X Chromosome Domain Architecture Regulates Caenorhabditis elegans Lifespan but Not Dosage Compensation

Mechanisms establishing higher-order chromosome structures and their roles in gene regulation are elusive. We analyzed chromosome architecture during nematode X chromosome dosage compensation, which represses transcription via a dosage-compensation condensin complex (DCC) that binds hermaphrodite Xs and establishes megabase-sized topologically associating domains (TADs). We show that DCC binding at high-occupancy sites (rex sites) defines eight TAD boundaries. Single rex deletions disrupted boundaries, and single insertions created new boundaries, demonstrating that a rex site is necessary and sufficient to define DCC-dependent boundary locations. Deleting eight rex sites (8rexΔ) recapitulated TAD structure of DCC mutants, permitting analysis when chromosome-wide domain architecture was disrupted but most DCC binding remained. 8rexΔ animals exhibited no changes in X expression and lacked dosage-compensation mutant phenotypes. Hence, TAD boundaries are neither the cause nor the consequence of DCC-mediated gene repression. Abrogating TAD structure did, however, reduce thermotolerance, accelerate aging, and shorten lifespan, implicating chromosome architecture in stress responses and aging.

Dynamic Control of Chromosome Topology and Gene Expression by a Chromatin Modification

The function of chromatin modification in establishing higher-order chromosome structure during gene regulation has been elusive. We dissected the machinery and mechanism underlying the enrichment of histone modification H4K20me1 on hermaphrodite X chromosomes during Caenorhabditis elegans dosage compensation and discovered a key role for H4K20me1 in regulating X-chromosome topology and chromosome-wide gene expression. Structural and functional analysis of the dosage compensation complex (DCC) subunit DPY-21 revealed a novel Jumonji C demethylase subfamily that converts H4K20me2 to H4K20me1 in worms and mammals. Inactivation of demethylase activity in vivo by genome editing eliminated H4K20me1 enrichment on X chromosomes of somatic cells, increased X-linked gene expression, reduced X-chromosome compaction, and disrupted X-chromosome conformation by diminishing the formation of topologically associated domains. H4K20me1 is also enriched on the inactive X of female mice, making our studies directly relevant to mammalian development. Unexpectedly, DPY-21 also associates specifically with autosomes of nematode germ cells in a DCC-independent manner to enrich H4K20me1 and trigger chromosome compaction. Thus, DPY-21 is an adaptable chromatin regulator. Its H4K20me2 demethylase activity can be harnessed during development for distinct biological functions by targeting it to diverse genomic locations through different mechanisms. In both somatic cells and germ cells, H4K20me1 enrichment modulates three-dimensional chromosome architecture, demonstrating the direct link between chromatin modification and higher-order chromosome structure.

Dynamic Control of X Chromosome Conformation and Repression by a Histone H4K20 Demethylase

Chromatin modification and higher-order chromosome structure play key roles in gene regulation, but their functional interplay in controlling gene expression is elusive. We have discovered the machinery and mechanism underlying the dynamic enrichment of histone modification H4K20me1 on hermaphrodite X chromosomes during C. elegans dosage compensation and demonstrated H4K20me1's pivotal role in regulating higher-order chromosome structure and X-chromosome-wide gene expression. The structure and the activity of the dosage compensation complex (DCC) subunit DPY-21 define a Jumonji demethylase subfamily that converts H4K20me2 to H4K20me1 in worms and mammals. Selective inactivation of demethylase activity eliminates H4K20me1 enrichment in somatic cells, elevates X-linked gene expression, reduces X chromosome compaction, and disrupts X chromosome conformation by diminishing the formation of topologically associating domains (TADs). Unexpectedly, DPY-21 also associates with autosomes of germ cells in a DCC-independent manner to enrich H4K20me1 and trigger chromosome compaction. Our findings demonstrate the direct link between chromatin modification and higher-order chromosome structure in long-range regulation of gene expression.

Rev: beyond nuclear export

Rev remains a hot topic. In this review, we revisit the insights that have been gained into the control of gene expression by the retroviral protein Rev and speculate on where current research is leading. We outline what is known about the role of Rev in translation and encapsidation and how these are linked to its more traditional role of nuclear export, underlining the multifaceted nature of this small viral protein. We discuss what more is to be learned in these fields and why continuing research on these 116 amino acids and understanding their function is still important in devising methods to combat AIDS.

