It is a very excellent animation which explains the hiv replication very clearly. For free download of this video please visit my webpage http://rufusrajadurai.wetpaint.com/ And other 3D animation videos visit http://rufusrajadurai.wetpaint.com/page/3D+Medical+Animation+Library Regards, Dr.Rufus The Lyrics of this video is here Targeting HIV replication The replication of HIV 1 is a multi-stage process. Each step is crucial to successful replication and is therefore a potential target of antiretroviral drugs. Step one is the infection of a suitable host-cell, such as a CD4-positive T-lymphocyte. Entry of HIV into the cell requires the presence of certain receptors on the cell surface, CD4 -- receptors and co-receptors such as CCR5 or CXCR4. These receptors interact with protein-complexes, which are embedded in the viral envelope. These complexes are composed of two glycoproteins: an extracellular gp 120 and a transmembrane gp 41 When HIV approaches the target cell gp120 binds to the CD4-receptors. This process is termed attachment. It promotes further binding to a co-receptor. Co-receptor binding results in a conformational change in gp120. This allows gp41 to unfold and insert its hydrophobic terminus into the cell membrane. Gp 41 then folds back on itself. This draws the virus towards the cell and facilitates the fusion of their membranes. The viral nucleocapsid enters the host cell and breaks open releasing two viral RNA-strands and 3 essential replication enzymes: Integrase, Protease and Reverse Transcriptase. Reverse Transcriptase begins the reverse transcription of viral RNA. It has two catalytic domains: The Ribonuclease-H active site And the polymerase active site Here single stranded viral RNA is transcribed into an RNA-DNA double helix. Ribonuclease- H breaks down the RNA. The polymerase then completes the remaining DNA-strand to form a DNA -- double helix. Now Integrase goes into action. It cleaves a dinucleotide from each 3-prime end of the DNA creating two sticky ends. Integrase then transfers the DNA into the cell nucleus and facilitates its integration into the host cell genome. The host cell genome now contains the genetic information of HIV. Activation of the cell induces transcription of proviral DNA into messenger RNA. The viral messenger RNA migrates into the cytoplasm where building blocks for a new virus are synthesised. Some of them have to be processed by the viral protease. Protease cleaves longer proteins into smaller core proteins. This step is crucial to create an infectious virus. Two viral RNA-strands and the replication enzymes then come together and core proteins assemble around them forming the capsid. This immature particle leaves the cell acquiring a new envelope of host and viral proteins. The virus matures and becomes ready to infect other cells. HIV replicates billions of times per day destroying the hosts` immune cells and eventually causing disease progression. Drugs which interfere with the key steps of viral replication can stop this fatal process. Entry into the host cell can be blocked by fusion inhibitors for example. Inhibition of reverse transcriptase by nucleoside inhibitors or by non-nucleoside Reverse Transcriptase- inhibitors is part of standard antiretroviral regimens. The action of Integrase can be blocked. Protease inhibitors are also part of standard antiretroviral therapy. Each blocked step in viral replication is a step towards better control of HIV disease. Script, Storyboard, Art Direction by: Frank Schauder, MD Animation: MACKEVISION Publicity: Dr.Rufus Rajadurai.MD.,D.DENS.,

It is a very excellent animation which explains the hiv replication very clearly The Lyrics of this video is here Targeting HIV replication The replication of HIV 1 is a multi-stage process. Each step is crucial to successful replication and is therefore a potential target of antiretroviral drugs. Step one is the infection of a suitable host-cell, such as a CD4-positive T-lymphocyte. Entry of HIV into the cell requires the presence of certain receptors on the cell surface, CD4 -- receptors and co-receptors such as CCR5 or CXCR4. These receptors interact with protein-complexes, which are embedded in the viral envelope. These complexes are composed of two glycoproteins: an extracellular gp 120 and a transmembrane gp 41 When HIV approaches the target cell gp120 binds to the CD4-receptors. This process is termed attachment. It promotes further binding to a co-receptor. Co-receptor binding results in a conformational change in gp120. This allows gp41 to unfold and insert its hydrophobic terminus into the cell membrane. Gp 41 then folds back on itself. This draws the virus towards the cell and facilitates the fusion of their membranes. The viral nucleocapsid enters the host cell and breaks open releasing two viral RNA-strands and 3 essential replication enzymes: Integrase, Protease and Reverse Transcriptase. Reverse Transcriptase begins the reverse transcription of viral RNA. It has two catalytic domains: The Ribonuclease-H active site And the polymerase active site Here single stranded viral RNA is transcribed into an RNA-DNA double helix. Ribonuclease- H breaks down the RNA. The polymerase then completes the remaining DNA-strand to