HIV mainly exist in the source of the blood, semen, vaginal secretions, chest water, cerebrospinal fluid, amniotic fluid, breast milk, and other body fluids. Main transmission routes: sexual transmission (including unsafe sex, heterosexual and bisexual sexual contact); blood transmission (including sharing needles, intravenous drug use, unsafe normative interventional medical operation, tattoos, etc.) ; mother-to-child transmission (including intrauterine infection, childbirth and lactation propagation)².
HIV mainly affects the body's immune system, including CD4⁺ T lymphocytes, mononuclear macrophages and dendritic cells, etc. Eventually leading to human cell immune function defects due to CD4⁺ T cells decline and causing all sorts of opportunistic infections and tumors.

From acute HIV infection to end-stage AIDS period is a relatively long and complicated process. According to the clinical manifestations, symptoms and signs, the whole process of HIV infection can be divided into acute infection period, asymptomatic period and AIDS period.
Acute infection period is usually 2-4 weeks after the primary infection with HIV. Most patients have mild symptom and can relieve 1-3 weeks after. The most common clinical manifestation is fever and may be accompanied with sore throat, night sweats, nausea, vomiting, diarrhea, skin rash, joint pain, swollen lymph nodes, and nervous system symptoms. Asymptomatic period: commonly last for 6 to 8 years. Because of HIV virus replication, human immune system is impaired and CD4⁺ T cells gradually decline. AIDS period is the end stage of HIV infection, during which CD4⁺ T cells count is mostly less than 200/ul and plasma viral load increase significantly. The major clinical manifestations are HIV related symptoms, signs and all kinds of opportunistic infections and tumors².

Once diagnosed of HIV infection, regardless of the CD4⁺ T cells count, patients are proposed to initiate therapy immediately. If patients have serious opportunistic infections and in acute phase of previous chronic disease, treatment should be started after opportunistic infection control. Lifelong treatment should be required after starting highly active antiretroviral therapy (HAART). The recommend regimen for naïve patients is two NRTIs (backbone) plus a third agent. A third agent can be NNRTIs or boosted PI or INSTIs; Patients with good economic condition can choose monolithic compound (STR)².
  

1.  http://www.chinaaids.cn/jkzt/mcjs/200903/t20090317_1164629.htm
2.  Chinese Guidelines for diagnosis and treatment of HIV/AIDS (2018)