An investigation into the source and spread of foot and mouth disease virus from a wildlife conservancy in Zimbabwe

African buffalo were introduced into a wildlife conservancy in the southeast of Zimbabwe in an effortto increase the conservancy's economic viability, which is primarily based on eco-tourism. The buffalo were infected with SAT serotypes (SAT-1, SAT-2 and SAT-3) of foot and mouth disease (FMD) virus, and in order to isolate the conservancy and prevent the transmission of FMD to adjacent populations of domestic livestock, the conservancy was surrounded by a double-fence system, 1.8 m in height. The intention was to prevent the movement of both wildlife and domestic animals across the perimeter. However, two years after the buffalo were introduced, FMD occurred in cattle farmed just outside of the conservancy. Using serological and molecular diagnostic tests, epidemiological investigations showed that it was most likely that antelope (impala or kudu), infected through contact with the buffalo herd within the conservancy, had jumped over the fence and transmitted the virus to the cattle.

A model-based method for identifying species hybrids using multilocus genetic data

We present a statistical method for identifying species hybrids using data on multiple, unlinked markers. The method does not require that allele frequencies be known in the parental species nor that separate, pure samples of the parental species be available. The method is suitable for both markers with fixed allelic differences between the species and markers without fixed differences. The probability model used is one in which parentals and various classes of hybrids (F(1)'s, F(2)'s, and various backcrosses) form a mixture from which the sample is drawn. Using the framework of Bayesian model-based clustering allows us to compute, by Markov chain Monte Carlo, the posterior probability that each individual belongs to each of the distinct hybrid classes. We demonstrate the method on allozyme data from two species of hybridizing trout, as well as on two simulated data sets.

Genetic heterogeneity of SAT-1 type foot-and-mouth disease viruses in southern Africa

Genetic relationships of 50 SAT-1 type foot-and-mouth disease viruses were determined by phylogenetic analysis of an homologous 417 nucleotide region encoding the C-terminal half of the VP1 gene and part of the 2A segment. Viruses obtained from persistently-infected African buffalo populations were selected in order to assess the regional genetic variation within the host species and compared with ten viruses recovered from recent and historical cases of clinical infection. Phylogenetic reconstructions identified three independently evolving buffalo virus lineages within southern Africa, that correspond with the following discrete geographic localities: (1) South Africa and southern Zimbabwe, (2) Namibia, Botswana and western Zimbabwe, and (3) Zambia, Malawi and northern Zimbabwe. This strict geographic grouping of viruses derived from buffalo was shown to be useful for determining the origin of recent SAT-1 epizootics in livestock. The percentage of conserved amino acid sites across the 50 SAT-1 viruses compared in this study was 50%. Most mutations were clustered within three discrete hypervariable regions, which coincide with the immunogenic G-H loop, H-1 loop and C-terminus region of the protein. Despite the high levels of variation within the primary sequence, secondary structural features appear to be conserved.

Monte Carlo evaluation of the likelihood for N(e) from temporally spaced samples

A population's effective size is an important quantity for conservation and management. The effective size may be estimated from the change of allele frequencies observed in temporally spaced genetic samples taken from the population. Though moment-based estimators exist, recently Williamson and Slatkin demonstrated the advantages of a maximum-likelihood approach that they applied to data on diallelic genetic markers. Their computational methods, however, do not extend to data on multiallelic markers, because in such cases exact evaluation of the likelihood is impossible, requiring an intractable sum over latent variables. We present a Monte Carlo approach to compute the likelihood with data on multiallelic markers. So as to be computationally efficient, our approach relies on an importance-sampling distribution constructed by a forward-backward method. We describe the Monte Carlo formulation and the importance-sampling function and then demonstrate their use on both simulated and real datasets.

The foot-and-mouth disease risk posed by African buffalo within wildlife conservancies to the cattle industry of Zimbabwe

Quantification of the risk that African buffalo (Syncerus caffer) (isolated within wildlife conservancies in Zimbabwe by a double fencing system) would infect cattle outside the conservancies with foot-and-mouth disease (FMD) virus was assessed by scenario-pathway analysis. Of the five scenarios considered, the greatest annual risk (1:5000) for cattle would be from antelope jumping over the outer perimeter fence of the conservancy and infecting cattle on the outside. The other transmission scenarios (including air-borne transmission) had a FMD risk that was low to very low. Risk management would include means to prevent the escape of antelope from the conservancies and restriction of cattle density in the proximity of the perimeter fence.

Typing of pestiviruses from eland in Zimbabwe

Pestiviruses were isolated from three eland (Taurotragus oryx) in Zimbabwe. The viruses were characterised by typing with monoclonal antibodies and by partial genetic sequencing. All were similar to bovine viral diarrhea viruses commonly isolated from cattle. This suggests that bovine viral diarrhea virus can spread from cattle to eland.

