Gerganov G, Surtmadzhiev K
Vet Med Nauki. 1981;18(7):26-33.
Studied was the persistance of 3 plaque clones of a velogenic viscerotropic Newcastle disease virus in nonimmune birds. It was found that the first plaque clone (4 mm dia of plaques) possessed higher virulence than that of the parental virus and killed all inoculated birds for 2 to 5 days. Plaque clone II (2.5 mm dia of the plaques) caused up to 30 per cent mortality, and plaque clone III (1.5 mm dia of the plaques) did not bring about death but a transient disease only. Birds inoculated with II and III plaque clones, at identical serologic response, were investigated virologically on the 40th and 60th day post infection. By means of the tracheal organ cultures the Newcastle disease virus was isolated only from birds that were inoculated with plaque clone II. No virus was demonstrated via the same method in birds inoculated with plaque clone III. It is believed that the long-term persistance of the Newcastle disease virus reported on a previous occasion was due to a subpopulation identical with plaque clone II.
研究了强毒嗜内脏型新城疫病毒的3个蚀斑克隆在未免疫禽类中的持续性。结果发现，第一个蚀斑克隆（蚀斑直径4毫米）的毒力高于亲代病毒，接种的所有禽类在2至5天内死亡。蚀斑克隆II（蚀斑直径2.5毫米）导致高达30%的死亡率，蚀斑克隆III（蚀斑直径1.5毫米）未造成死亡，仅引起短暂疾病。对接种蚀斑克隆II和III且血清学反应相同的禽类，在感染后第40天和第60天进行了病毒学调查。通过气管器官培养，仅从接种蚀斑克隆II的禽类中分离到新城疫病毒。用同样方法在接种蚀斑克隆III的禽类中未检测到病毒。据信，先前报道的新城疫病毒长期持续性是由于与蚀斑克隆II相同的亚群所致。
