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El virus de la inmunodeficiencia humana (VIH) es un lentivirus (de la familia Retrovertida), causante del síndrome de inmunodeficiencia adquirida (sida). Fue descubierto y considerado como el agente de la naciente epidemia de sida por el equipo de Luc Montagnier en Francia en 1983. El virión es esférico, dotado de una envoltura y con una cápside proteica. Su genoma es una cadena de ARN monocatenario que debe copiarse provisionalmente al ADN para poder multiplicarse e integrarse en el genoma de la célula que infecta. Los antígenos proteicos de la envoltura exterior se acoplan de forma específica con proteínas de la membrana de las células infectables, especialmente de los linfocitos T CD4.
El proceso de conversión de ARN en ADN es una característica principal de los retrovirus y se lleva a cabo mediante acciones enzimáticas de transcriptasa inversa. Con la demostración de la existencia de la transcriptasa inversa, se inició en la década de 1970 la búsqueda de los retrovirus humanos, que permitió el aislamiento en 1980 del virus de la leucemia de células T del adulto, HTLV-I (R. Gallo y cols.)
El VIH tiene un diámetro de aproximadamente 100 nanómetros. Su parte exterior es la "cubierta", una membrana que originalmente pertenecía a la célula de donde el virus emergió. En la cubierta se encuentra una proteína del virus, la gp41, o "glicoproteína transmembrana". Conectada a la gp41 está la gp120, la cual puede unirse al receptor CD4 localizado en la superficie de los linfocitos T para penetrar en ellos. El núcleo tiene la "cápside", compuesta por la proteína p24. En su interior está el ARN, la forma de información genética del VIH.
En diciembre de 2006, de acuerdo con la Organización Mundial de la Salud, había 39,5 millones de personas con VIH en el mundo, de las cuales 24,7 millones vivían en África Subsahariana.
El virus de inmunodeficiencia humana forma parte del género Lentivirus.1 Estos constituyen un grupo dentro de la familia Retroviridae.2 Los virus de este grupo poseen propiedades morfológicas y biológicas comunes. Varias especies son atacadas por los lentivirus, cuya característica principal consiste en un período de incubación prolongado que desemboca en enfermedad después de varios años.
Desde su ingreso a la célula hospedadora, la cadena simple de ácido ribonucleico (ARN) viral comienza su transformación en una doble cadena de ácido desoxirribonucleico (ADN) por acción de la enzima transcriptasa inversa que forma parte del virus. La integrasa y otros cofactores actúan para que el ADN del virus se fusione con el ADN de la célula hospedadora4 a través de la transcripción en el genoma de la célula que aloja al virus. De esta manera, la célula queda infectada por el virus. Después de este proceso, los lentivirus reaccionan de dos maneras posibles: puede ocurrir que el virus entre en latencia mientras la célula infectada continúa en funciones, o bien, que el virus comience a replicarse activamente y libere viriones capaces de infectar otras células.
Existen dos tipos del VIH, llamados VIH-1 y VIH-2. El primero de ellos corresponde al virus descubierto originalmente, que recibió los nombres de LAV y HTLV-III por parte de los dos equipos que estaban investigando el agente etiológico del sida durante la primera mitad de la década de 1980. El VIH-1 es más virulento e infeccioso que el VIH-25 y es el causante de la mayoría de infecciones por VIH en el mundo. El VIH-2 es menos contagioso y por ello se encuentra confinado casi exclusivamente a los países de África occidental.
English
The human immunodeficiency virus (HIV) is a lentivirus (family Retrovertida), which causes acquired immunodeficiency syndrome (AIDS). It was discovered and considered as the agent of the emerging AIDS epidemic by the team of Luc Montagnier in France in 1983. The virion is spherical, endowed with an envelope and with a protein capsid. Its genome is a single-stranded RNA strand to be copied temporarily to DNA to replicate and integrate into the genome of the cell it infects. Protein antigens of the outer casing are coupled specifically with membrane proteins of infectable cells, especially of T lymphocytes CD4.
