Role of lymphoid organ spheroids in chronic Taura syndrome virus (TSV) infections in Penaeus vannamei
Role of lymphoid organ spheroids in chronic Taura syndrome virus (TSV) infections in Penaeus vannamei
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DOI：
10.3354/dao038093
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发表时间：
1999-11-08
影响因子：
1.4
通讯作者：
White, BM
中科院分区：
文献类型：
--
作者：
Hasson, KW;Lightner, DV;White, BM
病变的发展记录在南美白对虾青少年与实验诱导的，慢性期桃拉综合征病毒（TSV）感染，常规组织学和原位杂交，在48周的时间过程中的研究。在组织学上，凡纳滨对虾TSV慢性化的定义特征包括不存在急性期组织学病变、异位球体发育的低发生率以及快速连续的淋巴器官球体（LOS）形成和形态发生。通过光学显微镜鉴定了三种不同的LOS形态型（A型、B型和C型）。最早可检测到的LOS，A型，似乎是从激活的LO小管吞噬细胞，隔离TSV。随后的LOS，B型，包含坏死细胞，这些细胞在急性期感染后长达32周的原位杂交中始终呈TSV阳性。这些持续的、长期的感染表明TSV复制发生在B型LOS内，这符合慢性感染的定义。终末C型LOS始终被发现为TSV阴性，其特征在于细胞具有浓缩的嗜碱性细胞核、总体细胞大小减小和进行性萎缩，导致降解而无炎症反应。这些细胞变化是凋亡细胞的特征，表明TSV感染的LOS细胞自毁，导致TSV消除。TSV感染似乎有3种潜在的结果：（1）病毒可能继续在LOS细胞内复制，（2）它可能被LOS细胞消除，或（3）病毒复制和消除可能同时发生，导致持续感染。异位球状体的TSV诱导和观察的附属物内的被盖腺通常占据的网站，这表明他们从血淋巴传播的吞噬细胞或固定的吞噬细胞与腺体。我们认为，这些细胞团产生的迁移和/或居民吞噬细胞转化的慢性病毒感染或非自我物质太小的血细胞包囊。球状体的发展代表了一个未开发的和重要的分支的细胞介导的免疫反应的对虾的可能性进行了讨论。
Lesion development was documented in Penaeus vannamei juveniles with experimentally induced, chronic phase Taura syndrome virus (TSV) infections, by both routine histology and in situ hybridization, during a 48 wk time course study. Histologically, the defining characteristics of TSV chronicity in P. vannamei Include the absence of acute phase histological lesions, a low prevalence of ectopic spheroid development, and rapid successive lymphoid organ spheroid (LOS) formation and morphogenesis. Three distinct LOS morphotypes (Types A, B, and C) were identified by light microscopy. The earliest detectable LOS, Type A, appeared to evolve from activated LO tubule phagocytes that had sequestered TSV. The succeeding LOS, Type B, contained necrotic cells that were consistently TSV-positive by in situ hybridization for up to 32 wk following an acute phase infection. These persistent, long-term infections suggested that TSV replication occurred within Type B LOS, and this satisfied the definition of a chronic infection. The terminal Type C LOS were consistently found to be TSV-negative and characterized by cells with condensed basophilic nuclei, a reduction in overall cell size, and progressive atrophy leading to degradation without an inflammatory response. These cellular changes are characteristic of apoptotic cells, suggesting that TSV-infected LOS cells self-destruct, resulting in TSV elimination. TSV infections appear to have 3 potential outcomes: (1) the virus may continue to replicate within LOS cells unchecked, (2) it may be eliminated by LOS cells, or (3) viral replication and elimination may occur concurrently, resulting in persistent infections. Ectopic spheroids were TSV-induced and observed in sites normally occupied by tegmental glands within appendages, suggesting that they developed from either hemolymph-borne phagocytes or fixed phagocytes associated with the gland. We suggest that these cellular masses arise from migrating and/or resident phagocytes transformed in response to chronic viral infections or non-self substances too small for hemocyte encapsulation. The possibility that spheroid development represents an unexplored and significant branch of the cell-mediated immune response of penaeid shrimp is discussed.