The presence of free infectious cytomegalovirus (CMV) in the plasma of donated CMV-seropositive blood and platelets.

An in vitro study was carried out to determine the presence of free infectious CMV in the supernatant of donated units of blood and platelets which were known to be CMV seropositive. One sample was taken from each of 10 units of CMV-seropositive platelet donations which were 4 days old. Ten units of seropositive blood were sampled at intervals over their storage lifespan. Each sample was divided into two and thrombin was added to one of them. The samples were all prepared by centrifugation. The resulting supernatant from the clotted samples was used in in vitro culture studies using the MRC-5 cell line to ascertain the infectivity of the samples. The anticoagulated supernatants were subjected to PCR analysis to detect the presence of free genomic CMV DNA. All of the units of blood and platelets tested positive for the presence of genomic CMV DNA by PCR. Seven out of the 10 units of blood were culture positive from samples taken 3-4 weeks into their shelf-life. None of the platelet samples was culture positive. The cultures of supernatants taken from seropositive blood were negative when the units were fresh, but further into their storage life, the cultures became positive, indicating that infectious material was released into the supernatant during storage, presumably due to the breakdown of intact white cells.

Comparison of paediatric viral gastroenteritis at large medical centres in Saudi Arabia and the United Kingdom.

A comparison of the prevalence of viral diarrhoeas in children was made between the United Kingdom and Saudi Arabia over a three-year period. Laboratory data from Saudi Arabia were compared with those of a large medical centre in the UK. The prevalence ratios of virus-associated diarrhoea as a fraction of all diarrhoeal cases over three years were found to be 23% in the UK and 14% in Saudi Arabia. The relative proportion due to rotavirus and adenovirus was higher in the UK than in Saudi Arabia, but small round viruses were comparable at the two centres.

Use of a nested PCR method for the detection of astrovirus serotype 1 in human faecal material.

In this paper we describe a reverse-transcription nested polymerase chain reaction method for detecting human astrovirus serotype 1. It has been evaluated on 56 UK diarrhoeal stool specimens and six non-UK specimens. The method has greater sensitivity than electron microscopy and may be a useful test in areas such as the UK where this serotype predominates.

Vaccination against hepatitis B: comparison of intradermal and intramuscular administration of plasma derived and recombinant vaccines.

A retrospective analysis of levels of antibody to hepatitis B surface antigen in 1419 health care workers was carried out to compare the efficacy of intramuscular and intradermal administration of plasma derived and recombinant hepatitis B vaccines. No significant difference was detected between the response to intradermal and intramuscular plasma derived vaccine. However of those who received intramuscular recombinant vaccine 81.6%, 13.8% and 4.7% were good (> or = 100 miu/ml), low (10-99 miu/ml) and non-responders (< 10 miu/ml) respectively, compared with 51.1%, 29.8% and 19.2% of the intradermal group (P < 0.0001). Low dose intradermal administration of recombinant vaccine did not produce satisfactory levels of antibody to hepatitis B surface antigen.

Cultural method for large-scale screening for Chlamydia trachomatis genital infection.

Idoxuridine-treated McCoy cells grown as monolayers in 96 well microplates provide a convenient method for the isolation of Chlamydia trachomatis. Staining of infected monolayers with periodic acid-Schiff reagent (PAS) allows easy recognition of C trachomatis inclusions without the need for dark-ground microscopy. By this method 384 clinical specimens can be examined concurrently. It is sufficiently sensitive to form the basis of a chlamydial culture service for patients attending Sexually Transmitted Diseases (STD) Clinics.