Molecular and epidemiological aspects of Streptococcus pyogenes disease in Finland: Severe infections and bacterial, non-necrotizing cellulitis

Streptococcus pyogenes (group A streptococcus) is an important human pathogen, causing a wide array of infections ranging in severity. The majority of S. pyogenes infections are mild upper respiratory tract or skin infections. Severe, invasive infections, such as bacteraemia, are relatively rare, but constitute a major global burden with a high mortality. Certain streptococcal types are associated with a more severe disease and higher mortality. Bacterial, non-necrotizing cellulitis and erysipelas are localised infections of the skin, and although they are usually not life-threatening, they have a tendency to recur and therefore cause substantial morbidity. Despite several efforts aimed at developing an effective and safe vaccine against S. pyogenes infections, no vaccine is yet available. In this study, the epidemiology of invasive S. pyogenes infections in Finland was described over a decade of national, population-based surveillance. Recent trends in incidence, outcome and bacterial types were investigated. The beta-haemolytic streptococci causing cellulitis and erysipelas infections in Finland were studied in a case-control study. Bacterial isolates were characterised using both conventional and molecular typing methods, such as the emm typing, which is the most widely used typing method for beta-haemolytic streptococci. The incidence of invasive S. pyogenes disease has had an increasing trend during the past ten years in Finland, especially from 2006 onwards. Age- and sex-specific differences in the incidence rate were identified, with men having a higher incidence than women, especially among persons aged 45-64 years. In contrast, more infections occurred in women aged 25-34 years than men. Seasonal patterns with occasional peaks during the midsummer and midwinter were observed. Differences in the predisposing factors and underlying conditions of patients may contribute to these distinctions. Case fatality associated with invasive S. pyogenes infections peaked in 2005 (12%) but remained at a reasonably low level (8% overall during 2004-2007) compared to that of other developed countries (mostly exceeding 10%). Changes in the prevalent emm types were associated with the observed increases in incidence and case fatality. In the case-control study, acute bacterial non-necrotizing cellulitis was caused predominantly by Streptococcus dysgalactiae subsp. equisimilis, instead of S. pyogenes. The recurrent nature of cellulitis became evident. This study adds to our understanding of S. pyogenes infections in Finland and provides a basis for comparison to other countries and future trends. emm type surveillance and outcome analyses remain important for detecting such changes in type distribution that might lead to increases in incidence and case fatality. Bacterial characterisation serves as a basis for disease pathogenesis studies and vaccine development.

