Types of HIV

Human Immunodeficiency Virus or HIV is a deadly virus that attacks the human immune system, thus weakening the body's ability to defend against pathogens.

Two Types of HIV - HIV-1 and HIV-2

There are two types of HIV at the present moment: HIV-1 and HIV-2. Worldwide, HIV-1 is prevalent, and when people talk about HIV without mentioning the type, they refer to HIV-1. Both HIV-1 and HIV-2 are transmitted sexually and seem to cause the same type of AIDS. However, transmitting HIV-2 is more difficult, and the latent period is longer than HIV-1.

Subtypes of HIV-1

HIV-1 is a virus that has many mutations, changing very rapidly. HIV-1 variants can be classified into groups and subtypes and there are two groups: M and O. In September 1998, French researchers announced that they had found a new variant of HIV-1 from a woman in Cameroon, West Africa. This variant does not belong to either group M or group O and was found in only three people, all of Cameroon. In group M subtypes, there are now 10 distinct genes known. These are subtypes A to J. The subtypes of group M differ as much as they differ from those in group O.

Subtypes are unevenly distributed around the world, for example subtype B is mostly found in: the Americas, Japan, Australia, Caribbean and Europe; subtype A and D predominate in the southern Sahara region; subtype C in South Africa and India, subtype E in Central African Republic, Thailand and other Southeast Asian countries. Subtype F (Brazil and Romania), G and H (Russia and Central Africa), I (Cyprus) and group A (Cameroon). Almost all subtypes can be found in Africa, although subtype B is less prevalent.

The Major Differences between these Subtypes

The biggest difference is the genetic structure; biological differences observed in vitro and / or in vivo may reflect this. Some subtypes were predominantly associated with certain modes of transmission, for example, subtype B corresponds to gay sexual contact and intravenous drug use. Subtypes E and C are associated with heterosexual contact. Researchers' studies have shown that subtypes C and E infect and multiply strongly than subtype B in the cell lining of the vagina, cervix and foreskin, but not of the rectal wall. These experiments suggest that subtypes E and C have a higher potential for heterosexual transmission rather than subtype B. However, results of studies are not yet finalized. Some studies suggest that subtype E is spreading faster than subtype B. Regular HIV tests detect all subtypes of the virus.

Recently, it was observed in the laboratory that some subtypes of HIV have a different immunological development and characteristics, but these differences still have to be demonstrated in vivo. It is unknown whether genetic variations in subtype E or other subtypes differ in terms of transmission, the response to antiviral therapy or prevention by vaccine. If these genetic variations differ in any way in terms of effective vaccine, this could represent a major obstacle in developing a general vaccine. Influenza vaccine should be regularly changed and updated due to genetic changes in influenza virus. You may need the same procedure in case of a vaccine against HIV.

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