Löfgren B, Nordenfelt E, Jonsson S, Kronvall G
J Med Virol. 1980;6(1):37-44. doi: 10.1002/jmv.1890060106.
Antibodies against hepatitis A virus (anti-HAV) can be determined by a commercially available radioimmunoassay (RIA) (HavabTM, Abbott). To discriminate between recent and past hepatitis A infection this RIA was used in combination with absorption with protein A-containing staphylococci. However, nonabsorbable anti-HAV was repeatedly detected in late-convalescent sera using this methods. The nature of these antibodies was studied in serum samples from 12 such patients. In all patients, the late-convalescent sera contained no IgM class anti-HAV as judged by sucrose density gradient centrifugation. The restricted specificity of staphylococcal protein A explains the lack of absorption. Some recently described streptococcal strains capable of binding all IgG subclasses (including IgG3) as well as both IgA subclasses were, therefore, added to the staphylococci. Absorption studies using these strains indicated that the previously nonabsorbable anti-HAV in these 12 patients was mainly of the IgA class. A bacterial mixture including IgA-binding streptococci seems preferable to routine determination of IgM anti-HAV in acute hepatitis A diagnosis. The results also indicate that IgA anti-HAV in serum can persist for more than two years after a hepatitis A infection.
抗甲型肝炎病毒抗体（抗-HAV）可通过市售的放射免疫测定法（RIA）（HavabTM，雅培公司）进行检测。为了区分近期和既往甲型肝炎感染，该RIA与含蛋白A的葡萄球菌吸收法联合使用。然而，使用这种方法在恢复期晚期血清中反复检测到不可吸收的抗-HAV。对12例此类患者的血清样本中这些抗体的性质进行了研究。通过蔗糖密度梯度离心判断，所有患者恢复期晚期血清中均不含IgM类抗-HAV。葡萄球菌蛋白A的特异性受限解释了吸收缺乏的原因。因此，将一些最近描述的能够结合所有IgG亚类（包括IgG3）以及两种IgA亚类的链球菌菌株添加到葡萄球菌中。使用这些菌株的吸收研究表明，这12例患者中先前不可吸收的抗-HAV主要为IgA类。在急性甲型肝炎诊断中，包含结合IgA链球菌的细菌混合物似乎比常规检测IgM抗-HAV更可取。结果还表明，甲型肝炎感染后，血清中的IgA抗-HAV可持续两年以上。
