Search

An Uhthoff-like phenomenon was recently observed in a patient with clinically definite MS who experienced transient dysphonia brought on by exertion and relieved by cooling. The patient's dysphonia was felt to be related to intermittent temperature-dependent conduction block associated with a demyelinating plaque in the region of the left nucleus ambiguus. We have termed the patient's intermittent dysphonia 'laryngeal Uhthoff's phenomenon'.

The phosphoprotein (P) gene of two subgroup A strains of avian pneumovirus comprised 855 nucleotides containing only one substantial open reading frame encoding a protein of 278 amino acids, with a predicted M(r) of 30,323. In vitro translation of P mRNA in a wheat germ system resulted in the synthesis of two polypeptides of M(r) 35,000. Comparison of the deduced P protein sequence with that of the known mammalian pneumoviruses revealed overall amino acid identities ranging from 31 to 34.5%, suggesting a distant relationship. However, there was a much higher identity (63.2-68.4%) in a region of 57 residues, which included a heptad repeat sequence.

Respiratory syncytial virus (RSV) is the major viral cause of lower respiratory tract disease (bronchiolitis and pneumonia) in babies and infants. Infections with the virus occur as annual winter epidemics in temperate climates, placing considerable pressure on the provision of hospital beds. The virus is unusual in that it can reinfect individuals and it can infect babies despite the presence of maternal antibody. RSV has a negative sense nonsegmented RNA genome and as such is liable to high levels of mutation. This paper describes methods developed to determine the degree of genetic variability of the virus both during individual epidemics and worldwide. It is necessary for these methods to be quick, easy and cheap so that large numbers of samples can be analysed readily. They are based on extraction of viral RNA directly from clinical samples or from viral cultures, reverse transcription of the viral RNA, and then amplification of selected regions of the genome by the polymerase chain reaction (PCR). PCR products are then analysed by restriction mapping, or, if necessary, direct nucleotide sequencing. In this way isolates of RSV have been shown to fall into a number of genotypes, with epidemics being made up of cocirculating genotypes whose relative proportions vary with each epidemic. An understanding of the molecular epidemiology of this important human pathogen will be of significance in the search for an effective vaccine.

Six different genotypes (designated lineages SHL1-6) of human respiratory syncytial (RS) virus have been defined by partial nucleotide sequence analysis of the variable SH and the hypervariable G membrane protein genes, and by restriction fragment analysis of the conserved N protein gene of viruses isolated in south Birmingham. Viruses of very similar genotype appear to be present worldwide at the present time. We have determined the nucleotide sequences of the fusion protein genes of five viruses isolated in south Birmingham in the same year, but belonging to different lineages, and have compared them with the sequences of four subgroup A viruses isolated at earlier times from diverse localities. The sequence diversity of the F genes of these five viruses, as measured by nucleotide (94.5-98.5%) and inferred amino acid (97.0-99.3%) identifies, is comparable with that of the nine subgroup A viruses considered as a whole. No sequence changes occur in any of the sites of known epitopes. Comparison of the nine subgroup A sequences with the published sequences of a subgroup B strain and three bovine RS viruses confirms that the F protein sequences are most divergent in the F2 region.

The epidemiological characteristics and relationship between respiratory syncytial virus (RSV) subgroup and virulence during an outbreak of RSV infection occurring in Southeast Texas in the winter season 1991/92 are described. Fifty-two infants and children were diagnosed with RSV infection by rapid viral antigen detection and/or viral isolation. Subgrouping of the isolates was carried out using 11-monoclonal anti-bodies. Ten isolates were found to be subgroup B, and 8 isolates were subgroup A. The subgroup B strains showed 3 different patterns of reaction with monoclonal antibodies; one of these subgroups was examined further by restriction analysis of parts of its nucleocapsid and attachment protein genes. The peak of RSV outbreak was in December 1991. Both subtypes A and B circulated simultaneously in the same territory, and caused lower respiratory tract infections in similar proportions. The more frequent occurrence of the B subgroup and the diversity of its simultaneously circulated RSV strains have made this outbreak unusual.

A relationship between epilepsy and damage to mesial temporal structures has long been recognized. Recent advances have clarified somewhat the issue of whether the pathological changes seen in mesial temporal sclerosis represent the cause or the effect of seizures. This paper reviews mesial temporal sclerosis from an historical perspective and summarizes recent developments in the fields of excitotoxicity, selective vulnerability, and synaptic reorganization as they pertain to the pathogenesis of mesial temporal sclerosis.