Campylobacter Infections of Domestic Origin in Finland

Campylobacter jejuni and C. coli are the leading causes of human bacterial gastroenteritis in developed countries. Most human Campylobacter infections are sporadic and a seasonal peak in the distribution of infections can be seen in the summer months in several countries, including Finland. A variety of risk factors for Campylobacter infections have been identified; handling and eating poultry, drinking unpasteurized milk, contact with domestic animals, and travelling abroad. However, the relative importance of the different risk factors in sporadic cases of Campylobacter infection remains unknown. In most cases, the infection is self-limiting and no specific treatment is required. Campylobacter enteritis can cause a wide range of complications, including reactive arthritis (ReA) that is reported in 1-5% of the cases. Seven clinical microbiology laboratories serving different geographical areas of Finland, participated in this multi-centre study, conducted during a seasonal peak in 2002. In a matched case-control study, domestically-acquired sporadic Campylobacter infections from three geographical areas were collected. The final study comprised 100 cases and 137 controls. Risk factors for sporadic domestically-acquired Campylobacter infections were identified on the basis of a questionnaire; swimming in natural waters was found to be a novel risk factor for Campylobacter infection. Other independent risk factors were tasting or eating raw or undercooked meat and drinking untreated water from a dug well. The role of bacterial strain and host characteristics are not fully understood in Campylobacter infections. Exposure factors, demographical characteristics, and the serotype of the Campylobacter isolate may affect the severity of the enteritis. This cross-sectional study comprised 114 patients with C. jejuni enteritis, diagnosed in three clinical microbiology laboratories; most of the patients had participated in the previous case-control study. Swimming was associated with age ≤ 5 years and serotype Pen 6,7 was found significantly more often among patients reporting swimming. The geographical distribution among serotypes varied; serotype Pen 4-complex appeared more often in patients from urban areas and serotype Pen 21 among patients from more rural areas. Thus, risk factors and sources of infection for C. jejuni infection may vary among individuals depending on age and geographical location. The in vitro susceptibilities of C. jejuni and C. coli strains isolated from patients infected abroad (85 strains) or domestically (393 strains) revealed that susceptibility to erythromycin is still high, even among isolates of foreign origin. However, the novel antimicrobial agent telithromycin did not offer any advantage over erythromycin; isolates with high minimal inhibitory concentrations (MICs) for erythromycin also showed reduced susceptibility to telithromycin. Reduced susceptibility to fluoroquinolones was detected almost exclusively among isolates of foreign origin and half of these isolates with high MICs for fluoroquinolones also showed elevated MICs for doxycycline. Questionnaires concerning complications associated with C. jejuni enteritis were sent to patients two months after becoming ill; 201 patients from seven different geographical areas were included in the study. Musculoskeletal complications after C. jejuni infection were commonly reported by patients (39%). The incidence of classical ReA was 4% and that of Achilles enthesopathy and/or heel pain 9%. Other C. jejuni-associated reactive joint symptoms were commonly reported, however, due to their milder nature seldom seen and diagnosed by a physician. The severity of the enteritis may predict further complications; stomach ache during enteritis was connected to the development of later joint pain. Early antimicrobial treatment, within two days from the start of symptoms, shortened the duration of diarrhoea by two days but did not prevent later musculoskeletal complications. Campylobacter is an important human enteropathogen and causes a significant burden of illness. As the incidence of Campylobacter infections is high, the importance of the infection and the occurrence of complications will increase. This stresses the importance of understanding the risk factors for acquiring Campylobacter infection and how bacterial strain and host characteristics may affect the risk for infection. The role of antimicrobial treatment for acute Campylobacter enteritis seems to be marginal and should be used restrictively.

Human Torque teno virus: epidemiology, cell biology and immunology

Torque teno virus (TTV) was discovered in 1997 in the serum of a Japanese patient who had a post-transfusion hepatitis of unknown etiology. It is a small virus containing a circular single-stranded DNA genome which is unique among human viruses. Within a few years after its discovery, the TTVs were noted to form a large family of viruses with numerous genotypes. TTV is highly prevalent among the general population throughout the world, and persistent infections and co-infections with several genotypes occur frequently. However, the pathogenicity and the mechanism for the sustained occurrence of the virus in blood are at present unclear. To determine the prevalence of TTV in Finland, we set up PCR methods and examined the sera of asymptomatic subjects for the presence of TTV DNA and for genotype-6 DNA. TTV was found to be highly prevalent also in Finland; 85% of adults harbored TTV in their blood, and 4% were infected with genotype-6. In addition, TTV DNA was detected in a number of different tissues, with no tissue-type or symptom specificity. Most cell-biological events during TTV infections are at the moment unknown. Replicating TTV DNA has, however, been detected in liver and the hematopoietic compartment, and three mRNAs are known to be generated. To characterize TTV cell biology in more detail, we cloned in full length the genome of TTV genotype 6. We showed that in human kidney-derived cells TTV produces altogether six proteins with distinct subcellular localizations. TTV mRNA transcription was detected in all cell lines transfected with the full-length clone, and TTV DNA replicated in several of them, including those of erythroid, kidney, and hepatic origin. Furthermore, the viral DNA replication was shown to utilize the cellular DNA polymerases. Diagnoses of TTV infections have been based almost solely on PCR, whereas serological tests, measuring antibody responses, would give more information on many aspects of these infections. To investigate the TTV immunology in more detail, we produced all six TTV proteins for use as antigens in serological tests. We detected in human sera IgM and IgG antibodies to occur simultaneously with TTV DNA, and observed appearance of TTV DNA regardless of pre-existing antibodies, and disappearance of TTV DNA after antibody appearance. The genotype-6 nucleotide sequence remained stable for years within the infected subjects, suggesting that some mechanism other than mutations is used by this minute virus to evade our immune system and to establish chronic infections in immunocompetent subjects.

