Origin of the viruses and their evolutionary history

Abstract

The human immunodeficiency virus (HIV) originated via a process of natural evolution, probably emerging from the primate SIV reservoir into the human population via hunting or other behavior involving contact with the blood of these animals. A particular subspecies of chimpanzee, the Pantroglodytes troglodytes, has been recognized as the most probable original source of human infection. Analysis of viral genetic sequences has allowed researchers to estimate that the native strain of HIV originated in 1931. In the West, sexual behavior patterns and injecting drug use subsequently began the epidemic. Polymerase Chain reaction (PCR), is a technique in molecular biology that amplifies a specific region of deoxyribonucleic acid (DNA), and has been useful in the molecular characterization of viruses. The Variola major, the virus that causes the smallpox, lethal virus in the 30% of the cases, was eradicated in 1979 in the human species, thanks to a capillary vaccination on global scale. It has now become a historical footprint in two known laboratories, one in the USA and another in Russia, leaving no obvious source for its often-theorized use as a bioterrorist weapon. Nevertheless, mass vaccination against smallpox continues to be a leading initiative in Western countries to guard against bioterrorist attack.