Origin of the Viruses and Their Evolutionary History: Recent Advancement

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.