国内外常用新城疫活疫苗的毒力和血凝滴度测定试验报告

本试验通过对国内外常用新城疫弱毒疫苗最小致死量（MLD）测定、鸡胚平均致死时间（MDT）测定，对疫苗的毒力强弱和致病型进行分析。对疫苗的血凝试验（HA）滴度进行测定。根据疫苗的抗原含量推断免疫效力。测定新城疫不同毒株的弱毒疫苗单苗和与传染性支气管火H120等的二联苗或三联苗共14种，对其中9种疫苗进行了鸡胚最小致死量（MLD）测定和鸡胚平均致死时间（MDT）试验，对所有的疫苗都进行了HA试验。不管是进口疫苗还是国产疫苗其MDT有较大的差异，其毒力有强有弱，有的为中发型（中等毒力）疫苗，主要是温和型（低毒力）疫苗，最小致死量（MLD）范围为10^-8-10^-10/0.1ml。不同厂家生产的疫苗HA滴度有较大的区别。国产疫苗的质量与进口疫苗无明显的差异，有的比进口疫苗质量还好。对出口养禽企业选用低毒力、HA滴度高的疫苗具有较好的指导作用。

A Report on Virulence Test and HA Test of Live Newcastle Disease Vaccines Commonly Used Both at Home and Abroad

Common attenuated ND vaccines were determined for their virulence and pathogenic types by means of minimum lethal dose (MLD), mean death time(MDT) of chicken embryos and hemagglutination (HA) test, and deduced for their immune potencies based on their antigen concentrations.14 ND vaccines ,including single vaccines of various NDV strains, binary or triple vaccines containing IBV H120 were analyzed in the experiment, 9 vaccines were tested with MLD and MDT, and all the vaccines were tested with HA. MDT values of both the imported and domestic vaccines varied greatly, and their virulence were different, some were vaccines of moderate strains, however most of them were vaccines of mild strain (low virulence) with MLD of 10-8~10-10/0.1ml. HA titers varied significantly in vaccines from different manufactures. There were no significant difference in quality of the domestic vaccines and the imported vaccines, and some domestic vaccines were better than the imported ones.The study offers reference for the poultry exporting enterprises in selecting vaccines with low virulence and high titer.