Distribution and Structure of HIV
Scientific Classification
Kingdom : Pararnavirae
Phylum : Artverviricota
Class : Revtraviricetes
Order : Ortervirales
Family : Retroviridae
Subfamily : Orthoretrovirinae
Genus : Lentivirus
Species : HIV 1 /HIV 2
HIV v/s AIDS
HIV : Human Immuno-deficiency Virus
Human : Infecting human beings
Immunodeficiency : Decrease or weakness in the body's ability to fight off infections and illnesses.
Virus : A pathogen having the ability to replicate only inside a living cell
AIDS : Acquired Immuno Deficiency Syndrome
A = not inherited
I = immune system
D = deficiency - inability to protect against illness
S = syndrome, a group of symptoms or illnesses that occur as a result of HIV infection.
* HIV is the virus the causes AIDS.
* Not everyone who is infected with HIV has AIDS.
* Everyone with AIDS is infected with HIV.
* AIDS is result of the progression of HIV Infection.
* Anyone infected with HIV, although healthy, can still transmit the virus to another person.
[ AIDS is the final stage of the disease caused by infection with a type of virus called HIV ]
Global History
* 1981 - beginning of the epidemic in united states.
- Centers for Disease control and prevention (CDC) published a report about five previously healthy homosexual men becoming infected with pneumocystis pneumonia.
- Because the disease appeared to affect mostly homosexual men, officials initially called it Gay-related immune deficiency or GRID.
- CDC noted that this type of pneumonia had never affected people with uncompromised immune systems.
* 1983 - Lymphadenopathy - Associated virus (or LAC ) retrovirus was discovered.
* 1984 - National cancer Institute found the cause of AIDS to be retrovirus HTLV-III.
* 1985 - Food and Drug Administration licensed the first Commercial blood test of HIV.
* 1986 - The International Committee on the Taxonomy of viruses officially named the virus as HIV (human immunodeficiency virus).
* 1988 - The World Health organization declared December 1st to be World AIDS day .
* 1991 - The red ribbon became an international symbol of AIDS awareness.
* 2008 - Luc Antoine Montagnier was awarded Nobel prize in physiology and medicine for his discovery of the human immunodeficiency virus (HIV).
INDIA
* Suniti solomon - first AIDS case was diagnosed in Chennai in 1986.
* In 2009, she was awarded, "National Women Bioscientist Award" by ministry of science and Technology, Govt. of India.
* On 25th January 2017, Govt. of India announced "Padma Shri" award for her contribution towards Medicine.
* "What has been killing people with AIDS more is the stigma and discrimination".
The HIV infection spreads through the following :
* Unprotected sexual interaction with an already infected person.
* Reusing needles used by an infected person.
* From an infected mother to the baby through the placenta.
* Blood transfusion from an infected person.
* This virus has a long incubation period before it starts to attack the immune system (10 years).
* The immune system is the human body's natural defense mechanism, hence HIV can make it harder for the patient to fight off infections and diseases.
* HIV demolishes a particular type of WBC (White Blood Cells) and the T-helper cells T.
* His virus also makes copies of itself inside these cells.
* T-helper cells are also known as CD4 cells.
Types of HIV
* The two major types of HIV strains are -
* HIV-1 : The most common types of virus found Worldwide.
* Group M - 'M' stands for ' major' implies that 90% of HIV AIDS all over the World are caused by this group of HIV.
* Group N - 'N' stands for "non-M, non-O".
* Group O - 'O' implies 'outlier' group of HIV.
* Group P - This type of virus is recently diagnosed in 2009.
HIV- 2
* This is found primarily in Western Africa, with some cases in India and Europe.
* There are 8 known HIV- 2 groups (A to H).
* HIV-2 is closely related to simian immunodeficiency virus endemic in a monkey species (sooty mangabeys).
Structure
HIV
* Enveloped ssRNA virus,
* Genus : Lentivirus, Family Retroviridae
* Lentivirus (HIV 1 and 2)
* Attack CD4 + cells
* Replicates in actively dividing T4 lymphocytes.
* The virus can remain in lymphoid tissues in latent phase until it is activated.
* Unique ability to destroy T4 Helper cells.
* Once a person gets infected, HIV remains in his body lifelong.
* The person is a symptomless carrier for years before the symptoms actually appear.
Core
* HIV is roughly spherical with a diameter of about 120 nm, around 60 times smaller than a red blood cell.
* It is composed of two copies of positive-sense single-stranded RNA that codes for the viruses nine genes.
* The single-stranded RNA is tightly bound to nucleocapsid proteins, P7 and enzymes needed for the development of the virion such as reverse transcriptase, proteases, ribonuclease and integrase.
Capsid
* It is enclosed by a conical capsid composed of 2,000 copies of the viral protein P24.
* A matrix composed of the viral protein P17 surrounds the capsid ensuring the integrity of the virion particle.
Envelope
* HIV has envelope, composed of the lipid bilayer taken from the membrane of a human host cell when the newly formed virus particle buds from the cell.
* The viral envelope contains proteins from the host cell and relatively few copies of HIV envelope protein.
* It consists of a cap made of three molecules known as glycoproteins (gp) 120, and a stem consisting of three gp41 molecules that anchor the structure into the viral envelope.
* The envelope protein, enclosed by the HIV env gene, allows the virus to attach to target cells and fuse the viral envelope with the largest cell's membrane releasing the viral contents into the cell and initiating the infectious cycle.
* As the sole viral protein on the surface of the virus, the envelope protein is a major target for HIV vaccine efforts.
