一株鸡传染性贫血病毒对不同日龄SPF鸡的致病性研究

Pathogenicity of a Chicken Anemia Virus in SPF Chickens at Different Ages

关键词:  鸡传染性贫血病毒，SPF鸡，致病性

Key words:  chicken anemia virus  SPF chickens  pathogenicity

摘要:

为评价鸡传染性贫血病毒AV1550株的致病性，取1日龄、7日龄和14日龄SPF鸡分别经胸部肌肉注射不同病毒含量的病毒液，同时设置正常对照，隔离饲养观察21日。感染后14日采血测定红细胞压积，21日统计死亡率、体重变化以及胸腺、骨髓、法氏囊病变情况并测定1日龄SPF鸡感染后不同组织中的病毒载量。结果表明，1日龄SPF鸡感染AV1550株后，表现出精神沉郁、增重减缓、贫血等明显的临床症状，死亡率为53.9%；死亡鸡或观察期结束时存活鸡剖检，可见胸腺萎缩，骨髓变成淡黄色；不同剂量感染后14日，均能引起红细胞压积显著下降；21日时，胸腺病毒载量最高，可达106.7copies/mg 。7日龄SPF鸡感染后，出现增重减缓，高感染剂量（100000EID50）出现贫血，部分鸡出现胸腺萎缩和骨髓病变，但病变率低于30%。14日龄SPF鸡感染后，不引起明显临床症状。研究证实，CAV对SPF鸡的致病性具有明显的日龄依赖性，红细胞压积降低、骨髓病变、胸腺萎缩以及胸腺病毒载量测定可作为评价CAV致病的指标。

Abstract:

In order to evaluate the pathogenicity of the chicken anemia virus AV1550 strain, 1-day-old, 7-day-old and 14-day-old SPF chickens were injected intramuscularly into the chest with different virus titers. At the same time, normal controls were set up and kept in isolation for 21 days. Blood was collected to measure the hematocrit on the 14th day after the challenge. Mortality, body weight changes, and lesions of the thymus, bone marrow, and bursa of Fabricius of all SPF chickens were counted, and the viral loads in different tissues of 1-day-old SPF chickens were measured on the 21st day after the challenge. 1-day-old SPF chickens infected with the AV1550 strain showed obvious clinical symptoms such as depression, slowed weight gain, and anemia, with a mortality rate of 53.9%; necropsy of dead chickens or surviving chickens at the end of the observation period showed thymus atrophy; the bone marrow turned light yellow or pink and the hematocrit was significantly reduced on 14th day after infection at different doses; the thymus virus load is the highest, reaching 106.7 copies/mg on the 21st day. 7-day-old SPF chickens showed weight gain slowed down and anemia occurred at high challenge doses (100,000 EID50), some chickens developed thymus atrophy and bone marrow lesions, but the lesion rate was less than 30%. No obvious clinical symptoms were caused after infection of 14-day-old SPF chickens. The study confirmed that the pathogenicity of CAV to SPF chickens was obviously age-dependent, and reduced hematocrit, bone marrow lesions, thymus atrophy and thymus viral load measurement could be used as indicators of CAV pathogenicity.