15株NDV地方株的分离鉴定与生物学特性

Isdation and identification of newcastle disease virus of 15 strains and their biological characteristics

从1998～2002年河南省洛阳地区代表性新城疫发病禽群中分离鉴定了15株新城疫病毒(NDV),并对其生物学特性进行了研究.结果表明,15株NDV均呈现良好的血凝活性和特异的血凝抑制特性;对鸡胚的致病作用可被新城疫阳性血清所抑制;对鸡胚最小致死量的平均死亡时间(MDT),1日龄雏鸡脑内接种的致病指数(ICPI)和6周龄鸡静脉内接种的致病指数(IVPI)的测定证实,LD-6-01和LR-2-00株是弱毒株,其余均为强毒株;弱毒株的血凝素热稳定性较好,属慢速血凝解脱型;强毒株的血凝素热稳定性差,属快速或中速血凝解脱型;所有毒株均可较好地凝集鸡和人(O型血)的红细胞,但对其他动物的红细胞凝集性差异较大.对HI抗体为6log2的12日龄雏鸡攻毒试验结果表明,15个分离株中2个弱毒株可得到100%保护;13个强毒株中,LG-1-99,LR-1-98,LD-4-01和LD-3-00得到了70%～90%的保护,而其他9个分离株(LD-1-98,LD-2-99,LD-5-01,LD-7-02,LR-3-02,LW-1-02,LG-2-00,LA-1-99和LE-1-01)基本上得不到保护(0～20%),但所有得不到保护的试验组鸡的发病死亡时间均明显向后推迟.

Representative NDV strains collected during 1998-2002 in different parts of Luoyang area were isolated ,and their biological characteristics were identified and studied. The results showed that 15 NDV strains were hemagglutination （HA） active and hemagglutination inhibition （HI） active,and the pathogenicity to chicken embryo could be inhibited by ND positive serum. By means of the test of mean death time （MDT） of chicken embryo,intracerebral pathogenicity index （ICPI） of 1-day-old chicken and intravenous pathogenicity index （IVPI） in 6-week-old chicken,LD-6-01 and LR-2-00 strains were verified to be lentogenic strains ,their hemagglutinin were stable to heat and belonged to slow type of hemagglutinating-free;the other strains were all virulent,their hemagglutinin were not stable to heat and belonged to fast type of hemagglutinating-free. 15 NDV strains were able to agglutinate chicken and human erythro- cytes, but, their ability of agglutinating the erythrocytes of sheep,goat, swine, horse and cow were different. Challenged by 2 lentogenic NDV strains,the chickens with 6log2 HI antibody obtained 100% protection, the same chickens challenged by LG-1-99,LR-1-98,LD-4-01 and LD-3-00 strains obtained 70%-90% protection,and the same chickens only obtained 0-20% protection after challenged by other 9 virulent strains. But the pathogenic and death time were postponed obviously in all the unprotected chickens.