Mo I P, Brugh M, Fletcher O J, Rowland G N, Swayne D E
Department of Veterinary Pathology, College of Veterinary Medicine, University of Georgia, Athens 30605, USA.
Avian Dis. 1997 Jan-Mar;41(1):125-36.
Pathologic changes and distribution of viral antigen as determined by immunohistochemistry were compared among 4-wk-old specific-pathogen-free chickens inoculated intratracheally with avian influenza virus (AIV) isolates of either low or high pathogenicity. Viruses of low pathogenicity, previously characterized as mildly pathogenic (MP), included A/chicken/Pennsylvania/21525/83 (H5N2) (MP-Penn) and A/chicken/Alabama/7395/75 (H4N8) (MP-Alab). Viruses of high pathogenicity included A/chicken/Pennsylvania/1370/83 (H5N2), A/chicken/Victoria/A185/85 (H7N7), and A/turkey/Ontario/7732/66 (H5N9). Extremely variable clinical signs ranging from mild respiratory distress to high mortality were present among chickens inoculated with these viruses. Chickens inoculated with highly pathogenic (HP) virus had histologic lesions of necrosis and inflammation in cloacal bursa, thymus, spleen, heart, pancreas, kidney, brain, trachea, lung, and skeletal muscle, whereas chickens inoculated with MP virus had histologic lesions most frequently in lung and trachea or lacked histologic lesions. Immunospecific staining for avian influenza viral proteins was most common in cells within heart, lung, kidney, brain, and pancreas of chicken inoculated with HP viruses, but immunospecific staining was present only and infrequently in trachea and lung of chickens inoculated with MP-Penn AIV. MP-Alab did not produce lesions nor have viral antigen in inoculated chickens but did produce serologic evidence of infection. The pattern of organ involvement and viral antigen distribution in chickens intratracheally inoculated with HP AIV isolates indicates a common capability to spread beyond the respiratory tract and confirms the pantrophic replicative, pathobiologic, and lethal nature of the viruses. However, variability in severity and lesion distribution exists between different HP AIVs. By contrast, MP viruses had the ability to replicate in respiratory or enteric tracts or both and produce lesions within the respiratory tract. These MP viruses exhibited a restricted ability to replicate or produce lesions or both in nonrespiratory or nonenteric tissues; such effects were associated with only sporadic deaths.
通过免疫组织化学法确定的病理变化和病毒抗原分布，在4周龄的无特定病原体鸡中进行了比较，这些鸡经气管内接种低致病性或高致病性禽流感病毒（AIV）分离株。低致病性病毒，先前被鉴定为轻度致病性（MP），包括A/鸡/宾夕法尼亚/21525/83（H5N2）（MP-宾夕法尼亚）和A/鸡/阿拉巴马/7395/75（H4N8）（MP-阿拉巴马）。高致病性病毒包括A/鸡/宾夕法尼亚/1370/83（H5N2）、A/鸡/维多利亚/A185/85（H7N7）和A/火鸡/安大略/7732/66（H5N9）。接种这些病毒的鸡出现了从轻度呼吸窘迫到高死亡率的极其多样的临床症状。接种高致病性（HP）病毒的鸡在泄殖腔法氏囊、胸腺、脾脏、心脏、胰腺、肾脏、大脑、气管、肺和骨骼肌中出现坏死和炎症的组织学病变，而接种MP病毒的鸡组织学病变最常出现在肺和气管中，或者没有组织学病变。禽流感病毒蛋白的免疫特异性染色在接种HP病毒的鸡的心脏、肺、肾脏、大脑和胰腺细胞中最为常见，但在接种MP-宾夕法尼亚AIV的鸡的气管和肺中仅偶尔出现免疫特异性染色。MP-阿拉巴马在接种的鸡中未产生病变，也没有病毒抗原，但确实产生了感染的血清学证据。经气管内接种HP AIV分离株的鸡的器官受累模式和病毒抗原分布表明，这些病毒具有扩散到呼吸道以外的共同能力，并证实了病毒的泛嗜性复制、病理生物学和致死性。然而，不同的HP AIV之间在严重程度和病变分布上存在差异。相比之下，MP病毒能够在呼吸道或肠道或两者中复制，并在呼吸道内产生病变。这些MP病毒在非呼吸道或非肠道组织中复制或产生病变或两者的能力有限；这种影响仅与零星死亡有关。
