Structural insights into peptidoglycan glycosidase EtgA binding to the inner rod protein EscI of the type III secretion system via a designed EscI-EtgA fusion protein

Bacteria express lytic enzymes such as glycosidases, which have potentially self-destructive peptidoglycan (PG)-degrading activity and, therefore, require careful regulation in bacteria. The PG glycosidase EtgA is regulated by localization to the assembling type III secretion system (T3SS), generating a hole in the PG layer for the T3SS to reach the outer membrane. The EtgA localization was found to be mediated via EtgA interacting with the T3SS inner rod protein EscI. To gain structural insights into the EtgA recognition of EscI, we determined the 2.01 Å resolution structure of an EscI (51-87)-linker-EtgA fusion protein designed based on AlphaFold2 predictions. The structure revealed EscI residues 72-87 forming an α-helix interacting with the backside of EtgA, distant from the active site. EscI residues 56-71 also were found to interact with EtgA, with these residues stretching across the EtgA surface. The ability of the EscI to interact with EtgA was also probed using an EscI peptide. The EscI peptide comprising residues 66-87, slightly larger than the observed EscI α-helix, was shown to bind to EtgA using microscale thermophoresis and thermal shift differential scanning fluorimetry. The EscI peptide also had a two-fold activity-enhancing effect on EtgA, whereas the EscI-EtgA fusion protein enhanced activity over four-fold compared to EtgA. Our studies suggest that EtgA regulation by EscI could be trifold involving protein localization, protein activation, and protein stabilization components. Analysis of the sequence conservation of the EscI EtgA interface residues suggested a possible conservation of such regulation for related proteins from different bacteria.

School age outcome of hospitalisation with respiratory syncytial virus infection of prematurely born infants

BACKGROUND

Hospitalisation due to respiratory syncytial virus (RSV) infection in the first 2 years after birth has been associated with increased healthcare utilisation and associated costs up to 5 years of age in children born prematurely at less than 32 weeks of gestation who developed bronchopulmonary dysplasia (BPD). A study was undertaken to determine whether hospitalisation due to RSV infection in the first 2 years was associated with increased morbidity and lung function abnormalities in such children at school age, and if any effects were influenced by age.

METHODS

Healthcare utilisation and cost of care in years 5-7 were reviewed in 147 children and changes in healthcare utilisation between 0 and 8 years were assessed also using results from two previous studies. At age 8-10 years, 77 children had their lung function assessed and bronchial hyper-responsiveness determined.

RESULTS

Children hospitalised with RSV infection (n = 25) in the first 2 years had a greater cost of care related to outpatient attendance than those with a non-respiratory or no admission (n = 72) when aged 5-7 years (p = 0.008). At 8-10 years of age, children hospitalised with RSV infection (n = 14) had lower forced expiratory volume in 0.75 s (FEV(0.75)) (p = 0.015), FEV(0.75)/forced vital capacity (p = 0.027) and flows at 50% (p = 0.034) and 75% (p = 0.006) of vital capacity than children hospitalised for non-RSV causes (n = 63). Healthcare utilisation decreased with increasing age regardless of RSV hospitalisation status.

CONCLUSIONS

In prematurely born children who had BPD, hospitalisation due to RSV infection in the first 2 years is associated with reduced airway calibre at school age.

Spatial and temporal distribution of bluetongue and its Culicoides vectors in Bulgaria

Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midges was carried out between 2001 and 2003, at 119 sites within a 50 x 50-km grid distributed across Bulgaria, using light trap collections around the time of peak adult midge abundance. Sentinel and ad hoc serum surveillance of hosts susceptible to bluetongue infection was carried out at around 300 sites between 1999 and 2003. Following the initial incursion of bluetongue virus 9 (BTV-9) into Bourgas province in 1999, affecting 85 villages along the southern border, a further 76 villages were affected along the western border in 2001, with outbreaks extending as far north as 43.6 degrees N. The BTV-9 strain in circulation was found to have a low pathogenicity for Bulgarian sheep populations, with less than 2% of susceptible individuals becoming sick and seroconversions detected up to 30 km from recorded outbreaks in the south. The major Old World vector Culicoides imicola Kieffer was not detected among over 70,000 Culicoides identified in summer collections, suggesting that BTV-9 transmission in Bulgaria was primarily carried out by indigenous European vectors. The most likely candidates, the Palaearctic species complexes - the Culicoides obsoletus Meigen and C. pulicaris L. complexes - were widespread and abundant across the whole country. The C. obsoletus complex represented 75% of all individuals trapped in summer and occurred in high catch sizes (up to 15,000 individuals per night) but was not found across all outbreak sites, indicating that both Palearctic complexes probably played a role in transmission. Within the C. pulicaris complex, only C. pulicaris s.s., C. punctatus Meigen and C. newsteadi Austen were sufficiently abundant and prevalent to have been widely involved in transmission, whilst within the C. obsoletus complex most trapped males were C. obsoletus s.s. Adult vectors were found to be largely absent from sites in west Bulgaria for a period of at least 3 months over winter, which, taken along with the spatiotemporal pattern of outbreaks in the region between years, indicates the virus may be overwintering here by an alternative mechanism - either by covert persistence in the vertebrate host or possibly by persistence in larval stages of the vector.

Preschool healthcare utilisation related to home oxygen status

OBJECTIVE

To determine, in prematurely born children who had bronchopulmonary dysplasia (BPD), if respiratory morbidity, healthcare utilisation, and cost of care during the preschool years were influenced by use of supplementary oxygen at home after discharge from the neonatal intensive care unit.

DESIGN

Observational study.

SETTING

Four tertiary neonatal intensive care units.

PATIENTS

190 children, median gestational age 27 weeks (range 22-31), 70 of whom received supplementary oxygen when discharged home.

INTERVENTIONS

Review of hospital and general practitioner records together with a parent completed respiratory questionnaire.

MAIN OUTCOME MEASURES

Healthcare utilisation, cost of care, cough, wheeze, and use of an inhaler.

RESULTS

Seventy children had supplementary oxygen at home (home oxygen group), but only one had a continuous requirement for home oxygen beyond 2 years of age. There were no significant differences in the gestational age or birth weight of the home oxygen group compared with the rest of the cohort. However, between 2 and 4 years of age inclusive, the home oxygen group had more outpatient attendances (p = 0.0021) and specialist attendances (p = 0.0023), and, for respiratory problems, required more prescriptions (p<0.0001). Their total cost of care was higher (p<0.0001). In addition, more of the home oxygen group wheezed more than once a week (p = 0.0486) and were more likely to use an inhaler (p<0.0001).

CONCLUSIONS

Children with BPD who have supplementary oxygen at home after discharge have increased respiratory morbidity and healthcare utilisation in the preschool years.

Health care utilisation of prematurely born, preschool children related to hospitalisation for RSV infection

BACKGROUND

In prematurely born infants with chronic lung disease (CLD), RSV hospitalisation is associated with increased health service utilisation and costs in the first two years after birth.

AIMS

To determine whether RSV hospitalisation in the first two years was associated with chronic respiratory morbidity during the preschool years in prematurely born children who had had CLD.

METHODS

Retrospective review of readmissions, outpatient attendances, and community care in years 2-4 and, at age 5 years, assessment of the children's respiratory status and their health related quality of life. Comparison was made of the results of children who had had at least one hospitalisation in the first two years after birth for RSV infection (RSV group) to those of the rest of the cohort. Participants were 190 of an original cohort of 235 infants with CLD and a median gestational age 27 (range 22-33) weeks.

RESULTS

The 33 children in the RSV group, compared to the rest of the cohort, had a greater duration of hospital stay and more outpatient appointments. The RSV group had required more prescriptions for all treatments and respiratory medications, and more had used an inhaler. The cost of care of the RSV group was higher (median 2630 pounds sterling [4000 Euros, US4800 dollars], range 124-18,091 pounds sterling versus 1360 pounds sterling [2500 Euros, US3000 dollars], range 5-18 929 pounds sterling ) and their health related quality of life was lower.

CONCLUSION

In prematurely born children who had developed CLD, RSV hospitalisation in the first two years was associated with chronic respiratory morbidity and increased cost of care.

