T Whistler1, N Blackburn. 1. National Institute for Virology, University of the Witwatersrand, Johannesburg, South Africa. toniw@niv.ac.za
Abstract
BACKGROUND: Large numbers of measles virus (MV) specimens are processed in our laboratory each year as part of a molecular epidemiological study of MV in South Africa. The development of a sensitive, rapid virus isolation system is needed to cope with the number of specimens processed. OBJECTIVES: A comparison was made of centrifugation-enhanced shell vial culture and standard tissue culture using B95a cells for the isolation of MV from throat swabs and urine. STUDY DESIGN: The rapid method was initially evaluated using Schwarz vaccine virus and then compared to standard culture using throat swab specimens. RESULTS: The shell via assay proved to be ten times more sensitive than standard culture in the initial evaluation. Of 43 throat swab specimens, 37 (86%) were positive and 6 (14%) negative in standard culture using B95a cells. The specimens were removed after adsorption in standard culture, frozen and then used in the shell vial assay. It was found that 16/27 were positive in the shell vial assay (24 of these 27 being positive in standard culture,) and 8 negative and 8 specimens gave an indeterminate result. For the 45 urine specimens used in the shell vial assay, 71% were positive, 11% negative and 18% gave an indeterminate result, due to too few cells being present for antigen determination by indirect fluorescent antibody assay. Results were obtained in 4 days, as opposed to the average of 14 days for confirmed isolation in standard culture. CONCLUSION: Rapid culture substantially reduced total test time, was less labour-intensive and was as sensitive as standard culture for the isolation of measles virus from clinical specimens.
BACKGROUND: Large numbers of measles virus (MV) specimens are processed in our laboratory each year as part of a molecular epidemiological study of MV in South Africa. The development of a sensitive, rapid virus isolation system is needed to cope with the number of specimens processed. OBJECTIVES: A comparison was made of centrifugation-enhanced shell vial culture and standard tissue culture using B95a cells for the isolation of MV from throat swabs and urine. STUDY DESIGN: The rapid method was initially evaluated using Schwarz vaccine virus and then compared to standard culture using throat swab specimens. RESULTS: The shell via assay proved to be ten times more sensitive than standard culture in the initial evaluation. Of 43 throat swab specimens, 37 (86%) were positive and 6 (14%) negative in standard culture using B95a cells. The specimens were removed after adsorption in standard culture, frozen and then used in the shell vial assay. It was found that 16/27 were positive in the shell vial assay (24 of these 27 being positive in standard culture,) and 8 negative and 8 specimens gave an indeterminate result. For the 45 urine specimens used in the shell vial assay, 71% were positive, 11% negative and 18% gave an indeterminate result, due to too few cells being present for antigen determination by indirect fluorescent antibody assay. Results were obtained in 4 days, as opposed to the average of 14 days for confirmed isolation in standard culture. CONCLUSION: Rapid culture substantially reduced total test time, was less labour-intensive and was as sensitive as standard culture for the isolation of measles virus from clinical specimens.
Authors: Brigitta M Laksono; Paola Fortugno; Bernadien M Nijmeijer; Rory D de Vries; Sonia Cordisco; Thijs Kuiken; Teunis B H Geijtenbeek; W Paul Duprex; Francesco Brancati; Rik L de Swart Journal: PLoS Pathog Date: 2020-10-08 Impact factor: 6.823