• 作者： 陳煒富
• 作者服務機構： 國立臺灣大學農學院獸醫學系
• 中文摘要： 從本地分離之新城?瘟病毒選出15株及毒性已知之新城?瘟5株以血球凝集，?胚腎細胞之細胞病變及斑點形成單位、 ?胚之感染單位、?胚與小?之平均致死時間、腦內及血管內病原性係數、以agar及agarose培養基下在?胚腎細胞形成 斑點大小之情形，以及於?胚腎細胞與幼倉鼠腎細胞（BHK-21)形成早期或晚期多核細胞之能力等方法測定病毒之力價與毒 性。手選出病毒之平均致死時間?58小時，小?腦內及血管內係數分別平均?1.65與2.65。 Agarose培養基上之斑點略比 agar上大，而弱毒株都能形成斑點但比所測定之其他病毒株小。於15小時後，病毒在感染細胞能否導引晚期多核細胞形成 之能力直接關係於?胚與小?之毒性；至於早期多核細胞之形成能力似與病毒株之毒性無關。從這些測定中發現所選出之15 種分離株似乎都屬於新城?瘟之?毒株。
• 英文摘要： Fifteen selected local isolates and five known Newcastle disease virus strains were examined for biological activity titers by hemagglutination in microtitration plates, cytopathic effects and plaque forming units in chick embryos kidney (CEK) cells, and egg-infectious units in chick embryos (CE). Mean death time (MDT), and intracerebral and intravenous pathogenic indexes (ICPI and IVPI) were used to determine virulence in CE and chicks. Isolates and strains were also tested for plaque size under agar or agarose overlay medium in CEK cells and the ability to cause polykaryocytosis of 'fusion from without' (FFWO) or 'fusion from within' (FFWI) in CEK and BHK-21 monolayer cells. The MDT of selected isolates varied from 49 to 69 hr, with a median of 58 hr. The ICPI values ranged from 1.50 to 1.78 with a median of 1.65, and IVPI values from 2.53 to 2.70 with a median of 2.65. The plaque under agarose overlay was clear and slightly larger than that of agar group. The lentogenic vaccine strains could form plaques, but their sizes were smaller than other tested viruses. The capacity of the different virus strains to induce FFWI polykaryocytes at 15 hr post-infection was related to their virulence for CE and chicks, but the polykaryocytes of FFWO did not seem to have any relationship with the virulence of the strains. Therefore, the fifteen selected isolates seem to be velogenic strains.
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