Dengue virus infection : Diagnostics and molecular epidemiology

Dengue is a mosquito-borne viral disease caused by the four dengue virus serotypes (DENV-1-4) and is currently considered as the most important arthropod-borne viral disease in the world. Nearly half of the human population lives in risk areas, and 50-100 million infections occur yearly according to World Health Organization. The disease can vary from a mild febrile disease to severe haemorrhagic fever and shock. A secondary infection with heterologous serotype increases the risk for severe disease outcome. During the last three decades the impact of dengue has dramatically increased in the endemic areas including the tropics and subtropics of the world. The current situation with massive epidemics of severe disease forms has been associated with socio-ecological changes that have increased the transmission and enabled the co-circulation of different serotypes. Consequently, an increase of dengue has also been observed in travelers visiting these areas. Currently approximately 30 cases are diagnosed yearly in Finnish travelers. In travelers dengue is rarely a life-threatening disease, however in the current study, a fatality was documented in a young Finnish patient who experienced a prolonged primary dengue infection. To improve particularly early laboratory diagnostics, a novel real-time RT-PCR method was developed for the detection of DENV-1-4 RNA based on TaqMan chemistry. The method was shown to be sensitive and specific for detecting DENV RNA and suitable for diagnostic use. The newly developed real-time RT-PCR was compared to other available early diagnostic methods including IgM and NS1 antigen detection using a panel of selected patient samples. The results suggest that the best diagnostic rates are achieved by a combination of IgM with RNA or NS1 detection. The dengue virus strains studied here included the first DENV strains isolated from serum samples of Finnish travelers collected in 2000-2005. The results of sequence analysis demonstrated that the 11 isolates included all four DENV serotypes and presented a global sample of DENV strains from different geographical areas including Asia, Africa and South America. In the present study sequence analysis was also carried out for a collection of 23 novel DENV-2 isolates from Venezuelan patients collected in 1999-2005. The Venezuelan DENV-2 exclusively represented the American-Asian genotype, suggesting that no foreign DENV-2 lineages have recently been introduced to the country. The results also suggest that the DENV-2 viruses detected earlier from Venezuela have been maintained in the area where they have evolved into several lineages. This is in contrast to the pattern observed in some other dengue endemic areas, where introductions of novel virus types and lineages are frequently detected.

Sweet potato chlorotic stunt virus: Studies on viral synergism and suppression of RNA silencing

