HIV mainly invasion CD4+ T lymphocytes and macrophages. In the previous stages ol infection, immune systems can clear out replicated virus in time and without any symptom.

• HIV主要侵犯CD_4~+的淋巴细胞和单核巨噬细胞，在感染最初的几年中，免疫系统能及时清除大量复制的病毒，感染者可不表现出任何症状；