第23章病毒的免疫与感染2010版.pptVIP

Entry into the Host Skin - dead cells, therefore cannot support virus replication. Most viruses which infect via the skin require a breach in the physical integrity of this effective barrier, e.g. cuts or abrasions. Many viruses employ vectors, e.g. ticks, mosquitos or vampire bats to breach the barrier. Respiratory tract - In contrast to skin, the respiratory tract and all other mucosal surfaces possess sophisticated immune defence mechanisms, as well as non-specific inhibitory mechanisms (cilliated epithelium, mucus secretion, lower temperature) which viruses must overcome. Entry into the Host Gastrointestinal tract - a hostile environment; gastric acid, bile salts, etc Genitourinary tract（泌尿生殖道） - relatively less hostile than the above, but less frequently exposed to extraneous viruses (?) Conjunctiva（结膜） - an exposed site and relatively unprotected 病毒逃逸免疫应答举例 　 天然干扰素α 、β、γ三型的特性比较 IFN Interferons are proteins produced by cells infected with viruses, or exposed to certain other agents, which protect other cells against virus infection or decrease drastically the virus yield from such cells. Interferon itself is not directly the anti-viral agent, but it is the inducer of one or many anti-viral mechanisms Anti-tumor and regulation of immunity Interferon inducing agents (1) Viruses. (2) dsRNA is a potent inducer, both viral intermediates, and synthetic polyI-C. ? (4) Certain Bacterial infections, and the production of endotoxin. ? (5) Metabolic activators/inhibitors. Mitogens for gamma induction, also a variety of tumor promoters induce IFNs. , in particular PTA-phorbol tetradecanoate acetate, butyrate, dexamethasone 　慢发病毒感染：库鲁病 第四节 抗病毒免疫 一、非特异性免疫 ㈠干扰素（interferon, IFN） 1、定义：是病毒或其他干扰素诱生剂（细菌内毒素、人工合成的双链RNA等）刺激人或动物细胞（巨噬细胞、淋巴细胞和体细胞）所产生的一类分泌性糖蛋白，具有抗病毒、抗肿瘤和免疫调节等多种生物活性。 干扰素的抗病毒特点：①高活性；②广谱性；③选择性；④间接性；⑤种属特异性；⑥不同的敏感性 2．主要特点： ⑴化学性质为糖蛋白；具有抗原性，可刺激机体产生抗干扰素抗体，抗体的形成可能会影响干扰素的生物学活性； ⑵分子量较小，对热比较稳定（4℃可保存较长时间，-20℃可长期保存活性，56℃被灭活）；可被蛋白酶破坏； ⑶干扰素具有广谱抗病毒作用，但只具有抑制病毒作用而无杀灭病毒的作用； ⑷干扰素