人类免疫不全病毒(HIV)
全名作human immunodeficiency virus
与爱滋病相关的反转录病毒。HIV病毒攻击并逐渐破坏免疫系统，导致受体不能抗御感染。它不会通过偶然的接触传播，而主要通过血液和血制品（例如共用皮下注射的针头或者偶然被感染过的针头刺中）、精液和妇女的阴道分泌液或者乳汁来传播。怀孕的妇女可以通过胎盘将病毒传给胎儿。病毒首先在接近感染部位的淋巴结中繁殖起来。通常约十年後，病毒扩散到全身，这时就会出现症状，标志着爱滋病的开始。多种药物合成的「鸡尾酒」可以推迟症状的发生，但是剂量不足会导致抗药性。像其他的病毒一样，HIV病毒也需要一个主体细胞来繁殖。它攻击辅助T细胞并感染其他的细胞。一次快速的突变率可以帮助它既击垮免疫系统又对抗药物治疗。还没有疫苗或治癒的方法。在性方面不要滥交，使用安全套或其他的手段来避免通过性来传播疾病，还要避免共用针头，在有些地区采取这些措施後已经降低了感染率。
English version：
HIV
Retrovirus associated with AIDS. HIV attacks and gradually destroys the immune system, leaving the host unprotected against infection. It cannot be spread through casual contact, but instead is contracted mainly through exposure to blood and blood products (e.g., by sharing hypodermic needles or by accidental needle sticks), semen and female genital secretions, or breast milk. A pregnant woman can pass the virus to her fetus across the placenta. The virus first multiplies in lymph nodes near the site of infection. Once it spreads through the body, usually about 10 years later, symptoms appear, marking the onset of AIDS. Multi-drug “cocktails” can delay onset, but missing doses can lead to drug resistance. Like other viruses, HIV needs a host cell to multiply. It attacks helper T cells and can infect other cells. A rapid mutation rate helps it foil both the immune system and treatment attempts. No vaccine or cure exists. Abstinence from sex, use of condoms or other means to prevent sexual transmittal of the disease, and avoidance of needle sharing have reduced infection rates in some areas.