The authors categorized 125 spinal lesions in cancer patients and 127 lesions in patients with back pain according to their location in the vertebra on single photon emission computed tomographic (SPECT) images. Forty-four lesions were metastases, all in patients with known malignancy. Lesions in the apophyseal joints were all benign. Lesions manifesting as abnormal uptake projecting beyond the vertebral body surface were osteophytes. Thirty-seven percent of the lesions detected in cancer patients were categorized in either of these two benign categories. Lesions showing focal or diffuse uptake in the body were usually benign (96% and 87%, respectively). Lesions showing uptake in the body and pedicle were usually metastases (83%). When abnormal uptake was seen in both the body and posterior elements but with an intervening normal pedicle, benign disease was the most common cause (93%). It was concluded that the location of lesions on tomographic images provides useful information for differentiation between malignant and benign lesions in the vertebrae.

The immunogenicity and pathogenicity of a strain of respiratory syncytial (RS) virus modified by sequential induction of three temperature-sensitive (ts) mutations have been evaluated by intranasal administration to 22 adult volunteers. This modified virus, a triple ts mutant designated ts1C, was derived from a double mutant ts1B evaluated in a previous trial. The original isolate (strain RSS-2) and all its derivatives were propagated throughout in human diploid cells in a specially assigned laboratory. The triple mutant ts1C is unable to multiply in MRC-5 cells at 37 degrees C and above. Following nasal administration of ts1C, immune responses were observed in volunteers with low pre-existing neutralizing antibody titres. The ability of mutant ts1C to induce upper respiratory tract disease in adults was greatly diminished in comparison with the non-ts wild-type virus, but not markedly more so than a previously tested double ts mutant (ts1B) which replicates at 37 degrees C. Mutant ts1C, however, may have greater potential as a live vaccine in view of its inherently greater genetic stability.

Respiratory syncytial virus strains (subgroup A) isolated from around the world during the period 1988-1991 were analysed to determine their relatedness. Analysis was by restriction mapping and nucleotide sequencing following amplification of selected regions of the virus genome by polymerase chain reaction (PCR). Twenty-three viruses of subgroup A isolated from cities in temperate regions of the Northern and Southern hemispheres and the tropics during the period 1988-1991 fell into distinct groupings closely related to four of the six lineages defined in analysis of recurrent epidemics within the same city (Birmingham, UK) during the same period. These observations confirm that multiple lineages of RS virus co-circulate locally, and show that very similar viruses are present simultaneously in widely separated countries.

A consensus sequence for the P protein gene of the RSN-2 strain of respiratory syncytial (RS) virus was obtained by PCR amplification of cDNA obtained by reverse transcription. This established that the extent of sequence variation between two P genes of strains of antigenic subtype B is similar to that among A strains, confirming the conservation of P genes within subtypes and the divergence of the two antigenic subtypes of RS virus. The P protein of RS virus exhibits anomalous electrophoretic mobility with respect to its molecular weight. In vitro transcription and translation of RSN-2 strain cDNA possessing single point mutations revealed that substitutions involving charged amino acids in the carboxy-terminal region had a marked effect on the electrophoretic mobility of the P protein.

We have previously demonstrated that a progestin-stimulatory factor(s) (PSF) is present in the supernate of concanavalin A-activated rat splenocytes. In the absence of FSH, PSF evokes dose-dependent increases in both progesterone and 20 alpha-hydroxypregn-4-en-3-one (20 alpha-OH-P) production by undifferentiated rat granulosa cells while basal estrogen production is unaffected. Because splenocytes are composed predominantly of T and B lymphocytes, we sought to determine if PSF production is restricted to one of these specific cell types. To accomplish this, dispersed splenocytes were prepared from the spleens of adult female rats. Macrophages were removed by standard adherence procedures, and highly enriched populations of T and B lymphocytes were obtained by negative selection panning utilizing monoclonal antibodies to T and B lymphocytes. Purity of the T- and B-cell populations (typically greater than 85-95%) was assessed by single-color flow cytometry. Enriched populations of T cells, B cells, or unseparated lymphocytes were then seeded into tissue culture flasks and stimulated with 2.5 micrograms/ml concanavalin A. Following a 48-h incubation at 37 degrees C, cytokine-rich fractions were prepared from the conditioned medium of these cultures by ammonium sulfate fractionation. The presence of PSF was assessed by the ability of the resulting fractions to specifically stimulate progestin production by undifferentiated rat granulosa cells in vitro. Granulosa cells were treated with increasing doses (ranging from 0-30% v/v) of supernatants from cultures of T cells, B cells, or unseparated splenocytes for 48 h. Media were removed and progesterone, 20 alpha-OH-P, and estrogen levels were quantified by RIA.(ABSTRACT TRUNCATED AT 250 WORDS)

