Different Domains of the RNA Polymerase of Infectious Bursal Disease Virus Contribute to Virulence

BACKGROUND: Infectious bursal disease virus (IBDV) is a pathogen of worldwide significance to the poultry industry. IBDV has a bi-segmented double-stranded RNA genome. Segments A and B encode the capsid, ribonucleoprotein and non-structural proteins, or the virus polymerase (RdRp), respectively. Since the late eighties, very virulent (vv) IBDV strains have emerged in Europe inducing up to 60% mortality. Although some progress has been made in understanding the molecular biology of IBDV, the molecular basis for the pathogenicity of vvIBDV is still not fully understood. METHODOLOGY, PRINCIPAL FINDINGS: Strain 88180 belongs to a lineage of pathogenic IBDV phylogenetically related to vvIBDV. By reverse genetics, we rescued a molecular clone (mc88180), as pathogenic as its parent strain. To study the molecular basis for 88180 pathogenicity, we constructed and characterized in vivo reassortant or mosaic recombinant viruses derived from the 88180 and the attenuated Cu-1 IBDV strains. The reassortant virus rescued from segments A of 88180 (A88) and B of Cu-1 (BCU1) was milder than mc88180 showing that segment B is involved in 88180 pathogenicity. Next, the exchange of different regions of BCU1 with their counterparts in B88 in association with A88 did not fully restore a virulence equivalent to mc88180. This demonstrated that several regions if not the whole B88 are essential for the in vivo pathogenicity of 88180. CONCLUSION, SIGNIFICANCE: The present results show that different domains of the RdRp, are essential for the in vivo pathogenicity of IBDV, independently of the replication efficiency of the mosaic viruses

Anchoring of proteins to lactic acid bacteria

The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.

Evaluating human papillomavirus vaccination programs in Canada: should provincial healthcare pay for voluntary adult vaccination?

Abstract Background Recently, provincial health programs in Canada and elsewhere have begun rolling out vaccination against human papillomavirus for girls aged 9–13. While vaccination is voluntary, the cost of vaccination is waived, to encourage parents to have their daughters vaccinated. Adult women who are eligible for the vaccine may still receive it, but at a cost of approximately CAN$400. Given the high efficacy and immunogenicity of the vaccine, the possibility of eradicating targeted types of the virus may be feasible, assuming the vaccination programs are undertaken strategically. Methods We develop a mathematical model to describe the epidemiology of vaccination against human papillomavirus, accounting for a widespread childhood vaccination program that may be supplemented by voluntary adult vaccination. A stability analysis is performed to determine the stability of the disease-free equilibrium. The critical vaccine efficacy and immunogenicity thresholds are derived, and the minimum level of adult vaccination required for eradication of targeted types is determined. Results We demonstrate that eradication of targeted types is indeed feasible, although the burden of coverage for a childhood-only vaccination program may be high. However, if a small, but non-negligible, proportion of eligible adults can be vaccinated, then the possibility of eradication of targeted types becomes much more favourable. We provide a threshold for eradication in general communities and illustrate the results with numerical simulations. We also investigate the effects of suboptimal efficacy and immunogenicity and show that there is a critical efficacy below which eradication of targeted types is not possible. If eradication is possible, then there is a critical immunogenicity such that even 100% childhood vaccination will not eradicate the targeted types of the virus and must be supplemented with voluntary adult vaccination. However, the level of adult vaccination coverage required is modest and may be achieved simply by removing the cost burden to vaccination. Conclusion We recommend that provincial healthcare programs should pay for voluntary adult vaccination for women aged 14–26. However, it should be noted that our model results are preliminary, in that we have made a number of simplifying assumptions, including a lack of age-dependency in sexual partner rates, a lack of sexual activity outside of the vaccine age-range among females and a uniform age of sexual debut; thus, further work is desired to enhance the external generalisability of our results.</p

