Phylogenetic analysis of avian retroviruses with neuropathogenicity in central nervous system

禽白血病病毒(ALV)主要引起鸡的血液系统肿瘤，而禽类胶质瘤诱导病毒(FGV)属于ALV A亚组，可引起鸡星形细胞瘤。富山A动物园饲养的家禽被认为是日本其他动物园口蹄疫病毒感染的来源。然而，FGV在神经系统获得独特致瘤性的背景和过程尚不清楚。首先，针对FGV的3‘非翻译区设计了特异性引物，建立了套式PCR检测FGV的方法。套式聚合酶链式反应检测A园131只日鸡的FGV感染率为40%，其他3个园129只接受A园蛋或雏鸡的FGV感染率为26%~56%。系统发育分析表明，14株ALV的3‘端非编码区，包括口蹄疫病毒特异性序列，具有较高的序列同源性，且与…有较高的亲缘关系与FGV的关系更密切。其次，检查了与A动物园的任何家禽没有出生关系的鸡的患病率。日本家禽的祖先被认为是在江户时代从东南亚带到日本的。沿着繁殖路径，从印度尼西亚、菲律宾、韩国和日本的264只鸡身上收集了羽毛纸浆和泄殖腔拭子。共检出29只鸡，其中9只为国外鸡群，扩增产物与口蹄疫病毒相应区域的核苷酸同源性为98%。从日本的这些鸡中分离到6株口蹄疫病毒。另一方面，从日本产蛋鸡脑内分离到不同的ALV毒株(Tyms_90)。另有两只日本家禽分别出现神经束膜瘤和神经纤维瘤，并从后者分离到一株具有内源性-1(EV-1)基因的ALV。这些结果表明，FGV的突变株在日本家禽中广泛传播，与A动物园中的禽类无关的少量国内外鸡感染了FGV，日本家禽感染了其他在基因组中含有EV-1基因的ALV，并在神经系统表现出致瘤性。综上所述，推测口蹄疫病毒已出现在A动物园外，部分感染口蹄疫病毒的鸡被带到该园内用于养殖。较少

Avian leukosis virus (ALV) mainly causes hematopoietic neoplasms in chicken, whereas fowl glioma-inducing virus (FGV), which belongs to ALV subgroup A, induces astrocytoma in chickens. Fowls kept in zoological garden A in Toyama have been considered as source for the FGV infection in other Japanese zoological gardens. However, the background and process how FGV acquired the unique oncogenicity in nervous system has not been clarified. At first, to detect FGV using nested PCR, primers were designed specific to the 3' untranslated region (UTR) and the PCR-protocol was established. The prevalence of FGV by the nested PCR in 131 Japanese fowls of zoological garden A was 40% and the prevalences in a total of 129 chickens in three other zoological gardens, which were received the eggs or chicks from the zoological garden A, were 26 to 56%. Phylogenetic analysis revealed that 3' UTRs, including the FGV-specific sequence, of the 14 isolated ALVs showed high sequence identity and a close relati … More onship with that of FGV. Secondly, the prevalence in chickens, which were not related by birth to any fowls of the zoological garden A, was examined. Ancestors of Japanese fowl are thought to be brought to Japan in the Edo era from Southeast Asia. Along the propagation path, feather pulps and cloaca swab were collected from 264 chickens in Indonesia, Philippines, South Korea and Japan. Twenty nine chickens, including 9 birds in the foreign countries, were positive for nested PCR and the amplified products of showed 98% nucleotide sequence homology to the corresponding region of FGV. Six strains of FGV were isolated from these chickens in Japan. On the other hand, different ALV strain (Tyms_90) was isolated from brains of layers affected with fowl glioma and subcutaneous mesenchymal neoplasm in Japan. Another two Japanese fowls in Japan showed perineurioma and neurofibroma, respectively and a strain of ALV having endogenous-1(ev-1) locus was isolated from the latter. These results suggest that mutants of FGV spread in Japanese fowls in Japan, that small number of domestic and foreign chickens unrelated to the birds in the zoological garden A is infected with FGV, and that Japanese fowls are infected with other ALVs having ev-1 locus in the genome and showing oncogenicity in nervous system. In conclusion, it is speculated that FGV has appeared outside of the zoological garden A and a part of FGV-infected chickens were brought to this garden and used for breeding. Less