Week 6: HIV

I.              Origin

a.    Zoonotic

                                              i.     HIV-1

1.    Worldwide, highly virulent

                                            ii.     HIV-2

1.    West Africa, slower, less virulent

b.    Virus Type

                                              i.     Lentivirus

1.    Lenti=slow

                                            ii.     Retrovirus

1.    RNA-DNA

2.    Transcriptase

c.    1981

                                              i.     Discovered in US

                                            ii.     Kaposi’s Sarcoma

d.    1983

                                              i.     Discovery of HIV

                                            ii.     Credited to Luc Montagnier and Robert Gallo

II.            Transmission

a.    Possibilities

                                              i.     Sexual contact

                                            ii.     Blood on blood

                                          iii.     Tissue transplant

                                           iv.     IV sharing

                                             v.     Trans placental

                                           vi.     Accidental healthcare infection

b.    Infection aided by STDs

c.    CD4 T lymphocytes

III.         Structure and Replication

a.    GP 120 Attachment and entry

b.    P24 core antigen

IV.         Natural History

a.    Antigen presenting dendritic cells bind the virus

b.    Stages

                                              i.     Acute infection (flu like or mono symptoms)

                                            ii.     Strong cell mediated and humoral immune defense

                                          iii.     Clinical latency

                                           iv.     Loss of CD 4+ T4 cells

                                             v.     Other cell type migration

c.    High initial viral load phase=often missed

d.    AIDS

                                              i.     Profound immunosuppression

                                            ii.     High viral loads, low CD4 counts <200

                                          iii.     Presence of opportunistic infection

                                           iv.     Positive HIV test

                                             v.     Paradox: High viral load leads to low CD4, but spread by CD4

V.           Lab Testing

a.    First test= high sensitivity, many false positives

b.    Second test= High Specificity

c.    Rapid tests = important for walk in clinics

d.    Testing is done in newborn clinics