Disruption of cleft palate repair following the use of the laryngeal mask airway

A 55-year-old man was admitted for routine examination of ears with insertion of grommets under general anaesthesia. At 2 years of age he had undergone successful repair of cleft lip and palate. A reinforced laryngeal mask airway was employed to maintain the airway. Postoperatively, it was evident he had suffered complete disruption of the soft palate repair, leading to velopharyngeal insufficiency with nasal regurgitation of fluids. We discuss the possible aetiology, having found no such reported injury pattern documented in the literature.

Seasonal abundance of four Culicoides spp. (Diptera: Ceratopogonidae) at Al-Ahsa oasis, Eastern Province, Saudi Arabia

This report constitutes the first study of Culicoides spp. and their seasonal abundance at Al-Ahsa, the largest oasis in the Eastern Province of Saudi Arabia. New Jersey light traps were used to collect the midges at Mastock farm and Al-Mansura village. The mean monthly abundance was determined from October 1993 to October 1994. The mean monthly number per trap reached its minimum value during January 1994, increasing gradually from February to reach its maximum value during September 1994. During the study period, the following species were collected: Culicoides schultzei group (September), non-spotted group of Culicoides (September), Culicoides imicola (May) and Culicoides newstaedi (March). The potential importance of the Culicoides spp. in relation to arboviral activity in Saudi Arabia is discussed.

Home oxygen status and rehospitalisation and primary care requirements of infants with chronic lung disease

OBJECTIVES

To determine whether the rehospitalisation and primary care requirements of infants with chronic lung disease (CLD) during the first two years after birth were influenced by a requirement for supplementary oxygen after discharge from the neonatal intensive care unit.

METHODS

Review of records from both the hospital and general practitioner.

PATIENTS

235 infants, median gestational age 27 (range 22-31) weeks, 88 of whom were receiving supplementary oxygen when discharged home.

RESULTS

Overall, the infants required a median of 2 (range 0-20) admissions per patient, 8 (0-41) outpatient attendances, 13 (0-76) contacts with the general practitioner, and 17 (0-169) consultations with other primary healthcare professionals. The home oxygen patients required significantly more and longer admissions (p < 0.01) and more outpatient attendances (p < 0.05). The total cost of care per infant of the home oxygen group was greater (p < 0.001); this reflected higher costs for hospital stay (p < 0.01), total inpatient care (p < 0.01), and primary care drugs (p < 0.01).

CONCLUSION

Despite routine use of antenatal steroids and postnatal surfactant, certain patients with CLD, particularly those who receive home oxygen treatment, show high rates of utilisation of health service resources after discharge from the neonatal care unit.

Health care utilisation of infants with chronic lung disease, related to hospitalisation for RSV infection

AIMS

To compare the use of health care resources and associated costs between infants with chronic lung disease (CLD) who had or had not an admission with a proven respiratory syncytial virus (RSV) infection.

METHODS

Review of community care, outpatient attendances, and readmissions in the first two years after birth.

PATIENTS

235 infants (median gestational age 27 weeks) evaluated in four groups: 45 infants with a proven RSV admission (RSV proven); 24 with a probable bronchiolitis admission; 60 with other respiratory admissions; and 106 with non-respiratory or no admissions.

RESULTS

The RSV proven compared to the other groups required more frequent and longer admissions to general paediatric wards and intensive care units, more outpatient attendances and GP consultations for respiratory related disorders, and had a higher total cost of care.

CONCLUSION

RSV hospitalisation in patients with CLD is associated with increased health service utilisation and costs in the first two years after birth.

Waterproofing in hypospadias: a refinement of the two-stage reconstruction

A new technique for 'waterproofing' during the second stage of a two-stage hypospadias repair is described. It is simpler and involves less tissue dissection than other waterproofing techniques. The senior author has used it over a period of 6 years as standard practice. The technique has been used in a total of 24 cases, in which the fistula rate was 8% (two cases).

Prevalence of malnutrition on admission to four hospitals in England. The Malnutrition Prevalence Group

AIMS

The primary objective was to estimate prevalence of malnutrition on admission to four hospitals. Secondary objectives included assessing the relationship between nutritional status and length of hospital stay, numbers of new prescriptions, new infections and disease severity.

