TYPES OF HIV:
HIV is a highly variable virus which mutates very readily. This means there are many different strains of HIV, even within the body of a single infected person. Based on genetic similarities, the numerous virus strains may be classified into types.
HIV-1 and HIV-2. Both types are transmitted by sexual contact, through blood, and from mother to child, and they appear to cause clinically indistinguishable AIDS. However, it seems that HIV-2 is less easily transmitted, and the period between initial infection and illness is longer in the case of HIV-2. Worldwide, the predominant virus is HIV-1, and generally when people refer to HIV without specifying the type of virus they will be referring to HIV-1. The relatively uncommon HIV-2 type is concentrated in West Africa and is rarely found elsewhere.
Human Immunodeficiency Virus Type 2
Both HIV-1 and HIV-2 have the same modes of transmission and are associated with similar opportunistic infections and AIDS. In persons infected with HIV-2, immunodeficiency seems to develop more slowly and to be milder. Compared with persons infected with HIV-1, those with HIV-2 are less infectious early in the course of infection. As the disease advances, HIV-2 infectiousness seems to increase; however, compared with HIV-1, the duration of this increased infectiousness is shorter.
HIV RETROVIRUS HIV is an enveloped retrovirus. Each virus particle contains two copies of an RNA genome. The virus also has a number of enzymes: reverse transcriptase, integrase and viral protease. These molecules play an important role in making new copies of HIV and can be the targets of antiretroviral drugs. The HIV viral particle, or virion, has a capsid which is cone-shaped and is enclosed in a lipid bilayer, or envelope. This envelope contains viral glycoproteins which bind specifically to CD4 T cell receptors, enabling the virus to enter its host.
The name retrovirus comes from the fact that the RNA genome is transcribed/copied back into DNA in the host cell (by reverse transcriptase). The DNA is then incorporated into the host cell chromosome.
HIV belongs to a group of retroviruses called lentiviruses, from the Latin lentus, meaning slow, because of the gradual course of the disease they cause.
Retrovirus: Contain a single strand of RNA. Replicate through DNA intermediates - Genetic information flows from RNA to DNA, DNA complimentary to viral RNA is synthesized in the host cell by reverse transcriptase, an enzyme brought into the cell by the infecting virus particle. Reverse transcriptase first catalyses the synthesis of DNA, then the digestion of RNA and finally the synthesis of a second strand of DNA.
HIV-1 and HIV-2. Both types are transmitted by sexual contact, through blood, and from mother to child, and they appear to cause clinically indistinguishable AIDS. However, it seems that HIV-2 is less easily transmitted, and the period between initial infection and illness is longer in the case of HIV-2. Worldwide, the predominant virus is HIV-1, and generally when people refer to HIV without specifying the type of virus they will be referring to HIV-1. The relatively uncommon HIV-2 type is concentrated in West Africa and is rarely found elsewhere.
Human Immunodeficiency Virus Type 2
Both HIV-1 and HIV-2 have the same modes of transmission and are associated with similar opportunistic infections and AIDS. In persons infected with HIV-2, immunodeficiency seems to develop more slowly and to be milder. Compared with persons infected with HIV-1, those with HIV-2 are less infectious early in the course of infection. As the disease advances, HIV-2 infectiousness seems to increase; however, compared with HIV-1, the duration of this increased infectiousness is shorter.
HIV RETROVIRUS HIV is an enveloped retrovirus. Each virus particle contains two copies of an RNA genome. The virus also has a number of enzymes: reverse transcriptase, integrase and viral protease. These molecules play an important role in making new copies of HIV and can be the targets of antiretroviral drugs. The HIV viral particle, or virion, has a capsid which is cone-shaped and is enclosed in a lipid bilayer, or envelope. This envelope contains viral glycoproteins which bind specifically to CD4 T cell receptors, enabling the virus to enter its host.
The name retrovirus comes from the fact that the RNA genome is transcribed/copied back into DNA in the host cell (by reverse transcriptase). The DNA is then incorporated into the host cell chromosome.
HIV belongs to a group of retroviruses called lentiviruses, from the Latin lentus, meaning slow, because of the gradual course of the disease they cause.
Retrovirus: Contain a single strand of RNA. Replicate through DNA intermediates - Genetic information flows from RNA to DNA, DNA complimentary to viral RNA is synthesized in the host cell by reverse transcriptase, an enzyme brought into the cell by the infecting virus particle. Reverse transcriptase first catalyses the synthesis of DNA, then the digestion of RNA and finally the synthesis of a second strand of DNA.
No hay comentarios:
Publicar un comentario