form a DNA -- double helix. Now Integrase goes into action. It cleaves a dinucleotide from each 3-prime end of the DNA creating two sticky ends. Integrase then transfers the DNA into the cell nucleus and facilitates its integration into the host cell genome. The host cell genome now contains the genetic information of HIV. Activation of the cell induces transcription of proviral DNA into messenger RNA. The viral messenger RNA migrates into the cytoplasm where building blocks for a new virus are synthesised. Some of them have to be processed by the viral protease. Protease cleaves longer proteins into smaller core proteins. This step is crucial to create an infectious virus. Two viral RNA-strands and the replication enzymes then come together and core proteins assemble around them forming the capsid. This immature particle leaves the cell acquiring a new envelope of host and viral proteins. The virus matures and becomes ready to infect other cells. HIV replicates billions of times per day destroying the hosts` immune cells and eventually causing disease progression. Drugs which interfere with the key steps of viral replication can stop this fatal process. Entry into the host cell can be blocked by fusion inhibitors for example. Inhibition of reverse transcriptase by nucleoside inhibitors or by non-nucleoside Reverse Transcriptase- inhibitors is part of standard antiretroviral regimens. The action of Integrase can be blocked. Protease inhibitors are also part of standard antiretroviral therapy. Each blocked step in viral replication is a step towards better control of HIV disease. Script, Storyboard, Art Direction by: Frank Schauder, MD Animation: MACKEVISION Publicity: Dr.Rufus Rajadurai.M.D.,D.DENS.,

About the Digestive System: The digestive tract is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients, and expels the remaining waste. The major functions of the GI tract are ingestion, digestion, absorption, and defecation. The GI tract differs substantially from animal to animal. Some animals have multi-chambered stomachs, while some animals' stomachs contain a single chamber. In a normal human adult male, the GI tract is approximately 6.5 meters (20 feet) long and consists of the upper and lower GI tracts. The tract may also be divided into foregut, midgut, and hindgut, reflecting the embryological origin of each segment of the tract. The upper GI tract consists of the mouth, pharynx, esophagus, and stomach. * The mouth contains the buccal mucosa, which contains the openings of the salivary glands; the tongue; and the teeth. * Behind the mouth lies the pharynx, which leads to a hollow muscular tube, the esophagus. * Peristalsis takes place, which is the contraction of muscles to propel the food down the esophagus which extends through the chest and pierces the diaphragm to reach the stomach. The lower GI tract comprises the intestines and anus. * Bowel or intestine o Small intestine, which has three parts: + Duodenum + Jejunum + Ileum o Large intestine, which has three parts: + Cecum (the vermiform appendix is attached to the cecum). + Colon (ascending colon, transverse colon, descending colon and sigmoid flexure) + Rectum * Anus Accessory organs to the alimentary canal include the liver, gallbladder, and pancreas. The liver secretes bile into the small intestine via the biliary system, employing the gallbladder as a reservoir. Apart from storing and concentrating bile, the gallbladder has no other specific function. The pancreas secretes an isosmotic fluid containing bicarbonate and several enzymes, including trypsin, chymotrypsin, lipase, and pancreatic amylase, as well as nucleolytic enzymes (deoxyribonuclease and ribonuclease), into the small intestine. Both of these secretory organs aid in digestion. The gut is an endoderm-derived structure. At approximately the 16th day of human development, the embryo begins to fold ventrally (with the embryo's ventral surface becoming concave) in two directions: the sides of the embryo fold in on each other and the head and tail fold towards one another. The result is that a piece of the yolk sac, an endoderm-lined structure in contact with the ventral aspect of the embryo, begins to be pinched off to become the primitive gut. The yolk sac remains connected to the gut tube via the vitelline duct. Usually this structure regresses during development; in cases where it does not, it is known as Meckel's diverticulum. During fetal life, the primitive gut can be divided into three segments: foregut, midgut, and hindgut. Although these terms are often used in reference to segments of the primitive gut, they are nevertheless used regularly to describe components of the definitive gut as well. Each segment of the primitive gut gives rise to specific gut and gut-related structures in the adult. Components derived from the gut proper, including the stomach and colon, develop as swellings or dilatations of the primitive gut. In contrast, gut-related derivatives—that is, those structures that derive from the primitive gut but are not part of the gut proper—in general develop as outpouchings of the primitive gut. The blood vessels supplying these structures remain constant throughout development. This was taken from wikipedia