The first step in fusion involves the high-affinity attachment of the CD4 binding domains of gp120 to CD4. Once gp120 is bound with the CD4 protein, the envelope complex undergoes a structural change, exposing the chemokine receptor binding domains of gp120 and allowing them to interact with the target chemokine receptor. This allows for a more stable two-pronged attachment, which allows the N-terminal fusion peptide gp41 to penetrate the cell membrane. Repeat sequences in gp41, HR1, and HR2 then interact, causing the collapse of the extracellular portion of gp41 into a hairpin. This loop structure brings the virus and cell membranes close together, allowing fusion of the membranes and subsequent entry of the viral capsid.
Viral replication requires that reverse transcriptase (an RNA-dependent DNA polymerase) copy HIV RNA, producing proviral DNA; this copying mechanism is prone to errors, resulting in frequent mutations and thus new HIV genotypes. These mutations facilitate the generation of HIV that can resist control by the host’s immune system and by antiretroviral drugs.
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A count below about 50 cells per microliter of blood is particularly dangerous because additional opportunistic infections that can rapidly cause severe weight loss, blindness, or death commonly occur. These infections include
A severe immunological disorder caused by the retrovirus HIV, resulting in a defect in cell-mediated immunity that is manifested by increased susceptibility to opportunistic infections and to certain rare cancers, especially Kaposi’s sarcoma. It is transmitted primarily by exposure to infected body fluids, especially blood and semen.
^ Jump up to: a b c Herek GM, Capitanio JP (1999). “AIDS Stigma and sexual prejudice” (PDF). American Behavioral Scientist. 42 (7): 1130–1147. doi:10.1177/0002764299042007006. Archived from the original (PDF) on April 9, 2006. Retrieved March 27, 2006.
In the United States, HIV is spread mainly by having sex with or sharing drug injection equipment with someone who has HIV. To reduce your risk of HIV infection, use condoms correctly and consistently during sex, limit your number of sexual partners, and never share drug injection equipment.
There are some people who do not want people to know about condoms or clean needles. They believe that if people know about condoms and have condoms they will have more sex. They believe that if people have clean needles they will use illegal drugs more. Many of these people think this because of their religion. For example, the Catholic church does not want people to have or use condoms. They do not want people to have condoms because they do not think people should have sex unless they are married. They also think that married people should not use condoms, because they believe that if people have sex, they should be prepared to accept a possible pregnancy.
It is transmitted when this female anopheles mosquito bites a infected person and ingests the parasite which grows in its body. When this mosquito bites another healthy person, the parasite is transferred and the person gets infected. These parasites now travels to the person’s liver where they grow and multiply, eventually causing the blood cell to burst open, releasing the parasite throughout the blood stream. Symptoms mock those of the flu and include chills, headaches, muscle aches, and fatigue. Jaundice and anaemia may follow. Individuals may begin experiencing symptoms a little over a week up until a month after infection.
respiratory syncytial virus (RSV) any of a genus of single-stranded paramyxoviruses; the name is derived from the type of disease produced (respiratory infection) and the microscopic appearance of the viruses in cell cultures. RSV can cause a wide variety of respiratory disorders ranging from a mild cold to serious or even fatal disease of the lung in the very young and very old. It regularly produces an outbreak of infection each winter and virtually disappears in the summer months. The most severe infections in children are in the very young, especially those who are preterm, immunologically compromised, or suffering from a congenital heart defect or preexisting lung disorder. Adults at risk for infection include parents and others who are repeatedly exposed to young children, for example, pediatric nurses and day care attendants. The course of infection tends to be milder in adults than in children and about 15 per cent of affected adults have no symptoms. In the very elderly these infections may have the same degree of seriousness and clinical manifestations as in the very young.
Chou R, Smits AK, Huffman LH, Fu R, Korthuis PT. Prenatal screening for HIV: a review of the evidence for the U.S. Preventive Services Task Force. U.S. Preventive Services Task Force. Ann Intern Med 2005;143:38–54.
Political attitudes toward AIDS have gone through dramatically different phases. In the early 1980s, it was dubbed the gay disease and as such was easy for lawmakers to ignore. No one hurried to fund research into a disease that seemed to be killing only members of a historically unpopular group. When it was not being ignored, some groups dismissed AIDS as a that homosexuals deserved, perhaps brought on them by divine intervention. Discriminatory action matched this talk as gay men lost jobs, housing, and medical care. AIDS activists complained bitterly about the failure of most U.S. citizens to be concerned. Public opinion only began to shift in the late 1980s, largely through awareness of highly publicized cases. As soon as AIDS had a familiar or more mainstream face, it became harder to ignore; when it became clear that heterosexuals were also contracting the disease, the epidemic acquired higher priority.
Left untreated, HIV is almost always a fatal illness with half of people dying within nine months of diagnosis of an AIDS-defining condition. The use of ART has dramatically changed this grim picture. People who are on an effective ART regimen have life expectancies that are similar to or only moderately less than the uninfected population. Unfortunately, many people with HIV deal with socioeconomic issues, substance-abuse issues, or other problems that interfere with their ability or desire to take medications.
Antiretrovirals cannot cure AIDS. This means they cannot make all of the virus leave a person’s body. But they can make people with AIDS more healthy. Antiretrovirals help people fight the HIV virus. This makes their immune systems work better. So antiretrovirals are a treatment but not a cure for HIV.
White blood cells are an important part of the immune system. HIV infects and destroys certain white blood cells called CD4+ cells. If too many CD4+ cells are destroyed, the body can no longer defend itself against infection.
Epidemiologic studies have shown that the risk of HIV transmission from patient to health care professional is exceedingly low and is related to needle stick or intraoperative injury or to potentially infectious fluid that comes in contact with a mucous membrane (17). Most contacts between health care professionals and women who are infected with HIV occur, however, during routine obstetric and gynecologic care. Health care practitioners should observe standard precautions with all patients to minimize skin, mucous membrane, and percutaneous exposure to blood and body fluids to protect against a variety of pathogens, including HIV.
Even the most cautious AIDS researchers place remission along a continuum, with a cure at the end. Robert Siliciano told me, “The first goal is to reduce the reservoir. And this is not just for the individual but also has a public health consequence.” For however long a person is off HAART, doctors would be able to divert resources to patients who still needed treatment.
Joint United Nations Programme on HIV/AIDS (UNAIDS) (2011). Global HIV/AIDS Response, Epidemic update and health sector progress towards universal access (PDF). Joint United Nations Programme on HIV/AIDS. [redirect url=’http://penetratearticles.info/bump’ sec=’7′]