The studies presented in this thesis aimed to a better understanding of the molecular biology of Sweet potato chlorotic stunt virus (SPCSV, Crinivirus, Closteroviridae) and its role in the development of synergistic viral diseases. The emphasis was on the severe sweet potato virus disease (SPVD) that results from a synergistic interaction of SPCSV and Sweet potato feathery mottle virus (SPFMV, Potyvirus, Potyviridae). SPVD is the most important disease affecting sweetpotato. It is manifested as a significant increase in symptom severity and SPFMV titres. This is accompanied by a dramatic sweetpotato yield reduction. SPCSV titres remain little affected in the diseased plants. Viral synergistic interactions have been associated with the suppression of an adaptive general defence mechanism discovered in plants and known as RNA silencing. In the studies of this thesis two novel proteins (RNase3 and p22) identified in the genome of a Ugandan SPCSV isolate were shown to be involved in suppression of RNA silencing. RNase3 displayed a dsRNA-specific endonuclease activity that enhanced the RNA-silencing suppression activity of p22. Comparative analyses of criniviral genomes revealed variability in the gene content at the 3´end of the genomic RNA1. Molecular analyses of different isolates of SPCSV indicated a marked intraspecific heterogeneity in this region where the p22 and RNase3 genes are located. Isolates of the East African strain of SPCSV from Tanzania and Peru and an isolate from Israel were missing a 767-nt fragment that included the p22 gene. However, regardless of the absence of p22, all SPCSV isolates acted synergistically with SPFMV in co-infected sweetpotato, enhanced SPFMV titres and caused SPVD. These results showed that p22 is dispensable for development of SPVD. The role of RNase3 in SPVD was then studied by generating transgenic plants expressing the RNase3 protein. These plants had increased titres of SPFMV (ca. 600-fold higher in comparison with nontransgenic plants) 2-3 weeks after graft inoculation and displayed the characteristic SPVD symptoms. RNA silencing suppression (RSS) activity of RNase3 was detected in agroinfiltrated leaves of Nicotiana bethamiana. In vitro studies showed that RNase3 was able to cleave small interferring RNAs (siRNA) to products of ~14-nt. The data thus identified RNase3 as a suppressor of RNA silencing able to cleave siRNAs. RNase3 expression alone was sufficient for breaking down resistance to SPFMV in sweetpotato and for the development of SPVD. Similar RNase III-like genes exist in animal viruses which points out a novel and possibly more general mechanism of RSS by viruses. A reproducible method of sweetpotato transformation was used to target RNA silencing against the SPCSV polymerase region (RdRp) with an intron-spliced hairpin construct. Hence, engineered resistance to SPCSV was obtained. Ten out of 20 transgenic events challenged with SPCSV alone showed significantly reduced virus titres. This was however not sufficient to prevent SPVD upon coinfection with SPFMV. Immunity to SPCSV seems to be required to control SPVD and targeting of different SPCSV regions need to be assessed in further studies. Based on the identified key role of RNase3 in SPVD the possibility to design constructs that target this gene might prove more efficient in future studies.

Identification of diverse full-length endogenous betaretroviruses in megabats and microbats

Background: Betaretroviruses infect a wide range of species including primates, rodents, ruminants, and marsupials. They exist in both endogenous and exogenous forms and are implicated in animal diseases such as lung cancer in sheep, and in human disease, with members of the human endogenous retrovirus-K (HERV-K) group of endogenous betaretroviruses (βERVs) associated with human cancers and autoimmune diseases. To improve our understanding of betaretroviruses in an evolutionarily distinct host species, we characterized βERVs present in the genomes and transcriptomes of mega- and microbats, which are an important reservoir of emerging viruses.Results: A diverse range of full-length βERVs were discovered in mega- and microbat genomes and transcriptomes including the first identified intact endogenous retrovirus in a bat. Our analysis revealed that the genus Betaretrovirus can be divided into eight distinct sub-groups with evidence of cross-species transmission. Betaretroviruses are revealed to be a complex retrovirus group, within which one sub-group has evolved from complex to simple genomic organization through the acquisition of an env gene from the genus Gammaretrovirus. Molecular dating suggests that bats have contended with betaretroviral infections for over 30 million years.Conclusions: Our study reveals that a diverse range of betaretroviruses have circulated in bats for most of their evolutionary history, and cluster with extant betaretroviruses of divergent mammalian lineages suggesting that their distribution may be largely unrestricted by host species barriers. The presence of βERVs with the ability to transcribe active viral elements in a major animal reservoir for viral pathogens has potential implications for public health. © 2013 Hayward et al.; licensee BioMed Central Ltd.

Foodborne Yersinia : Identification and Molecular Epidemiology of Isolates from Human Infections