We have cloned eight intergenic regions from the Pneumovirus pneumonia virus of mice that link the nine small and medium sized genes previously described (Chambers et al., 1990). The nucleotide sequences of the clones confirm the locations of these genes and their mRNA transcripts in the viral genome. The intergenic regions vary in size from 2-56 nucleotides and show only faint homology to each other or to their analogues in respiratory syncytial virus. Sequence alignments suggest that the location of the transcriptional start site for the mRNA encoding the major nucleocapsid protein of pneumonia virus of mice and respiratory syncytial virus may have altered during virus evolution by gain or loss of a transcriptional start signal.

The virulence and immunogenicity of a wild-type respiratory syncytial (RS) virus together with four temperature sensitive (ts) mutants derived from this isolate were tested by intranasal inoculation into adult volunteers. Resistance to challenge correlated with neutralizing antibody titres in nasal secretions and to a lesser extent in serum. All ts mutants were reduced in virulence. Mutant ts1B caused mild or asymptomatic infections yet induced antibody responses comparable with wild-type RS virus. Ts1B might be developed further to produce a live-virus vaccine.

A simple and rapid procedure for determining the genotypes of viruses has been applied to analysis of genome subunit reassortment in heterologous crosses of Batai virus, Bunyamwera virus, and Maguari virus, three members of the Bunyamwera serogroup of bunyaviruses. The procedure for determining genotype made use of specific molecular probes to identify the parental origin of the L and M RNA subunits. Complementary DNA copies of the three RNA segments of Bunyamwera virus were prepared by reverse transcription using synthetic oligonucleotide primers for first and second strand synthesis. The cDNA transcripts were inserted into a pBR322 vector and gene-specific probes prepared from nick-translated plasmid DNA. L and M gene-specific probes were identified which could unequivocally discriminate Bunyamwera virus genome subunits in a dot-hybridization test using cytoplasmic RNA extracts immobilised on nitrocellulose filters. None of the S gene-specific probes were sufficiently discriminatory for use in this test. Instead the parental origin of the S RNA subunit was inferred from the electrophoretic mobility of the virion N protein. It was observed that reassortment did not occur at random in heterologous crosses of is mutants of the three viruses, and only the M RNA subunit appeared to segregate freely. However, unrestricted reassortment was observed when recombinant viruses with nonhomologous subunit combinations were used as the parental viruses. It was concluded, therefore, that restriction was mediated at the gene product level and that nonrandom reassortment was not due to incompatibility of genome subunits.

A simple method of the so-called pinpoint hybridization for the detection of genome RNAs and individual fragments of genome of the Bunyamwera family viruses is described. The method established linking of 2 out of 3 fragments of genome RNA of different members of the family.

The bee venom peptide melittin activated the virion transcriptase activity of three vesiculoviruses with preservation of virion structure. The kinetics of RNA synthesis were similar to those observed with purified transcribing nucleoprotein (TNP) preparations. Six temperature-sensitive host range (tdCE) mutants of Chandipura virus displayed 1.7- to 5.5-fold greater efficiencies of transcription at 39 degrees with melittin-permeabilized virions in comparison with TNP preparations. Comparative study of other host range mutants (tdCE3) and tsB1) of vesicular stomatitis virus (VSV) New Jersey and a thermosensitive polymerase mutant (tsG114) of VSV Indiana suggested that the enhanced transcription at 39 degrees associated with melittin-activated tdCE mutants was due to the retention of host factors in the virions.