METHODS

We entered eligible patients according to predefined quotas for elective and emergency admissions to 23 specialties. We measured height, weight, Body Mass Index and anthropometrics, and recorded history of unintentional weight loss. Patients who had lost > or = 10% of their body weight, had a Body Mass Index <20, or had a Body Mass Index <20 with one anthropometric measurement <15th centile were considered malnourished.

RESULTS

Of 1611 eligible patients, 761 did not participate; 269 were too ill; 256 could not be weighed; and 236 refused consent. Eight hundred and fifty were subsequently evaluated. Prevalence of malnutrition on admission was 20%. Length of stay, new prescriptions and infections and disease severity were significantly higher in the malnourished.

CONCLUSIONS

One patient in every five admitted to hospital is malnourished. Although this figure is unacceptably high, it may underestimate true prevalence. Malnutrition was associated with increased length of stay, new prescriptions and infections. Malnutrition may also have contributed to disease severity.

Culicoides biting midges: their role as arbovirus vectors

Culicoides biting midges are among the most abundant of haematophagous insects, and occur throughout most of the inhabited world. Across this broad range they transmit a great number of assorted pathogens of human, and domestic and wild animals, but it is as vectors of arboviruses, and particularly arboviruses of domestic livestock, that they achieve their prime importance. To date, more than 50 such viruses have been isolated from Culicoides spp. and some of these cause diseases of such international significance that they have been allocated Office International des Epizooties (OIE) List A status. Culicoides are world players in the epidemiology of many important arboviral diseases. In this context this paper deals with those aspects of midge biology facilitating disease transmission, describes the factors controlling insect-virus interactions at the individual insect and population level, and illustrates the far-reaching effects that certain components of climate have upon the midges and, hence, transmission potential.

Culicoides in relation to transmission of African horse sickness virus in The Gambia

Twelve light trap collections made near overnight shelters of horses and donkeys in four villages in the Central River Division of The Gambia captured fourteen species of biting midge of the genus Culicoides. Five species new to The Gambia were identified. This brought the number of recognized species of Culicoides (after a revision of C. schultzei) to twenty-nine in The Gambia. Species known or suspected as vectors of African horse sickness virus (AHSV) and bluetongue virus (BTV) comprised 83% of female captures, 65% of captures being C. imicola or its sibling species, C. miombo. Captures of female Culicoides in the late dry season were almost as large as in the early dry season, despite the extreme heat and dryness at this time of the year. Tests on batches of formalin-preserved female midges, using AHSV or BTV antigen capture ELISAs, did not show the presence of any virus amongst 2286 females in 240 aliquots. Nearly all Gambian equines are reportedly seropositive to AHSV and these results suggest that virus challenge from Culicoides vectors may be a factor in the health of Gambian horses and donkeys.

A new species of Culicoides (Diptera, Ceratopogonidae) from southern Italy

Culicoides paolae, a new species of Ceratopogonidae from southern Italy, and which superficially resembles an important vector of animal diseases, is described in both sexes. Its potential veterinary importance is discussed briefly.

The transmission and geographical spread of African horse sickness and bluetongue viruses

African horse sickness virus (AHSV) and bluetongue virus (BTV) are dsRNA viruses within the genus Orbivirus. Both are able to cause non-contagious, infectious arthropod-borne diseases in their respective vertebrate hosts. AHSV infects equines and occasionally dogs, whereas BTV replicates in ruminants. The disease caused by AHSV is usually at its most severe in horses, whereas certain breeds of sheep are particularly sensitive to BTV infection. AHSV is endemic in sub-Saharan Africa but periodically makes brief excursions beyond this area. BTV occurs much more widely and can be found in a band around the World, stretching from approximately 40 degrees N to 35 degrees S. In the wild, both viruses are transmitted between their vertebrate hosts almost entirely via the bites of arthropod vectors, although dogs can occasionally acquire AHSV by eating virus-contaminated meat and BTV may be infrequently transmitted via infected semen or transplacentally. Because of their reliance upon arthropod vectors, BTV and AHSV have a global distribution which is limited not only by the requirement for susceptible vertebrates but also by the necessity for competent arthropod vectors. The major vectors of AHSV and BTV are certain species of Culicoides biting midge, which are true biological vectors but mosquitoes and/or ticks may also be involved to a greater or lesser extent. Until recently, AHSV has apparently been unable to survive beyond its traditional endemic zones in sub-Saharan Africa for more than 2-3 years at most. This has been interpreted as being due to a number of factors, including the absence of a long-term vertebrate reservoir, a lower prevalence, shorter, seasonal incidence and decreased transmission efficiency of the local vectors and also possibly to the effect of control measures (vector abatement, vaccination). The recent outbreaks of African horse sickness (AHS) in Spain, Portugal and Morocco, which persisted for at least 5 years (1987-1991) therefore seem to have established a new pattern in AHSV survival in an epidemic zone. This extended persistence may be due to the 'all-year-round' presence in the area of adult Culicoides imicola, the major AHSV vector. This is basically an Afro-Asiatic species and its continuous presence in parts of Iberia and may be due to some recent moderation in the climate. Further northerly extensions in the range of Culicoides imicola, in response to 'climatic moderation', cannot be ruled out and could substantially increase the area of Europe 'at risk' to AHS.(ABSTRACT TRUNCATED AT 400 WORDS)

