HUMAN IMMUNODEFICENCY HUMAN IMMUNODEFICENCY VIRUS (HIV)VIRUS (HIV)

INTRODUCTIONINTRODUCTION

HIV VIRUS IS HUMAN HIV VIRUS IS HUMAN

IMMUNODEFICENCY VIRUS IT IMMUNODEFICENCY VIRUS IT

CAUSES (ACQUIRED CAUSES (ACQUIRED

IMMUNODEFICENCY SYNDROME)IMMUNODEFICENCY SYNDROME)

(AIDS)(AIDS)

HIV VIRUS exists as roughly HIV VIRUS exists as roughly

spherical particles surface pf spherical particles surface pf

each particle has studded spikes each particle has studded spikes

outside the human body called outside the human body called

as virions or in infected immune as virions or in infected immune

cellscells

TAXONMICTAXONMIC STATUS: STATUS: GROUPGROUP: : GROUPVI (ss RNA_RT)GROUPVI (ss RNA_RT) FAMILYFAMILY: : RETROVIRIDAERETROVIRIDAE GENUS: GENUS: LENTIVIRUSLENTIVIRUS

The viruses of Lentivirus family cause diseases in The viruses of Lentivirus family cause diseases in

monkeys cattle sheep, cats and goats. HIV is a monkeys cattle sheep, cats and goats. HIV is a

retrovirus .it is host specific virus. It was discovered retrovirus .it is host specific virus. It was discovered

in monkeys for the first time but it does not affect in monkeys for the first time but it does not affect

the monkeys rather causes aids in humansthe monkeys rather causes aids in humans

TYPES OF HIV VIRUS:TYPES OF HIV VIRUS:

It has two types HIV- 1 AND HIV- 2.It has two types HIV- 1 AND HIV- 2. TYPE 1 is highly infectious and causes 90%of TYPE 1 is highly infectious and causes 90%of

the infection globally.the infection globally. HIV-2 is found in west Africa and confined thereHIV-2 is found in west Africa and confined there

SpecieSpecie VirulenceVirulence InfectivityInfectivity PrevalencePrevalence OriginOrigin

HIV-1HIV-1 HighHigh HighHigh GlobalGlobal ChimpanzeChimpanzeee

HIV-2HIV-2 LowLow LowLow West West AfricaAfrica

Sooty Sooty MangabeyMangabey

MORPHOLOGYMORPHOLOGY

SIZE:SIZE:0.1micron0.1micron1/201/20thth of the length of an inch of the length of an inchIt is too small to be seen with It is too small to be seen with

an a compound microscope an a compound microscope and it is visible with the and it is visible with the electron microscope.electron microscope.

Structure:Structure:

HIV is a retrovirusHIV is a retrovirus

It has an enzyme (reverse It has an enzyme (reverse

trancriptase trancriptase which converts which converts

single stranded RNA to single stranded RNA to

double stranded DNA)double stranded DNA)

It has a coat of fatty material It has a coat of fatty material

called as viral envelope or called as viral envelope or

capsidcapsid

It has 72 little spikELTS It has 72 little spikELTS

projecting from the capsid.projecting from the capsid.

ENZYME AND PROTIEN ENZYME AND PROTIEN STRUCTURESTRUCTURE

VIRAL ENVELOPE:VIRAL ENVELOPE: The envelope is made up of gp120 and gp 4 and The envelope is made up of gp120 and gp 4 and

gp4 .just below the viral layer is made from gp4 .just below the viral layer is made from protein p17.protein p17.

Capsid is made up of p24 it is bullet shape.Capsid is made up of p24 it is bullet shape.

EnzymesEnzymes Integrase Integrase ProteaseProtease Reverse transcriptaseReverse transcriptase

Diagram explaining a retrovirusDiagram explaining a retrovirus

GenomeGenome

The HIV virus is a retrovirus it has single The HIV virus is a retrovirus it has single stranded RNA in its genome and it does not stranded RNA in its genome and it does not have a complex genome it ois comprised of 9 have a complex genome it ois comprised of 9 genes onlygenes only

3 are (3 are (gag pol env) these are encoded to gag pol env) these are encoded to make new virus particlesmake new virus particles

The rest 6 (The rest 6 (tat ,rev ,nef, vif, vpr, and vpu) tat ,rev ,nef, vif, vpr, and vpu) are used in the formation of proteins are used in the formation of proteins that control the ability of HIV to infect a that control the ability of HIV to infect a cell and cause diseasecell and cause disease

Lifecycle of HIV virus:Lifecycle of HIV virus:

Entry: Entry: The first step of the lifecycle of HIV The first step of the lifecycle of HIV is its attachment on the CD4 receptor site is its attachment on the CD4 receptor site of the of the helper Thelper T cellcell where it s spikes stick where it s spikes stick to the protein of to the protein of CD4CD4 site site

REVERSETRANSCRIPTION AND REVERSETRANSCRIPTION AND INTEGRATION: INTEGRATION: once inside the cell the HIV once inside the cell the HIV enzyme enzyme REVERSETRANSCRIPTASEREVERSETRANSCRIPTASE converts the single stranded mRNA into converts the single stranded mRNA into double stranded DNA using the host double stranded DNA using the host genome which is compatible to host genome which is compatible to host genome .The enzyme genome .The enzyme INTEGRASE slices INTEGRASE slices the human dna into viral DNA.the human dna into viral DNA.

Transcription and translation: Transcription and translation: HIV is a HIV is a provirus it stays in host genome for a long time .It becomes provirus it stays in host genome for a long time .It becomes activated and expressed in the same way as the human activated and expressed in the same way as the human genes .the mRNA is used as blue print to make new HIV genes .the mRNA is used as blue print to make new HIV virus copies viral proteins and enzymes .virus copies viral proteins and enzymes .

Assembly budding and integration: Assembly budding and integration: when the cell produces and translates mRNA when the cell produces and translates mRNA copies they are the complete copies of HIV copies they are the complete copies of HIV material and they gather together with the newly material and they gather together with the newly made HIV proteins and enzymes to form new viral made HIV proteins and enzymes to form new viral proteins which are released from the cell .Enzyme proteins which are released from the cell .Enzyme Protease Protease plays an important role in chopping up of plays an important role in chopping up of DNA strands to make anew viral core. the new DNA strands to make anew viral core. the new vcirions are ready to infect other cells and they vcirions are ready to infect other cells and they grow and mature by body fluids.grow and mature by body fluids.

Diagram of lifecycle of HIVDiagram of lifecycle of HIV

Electron microscopeElectron microscope

Electron Microscope slide showing virus transmission from cell membrane of T helper cell

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