Het Rijksvaccinatieprogramma in Nederland. Ontwikkelingen in 2006

In 2006 several changes were made in the Dutch National Immunisation Programme (NIP): Hepatitis B vaccination at birth was added for children born to mothers positive for hepatitis B surface antigen; a new vaccine for diphtheria, tetanus, pertussis (a-cellular), poliomyelitis and Haemophilus influenzae (DTaP-IPV/Hib) was introduced; vaccination against pneumococcal disease was added at two, three, four and eleven months; risk groups for hepatitis B receive a combined vaccine for DTaP-IPV/Hib and HBV at the same ages; DT-IPV and aP at the age of four years were combined in one vaccine; and new MMR vaccines were introduced. As new information became available in 2006, the desirability to introduce vaccinations in the NIP for the following diseases could be (re)considered: hepatitis B (universal vaccination), rotavirus, varicella and human papillomavirus. For respiratory syncytial virus and meningococcal serogroup B disease no candidate vaccines are available yet. Extension of the programme with available vaccines for hepatitis A, influenza and tuberculosis is not (yet) recommended. The NIP in the Netherlands is effective and safe. However, continued monitoring of the effectiveness and safety of the NIP is important as changes are made regularly. Maintaining high vaccine uptake is vital to prevent (re)emergence of diseases. Furthermore, the programme should be regularly reviewed as new vaccines become available.In 2006 traden verschillende veranderingen op in het Rijksvaccinatieprogramma (RVP) in Nederland: kinderen die geboren worden uit moeders die chronisch geinfecteerd zijn met hepatitis B krijgen vlak na de geboorte een hepatitis B vaccinatie; er is een ander vaccin geintroduceerd voor difterie, kinkhoest (a-cellulair), tetanus, poliomyelitis en Haemophilus influenzae (DaKTP/Hib); vaccinatie tegen pneumokokken is toegevoegd op de leeftijd van 2, drie, vier en elf maanden; risicogroepen voor hepatitis B krijgen op diezelfde leeftijden een combinatievaccin voor DaKTP/Hib en hepatitis B; DTP en aK zijn gecombineerd in een vaccin op vierjarige leeftijd; en er zijn nieuwe BMR vaccins geintroduceerd. Op basis van informatie die in 2006 beschikbaar is gekomen wordt geadviseerd de introductie van vaccinaties voor de volgende ziekten te overwegen: hepatitis B (universele vaccinatie), rotavirus, waterpokken en humaan papillomavirus. Voor respiratoir syncytieel virus en meningokokken B zijn nog geen kandidaatvaccins beschikbaar en uitbreiding van het RVP met beschikbare vaccins voor hepatitis A, influenza en tuberculose wordt nog niet aanbevolen. Het RVP is effectief en veilig, maar voortdurende bewaking hiervan is groot belang, omdat er regelmatig veranderingen optreden. Handhaven van de hoge vaccinatiegraad is essentieel om terugkeer van ziekten te voorkomen. Verder moet regelmatig bekeken worden of het RVP aangepast moet worden aangezien er steeds nieuwe vaccins beschikbaar komen

Relation between perceived health and sick leave in employees with a chronic illness

Introduction: To improve work participation in individuals with a chronic illness, insight into the role of work-related factors in the association between health and sick leave is needed. The aim of this study was to gain insight into the contribution of work limitations, work characteristics, and work adjustments to the association between health and sick leave in employees with a chronic illness. Methods: All employees with a chronic illness, between 15 and 65 years of age (n = 7,748) were selected from The Netherlands Working Conditions Survey. The survey included questions about perceived health, working conditions, and sick leave. Block-wise multivariate linear regression analyses were performed and, in different blocks, limitations at work, work characteristics, and work adjustments were added to the model of perceived health status. Changes in regression coefficient (B) (%) were calculated for the total group and for sub-groups per chronic illness. Results: When work limitations were added to the model, the B between health and sick leave decreased by 18% (5.0 to 4.1). Adding work characteristics did not decrease the association between health and sick leave, but the B between work limitations and sick leave decreased by 14%, (5.3 to 4.5). When work adjustments were added to the model, the Bs between sick leave and work limitations and work characteristics changed from 4.5 to 3.4 for work limitations and from 2.1 to 1.9 for temporary contract and from -0.8 to -1.0 for supervisor support. Conclusions: The association between health and sick leave was explained by limitations at work, work characteristics, and work adjustments. Paying more attention to work limitations, characteristics and adjustments offers opportunities to reduce the negative consequences of chronic illness. © The Author(s) 2010