Susceptibility and carrier status of impala, sable, and tsessebe for Cowdria ruminantium infection (heartwater)

Three species of wild African ruminants, impala (Aepyceros melampus), sable (Hippotragus equinus), and tsessebe (Damaliscus lunatus), were experimentally inoculated with in vitro culture-derived Cowdria ruminantium organisms, the tick-borne causative agent of heartwater in domestic ruminants, to determine their susceptibility to infection. No clinical disease was observed in any of the ruminants. However, C. ruminantium was detected in the sable by the transmission of heartwater to susceptible sheep, through the tick vector Amblyomma hebraeum, at 10 and 37 days postinfection (PI). Attempts to detect infection in the impala and tsessebe by tick transmission at 54 days PI failed. The impala and tsessebe were reinoculated with C. ruminantium organisms at 146 days after the first inoculation; however, a tick transmission attempt at 66 days after the reinoculation also failed. Seroconversion, as detected by immunoblotting, was demonstrated in the sable and the tsessebe but not in the impala. The results demonstrate that sable can be carriers of C. ruminantium. The susceptibility of tsessebe and impala, however, remains undetermined.

The prevalence of antibody to the viruses of bovine virus diarrhoea, bovine herpes virus 1, rift valley fever, ephemeral fever and bluetongue and to Leptospira sp in free-ranging wildlife in Zimbabwe

The prevalence of antibody to the viruses of bovine virus diarrhoea (BVD), bovine herpes virus typel (BHV1), rift valley fever (RVF), bovine ephemeral fever (BEF) and bluetongue (BT) and to Leptospira sp. was determined in wildlife populations in Zimbabwe. Evidence of infection with BVD virus was found in 14 of the 16 species examined but was greatest in eland Taurotragus oryx, nyala Tragelaphus angasi and bushbuck Tragelaphus scriptus. Persistent infection with BVD virus was found in 1 of 303 antibody-free eland but not in the smaller sample of 102 antibody-free buffalo Syncerus caffer. Antibody to BHV1 was widespread, being found in 10 of 16 species with the highest prevalence being in buffalo and eland. Antibody to RVF was most prevalent in black rhino Diceros bicornis and white rhino Ceratotherium simum, buffalo and waterbuck Kobus ellipsiprymnus. Both BEF and BT were widespread in all the species examined. Evidence of infection with Leptospira sp. was found in 7 species. Infections were due to up to 3 of 8 different serovars.

Demonstration of a carrier state for Cowdria ruminantium in wild ruminants from Africa

Four wild African ruminants, eland (Taurotragus oryx), giraffe (Giraffa camelopardalis), kudu (Tragephalus strepsiceros strepsiceros), and blue wildebeest (Connochaetes taurinus), were experimentally infected with the rickettsia Cowdria ruminantium, the tickborne agent causing heartwater in domestic ruminants. The infections were established, and C. ruminantium was transmitted to naive small ruminants by the vector Amblyomma hebraeum when transmission attempts were made at days 128 (eland and wildebeest), 85 (giraffe), and 24 (kudu) post infection. These wild ruminants, which are natural hosts for the tick vector, and which commonly occur within heartwater-endemic areas of Africa, are likely to play important roles in the epidemiology of heartwater as reservoirs of C. ruminantium infection. These findings also demonstrate that considerable risks are associated with the translocation of wild ruminants from heartwater-endemic areas to heartwater-free areas such as the northern and southern American mainlands, which have large populations of susceptible domestic and wild ruminant hosts and tick species that are capable of transmitting the disease.

African swine fever virus infection of the bushpig (Potamochoerus porcus) and its significance in the epidemiology of the disease

Warthog (Phacochoerus aethiopicus), giant forest hog (Hylochoerus meinertzhageni) and bushpig (Potamochoerus porcus) are known to be susceptible to infection with African swine fever (ASF) virus. Little however, is known about the ecology of the disease in the bushpig. This study has shown that the bushpig remains viraemic for between 35 and 91 days following infection during which time it is able to infect the tick vector O. moubata. These ticks were able to transmit the disease to pigs. The virus persists in the lymphatic tissues for less than 34 weeks. Bushpigs infected with LIL 20/l virus but not VIC T90/l virus transmitted infection to in-contact pigs. Infected domestic pigs did not transmit the infection to in-contact bushpigs. ASF virus was able to replicate in in vitro cultures of bushpig leucocytes and endothelial cells. Recovered bushpigs could be reinfected with some strains of virus but not others. While it has been demonstrated that bushpigs remain carriers of ASFV following infection a complete understanding of their significance in the epidemiology of the disease awaits further investigations of their association with O. moubata.