A test for blood in haematophagous insects and its application to apparent blood feeding in insectivorous Ceratopogonidae (Diptera)

A method is described to confirm the presence of blood in fixed haematophagous insects. It was used to establish that the dark gut contents of individuals of five genera of insectivorous midges (Ceratopogonidae) was not blood.

Laboratory infection of the mosquito, Toxorhynchites brevipalpis (Diptera, Culicidae), with bluetongue virus

The use of Toxorhynchites brevipalpis as a system for the propagation and isolation of bluetongue virus (BTV) was investigated. BTV was found to multiply in T. brevipalpis after infection by intrathoracic inoculation. Virus concentrations of up to 6.9 log 10 TCID50 per mosquito were found within 7 days of infection and were maintained for at least 6 days. Virus could be detected by an indirect fluorescent antibody test applied to head and thorax tissue smears. These results are comparable to those obtained after inoculation of Culicoides variipennis with the same virus. Comparison of T. brevipalpis and baby hamster kidney (BHK) cells as systems for isolation of BTV showed that there was little difference in sensitivity between the two systems for the stock BTV used. Field samples were not available for test. It was concluded that the use of T. brevipalpis as an isolation system for BTV would have no apparent advantage if BHK cells were available.

Laboratory infection of the sandfly Phlebotomus papatasi Scopoli (Diptera, Psychodidae) with three Phleboviruses

Membrane feeding and intrathoracic inoculation techniques were used to infect Phlebotomus papatasi sandflies with Phlebotomus fever group viruses. Sandflies were orally infected with Pacui virus, and were inoculated with Pacui, Sicilian sandfly fever and Naples sandfly fever viruses. Pacui virus did not multiply in these insects after oral infection, but an 8 X 10(4)-fold increase in virus concentration occurred within four days of intrathoracic inoculation of this virus. The infection rate was 100%. Sicilian sandfly fever virus multiplied in P. papatasi after infection by inoculation, although the yield was lower, a 20-fold increase in the mean virus concentration occurring over eight days. The results for Naples sandfly fever were inconsistent. A 32-fold increase in mean virus concentration was recorded in a small percentage of insects 14 days after inoculation of the virus.

Infection of Israeli culicoides with African horse sickness, blue tongue and akabane viruses

Type 9 African horse sickness virus and type 4 bluetongue virus multiplied to a high titre in an Israeli strain of Culicoides puncticollis after intrathoracic inoculation. Akabane virus persisted for at least 10 days in this midge after intrathoracic inoculation but with little evidence of virus multiplication. All 3 viruses failed to multiply in C. puncticollis after ingestion by the oral route and all were inactivated by 4 days post infection. Five other species of Israeli Culicoides supported multiplication of bluetongue virus after intrathoracic inoculation.

The susceptibility of the sandfly Lutzomyia longipalpis (Lutz & Neiva), diptera, phlebotomidae, to laboratory infection with bluetongue virus

Bluetongue virus multiplied in the sandfly Lutzomyia longipalpis after intrathoracic inoculation but not after oral ingestion of virus. The level of virus multiplication was lower than that observed in similar experiments with the North American vector of bluetongue, Culicoides variipennis. Inoculated sandflies did not transmit virus after 6 to 9 days incubation at 25 degrees C. It is unlikely that L. longipalpis would be important in the maintenance of bluetongue virus in the wild.

