The gene coding for the major inner capsid protein VP6 of human group C rotavirus was cloned into baculovirus using the pBlueBac2 vector and expressed in insect cells. When cultured in High Five cells, VP6 was expressed at a high level and exported to the cell culture medium. Purified VP6 was used to immunise rabbits. Hyperimmune rabbit serum, which reacted with native human group C rotavirus in infected cells, was used to develop and optimise an EIA for the detection of antibodies to group C rotavirus using the recombinant VP6 as a source of antigen. In a local epidemiological survey of 1000 sera grouped by age, an average of 43% of samples were found to have antibodies to human group C rotavirus with the highest proportion (66%) in the 71-75 year age group. In comparison, 97% of adults and 85% of children had antibodies to recombinant VP6 from the bovine RF strain of group A rotavirus. These results suggest that infection with human group C rotavirus is a common occurrence despite the apparent rarity of reports of human group C rotavirus in clinical samples from patients with gastroenteritis.
A recent study showed that 43% of a population in the United Kingdom were seropositive for group C rotavirus. The higher than expected incidence may be due to limited diagnosis of acute human group C rotavirus infections because no routine test is available. Human group C rotavirus infections are routinely diagnosed by electron microscopy (EM) and a negative group A rotavirus enzyme-linked immunosorbent assay (ELISA) result. An antigen-detection ELISA was developed with hyperimmune antibodies raised to human group C rotavirus recombinant VP6 (Bristol strain) expressed in insect cells. The assay was used to screen fecal samples to determine the prevalence of group C rotavirus infection. Samples positive by ELISA were confirmed by EM, polyacrylamide gel electrophoresis of double-stranded RNA, or detection of the VP6 gene by reverse transcription-PCR. Retrospective analysis indicated a 1 to 2% detection rate of positivity among samples from patients with acute diarrhea.
Viral load testing is an essential parameter in guiding antiretroviral therapy for individuals infected with human immunodeficiency virus type 1 (HIV-1). An external quality assessment scheme for the molecular quantification of HIV-1 RNA was introduced by the United Kingdom National External Quality Assessment Service for Microbiology in 2000. Specimen pairs of freezedried plasma were distributed to a median of 141 participants three times a year. The aim of this study was to analyze the quantification of HIV-1 RNA results between 2000 and 2010. Overall variability, measured by the standard deviations of all viral load results for each specimen, was below 0.5 log copy/ml (n ؍ 48). When we compared assay results, the medians of the viral load by assay were within a range of 0.25 to 1.08 log copies/ml, with the lowest median values being consistently reported with the Siemens branched-chain DNA assay. The spread of participant results and, hence, differences between assay medians were greater when quantifying non-B subtypes. Laboratories were scored on the proximity of their reported log difference for the specimen pair to the median log difference reported by all laboratories. The overall level of performance with the HIV-1 RNA specimens over the past 10 years has been consistently good, with more than 90% of the participants reporting in the accepted range (median difference, ؎0.5 log unit). Future distributions may result in tightening the acceptance levels of quantification and the use of more challenging specimens, including a variety of subtypes, with developments focusing on maintaining the clinical relevance and educational value of the scheme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.