The burden of varicella from a parent's perspective and its societal impact in The Netherlands: an Internet survey

<p>Abstract</p> <p>Background</p> <p>Varicella is a common childhood disease. Only 5% of first varicella-zoster-virus infections occur asymptomatically. Most data on the burden of varicella stem from health service databases. This study aims to provide insight in the burden of varicella from a parent's perspective including cases outside the healthcare system.</p> <p>Methods</p> <p>An internet questionnaire was developed for parents in the Netherlands to report health care resource use and productivity losses during the varicella episode in their child younger than 6 years. 11,367 invitations were sent out to members with children of an internet panel of a market research agency. 4,168 (37%) parents started the questionnaire (response rate), of which 360 (9%) stopped before completion and 1,838 (44%) were out of the target group. In total 1,970 parents completed the questionnaire. The questionnaire provided a symptom list ranging from common symptoms, such as skin vesicles, itching to fits or convulsions. A posteriori, in the analyses, the symptoms 'skin infections', 'fits/convulsions', 'unconsciousness', and 'balance and movement disorders' were labelled as complications. There was no restriction to time since the varicella episode for inclusion in the analyses.</p> <p>Results</p> <p>The 1,970 respondents had in total 2,899 children aged younger than six years, of which 2,564 (88%) children had had varicella. In 62% of the episodes the parent did not seek medical help. In 18% of all episodes symptoms labelled as complications were reported; in 11% of all episodes parents visited a medical doctor (MD) for a complication. Reporting of complications did not differ (X²; p = 0.964) between children with a recent (≤ 12 months ago) or a more distant (> 12 months) history of varicella. Prescription drugs were used in 12% of the children with varicella; OTC drugs in 72%. Parents reported work loss in 17% of the varicella-episodes (23% when MD visit; 14% when no MD-visit) for on average 14 hours, which equals to 2.5 hours of work loss for any given varicella-episode.</p> <p>Conclusions</p> <p>This study shows the full spectrum of varicella-episodes and associated healthcare use, including the large proportion of cases not seeking medical care and the societal impact associated with those cases.</p

A cost-utility analysis of cervical cancer vaccination in preadolescent Canadian females

<p>Abstract</p> <p>Background</p> <p>Despite the fact that approximately 70% of Canadian women undergo cervical cancer screening at least once every 3 years, approximately 1,300 women were diagnosed with cervical cancer and approximately 380 died from it in 2008. This study estimates the effectiveness and cost-effectiveness of vaccinating 12-year old Canadian females with an AS04-adjuvanted cervical cancer vaccine. The indirect effect of vaccination, via herd immunity, is also estimated.</p> <p>Methods</p> <p>A 12-health-state 1-year-cycle Markov model was developed to estimate lifetime HPV related events for a cohort of 12-year old females. Annual transition probabilities between health-states were derived from published literature and Canadian population statistics. The model was calibrated using Canadian cancer statistics. From a healthcare perspective, the cost-effectiveness of introducing a vaccine with efficacy against HPV-16/18 and evidence of cross-protection against other oncogenic HPV types was evaluated in a population undergoing current screening practices. The base-case analysis included 70% screening coverage, 75% vaccination coverage, $135/dose for vaccine, and 3$18,672-$31,687 per QALY-gained, the lower range representing inclusion of cross-protective efficacy and herd immunity. The cost per QALY-gained was most sensitive to duration of vaccine protection, discount rate, and the correlation between probability of screening and probability of vaccination.</p> <p>Conclusion</p> <p>In the context of current screening patterns, vaccination of 12-year old Canadian females with an ASO4-ajuvanted cervical cancer vaccine is estimated to significantly reduce cervical cancer and mortality, and is a cost-effective option. However, the economic attractiveness of vaccination is impacted by the vaccine's duration of protection and the discount rate used in the analysis.</p