The susceptibility of cell lines of Aedes aegypti (Linn.), Aedes albopictus (Skuse) and Aedes pseudoscutellaris (Therobald) to infection with blutongue virus

Bluetongue virus multiplied in cell lines derived from Aedes albopictus and Aedes pseudoscutellaris cells. Virus reached a maximum titre in the Ae. pseudoscutellaris cells three days post inoculation, and in Ae. albopictus cells six days p.i. Virus growth was demonstrated in both cell lines at 27 degrees C and 37 degrees C. Significant titres of virus were still present in the Ae. albopictus cells after five subcultures at 27 degrees C over a period of six weeks. No cytopathic effect was observed in either cell line. A third cell line derived from the mosquito Ae. aegypti did not support the growth of Bluetongue virus.

Rates of infection in, and transmission of, African horse-sickness virus by Aedes aegypti mosquitoes

Very low infection rates (less than 3%) were obtained when Aedes aegypti mosquitoes ingested blood contained 5.8--6.5 log10 MLD50/0.02 ml African horse sickness virus (AHSV). When A. aegypti mosquitoes were inoculated intrathoracically with virus, however, high infection rates were achieved. Mosquitoes infected by inoculum failed to transmit virus to embryonated hens eggs by bite, and virus could not be detected in membrane or blood when inoculated mosquitoes were allowed to engorge on uninfected blood through a chick skin membrane. It was concluded that the mosquito A. aegypti is unlikely to be an effective vector of AHSV.

[Hepatocystis of Malaysia. III.--Development of Hepatocystis brayi in C. nubeculosus and C. variipenis (author's transl)]

The development of H. brayi was followed mainly in C. variipenis up to the stage of mature oocysts. Unlike H. kochi, the oocysts of H. brayi develop at the same site as those of Plasmodium between the epithelium and the basal membrane of the stomach.

The multiplication of African horse-sickness virus in two species of Culicoides (Diptera, Ceratopogonidae)

Type 9 African horse-sickness virus multiplied to a high titre in both Culicoides nubeculosus and C. variipennis after intrathoracic inoculation and in C. variipennis after oral ingestion. The orally infected C. variipennis were able to transmit the virus by biting after 13 days incubation at 26 degrees C but not after 6 days incubation. Intrathoracically inoculated C. variipennis were able to transmit the virus after 4 days incubation. It is suggested that C. variipennis can act as a biological vector of African horse-sickness virus.

The growth of African horse-sickness virus in embryonated hen eggs and the transmission of virus by Culicoides variipennis Coquillett (Diptera, Ceratopogonidae)

Seven-day-old embryonated hen eggs were infected with African Horse Sickness virus by the yolk sac and intravenous routes. Virus reached a high titre in the blood of infected embryos. Culicoides variipennis midges which took a blood meal from infected eggs became infected with virus, and after 7 days at 26 degrees - 27 degrees C transmitted African Horse Sickness virus to uninfected eggs. C. variipennis may therefore be considered a biological vector of African Horse Sickness virus in the laboratory.

Observations on the biology of Culicoides impunctatus Goetgh. (Dipt., Ceratopogonidae) in southern England

Catches of Culicoides spp. in a Surrey copse in 1967–69 showed the univoltine C. impunctatus Goetgh. to be dominant. This species reached peak numbers from late May to early June, when nulliparous females were commonly seen at rest on tree trunks. Proterandry was marked in catches from light-traps but not apparent in those from emergence traps or taken at rest. Biting was most frequent 1–2 h before sunset; many bites did not result in a blood-meal. Females taken at rest and from emergence traps could complete their ovarian cycle without a blood-meal, most eggs being matured by the former; midges taken biting matured the fewest eggs but could not do so without a blood-meal. Large full fat-bodies were an indication of nulliparity. It was concluded that C. impunctatus can develop the first egg-batch autogenously, and that the resting habits and responses of females to light and human bait change subsequent to the laying of the first batch of eggs.