Jusa E R, Inaba Y, Kouno M, Hirose O, Shibata I, Kubota M, Yasuhara H
Department of Veterinary Epizootiology, College of Biosesource Sciences, Nihon University, Kanagawa, Japan.
J Vet Med Sci. 1996 Aug;58(8):749-53. doi: 10.1292/jvms.58.749.
Various conditions were evaluated and modified to enhance the sensitivity of the neutralization (NT) test for detecting antibody in swine infected with porcine reproductive and respiratory syndrome (PRRS) virus. Higher NT antibody titers were consistently obtained by the addition of 10% (v/v) complement, fresh guinea pig serum, to the virus diluent and by the incubation of serum-virus mixture at 4 degrees C for 24 hr. The appearance and persistence of antibodies detected by the modified NT test showed a similar pattern to those of antibodies detected by the indirect fluorescent antibody (IFA) assay, although the antibody titers obtained by the former method were consistently lower than those obtained by the latter method. Slow-reacting complement-requiring NT antibody was detected in sera from pig 2 weeks after infection with PRRS virus. The slow-reacting complement-requiring NT antibody in the early serum samples was sensitive to 2-mercaptoethanol (2-ME), whereas the slow-reacting complement-requiring NT antibody in the late serum samples was resistant to 2-ME. The initial phase may represent the IgM response and the later phase a change to IgG. A NT test was developed in which serum-virus mixtures were incubated at 4 degrees C for 24 hr with complement; this gave an improved sensitivity over the previous incubation at 37 degrees C for 60 min.
对多种条件进行了评估和调整，以提高中和（NT）试验检测感染猪繁殖与呼吸综合征（PRRS）病毒的猪体内抗体的敏感性。通过在病毒稀释液中添加10%（v/v）补体（新鲜豚鼠血清），以及将血清-病毒混合物在4℃孵育24小时， consistently获得了更高的NT抗体滴度。尽管改良NT试验获得的抗体滴度始终低于间接荧光抗体（IFA）试验获得的滴度，但改良NT试验检测到的抗体的出现和持续情况与IFA试验检测到的抗体相似。在感染PRRS病毒2周后的猪血清中检测到了需要补体的慢反应NT抗体。早期血清样本中需要补体的慢反应NT抗体对2-巯基乙醇（2-ME）敏感，而晚期血清样本中需要补体的慢反应NT抗体对2-ME具有抗性。初始阶段可能代表IgM反应，后期阶段则转变为IgG反应。开发了一种NT试验，其中血清-病毒混合物在4℃下与补体孵育24小时；与之前在37℃孵育60分钟相比，这种方法提高了敏感性。
