Pinto A M, Cabral M C, Couceiro J N
Departamento de Virologia, Universidade Federal do Rio de Janeiro, Brasil.
Braz J Med Biol Res. 1994 May;27(5):1141-7.
The present study was conducted to investigate the characteristics of two samples of influenza A/England/42/72 (H3N2) virus, one of them selected by an adsorption-elution technique, to determine the possible existence of virus variants or subpopulations. Based on specificity of virulence-related cell receptor-binding and sialidase activities, this selection technique using human O group erythrocytes revealed the presence of variants within a standard virus sample with diversity for their hemagglutinating and sialidase activities. The standard-like (E1) sample exhibited titers of 4 and 32 HAU (hemagglutinating units in 25 microliters) with human O group and chicken erythrocytes, respectively, while the sample obtained by the adsorption-elution process (E2) exhibited titers of 32 and 4 HAU, respectively, with these same types of erythrocytes. The E2 sample showed higher sialidase activity at pH values between 5.4 and 6.6 with human erythrocytes (128-256 HAU), but the E1 sample did not exhibit significant sialidase activity with either human or chicken erythrocytes. The different pH optima for hemolysis (5.2) and sialidase (5.4-6.6) activities and the higher hemolysis indexes present in samples with sialidase activity inhibited by heating (at 56 degrees C for 30 min) or by treatment with EDTA (dilution in buffer containing 2 mM EDTA, a chelating agent on calcium-dependent sialidase activity) demonstrate the independence of these activities in the selected sample: native E2 (absorbance = 0.18), EDTA-treated native E2 (absorbance = 0.28), heated E2 (absorbance = 0.26), EDTA-treated heated E2 (absorbance = 0.41).(ABSTRACT TRUNCATED AT 250 WORDS)
本研究旨在调查甲型流感病毒/英格兰/42/72（H3N2）的两个样本的特征，其中一个样本是通过吸附-洗脱技术选取的，以确定病毒变体或亚群的可能存在情况。基于与毒力相关的细胞受体结合和唾液酸酶活性的特异性，这种使用人O型红细胞的选择技术揭示了标准病毒样本中存在具有不同血凝和唾液酸酶活性的变体。标准样（E1）样本与人O型红细胞和鸡红细胞的血凝滴度分别为4和32 HAU（25微升中的血凝单位），而通过吸附-洗脱过程获得的样本（E2）与这些相同类型红细胞的血凝滴度分别为32和4 HAU。E2样本在pH值5.4至6.6之间与人红细胞的唾液酸酶活性较高（128 - 256 HAU），但E1样本与人或鸡红细胞均未表现出显著的唾液酸酶活性。溶血（5.2）和唾液酸酶（5.4 - 6.6）活性的不同最适pH值，以及唾液酸酶活性样本中存在的较高溶血指数（通过加热（56℃ 30分钟）或用EDTA处理（在含有2 mM EDTA的缓冲液中稀释，EDTA是一种对钙依赖性唾液酸酶活性起螯合作用的试剂）而受到抑制）证明了所选样本中这些活性的独立性：天然E2（吸光度 = 0.18）、经EDTA处理的天然E2（吸光度 = 0.28）、加热的E2（吸光度 = 0.26）、经EDTA处理的加热E2（吸光度 = 0.41）。（摘要截于250字）