Yersinia enterocolitica and Yersinia pseudotuberculosis are among the major enteropathogenic bacteria causing infections in humans in many industrialized countries. In Finland, Y. pseudotuberculosis has caused 10 outbreaks among humans during 1997-2008. Some of these outbreaks have been very extensive involving over 400 cases; mainly children attending schools and day-care. Y. enterocolitica, on the contrary, has caused mainly a large number of sporadic human infections in Finland. Y. pseudotuberculosis is widespread in nature, causing infections in a variety of domestic and wild animals. Foodborne transmission of human infections has long been suspected, however, attempts to trace the pathogen have been unsuccessful before this study that epidemiologically linked Y. pseudotuberculosis to a specific food item. Furthermore, due to modern food distribution systems, foodborne outbreaks usually involve many geographically separate infection clusters difficult to identify as part of the same outbreak. Among pathogenic Y. enterocolitica, the global predominance of one genetically homogeneous type (bioserotype 4/O:3) is a challenge to the development of genetic typing methods discriminatory enough for epidemiological purposes, for example, for tracing back to the sources of infections. Furthermore, the diagnostics of Y. enterocolitica infections is hampered because clinical laboratories easily misidentify some other members of the Yersinia species (Y. enterocolitica–like species) as Y. enterocolitica. This results in misleading information on the prevalence and clinical significance of various Yersinia isolates. The aim of this study was to develop and optimize molecular typing methods to be used in epidemiological investigations of Y. enterocolitica and Y. pseudotuberculosis, particularly in active surveillance and outbreak investigations of Y. pseudotuberculosis isolates. The aim was also to develop a simplified set of phenotypic tests that could be used in routine diagnostic laboratories for the correct identification of Y. enterocolitica and Y. enterocolitica –like species. A PFGE method designed here for typing of Y. pseudotuberculosis was efficient in linking the geographically dispersed and apparently unrelated Y. pseudotuberculosis infections as parts of the same outbreak. It proved to be useful in active laboratory-based surveillance of Y. pseudotuberculosis outbreaks. Throughout the study period, information about the diversity of genotypes among outbreak and non-outbreak related strains of human origin was obtained. Also, to our knowledge, this was the first study to epidemiologically link a Y. pseudotuberculosis outbreak of human illnesses to a specific food item, iceberg lettuce. A novel epidemiological typing method based on the use of a repeated genomic region (YeO:3RS) as a probe was developed for the detection and differentiation between strains of Y. enterocolitica subspecies palearctica. This method was able to increase the discrimination in a set of 106 previously PFGE typed Finnish Y. enterocolitica bioserotype 4/O:3 strains among which two main PFGE genotypes had prevailed. The developed simplified method was a more reliable tool than the commercially available biochemical test kits for differentiation between Y. enterocolitica and Y. enterocolitica –like species. In Finland, the methods developed for Y. enterocolitica and Y. pseudotuberculosis have been used to improve the identification protocols and in subsequent outbreak investigations.

Agricultural intensification, priming for persistence and the emergence of Nipah virus: a lethal bat-borne zoonosis

Emerging zoonoses threaten global health, yet the processes by which they emerge are complex and poorly understood. Nipah virus (NiV) is an important threat owing to its broad host and geographical range, high case fatality, potential for human-to-human transmission and lack of effective prevention or therapies. Here, we investigate the origin of the first identified outbreak of NiV encephalitis in Malaysia and Singapore. We analyse data on livestock production from the index site (a commercial pig farm in Malaysia) prior to and during the outbreak, on Malaysian agricultural production, and from surveys of NiV's wildlife reservoir (flying foxes). Our analyses suggest that repeated introduction of NiV from wildlife changed infection dynamics in pigs. Initial viral introduction produced an explosive epizootic that drove itself to extinction but primed the population for enzootic persistence upon reintroduction of the virus. The resultant within-farm persistence permitted regional spread and increased the number of human infections. This study refutes an earlier hypothesis that anomalous El Nino Southern Oscillation-related climatic conditions drove emergence and suggests that priming for persistence drove the emergence of a novel zoonotic pathogen. Thus, we provide empirical evidence for a causative mechanism previously proposed as a precursor to widespread infection with H5N1 avian influenza and other emerging pathogens.

