Joseph Tomy, Kibenge Molly T, Kibenge Frederick S B
Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PEI, Canada C1A 4P3.
J Gen Virol. 2003 Jul;84(Pt 7):1701-1710. doi: 10.1099/vir.0.19087-0.
Infectious salmon anaemia virus (ISAV), a pathogen in marine aquaculture, belongs to the genus Isavirus, family Orthomyxoviridae. There is limited information on how ISAV interacts with host defences. To study ISAV-antibody interactions, virus neutralization (VN) assays were performed in the cell lines CHSE-214, SHK-1 and TO using three strains of ISAV and rabbit or fish anti-ISAV sera. Homologous VN titres of >1 : 1280 in CHSE-214 cells corresponded to titres of only 1 : 80 in the macrophage-like fish cell lines SHK-1 and TO, despite using 1000 and 2000 times less virus, respectively. However, rabbit antiserum to infectious pancreatic necrosis virus (IPNV) had a VN titre of 1 : 10,260 against IPNV in both CHSE-214 and TO cells. Poor ISAV neutralization in TO cells was attributed to Fc receptors mediating virus infectivity, because (1) neutralization by rabbit antiserum to ISAV was increased 48-fold in the presence of staphylococcal Protein A and (2) when using FITC-labelled virus and spectrofluorometry, a significant increase (P=0.018) in the intensity of fluorescence of intracellular virus was observed in assays of virus-antiserum mixtures in the absence of Protein A as compared to those in the presence of Protein A. Neutralization of ISAV with fish antisera was observed only in CHSE-214 cells, as Protein A could not restore neutralization in TO cells. These findings demonstrate for the first time antibody-mediated infection of macrophage-like fish cell lines by a fish virus, ISAV, and, as ISAV in Atlantic salmon targets leukocytic and endothelial cells, this may have implications for ISA pathogenesis and vaccination.
传染性鲑鱼贫血病毒（ISAV）是海水养殖中的一种病原体，属于正黏液病毒科异病毒属。关于ISAV如何与宿主防御系统相互作用的信息有限。为了研究ISAV与抗体的相互作用，使用三株ISAV以及兔或鱼抗ISAV血清，在CHSE-214、SHK-1和TO细胞系中进行了病毒中和（VN）试验。尽管在CHSE-214细胞中同源VN滴度>1:1280，但在巨噬细胞样鱼类细胞系SHK-1和TO中，相应滴度仅为1:80，尽管分别使用的病毒量少了1000倍和2000倍。然而，兔抗传染性胰腺坏死病毒（IPNV）血清在CHSE-214和TO细胞中对IPNV的VN滴度为1:10260。TO细胞中ISAV中和效果不佳归因于Fc受体介导病毒感染性，原因如下：（1）在葡萄球菌蛋白A存在的情况下，兔抗ISAV血清的中和作用增强了48倍；（2）当使用异硫氰酸荧光素标记的病毒和荧光分光光度法时，与存在蛋白A的情况相比，在不存在蛋白A的病毒-抗血清混合物试验中，观察到细胞内病毒荧光强度显著增加（P=0.018）。仅在CHSE-细胞中观察到鱼抗血清对ISAV的中和作用，因为蛋白A无法恢复TO细胞中的中和作用。这些发现首次证明了鱼类病毒ISAV可通过抗体介导感染巨噬细胞样鱼类细胞系，而且由于大西洋鲑鱼中的ISAV靶向白细胞和内皮细胞，这可能对ISA的发病机制和疫苗接种有影响。
