THE CHARACTERISTIC OF SO-CALLED FOWL GLIOMA, WHICH IS A UNIQUE CENTRAL NERVOUS SYSTEM NEOPLASM IN ANIMALS CAUSED BY A RETROVIRUS

所谓的鸡神经胶质瘤是以多发结节状胶质瘤样生长为特征，伴有播散性非化脓性脑炎。致病因素仍不清楚。本研究的目的是检查所谓的家禽神经胶质瘤和禽白血病病毒（ALV）之间的关系作为致病候选人。日本矮脚鸡和无特定病原体（SPF）鸡的一日龄雏鸡脑内接种的脑匀浆或培养上清液从受影响的矮脚鸡。接种组中大多数鸡表现为非化脓性脑炎，18只矮脚鸡（82%）和5只鸡（28%）在大脑中出现由星形胶质细胞聚集组成的多发性结节。这些星形胶质细胞化学上具有ALV抗原。通过Southern印迹分析，在来自接种的鸟的脑的DNA和来自接种物的DNA中均检测到ALV前病毒序列。在接种物中检测到直径约100 nm的蝌蚪状颗粒，并在感染的CEF的细胞表面上注意到颗粒的出芽。CEF的env基因序列与ALV-B亚群的env基因最相似（> 92%）。在接种SPF鸡中也观察到非化脓性心肌炎。早期胶质瘤结节的超微结构包括星形胶质细胞的瘤样增生和外膜成纤维细胞的轻度促纤维增生反应。在鸟类的外周神经中很少观察到神经束膜瘤样肿瘤，这种肿瘤也被怀疑与ALV有关。本研究证明，所谓的鸡神经胶质瘤是由ALV的A或B亚群引起的病毒性疾病。我们的研究结果表明，感染后立即出现非化脓性脑炎和心肌炎，这些鸟大多数发展胶质瘤/胶质间充质混合瘤或周围神经肿瘤，因为4个月的年龄。

So-called fowl glioma is characterized by multiple nodular gliomatous growths associated with disseminated nonsuppurative encephalitis. The causal agent is still unknown. The purpose of the present study was to examine the relationship between so-called fowl glioma and an avian leukosis virus (ALV) as the causative candidate. One-day-old chicks of Japanese bantams and specific pathogen-free (SPF) chickens were intracerebrally inoculated with the brain homogenate or culture supernatant from the affected bantam. Most of birds in the inoculated roups showed nonsuppurative encephalitis, and the 18 bantams (82%) and five chickens (28%) developed multiple nodules consisting of aggregations of astrocytes in the cerebrum. These astrocytes immunohistochemically had ALV antigen. By Southern blot analysis, the ALV proviral sequence was detected both in DNA from the brains of the inoculated birds and in DNA from the inoculum. Tadpole-shaped particles, approximately 100 nm in diameter, were detected in the inoculum, and budding of the particles was noted on the cell surface of the infeced CEF. The env gene sequence of the DNA from the CEF was most similar (> 92% identity) to the env gene of ALV-B subgroup. Nonsuppurative myocarditis was also observed in the inoculated SPF chickens. The gliomatous nodules at the initial stage ultrastructurally consisted of neoplastic proliferation of astrocytes and mild desmoplastic reaction of the adventitial fibroblasts. Perineurioma-like neoplasm, which were also suspected to be related with the ALV, was rarely observed in the peripheral nerves of the birds. The present study demonstrated that so-called fowl glioma is a viral disease caused by a subgroup A or B of ALV. Our results suggest that the infected birds reveal nonsuppurative encephalitis and myocarditis immediately after the infection and most of these birds develop glioma/gliomesenchymal mixed tumor or peripheral nerve neoplasm since 4 months of age.