A differential screen for ligand-regulated genes: identification of HoxA10 as a target of vitamin D3 induction in myeloid leukemic cells

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the hormonal ligand for vitamin D3, is a potent inducer of myeloid-leukemic-cell differentiation. Such cells differentiate exclusively into monocytes/macrophages in response to this ligand. Since 1,25(OH)2D3 transduces its hormone signal through the vitamin D3 receptor (VDR), a ligand-modulated transcription factor and member of the nuclear hormone receptor superfamily, we sought to identify direct VDR target genes induced during this differentiation process. To do so, we applied a modified differential screen with a nascent-RNA purification strategy using biases for immediate-early-response genes induced by 1,25(OH)2D3 in the myelomonocytic cell line U937. Using this screen, we had previously identified p21Waf1/Cip1 as a gene transcriptionally induced by 1,25(OH)2D3 and demonstrated that this induction facilitates the differentiation of U937 cells into monocytes/macrophages (24). Here, we describe in detail our differential screen strategy and the identification and isolation of 20 1,25(OH)2D3-inducible genes or unknown cDNAs by means of this screen. One gene newly identified as a target of VDR regulation in myeloid cells is the homeobox HoxA10 gene. HoxA10 protein may act as a general regulator of cell growth, since overexpression of HoxA10 facilitated the differentiation of U937 cells into monocytes/macrophages independent of 1,25(OH)2D3 and acted to strongly inhibit the growth of the breast cancer cell line MCF-7 by arresting these cells in G1.

Growth of Cowdria ruminantium in tissue culture endothelial cell lines from wild African mammals

Endothelial cell cultures were established from several wild African mammalian species. Long-term cultures were established from three ruminants, stable antelope (Hippotragus niger), buffalo (Syncerus caffer), and eland (Tragelaphus oryx), and from an omnivore, the bushpig (Potamochoerus porcus). Cowdria ruminanntium was isolated from plasma of clinically affected animals in these four cell lines and in bovine endothelial cells used routinely for C. ruminantium propagation. Nineteen different strains of C. ruminantium from Africa and the Caribbean region were grown and maintained in these cell lines and their growth was comparable with growth in the bovine endothelial cells. The role of sable antelope, eland, and bushpigs in the epidemiology of heartwater is unknown. However, these results extend the number of cell lines that can be used to isolate and grow C. ruminantium.

Jejunal phlebectasia presenting with massive gastrointestinal hemorrhage

Our case report illustrates the clinicopathologic features of this rare vascular lesion and highlights that phlebectasia should be considered as a cause of gastrointestinal bleeding of undetermined etiology in adult patients.

Epidemiology of invasive Haemophilus influenzae infections in England and Wales in the pre-vaccination era (1990-2)

This survey defined the pattern of invasive Haemophilus influenzae infections during 1990-2 in six regions in England and Wales during the pre-vaccination era providing a baseline against which any changes in patterns of disease due to the introduction of the Haemophilus influenzae type b vaccination programme can be monitored. A total of 946 cases of invasive Haemophilus influenzae were recorded during the survey period of which almost 90% were due to type b and most of the remainder were non-typeable. Type b infections occurred predominantly in children less than 5 years of age (88%) with the highest attack rate in male infants in the 6-11 month age group. Diagnostic category varied with both age and serotype; meningitis was the commonest presentation overall but pneumonia and bacteraemia were more common in adults and non-typeable isolates. Mortality was highest in neonates and the elderly (over 65 years of age) who were more likely to have an underlying predisposing condition than older children and adults. Children under 5 years of age had a higher case fatality rate for non-typeable than for type b infections. Ampicillin resistance was 15% and there were no cefotaxime resistant type b isolates.

Morbillivirus infections in wildlife (in relation to their population biology and disease control in domestic animals)

The three members of the morbillivirus genus that infect wildlife in ecosystems where domestic animals occur are rinderpest, peste des petits ruminants (PPR) and canine distemper. Data on the relative susceptibility of species of the Order Artiodactyla for rinderpest have been obtained from historical records of outbreaks. Rinderpest in wildlife has only occurred in equatorial and eastern Africa since the great pandemic of 1889-1897. The distributions, densities and population dynamics of susceptible species in this region are described. There has only been one recorded outbreak of PPR in wildlife but the possibility of its occurrence in the future now that it is present in many parts of west and eastern Africa is discussed. Wild carnivora are not likely to be important maintenance hosts for canine distemper but the disease is of significance in free-ranging carnivores and particularly in small populations of endangered susceptible wildlife species. It is also of great significance in zoo populations.

