Optimal conditionsfor propagation of rotavirus monovalent vaccine strain to use as a referencerotavirus for evaluation of potency valuesof monovalent rotavirus vaccine

Abstract

       Rotavirus vaccine will be introduced to National Immunization Program in the future to reduce child mortality in Thailand caused a severe diarrhea in infants and children. Quality control of the vaccine to ensure the safety and effectiveness of rotavirus vaccine will be increased as well. Therefore, it is necessary to prepare rotavirus monovalent vaccine strain for using in quality control laboratory. This study was to determine optimal conditions for preparation of rotavirus monovalent vaccine strain infected cell culture in the presence of various concentrations of trypsin and to study harvesting virus in culture fluid in various conditions after freeze-thaw cycle 1 time, 2 times and 3 times, respectively comparing with harvesting viral vaccine directly from culture supernatant. Optimal conditions were used for the preparation of rotavirus monovalent vaccine strain that would be assigned with the potency values. The result showed that use of trypsin couldenhance rotavirus quantity in MA104 cells. Trypsin at 7.5 μg/ml trypsin/washing mediumboth in the titration medium and the maintenance medium and harvesting virus with 1F-T method were optimal conditions for preparation of rotavirus vaccine due to a highest potency values. When optimal conditions used for preparation of rotavirus monovalent vaccine strain, it was found that the geometric mean was 7.93 log₁₀CCID₅₀/1.5 ml with the range between 7.46-8.40 log₁₀CCID₅₀/1.5 ml. Each individual value from three analysts was not more than 0.5 log₁₀CCID₅₀/1.5 ml. It can be concluded that rotavirus monovalent vaccine strain prepared in the laboratory can be used as a reference rotavirus for quality control of monovalent rotavirus vaccine potency.