A few words on HIV The virus = HIV The disease = AIDS (Aquired Immunodeficiency Syndrome) First recognized clinically in 1981 By 1992, it had become.
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The virus = HIV
The disease = AIDS (Aquired Immunodeficiency Syndrome)
First recognized clinically in 1981
By 1992, it had become the major cause of death in individuals 25-44 years of age in the States.
Human Immunodeficiency Virus (HIV)
Till Dec 2007: 25 million people died of AIDS (20 million in 2002)
People living with HIV/AIDS in 2007 33.2 million
Africa has 12 million AIDS orphans (2007)
8 out of every 1000 adults of age 15-49 in the world population (2007; 1 out of 20 in Sub-Saharan Africa)
HIV Statistics
The territories south to the Sahara. In the past the term ‘Black Africa’ has also been used to refer to the same region however today it is obsolete due to its ”politically incorrectness”
Sub-Saharan Africa
Species = HIVGenus = LentivirusesFamily = Retroviridae
Lentiviruses have long incubation time, and are thus called “slow viruses”.
HIV is a lentivirus
In 1986, a distinct type of HIV prevalent in certain regions of West Africa was discovered and was termed HIV type 2.
Individuals infected with type 2 also had AIDS, but had longer incubation time and lower morbidity (# of cases/population size).
HIV-1 and HIV-2
•Primates: ~350 species and ~13 families
•The smallest living primate is the mouse lemur which weighs around 35g; the largest is the gorilla, weighing up to around 200 kg.
Primates
•Most primate species live in the tropics or subtropics, although a few, most notably humans, also inhabit temperate regions. •Except for a few terrestrial species, primates are arboreal. Some species eat leaves or fruit; others are insectivorous or carnivorous.
Arbor = tree in Latin
Primates
Prosimians(Strepsirhines)
Tarsiers
New world monkeys(Platyrrhines)
Catarrhines
Gibbons
Hominidae
Old world monkeys
Haplorhines = Higher primates =Monkeys+Apes
The primate tree
Great apes
Apes
Hominidae is the primate family, which includes the extant species of humans, chimpanzees, gorillas, and orangutans, as well as many extinct species.
The members of the family are called hominids. The family is also called “great apes”.
Great apes
Originally non-human great apes were called Pongidae. However, this original definition suggests that Pongidae is a monophyletic family – which is not the case.
Great apes
HIV-1 is most similar in sequence and genomic organization to viruses found in chimpanzees (SIVcpz).
HIV-1 and SIVcpz evolutionary relationships
Five lines of evidence have been used to substantiate zoonotic transmission of primate lentivirus:
1. Similarities in viral genome organization;2. Phylogenetic relatedness;3. Prevalence in the natural host;4. Geographic coincidence;5. Plausible routes of transmission.
Zoonotic transfer
Zoonotic transfer: The transmission of a disease from an animal host to a human.
For HIV-2, a virus (SIVsm) that is genomically indistinguishable and closely related phylogenetically was found in substantial numbers of wild-living sooty mangabeys whose natural habitat coincides with the epicenter of the HIV-2 epidemic
Zoonotic transfer of HIV-2 from SIVsm
Close contact between sooty mangabeys and humans is common because these monkey are hunted for food and kept as pets.
No fewer than six independent transmissions of SIVsm to humans have been proposed.
Zoonotic transfer of HIV-2 from SIVsm
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