Cham Tat-Chuan, Chang Yen-Chen, Tsai Pei-Shiue, Wu Ching-Ho, Chen Hui-Wen, Jeng Chian-Ren, Pang Victor Fei, Chang Hui-Wen
School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
Institute of Veterinary Clinical Science, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
Microbiol Immunol. 2017 Aug;61(8):318-327. doi: 10.1111/1348-0421.12498.
Unlike for serotype II feline coronaviruses (FCoV II), the cellular receptor for serotype I FCoV (FCoV I), the most prevalent FCoV serotype, is unknown. To provide a platform for assessing the pattern by which FCoV I attaches to its host receptor(s), HEK293 cell lines that stably express the ectodomains of the spike (S) proteins derived from a FCoV I feline enteric coronavirus strain UU7 (FECV UU7) and a feline infectious peritonitis virus strain UU4 (FIPV UU4) were established. Using the recombinant S proteins as probes to perform S protein affinity histochemistry in paraffin-embedded tissues, although no tissue or enteric binding of FECV UU7 S protein was detected, it was found that by immunohistochemistry that the tissue distribution of FIPV UU4 S protein-bound cells correlated with that of FIPV antigen-positive cells and lesions associated with FIP and that the affinity binding of FIPV UU4 S protein on macrophages was not affected by enzymatic removal of host cell-surface sialic acid with neuraminidase. These findings suggest that a factor(s) other than sialic acid contribute(s) to the macrophage tropism of FIPV strain UU4. This approach allowed obtaining more information about both virus-host cell interactions and the biological characteristics of the unidentified cellular receptor for FCoV I.
与II型猫冠状病毒（FCoV II）不同，I型猫冠状病毒（FCoV I）是最常见的FCoV血清型，其细胞受体尚不清楚。为了提供一个平台来评估FCoV I与其宿主受体结合的模式，建立了稳定表达源自FCoV I猫肠道冠状病毒株UU7（FECV UU7）和猫传染性腹膜炎病毒株UU4（FIPV UU4）的刺突（S）蛋白胞外域的HEK293细胞系。使用重组S蛋白作为探针在石蜡包埋组织中进行S蛋白亲和组织化学，尽管未检测到FECV UU7 S蛋白的组织或肠道结合，但通过免疫组织化学发现，FIPV UU4 S蛋白结合细胞的组织分布与FIPV抗原阳性细胞以及与FIP相关的病变的分布相关，并且用神经氨酸酶酶促去除宿主细胞表面唾液酸不会影响FIPV UU4 S蛋白在巨噬细胞上的亲和结合。这些发现表明，除唾液酸外的其他因素促成了FIPV株UU4的巨噬细胞嗜性。这种方法有助于获得更多关于病毒-宿主细胞相互作用以及FCoV I未鉴定细胞受体生物学特性的信息。
