene ieI encodes a non-structural viral phosphoprotein, pp89, which resides in the nucleus of infected cells where it acts as transcriptional regulator. Expression of gene ieI is under temporal control, and membrane presentation of the protein domain detected by CTL is down-regulated by MCMV early-phase products. A recombinant vaccinia virus expressing gene ieI induced immunity that protected mice against a subsequent challenge with a lethal dose of MCMV. The protective effect was entirely mediated by CD8+ T lymphocytes. Thus, an experimental vaccine expressing a single nonstructural herpesvirus protein can induce a protective cellular immune response.

[Borderline infarcts with symptomatic epilepsy--clinical and electroencephalographic findings]

In 6 patients with repeating seizures early after stroke periodic lateralizing epileptiform discharges were detected in EEG. Computed tomography scans showed border-zone infarctions including the territories of the middle and the posterior cerebral artery in four patients; sonographic and angiographic findings were suspicious of embolic stroke in five cases. Seizures and EEG-discharges resolved during a short term treatment with anticonvulsants. In contrast to cerebral infarctions of other regions with comparable EEG-changes long term treatment was necessary in none of the patients.

Investigations on the role of ethylene in phytochrome-mediated photomorphogenesis : I. Anthocyanin Synthesis

The etiolating, intact mustard (Sinapis alba L.) seedling exhibits a distinct temporal pattern of ethylene production. Light, operating through phytochrome, increases the rate of ethylene production without changing the pattern. Ethylene production of the isolated plant parts (segments), added together, exceed the production of the intact system even if the wound effect is taken into account. There is no significant light effect on ethylene production of the segments. Phytochrome-mediated anthocyanin synthesis in the cotyledons is inhibited by ethylene. The responsiveness towards ethylene of the anthocyanin producing metabolic chain is decreased by phytochrome. As anthocyanin synthesis is only partly inhibited under saturating ethylene concentrations in the atmosphere around the seedlings (100 μl l(-1)), a twofactor analysis becomes feasible. This analysis leads to the result that phytochrome and ethylene show multiplicative behavior, meaning that phytochrome and ethylene act on the same metabolic sequence (leading to anthocyanin) but independently of each other, and at different sites. Therefore, the hypothesis that ethylene mediates the action of phytochrome in anthocyanin synthesis and photomorphogenesis in general appears to be inapplicable.

Investigations on the role of ethylene in phytochrome-mediated photomorphogenesis : II. Enzyme levels and chlorophyll synthesis

The concept (Burg, 1973) that ethylene mediates the action of phytochrome in seedling photomorphogenesis was tested in the intact mustard (Sinapis alba L.) seedling. The effect of exogenous ethylene (100 μl l(-1)) on five distinct, phytochrome-mediated photoresponses of the cotyledons was investigated. It was found that anthocyanin contents (see Bühler et al., 1978) and phenylalanine ammonia-lyase levels (EC 4.3.1.5) are strongly reduced by ethylene while the capacity of chlorophyll synthesis is considerably enhanced. Levels of glutathione reductase (EC 1.6.4.2) and pools of photoconvertible protochlorophyll(ide) are unaffected by ethylene. It is concluded that these findings are incompatible with the idea that ethylene plays the role of a mediator in phytochrome-induced photomorphogenesis.