胚胎接种和1日龄肌肉注射鸡传染性贫血病毒SDLY08株的致病性比较

The Comparison of Pathogenicity between Intramuscular Inoculation in 1-day-old Chicks and Intravenous Inoculation in Embryos with CAV SDLY08 Strain

旨在比较鸡传染性贫血病毒(CAV)SDLY08株不同感染途径对感染鸡群的致病性、免疫抑制以及水平传播能力的强弱。将试验SPF鸡群分为四组:胚胎静脉接种10胚龄鸡胚组,肌肉接种1日龄SPF鸡组,接触感染组和对照组。分别于14日龄和42日龄称量各组SPF鸡体重,检测免疫器官指标、血液指标和CAV抗体水平。14日龄常规免疫禽流感病毒(AIV-H9N2)灭活苗和新城疫病毒(NDV)灭活苗,并于28、35和42日龄检测对AIVH9N2和NDV疫苗的抗体滴度。结果表明,与对照组相比,胚胎静脉注射组、肌肉注射组均可表现出明显生长抑制,诱发免疫器官胸腺严重萎缩和血液红细胞、白细胞数显著下降,显著降低对NDV和H9N2灭活疫苗免疫后的抗体水平(P<0.05),但这二种接种途径间指标的差异不显著(P>0.05)。然而,胚胎静脉接种可引起一定的死亡率(4/25),肌肉接种没有引起死亡(0/25)。相对于对照组,接触感染组鸡也表现明显的生长迟缓和免疫抑制(P<0.05),但多数指标低于直接感染组的鸡(P<0.05)。在42d时,所有直接感染鸡血清均为CAV抗体阳性,接触感染组的抗体阳性率也达95%,说明SDLY08株有非常强的水平传播能力。

This experiment was conducted to compare the pathogenicity,immune suppression,and the horizontal transmission capacity between intramuscular inoculation in 1-day-old chicks and intravenous inoculation in embryos with chicken anemia virus(CAV)strain SDLY08.SPF chickens were divided into four groups:chickens from embryos inoculated intravenously with CAV at 10 days of incubation,1day-old SPF chicken inoculated with CAV intramuscularly,contact infection group and the control group.The Ratios of thymus and the Bursa to body weigh,indexes of hematology,and CAV antibody levels were examined at 14 and 42days of age.All groups were immunized with inactivated vaccines to avian influenza virus(AIV-H9N2)and Newcastle disease virus(NDV)at 2weeks of age,and antibody titers to AIV-H9N2 and NDV were tested at 28,35 and 42days of age.Results indicated that both CAV-inoculated groups showed growth retardation,severe atrophy of thymus,significant decrease of HI antibody titers to NDV and H9N2,lower levels ofred blood cells,white blood cells and the haematocrit(P<0.05)when compared to the control group,but there was no significant difference in these parameters between chicken groups inoculated with different routes(P<0.05).However,chicken group with embryo inoculation demonstrated some mortality(4/25)by 28 days of age and there was no mortality(0/25)in the group inoculated muscularly.Contact infection also induced growth retardation,immunosuppression and anemia,but not as strong as direct inoculation with CAV(P<0.05).At 42 days of age,all chickens inoculated muscularly at 1day or in embryos developed antibodies positive to CAV,and 95%of in contact infected birds were also antibody positive to CAV,indicating its effective horizontal transmission.