微生物感染是否总是有害？

Is microbial infection always harmful？

微生物感染（包括寄生虫感染）可以打破机体自身免疫耐受，导致免疫系统功能紊乱，从而诱发机体出现自身免疫症状。分子模拟作为外来抗原与自身抗原之间的一种常见现象，被认为在自身免疫性疾病的发病中起着至关重要的作用。然而，大量研究表明，许多微生物中的模拟抗原肽非但不会诱导机体出现自身免疫症状，甚至还可以作为一种天然的修饰抗原肽，对再次受到相似抗原入侵的机体从抗体水平或者T细胞水平起到一定的保护作用。本文立足于分子模拟的机制，综述了微生物感染后被感染机体可能的预后。

It is possible for microbial infection （including parasitic infection） to disrupt the balance of autoimmune tolerance,result in the dysfunction of immune system, and make the organism encountered with the attack of the aotoimmune disease. As one of the common places between foreign antigens and autoantigens, molecular mimicry is believed to play a vital role in the pathogenesis of autoimmune diseases. However,a large number of studies suggest that rather than inducing various symptoms of autoimmune diseases, many infection of microorganisms covered with mimic peptide of the autoantigen may even protect the infected organism from the disease at the level of antibodies or T cells when the analogous antigen invaded again. The present paper reviews the possible prognosis after microbial infection based on molecular mimicry.