In vivo delivery of bovine viral diahorrea virus, E2 protein using hollow mesoporous silica nanoparticles

Our work focuses on the application of mesoporous silica nanoparticles as a combined delivery vehicle and adjuvant for vaccine applications. Here we present results using the viral protein, E2, from bovine viral diarrhoea virus (BVDV). BVDV infection occurs in the target species of cattle and sheep herds worldwide and is therefore of economic importance. E2 is a major immunogenic determinant of BVDV and is an ideal candidate for the development of a subunit based nanovaccine using mesoporous silica nanoparticles. Hollow type mesoporous silica nanoparticles with surface amino functionalisation (termed HMSA) were characterised and assessed for adsorption and desorption of E2. A codon-optimised version of the E2 protein (termed Opti-E2) was produced in Escherichia coli. HMSA (120 nm) had an adsorption capacity of 80 [small mu ]g Opti-E2 per mg HMSA and once bound E2 did not dissociate from the HMSA. Immunisation studies in mice with a 20 [small mu ]g dose of E2 adsorbed to 250 [small mu ]g HMSA was compared to immunisation with Opti-E2 (50 [small mu ]g) together with the traditional adjuvant Quillaja saponaria Molina tree saponins (QuilA, 10 [small mu ]g). The humoral responses with the Opti-E2/HMSA nanovaccine although slightly lower than those obtained for the Opti-E2 + QuilA group demonstrated that HMSA particles are an effective adjuvant that stimulated E2-specific antibody responses. Importantly the cell-mediated immune responses were consistently high in all mice immunised with Opti-E2/HMSA nanovaccine formulation. Therefore we have shown the Opti-E2/HMSA nanoformulation acts as an excellent adjuvant that gives both T-helper 1 and T-helper 2 mediated responses in a small animal model. This study has provided proof-of-concept towards the development of an E2 subunit nanoparticle based vaccine.

Association between feline immunodeficiency virus (FIV) plasma viral RNA load, concentration of acute phase proteins and disease severity

Veterinarians have few tools to predict the rate of disease progression in FIV-infected cats. In contrast, in HIV infection, plasma viral RNA load and acute phase protein concentrations are commonly used as predictors of disease progression. This study evaluated these predictors in cats naturally infected with FIV. In older cats (>5 years), log10 FIV RNA load was higher in the terminal stages of disease compared to the asymptomatic stage. There was a significant association between log10 FIV RNA load and both log10 serum amyloid A concentration and age in unwell FIV-infected cats. This study suggests that viral RNA load and serum amyloid A warrant further investigation as predictors of disease status and prognosis in FIV-infected cats.

Frequency of dressing changes for central venous access devices on catheter-related infections