Outer membrane protein profiling to distinguish between Haemophilus aegyptius and non-capsulate Haemophilus influenzae biotype III

Outer membrane protein profiling was used to assist in determining the identity of an isolate of Haemophilus spp. that was presumptively identified as non-capsulate Haemophilus influenzae biotype III. The possibility that this strain was in fact Haemophilus aegyptius was queried because of clinical information and the source of the isolate. Sodium dodecyl-sulphate polyacrylamide gel electrophoresis was used to establish the identity of the isolate as non-capsulate H. influenzae biotype III and no H. aegyptius. Generally, protein profiling compared very favourably with other standard tests for identifying H. aegyptius: the method was easily and rapidly performed and gave an unequivocal result.

Natural transmission of foot-and-mouth disease virus from African buffalo (Syncerus caffer) to cattle in a wildlife area of Zimbabwe

An outbreak of foot-and-mouth disease (FMD) occurred during April 1991 in a trypanosomiasis sentinel cattle herd by the Rifa River to the east of Lake Kariba, Zimbabwe. Despite the cattle having been vaccinated biannually for the previous five years the disease was severe. The viruses isolated from the affected animals were typed as FMD virus type SAT 1. Free-living African buffalo (Syncerus caffer) which had been using the same watering place as the affected cattle were sampled and FMD type SAT 1 virus was isolated. Partial nucleotide sequencing of the gene coding for the capsid protein 1D (VP1) of one of the viruses isolated from cattle and two of the viruses isolated from buffalo demonstrated a close relationship between the three viruses. Since no other cattle were present in the area and no outbreaks of SAT 1 had occurred in Zimbabwe since 1989, it was concluded that the disease had been transmitted from buffalo to cattle.

The role of wild animals, other than buffalo, in the current epidemiology of foot-and-mouth disease in Zimbabwe

Between 1989 and 1992, 7970 wild ungulates, comprising 14 different species, were tested for antibodies to types SAT 1, SAT 2 and SAT 3 foot-and-mouth disease (FMD) virus. Of these 1.2% were found to be positive and these included impala (Aepyceros melampus), eland (Taurotragus oryx), waterbuck (Kobus ellipsiprymnus) and sable (Hippotragus niger). All the positive animals were either from the wildlife areas where buffalo (Syncerus caffer) occur or from ranches where clinical FMD had occurred in cattle. The role of these animal species in the current epidemiology of FMD in Zimbabwe is discussed.

Polymerase chain reaction-based strain characterization of noncapsulate Haemophilus influenzae

A polymerase chain reaction-based typing method for noncapsulate Haemophilus influenzae was developed. Randomly amplified polymorphic DNA fingerprints were generated from boiled supernatants prepared directly from bacterial colonies without the need for DNA extraction. The technique was applied to isolates obtained during putative outbreaks of chest infection and validated by comparison with sodium dodecyl sulfatepolyacrylamide gel electrophoresis analysis of outer membrane protein-enriched preparations and rRNA gene restriction analysis. There was complete concordance between the three techniques. The results show that randomly amplified polymorphic DNA analysis provides a highly discriminatory method of characterizing strains of noncapsulate H. influenzae which is eminently suitable as an epidemiological tool for the rapid investigation of outbreaks of infection.

Efficacy of psyllium in reducing serum cholesterol levels in hypercholesterolemic patients on high- or low-fat diets

OBJECTIVES

To determine the efficacy of psyllium in reducing serum cholesterol levels in patients on high- or low-fat diets.

DESIGN

Double-blind, placebo-controlled, 16-week parallel trial. The study included an 8-week baseline period and an 8-week treatment period.

PATIENTS

Healthy men and women, 21 to 70 years old, with primary hypercholesterolemia (total serum cholesterol > or = 5.7 mmol/L [220 mg/dL]). Thirty-seven participants followed a high-fat diet and 81 participants followed a low-fat diet.

INTERVENTION

Participants were randomly assigned to either psyllium, 5.1 g twice a day, or placebo.

MEASUREMENTS

Fasting lipid and apolipoprotein concentrations, including direct low-density lipoprotein (LDL) cholesterol quantification; nutritional analyses of 4 days of 7-day food records to monitor dietary compliance; and physical examinations, clinical chemistry and hematologic studies, and urinalysis to assess treatment safety.

MAIN RESULTS

Psyllium recipients in both the high- and low-fat diet groups showed small but significant decreases (P < 0.05) in total cholesterol and low-density lipoprotein (LDL) cholesterol levels. Total cholesterol and LDL cholesterol levels decreased 5.8% and 7.2%, respectively, in psyllium recipients on high-fat diets and 4.2% and 6.4%, respectively, in psyllium recipients on low-fat diets. No significant difference was seen in LDL cholesterol response when psyllium recipients on low- and high-fat diets were compared (P > 0.2). No significant reductions in lipid levels were observed in placebo recipients. Based on the National Cholesterol Education Program LDL cholesterol classification system, 39% of the psyllium recipients improved in LDL cholesterol classification (P < 0.0001) compared with 20.3% of placebo recipients (P > 0.2).

