Final Research Paper
HIV: Introspective Overview
What is HIV?
Figure 1 HIV 1 virus electron micrograph, (Goldsmith)
Human immunodeficiency virus (HIV) is a retrovirus of the lentivirus genus. HIV attacks the immune system by invading and destroying certain white blood cells such as helper T cells (mainly CD4+ T cells), dendritic cells, and macrophages. The infection and destruction of the CD4+ T cells takes place through three methods: The direct viral killing of the infected cells, the apoptosis (programmed cell death) of infected cells, and the killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that ...view middle of the document...
These subtypes are lettered A, B, C, D, F, G, H, J and K. It is also noteworthy that on occasion two viruses of different subtypes meet in the cell of an infected person and, in a method similar to procreation, mix together their genetic material to create a new hybrid virus (sometimes called "viral sex"). The majority of these hybrid strains created by this process do not survive for long. The strains that do survive and infect more than one person are known as "circulating recombinant forms" or CRFs. Due to the fact that viral mutation and recombination shall continue, the future discovery of new HIV subtypes and CRFs is a certainty and the epidemic of current subtypes will persist (Noble, AVERT).
Through the study of the subtypes of some of the earliest known instances of infection, clues about the time at which HIV first appeared in humans, and its subsequent evolution, can be provided. A blood sample taken from an adult male living in what is now the Democratic Republic of the Congo in 1959, a lymph node sample taken in 1960 from an adult female (also from the Democratic Republic of the Congo), and tissue samples taken from both an American teenager who died in St. Louis in 1969 and from a Norwegian sailor who died around 1976 are four of the earliest found cases of HIV. An analysis of the blood sample from 1959, suggested that HIV was introduced into humans around the 1940s or the early 1950s. However, a study in 2008 dated the origin of HIV to between 1884 and 1924. After a comparison of the viral sequence from 1959 to the sequence discover in 1960, researchers found a major genetic difference between them. Such a discovery illustrates diversification of HIV occurred long before the AIDS pandemic was recognized (AVERT).
Transmission of HIV
The majority of HIV infections occur through sexual contact. Sexual transmission occurs when the infected sexual secretions of an infected person come into contact with the genital, oral, or rectal mucous membranes of someone who is not infected.
Blood-linked transmission takes place when sharing needles and/or syringes with someone who is infected (primarily for drug injection), or through transfusions of infected blood or blood clotting factors from someone who is already infected. However, in countries where blood is screened for HIV antibodies, infection through blood transfusion is extremely rare.
Babies born to HIV-infected women may become infected. The infection occurs through exposure to the mother’s blood and vaginal secretions during labor and delivery, or, in less common cases, the HIV virus crossing the placenta and infecting the baby before birth.
On the worldwide spectrum, according to estimates from the UNAIDS 2009 AIDS Epidemic Update, around 31.3 million adults and 2.1 million children were living with HIV at the end of 2008, with the highest concentration of cases in sub-Sahara Africa, with an estimated 22.4 million adults and children....