The conversion process from RNA into DNA is a principal feature of retroviruses and is carried out through reverse transcriptase enzymatic actions. With the demonstration of reverse transcriptase, began in the 1970 search for human retroviruses, which allowed the isolation in 1980 of leukemia virus of adult T cell, HTLV-I (R. Gallo and cols.)
HIV has a diameter of approximately 100 nanometers. Its outer part is the "cover", a membrane that originally belonged to the cell where the virus emerged. On deck is located a virus protein, gp41, or "transmembrane glycoprotein". Connected to the gp41 is gp120, which can bind to the CD4 receptor located on the surface of T lymphocytes to penetrate them. The core has a "capsid", composed by protein p24. In its interior 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.
The human immunodeficiency virus is part of the genus Lentivirus.1 These are a group within the family Retroviridae.2 viruses in this group have common morphological and biological properties. Several species are attacked by the lentivirus, whose main feature is a long incubation period leading to disease after several years.
Since joining the host cell, the single-stranded ribonucleic acid (RNA) begins its transformation into a double-stranded deoxyribonucleic acid (DNA) by the enzyme reverse transcriptase which is part of the virus. Integrase and other cofactors act to that DNA virus fuses with the cell DNA hospedadora4 through transcription in the cell genome that hosts to the virus. In this way, the cell becomes infected by the virus. After this process, lentiviruses react in two ways: it may be that the virus enters the infected cell latency while still in office, or the virus to begin replicating actively and release virions capable of infecting other cells.
There are two types of HIV, called HIV-1 and HIV-2. The first one corresponds to the originally discovered virus, which received the names of LAV and HTLV-III by two teams who were investigating the etiological agent of AIDS during the first half of the 1980s. HIV-1 is more virulent and infectious than HIV-25 and is responsible for most HIV infections in the world. HIV-2 is less contagious and so is confined almost exclusively to countries in West Africa.
The conversion process from RNA into DNA is a principal feature of retroviruses and is carried out through reverse transcriptase enzymatic actions. With the demonstration of reverse transcriptase, began in the 1970 search for human retroviruses, which allowed the isolation in 1980 of leukemia virus of adult T cell, HTLV-I (R. Gallo and cols.)
HIV has a diameter of approximately 100 nanometers. Its outer part is the "cover", a membrane that originally belonged to the cell where the virus emerged. On deck is located a virus protein, gp41, or "transmembrane glycoprotein". Connected to the gp41 is gp120, which can bind to the CD4 receptor located on the surface of T lymphocytes to penetrate them. The core has a "capsid", composed by protein p24. In its interior 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.
The human immunodeficiency virus is part of the genus Lentivirus.1 These are a group within the family Retroviridae.2 viruses in this group have common morphological and biological properties. Several species are attacked by the lentivirus, whose main feature is a long incubation period leading to disease after several years.
Since joining the host cell, the single-stranded ribonucleic acid (RNA) begins its transformation into a double-stranded deoxyribonucleic acid (DNA) by the enzyme reverse transcriptase which is part of the virus. Integrase and other cofactors act to that DNA virus fuses with the cell DNA hospedadora4 through transcription in the cell genome that hosts to the virus. In this way, the cell becomes infected by the virus. After this process, lentiviruses react in two ways: it may be that the virus enters the infected cell latency while still in office, or the virus to begin replicating actively and release virions capable of infecting other cells.
There are two types of HIV, called HIV-1 and HIV-2. The first one corresponds to the originally discovered virus, which received the names of LAV and HTLV-III by two teams who were investigating the etiological agent of AIDS during the first half of the 1980s. HIV-1 is more virulent and infectious than HIV-25 and is responsible for most HIV infections in the world. HIV-2 is less contagious and so is confined almost exclusively to countries in West Africa.
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