Daily Health Advices

Posts Tagged ‘RNA’

The virion (particle infectivity) of HIV differs in structure from other retroviruses previously known. It is about 120 nm in diameter and is roughly spherical. Its genome is based physically in two  RNA copies (its sequence is as the corresponding messenger RNA) clothed by proteins, which form the nucleocapsid, and enclosed within a conical capsid, in turn surrounded by a shell of lipid bilayer , stolen first to the plasma membrane of the host cell, but endowed with self proteins. Inside the envelope there are enzymes in the virus, including a reverse transcriptase, an integrase – within the capsid – and a protease. The former is necessary for reverse transcription, DNA synthesis taking the viral RNA as template, and the second for the DNA so produced is integrated into the human genome became provirus.

It was discovered and considered as the agent of the emerging AIDS epidemic by Luc Montagnier’s team in France in 1983. The virion is spherical, equipped with an envelope and a capsid protein. The genome of a chain of single-stranded RNA to be temporarily copied into DNA in order to multiply and integrate into the genome of the cell it infects. The protein antigens of the outer casing are coupled specifically with membrane proteins of infected cells, especially T4 lymphocytes.

The process of converting RNA into DNA is a major characteristic of retroviruses and is performed by reverse transcriptase enzyme actions. With the demonstration of reverse transcriptase, began in the 1970s the search for human retrovirus, which in 1980 allowed the isolation of leukemia virus of adult T cells, HTLV-I (R. Gallo and al.)

HIV has a diameter of about 100 nanometers. Its outside is the “deck”, a membrane that originally belonged to the cell where the virus emerged. On the cover is a virus protein, gp41, or “transmembrane glycoprotein. Gp41 is connected to gp120, which can bind to the CD4 receptor located on the surface of T lymphocytes to penetrate them. The nucleus has a “capsid”, composed by the p24 protein. Inside is the RNA, the form of HIV genetic information.

In December 2006, according to the World Health Organization, 39.5 million people with HIV worldwide, of which 24.7 million lived in sub-Saharan Africa.