Umino Y
Department of Virus Disease and Vaccine Control, National Institute of Health, Tokyo, Japan.
J Virol Methods. 1995 Feb;51(2-3):317-28. doi: 10.1016/0166-0934(94)00127-3.
Parameters for plaque formation by rubella vaccine strains licensed in Japan were studied. Formation of clear and large plaques on RK13 cells depends on several essential parameters. Plaques differed in morphology among five vaccine strains and the distinctiveness of the plaques was affected by pH of the agar overlay medium during incubation at 35 degrees C. Plaques became progressively larger in size as the concentration of sodium bicarbonate in the agar overlay medium increased from 0.04% to 0.15%, but the contrast of plaques to the background cells decreased markedly. The most distinct plaques of all vaccine strains were formed in the agar overlay medium containing 0.07% of sodium bicarbonate, i.e., pH 6.83, incubated in a humidified atmosphere containing 5% CO2. The number of plaques formed by vaccine strains decreased at 37 degrees C. Vaccine strains other than MEQ11 and TCRB19 formed larger and more contrasted plaques with sharp outline at 35 degrees C than at 32 degrees C. MEQ11 and TCRB19 strains yielded higher infective virus titres at 32 degrees C, but they formed distinct plaques at 35 degrees C and 32 degrees C. For the plaque test, the inoculum volume was another critical factor for obtaining an approximate titre that reflected the absolute titre of the sample. A volume of 0.1 ml was feasible for a well with a diameter of 35 mm.
对日本许可使用的风疹疫苗株形成蚀斑的参数进行了研究。在RK13细胞上形成清晰且大的蚀斑取决于几个关键参数。五种疫苗株的蚀斑形态各异，在35℃孵育期间，蚀斑的独特性受上层琼脂培养基pH值的影响。随着上层琼脂培养基中碳酸氢钠浓度从0.04%增加到0.15%，蚀斑尺寸逐渐增大，但蚀斑与背景细胞的对比度显著降低。所有疫苗株中最明显的蚀斑是在含有0.07%碳酸氢钠（即pH 6.83）的上层琼脂培养基中形成的，在含5%二氧化碳的湿润气氛中孵育。疫苗株形成的蚀斑数量在37℃时减少。除MEQ11和TCRB19外的疫苗株在35℃时比在32℃时形成更大、对比度更高且轮廓清晰的蚀斑。MEQ11和TCRB19株在32℃时产生更高的感染性病毒滴度，但它们在35℃和32℃时均形成明显的蚀斑。对于蚀斑试验，接种量是获得反映样品绝对滴度的近似滴度的另一个关键因素。对于直径为35 mm的孔，0.1 ml的体积是可行的。
