Retrovirus

Retroviridae –Retrovirus HTLV (human T-cell lymphotropic virus) –Lentivirus HIV

Common Properties Spherical, 100nm; enveloped Two copies of +ssRNA Reverse transcriptase and Integrase Replication: DNA intermediate Structure genes: gag, pol, env genes Tissue tropism: determinated by receptor Budding

Human Immunodeficiency Virus (HIV)

Clinical case A 32-year-old ex-heroin addict had a mononucleosis-like illness for 2 weeks, occasional nigh sweats and fever for 3 years and then presented with thrush, cytomegalovirus retinitis, and pneumocystis pneumonia. His CD4 T cell count is less than 200/ul.

HIV CD4+ T helper lymphocyte AIDS (acquired immunodeficiency disease syndrome) –Fatal –40 million –1.5 million (2004); 10 million (2010)

Biological Properties Structure

Biological Properties Replication –Receptor: CD4 antigen –Main host cell: CD4+ T4 helper cells –Co-receptor: CCR5, CXCR4

Biological Properties Typing and Variation –HIV-1 –HIV-2 –High variation gp120

Pathogenicity Source: human Transmission –Sexual transmission –Blood transmission –Vertical transmission –Route not involved in transmission: close personal contact

Clinical Findings Acute infection Clinical latency AIDS related complex AIDS –Kaposi's sarcoma –Opportunistic infection

Pathogenesis Virus tropism for CD4+ T cells and macrophages Reduction in the number of CD4+ T cells

Pathogenesis CD4+ T cells and memory cells –Lytic infection of CD4 T cells –Syncytia formation –CTL effect on the viral proteins on the cell surface –Free gp120-CD4 Ag –Auto-immune defense-gp120 –Apoptosis –Cellular latency: T4 cells CD8+ cells: apoptosis

Microbiological Diagnosis Serology Genomics Viral particles

Treatment and Prevention Prevention –Education –Vaccine: no effective in practice Treatment –Highly active anti-retroviral therapy (HAART) 高效抗反转录病毒治疗