Impact of changes in Clostridium difficile diagnostic testing on detection of C. difficile infection and all England mandatory surveillance data.

Following the report of the Centre for Evidence-based Purchasing, which suggested poor performance of Clostridium difficile testing kits, revised guidance was issued by the Department of Health (England) recommending a two-test algorithm. The aim of this study was to survey English National Health Service (NHS) diagnostic microbiology laboratories using an electronic questionnaire to investigate changes in laboratory procedures in response to the guidance and model the impact these changes had on national and locally reported data. It was found that 24% of laboratories had changed testing procedures and there was no evidence of an overall effect on the English mandatory surveillance data used for performance management. It was shown that there could be an impact on an individual NHS Trust's case numbers, and a simple model for Trusts to predict these changes in C. difficile laboratory diagnosis was developed. There was also evidence of the use of variable sample selection criteria, which could affect the positive and negative predictive values of local testing.

Expression of the major core structural protein (VP7) of bluetongue virus, by a recombinant capripox virus, provides partial protection of sheep against a virulent heterotypic bluetongue virus challenge.

A recombinant capripox virus was constructed containing a cDNA copy of genome segment 7 of bluetongue virus (BTV) serotype 1 from South Africa (BTV 1SA), which expressed high levels of the major BTV core protein VP7 in infected lamb testis (LT) cells. Sheep vaccinated with this recombinant virus developed antibodies to VP7 (detected by ELISA) but no neutralizing antibodies to either the homologous or heterologous BTV serotype, prior to challenge (BTV 1 or BTV 3, respectively). Following challenge with a virulent heterotypic strain of BTV (BTV3 SA), all of the animals developed clinical signs of disease, indicating that they were infected and that the challenge virus did replicate. While all of the control animals died, six of the eight animals that were vaccinated with the recombinant capripox virus expressing VP7 recovered fully. This is the first report of a significant level of cross serotype protection against the lethal effects of a challenge with virulent BTV, produced by vaccination with a single BTV core protein, which did not generate a neutralizing antibody response.