Single temperature-sensitive (ts) mutants of a subgroup A strain of respiratory syncytial (RS) virus whose multiplication is restricted at 39 degrees C in MRC-6 cells and double ts mutants that are restricted at 38 degrees C, were obtained following mutagenesis using 5-fluorouracil and acridine-like compounds. Isolation and propagation of the parental RSS-2 strain of RS virus and its derived ts mutants were carried out entirely in MRC-5 human diploid cells. The immunogenicity and disease-producing ability of four of these mutants and the parental unmodified strain have been assessed by intranasal administration into groups of about 20 adult volunteers. The results of these trials indicate that the capacity of the parental RSS-2 strain to produce upper respiratory tract infection in adults was not diminished by limited propagation in MRC-5 cells. The mutants on the other hand were impaired in this respect to varying extents. The double mutant tslB in particular has characteristics that suggest that it may be suitable for further development as a live RS virus vaccine. It retained near normal immunogenicity and replicative ability in the upper respiratory tract, while exhibiting greatly reduced disease-producing potential.

The complete nucleotide sequence of the Bunyamwera virus M RNA segment was determined from four overlapping cDNA clones and by primer extension. The RNA segment is 4458 bases in length, and encodes a single gene product in the viral complementary RNA. The predicted protein is 1433 amino acids long (mol wt 162,065), contains four potential glycosylation sites, and is relatively cysteine rich. It is presumed that the three proteins G1, G2, and NSM which have been mapped to the M RNA segment are synthesized as a precursor polyprotein which is subsequently proteolytically cleaved. A putative hydrophobic signal sequence at the amino terminus and a hydrophobic anchor sequence at the carboxy terminus of the predicted protein have been identified, in addition to internal regions of hydrophobicity of unknown function. The nucleotide and amino acid sequences of the Bunyamwera virus M segment have been compared with those of the snowshoe hare virus M segment (Y. Eshita and D. H. L. Bishop, Virology 137, 227-240, 1984). Common features include the overall architecture of the RNAs, single cysteine-rich primary gene products, and conservation of hydrophobic domains in the gene products. When aligned the amino acid sequences are 43% homologous, and 66 of 70 cysteine residues can be matched. The evolutionary significance of these findings is discussed.

The family Rhabdoviridae comprises approximately 75 viruses infecting vertebrates, invertebrates and plants. The main characteristics of the member viruses are: (i) the viruses infecting vertebrates and invertebrates are bullet-shaped and the viruses infecting plants are usually bacilliform; (ii) the viruses have particle lengths varying from 130 to 380 nm and widths varying from 60 to 95 nm; (iii) the viruses possess unit-membrane envelopes from which protrude spikes 5 to 10 nm long; (iv) the viruses have precisely coiled helical nuecleocapsids with a diameter of approx. 50 nm; (v) most of the viruses which have been studied contain 5 proteins; the prototype, vesicular stomatitis virus, contains proteins designated L (large), G (glycoprotein), N (nucleoprotein), NS (nonstructural) and M (matrix); N or NS is phosphorylated in most members which have been studied; (vi) the viruses contain single-stranded RNA which is transcribed into several messenger RNA species with sizes corresponding to the structural proteins; (vii) the nucleocapsid contains the RNA-dependent RNA polymerase and is infectious; and (viii) many of the viruses produce morphologically distinct defective-interfering (T) particles.

Sleep logs over 9 months document the delayed sleep phase of a healthy male student at Oxford. The lack of any imperative zeitgebers also permits the rest-activity cycle to exhibit very long (circabidian) days similar to those seen under conditions of temporal isolation. No psychopathology or subjective distress was associated with this unusual rest-activity cycle: It was a preferred life-style.

Many of the common respiratory illnesses of infancy and childhood are caused by viruses of the Paramyxoviridae family, in particular measles virus, respiratory syncytial (RS) virus and parainfluenzavirus type 3 (PI3). Effective measles vaccine was developed by classical methods, but these same methods have failed to provide vaccines to control RS and PI3 virus infections. The WHO Programme for Vaccine Development was initiated in 1983 to encourage the application of the new biotechnologies to continuing problems, such as the acute virus-induced respiratory diseases of childhood. At a meeting of research workers held in July 1986 under the auspices of this programme, renewed optimism was expressed concerning the prospects for immunoprophylaxis of RS virus-induced disease. Animal models are now available for evaluation of the immunogenic potential of candidate vaccines. Vaccinia/RS recombinant viruses have been produced which have allowed the immunogenic properties of individual RS virus proteins to be defined. Complete protection without the exacerbation of disease, which earlier had accompanied the use of formalin-inactivated vaccines, has been achieved in animals immunized with vaccinia virus recombinants expressing the F protein; partial protection was obtained using G protein gene vectors. PI3 appears to be an inherently stable virus and evidence from animal experiments suggests that bovine PI3 might be suitable for use as a live vaccine in man.