Background People admitted to intensive care units and those with chronic health care problems often require long-term vascular access. Central venous access devices (CVADs) are used for administering intravenous medications and blood sampling. CVADs are covered with a dressing and secured with an adhesive or adhesive tape to protect them from infection and reduce movement. Dressings are changed when they become soiled with blood or start to come away from the skin. Repeated removal and application of dressings can cause damage to the skin. The skin is an important barrier that protects the body against infection. Less frequent dressing changes may reduce skin damage, but it is unclear whether this practice affects the frequency of catheter-related infections. Objectives To assess the effect of the frequency of CVAD dressing changes on the incidence of catheter-related infections and other outcomes including pain and skin damage. Search methods In June 2015 we searched: The Cochrane Wounds Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE and EBSCO CINAHL. We also searched clinical trials registries for registered trials. There were no restrictions with respect to language, date of publication or study setting. Selection criteria All randomised controlled trials (RCTs) evaluating the effect of the frequency of CVAD dressing changes on the incidence of catheter-related infections on all patients in any healthcare setting. Data collection and analysis We used standard Cochrane review methodology. Two review authors independently assessed studies for inclusion, performed risk of bias assessment and data extraction. We undertook meta-analysis where appropriate or otherwise synthesised data descriptively when heterogeneous. Main results We included five RCTs (2277 participants) that compared different frequencies of CVAD dressing changes. The studies were all conducted in Europe and published between 1995 and 2009. Participants were recruited from the intensive care and cancer care departments of one children's and four adult hospitals. The studies used a variety of transparent dressings and compared a longer interval between dressing changes (5 to15 days; intervention) with a shorter interval between changes (2 to 5 days; control). In each study participants were followed up until the CVAD was removed or until discharge from ICU or hospital. - Confirmed catheter-related bloodstream infection (CRBSI) One trial randomised 995 people receiving central venous catheters to a longer or shorter interval between dressing changes and measured CRBSI. It is unclear whether there is a difference in the risk of CRBSI between people having long or short intervals between dressing changes (RR 1.42, 95% confidence interval (CI) 0.40 to 4.98) (low quality evidence). - Suspected catheter-related bloodstream infection Two trials randomised a total of 151 participants to longer or shorter dressing intervals and measured suspected CRBSI. It is unclear whether there is a difference in the risk of suspected CRBSI between people having long or short intervals between dressing changes (RR 0.70, 95% CI 0.23 to 2.10) (low quality evidence). - All cause mortality Three trials randomised a total of 896 participants to longer or shorter dressing intervals and measured all cause mortality. It is unclear whether there is a difference in the risk of death from any cause between people having long or short intervals between dressing changes (RR 1.06, 95% CI 0.90 to 1.25) (low quality evidence). - Catheter-site infection Two trials randomised a total of 371 participants to longer or shorter dressing intervals and measured catheter-site infection. It is unclear whether there is a difference in risk of catheter-site infection between people having long or short intervals between dressing changes (RR 1.07, 95% CI 0.71 to 1.63) (low quality evidence). - Skin damage One small trial (112 children) and three trials (1475 adults) measured skin damage. There was very low quality evidence for the effect of long intervals between dressing changes on skin damage compared with short intervals (children: RR of scoring ≥ 2 on the skin damage scale 0.33, 95% CI 0.16 to 0.68; data for adults not pooled). - Pain Two studies involving 193 participants measured pain. It is unclear if there is a difference between long and short interval dressing changes on pain during dressing removal (RR 0.80, 95% CI 0.46 to 1.38) (low quality evidence). Authors' conclusions The best available evidence is currently inconclusive regarding whether longer intervals between CVAD dressing changes are associated with more or less catheter-related infection, mortality or pain than shorter intervals.

Silica vesicles as nanocarriers and adjuvants for generating both antibody and T-cell mediated immune resposes to Bovine Viral Diarrhoea Virus E2 protein

Bovine Viral Diarrhoea Virus (BVDV) is widely distributed in cattle industries and causes significant economic losses worldwide annually. A limiting factor in the development of subunit vaccines for BVDV is the need to elicit both antibody and T-cell-mediated immunity as well as addressing the toxicity of adjuvants. In this study, we have prepared novel silica vesicles (SV) as the new generation antigen carriers and adjuvants. With small particle size of 50 nm, thin wall (similar to 6 nm), large cavity (similar to 40 nm) and large entrance size (5.9 nm for SV-100 and 16 nm for SV-140), the SV showed high loading capacity (similar to 250 mu g/mg) and controlled release of codon-optimised E2 (oE2) protein, a major immunogenic determinant of BVDV. The in vivo functionality of the system was validated in mice immunisation trials comparing oE2 plus Quil A (50 mu g of oE2 plus 10 mu g of Quil A, a conventional adjuvant) to the oE2/SV-140 (50 mu g of oE2 adsorbed to 250 mu g of SV-140) or oE2/SV-140 together with 10 mu g of Quil A. Compared to the oE2 plus Quil A, which generated BVDV specific antibody responses at a titre of 10(4), the oE2/SV-140 group induced a 10 times higher antibody response. In addition, the cell-mediated response, which is essential to recognise and eliminate the invading pathogens, was also found to be higher [1954-2628 spot forming units (SFU)/million cells] in mice immunised with oE2/SV-140 in comparison to oE2 plus Quil A (512-1369 SFU/million cells). Our study has demonstrated that SV can be used as the next-generation nanocarriers and adjuvants for enhanced veterinary vaccine delivery. (C) 2014 Elsevier Ltd. All rights reserved.