CONCLUSIONS

Psyllium produces a modest but significant improvement in total cholesterol and LDL cholesterol levels in persons on either low-fat or high-fat diets. Psyllium, when added to a prescribed low-fat diet, may obviate the need for typical lipid-lowering medications or may prove to be a valuable adjunct to other treatments in patients with moderately elevated LDL cholesterol levels.

Invasive Haemophilus influenzae type b disease in the Oxford region (1985-91)

For a seven year period (1985-91) clinical and epidemiological data were prospectively collected on children aged < 10 years with microbiologically confirmed invasive Haemophilus influenzae type b infection in the Oxford region to study the epidemiology of the disease and determine the potential impact of early primary immunisation in infants. Computer records of primary immunisations given to these cases were retrospectively analysed and, where necessary, hospital and general practitioner records were searched to determine the immunisation history. Over the seven year period, 416 cases of invasive H influenzae type b disease were reported. Widescale immunisation against H influenzae type b began in 1991 as part of a regional trial. The estimated annual incidence for invasive disease between 1985 and 1990 was 35.5 cases per 100,000 children aged less than 5 years; for H influenzae type b meningitis it was 25.1 per 100,000 children aged less than 5 years. The cumulative risks for invasive disease and meningitis by the fifth birthday were one in 560 and one in 800 respectively. The majority of disease (71%) occurred in children less than 2 years of age with the peak monthly incidences at 6 and 7 months of age. The overall mortality was 4.3% and 50% of these deaths occurred suddenly. Most (91%) of the children had received at least one primary immunisation against diphtheria, tetanus, and pertussis before H influenzae type b infection and there was only one case of parental refusal of immunisation. None had received H influenzae type b immunisation. Given a vaccine uptake of 90% by 5 months of age it is estimated that at least 82% of the H influenzae type b infections could have been prevented. Extrapolated nationally, 1150 cases of infection and 50 deaths could be prevented each year by routine primary immunisation.

Population-based study of non-typable Haemophilus influenzae invasive disease in children and neonates

The extent of non-capsulate, non-serotypable Haemophilus influenzae (NST) as a cause of serious invasive disease in children has not been fully defined. We describe the epidemiology of these childhood infections from cases identified during a continuing prospective survey of invasive H influenzae disease in the Oxford region, UK. 408 strains of H influenzae were isolated from cases of invasive disease. 383 (94%) were H influenzae type b (Hib), 24 (6%) were NST strains, and 1 was a type f strain. 3 of the NST strains were non-capsulate type b mutants (b-), but the remaining 21 strains were from the phylogenetically distinct and heterogeneous population of non-capsulate H influenzae (NC). 10 of the NC strains were isolated from neonates with sepsis; crude mortality rate was 40%, with an incidence of 4.6 cases per 100,000 livebirths. 11 NC strains were isolated from children after the neonatal period and under 10 years of age, 4 (36%) of which had severe, unrelated, predisposing conditions. The incidence of NC invasive diseases in these children was 0.5 per 100,000 per year. The attributable mortality for these infections was 10%. Infections due to these H influenzae strains are, after the implementation of Hib vaccines, likely to persist and represent a substantial proportion of the serious infections caused by this species.

Molecular epidemiology of unrelated clusters of multiresistant strains of Haemophilus influenzae

Three epidemiologically unrelated clusters of Haemophilus influenzae resistant to ampicillin, chloramphenicol, and tetracycline were studied. The biotypes and cell-envelope protein patterns were determined for 17 nonencapsulated strains, 6 from Dundee and 11 from Cheltenham, and for 6 type b encapsulated strains from Guildford. After mobilization by conjugation, large 32- to 36-MDa plasmids were purified from all the strains. The restriction fragment patterns of the plasmids were determined by ethidium bromide staining of digested purified plasmid or by Southern hybridization of digested total cellular DNA of the parent strains, probed with purified plasmid. Evidence is presented for a chromosomal location of the plasmids in the parent strains, the spread in nature of a plasmid between distinguishable strains of H. influenzae, the person-to-person spread of a strain within a cluster, and a high degree of sequence homology between distinguishable plasmids, implying their close relatedness.

The detection of African horse sickness virus antigens and antibodies in young Equidae

Four ponies were each inoculated with a different serotype of African horse sickness virus (AHSV) which had been passaged through cell culture in order to achieve attenuation. Three of the ponies died suddenly after showing mild clinical signs, the fourth pony remained clinically normal and was killed at day 38. Infectious AHSV was isolated from blood samples collected at intervals from all four ponies. Positive antigen ELISA reactions were only observed with blood samples from two of the ponies on the two days preceding death. Specific AHSV antibodies were detected by ELISA in serum samples from the other two ponies although one eventually died. African horse sickness viral antigens were detected by ELISA in post-mortem tissue samples collected from all four ponies. No infectious virus could be detected in tissue samples taken post-mortem from the pony which survived African horse sickness (AHS) infection. In the event of a suspected outbreak of AHS it is recommended that sera and heparinized blood should be tested for specific antibodies and AHSV antigen respectively. When available, post-mortem tissues, including spleen, heart, lung and liver, should also be tested for AHSV antigen. Although the ELISA used for the detection of AHSV antigen is highly sensitive and specific, negative ELISA results should be confirmed by virus isolation attempts.

Antibodies to some pathogenic agents in free-living wild species in Tanzania

A total of 535 sera from eight species of wildlife were collected from different game areas in Tanzania between 1987 and 1989. These sera were tested for antibodies against foot-and-mouth disease, bovine herpes virus types 1 and 2, lumpy skin disease, bovine viral diarrhoea, Akabane, bovine ephemeral fever, bluetongue, enzootic bovine leucosis, African horse sickness and African swine fever viruses and Brucella abortus based on the expected species susceptibility. Sera from buffalo Syncerus caffer, wildebeest Connochaetes taurinus and topi Damaliscus korrigum contained antibodies against the majority of the pathogens tested. Antibodies to fewer pathogens were detected in sera from the other species. No antibodies to lumpy skin disease virus were detected in any of the sera examined. African horse sickness antibodies were detected in sera from Zebra and African swine fever antibodies were detected in wart hog. The occurrence of antibodies to these agents suggests that wild species act as reservoirs of infection for some of these pathogens. However, until the susceptibility of individual species is proven by isolation of the aetiological agents their role must remain speculative.

A serological survey of rinderpest antibody in wildlife and sheep and goats in northern Tanzania

An extensive serological survey for rinderpest antibody in wildlife, principally buffalo (Syncerus caffer), and sheep and goats has been undertaken in the previously endemic region of Northern Tanzania to determine whether or not the virus has continued to cycle in susceptible species since the last occurrence of overt disease in 1982. The results show that infection but not disease has occurred at least until 1987 in buffalo in parts of the Serengeti National Park but not in the other game areas of Tanzania where samples were taken. Sero-positive sheep and goats were widely distributed and have been found in 10 of the 14 districts sampled but there have been no reports of disease. These findings bring into question the possibility of eradicating the disease from Africa and continuous annual monitoring of this and other similar ecological zones will be required.

Cross-infection by non-encapsulated Haemophilus influenzae

From October, 1988, to January, 1989, 18 patients admitted to an acute medical chest ward were infected with an ampicillin-resistant beta-lactamase-producing strain of Haemophilus influenzae. All 18 isolates were non-encapsulated strains of biotype III and showed identical cell envelope protein profiles, as judged by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The organism was not isolated from repeated environmental samples but there was strong circumstantial evidence that a spirometer was a common iatrogenic source of the cross-infection.

A competitive ELISA for the detection of group-specific antibodies to African horse sickness virus

A competition enzyme-linked immunosorbent assay (ELISA) has been developed for the rapid identification and quantification of antibodies against African horse sickness (AHS) in sera from solipeds. The data showed the ELISA to be sensitive, specific and reliable. More than 1600 sera from 37 different countries were examined and results compared with those obtained by agar gel immuno-diffusion (AGID) tests. In no case did any of 775 sera from countries where AHS has never been reported and where AHS vaccines are not used, record an ELISA titre greater than 4. A titre equal to or greater than 8 was considered positive. Using this criterion, 96.3% of sera tested in both assays were in agreement. Doubtful results by AGID (1.7%) were clearly defined in terms of positivity and negativity by ELISA. This ELISA is suited for the rapid laboratory confirmation of AHS and should be considered as a replacement for the traditional AGID test.

Observations on the pathogenicity for sheep and goats and the transmissibility of the strain of virus isolated during the rinderpest outbreak in Sri Lanka in 1987

The pathogenicity for sheep and goats of the virus strain that caused acute rinderpest in cattle and domestic buffalo in Sri Lanka after an interval of over 40 years has been examined. The results show that it can cause overt clinical disease in goats, but only mild or unapparent infection in sheep. The disease was transmitted from infected sheep to in-contact susceptible sheep and calves.

Immune response and protection of cattle and pigs generated by a vaccinia virus recombinant expressing the F protein of rinderpest virus

The immune response of cattle and pigs to a vaccinia recombinant virus containing the fusion (F) protein gene of rinderpest virus was examined. Half the cattle and all the pigs gave humoral response to primary vaccination and all the cattle gave an anamnestic response to a second vaccination 28 days after the primary vaccination. All the cattle after a single or secondary vaccination were completely protected clinically after exposure to a lethal dose of the Saudi 1/81 strain of virus. Prior vaccination with another TK- vaccinia recombinant (VVCAT) suppressed, but did not abrogate, the immune response to the rinderpest F recombinant. The pigs gave a humoral immune response in the absence of any local reaction at the site of vaccination.

Arachidonic acid metabolites in the pathophysiology of thrombocytopenia and haemorrhage in acute African swine fever

Changes in the production of proaggregatory (thromboxane A2 and prostaglandin E2) and antiaggregatory (prostacyclin) prostaglandins by blood platelets, macrophages and endothelial cells during acute African swine fever caused by both a highly virulent virus and a less virulent virus were studied. No impairment in thromboxane A2 release by either platelets or macrophages could be detected but prostacyclin production by the endothelium was impaired. There was also a significant increase in prostaglandin E2 release by macrophages at the time when thrombocytopenia was most marked. However, the early event that causes primary aggregation remains obscure.

Vertebral artery trauma: transcatheter embolization

Injuries of the vertebral arteries in four patients were treated by transcatheter embolization. Embolotherapy was performed after incomplete or unsuccessful surgery in three of the patients and as a preventive measure in lieu of surgery in the fourth patient. All procedures were successful and without complications. An injured vertebral artery is usually extremely difficult to approach surgically, but because of extensive collateral blood supply it is usually expendable; therefore, it becomes an inviting target for management by interventional angiographic techniques. Embolotherapy of an injured vertebral artery is easier, faster, and safer than its surgical ligation and, therefore, decidedly superior. With few exceptions, embolotherapy should be considered the preferred method in the management of vertebral artery trauma.

Potential for the transmission of foot-and-mouth disease virus from African buffalo (Syncerus caffer) to cattle

Foot-and-mouth disease viruses of types SAT 1 and SAT 2 isolated from diseased cattle and carrier buffalo, either on the same farm or in the same ecological area within a short time of each other, were compared by T1 oligonucleotide mapping. No similarity was observed between the maps obtained, indicating that the different populations of virus were unique to each species and that no interspecies transmission had occurred.

Weight loss improves lipoprotein lipid profiles in patients with hypercholesterolemia

Risk for coronary artery disease is directly related to plasma levels of total and low-density lipoprotein (LDL) cholesterol and inversely related to high-density lipoprotein (HDL) cholesterol concentrations. Weight gain in four of five patients with hypercholesterolemia given colestipol for 37 +/- 6 months was associated with a decrease in HDL cholesterol levels and an increase in LDL cholesterol/HDL cholesterol ratios. Weight loss (-7 +/- 2 kg) in these five and two other patients given colestipol increased plasma HDL cholesterol (17% +/- 6%) and lowered total cholesterol (-8% +/- 1%), LDL cholesterol (-13% +/- 2%), and total triglyceride (-20% +/- 4%) concentrations. However, in six patients given treatment by diet alone (no colestipol), comparable weight loss (-6 +/- 1 kg) did not alter plasma HDL cholesterol or total triglyceride concentrations, but reduced total cholesterol (-9% +/- 3%) and LDL cholesterol (-11% +/- 3%) levels. These results suggest that weight reduction increases plasma HDL cholesterol levels only in those patients with hypercholesterolemia given colestipol but not in those given treatment by diet alone. Nevertheless, the effects of weight loss on plasma total cholesterol and LDL cholesterol levels were comparable in the two groups of patients. This indicates that weight loss is an important adjunct in the treatment of moderately obese patients with hypercholesterolemia and may reduce their risk for coronary artery disease by improving their lipid profiles.

Observations on the stability of foot and mouth disease vaccine antigens

The 146S particle of the foot and mouth disease virus which is used as a vaccine antigen was found to be relatively stable when stored for prolonged periods at 4 degrees C. However, stored antigens of virus strains of the SAT serotypes but not of a virus strain of the type O serotype became less thermostable at 37 degrees C following 4 degrees C storage. Vaccines returned from the field 10 months after they were made were shown to contain significant amounts of 146S antigen of the O, A, SAT 1 and SAT 2 serotypes. Vaccine containing antigens at least 6 months old was shown to stimulate an acceptable immune response.