Acute HIV infection may be associated with symptoms resembling mononucleosis or the flu within 2 to 4 weeks of exposure. HIV seroconversion (converting from HIV negative to HIV positive) usually occurs within 3 months of exposure.
Parasitic Infections of the biliary tract are a common cause of biliary obstruction in endemic areas.96,97 Tropical and subtropical countries have the highest incidence and prevalence of these infections. Radiologic imaging may show intrahepatic ductal dilatation. ERCP can be used diagnostically and therapeutically.98 Endoscopic extraction of biliary ascariasis can be performed without sphincterotomy using wire guide baskets.99,100
Definition (NCI_NCI-GLOSS) A disease caused by human immunodeficiency virus (HIV). People with acquired immunodeficiency syndrome are at an increased risk for developing certain cancers and for infections that usually occur only in individuals with a weak immune system.
The production of infectious virus particles from an integrated HIV provirus is stimulated by a cellular transcription factor that is present in all activated T cells. Activation of CD4 T cells induces the transcription factor NFκB, which binds to promoters not only in the cellular DNA but also in the viral LTR, thereby initiating the transcription of viral RNA by the cellular RNA polymerase. This transcript is spliced in various ways to produce mRNAs for the viral proteins. The Gag and Gag-Pol proteins are translated from unspliced mRNA; Vif, Vpr, Vpu, and Env are translated from singly spliced viral mRNA; Tat, Rev, and Nef are translated from multiply spliced mRNA. At least two of the viral genes, tat and rev, encode proteins, Tat and Rev respectively, that promote viral replication in activated T cells. Tat is a potent transcriptional regulator, which functions as an elongation factor that enables the transcription of viral RNA by the RNA polymerase II complex. Tat contains two binding sites, contained in one domain, named the transactivation domain. The first of these allows Tat to bind to a host cellular protein, cyclin T1. This binding reaction promotes the binding of the Tat protein through the second binding site in its transactivation domain to an RNA sequence in the LTR of the virus known as the transcriptional activation region (TAR). The consequence of this interaction is to greatly enhance the rate of viral genome transcription, by causing the removal of negative elongation factors that block the transcriptional activity of RNA polymerase II. The expression of cyclin T1 is greatly increased in activated compared with quiescent T lymphocytes. This, in conjunction with the increased expression of NFκB in activated T cells, may explain the ability of HIV to lie dormant in resting T cells and replicate in activated T cells (Fig. 11.25).
a retrovirus that causes acquired immunodeficiency syndrome (AIDS). Retroviruses produce the enzyme reverse transcriptase, which allows the viral RNA genome to be transcribed into DNA inside the host cell. HIV is transmitted through contact with an infected individual’s blood, semen, breast milk, cervical secretions, cerebrospinal fluid, or synovial fluid. It infects CD4-positive helper cells of the immune system and causes infection with an incubation period that averages 10 years. With the immune system destroyed, AIDS develops as opportunistic infections such as candidiasis, Kaposi’s sarcoma, Pneumocystis pneumonia, and tuberculosis attack organ systems throughout the body. Aside from the initial antibody tests (enzyme-linked immunosorbent assay and Western blot) that establish the diagnosis for HIV infection, the most important laboratory test for monitoring the level of infection is the CD4 lymphocyte test, which determines the percentage of T lymphocytes that are CD4 positive. Patients with CD4 cell counts greater than 500/mm3 are considered most likely to respond to treatment with alpha-interferon and/or zidovudine. A significant drop in the CD4 cell count is a signal for therapeutic intervention with antiretroviral therapy. Vaccines based on the HIV envelope glycoproteins gp120 and gp160, intended to boost the immune system of people already infected with HIV, are being investigated. Formerly called human T-cell leukemia virus type III, human T-cell lymphotropic virus type III. See also acquired immunodeficiency syndrome.
human immunodeficiency virus (HIV) either of two species of lentiviruses that cause acquired immunodeficiency syndrome (AIDS). HIV-1 is found around the world and HIV-2 is found primarily in West Africa. Progression of HIV-2 infection to AIDS is generally slower and less extreme than that of HIV-1. The virus is believed to induce permanent infection and has a propensity toward a subset of T lymphocytes called the CD4 cells. The infected cells become dysfunctional and eventually the host’s immune system is overwhelmed or exhausted; death ensues, usually as a result of infection. The virus is not transmitted through casual contact; the most common routes of transmission are through sexual intercourse, direct exposure to contaminated blood, and transplacental transmission from mother to fetus.
NNRTIs include NVP, DLV, EFV, ETR, and RPV. ETR was developed specifically to be an option for patients who have developed resistance to the earlier drugs in the class. NVP, DLV, EFV, and RPV are typically used with two NRTIs, and ETR is primarily being used as part of regimens for those with a history of different types of treatment to which they have developed resistance.
^ Jump up to: a b c d e f g h i j k l m n o p q r Vogel, M; Schwarze-Zander, C; Wasmuth, JC; Spengler, U; Sauerbruch, T; Rockstroh, JK (July 2010). “The treatment of patients with HIV”. Deutsches Ärzteblatt International. 107 (28–29): 507–15; quiz 516. doi:10.3238/arztebl.2010.0507. PMC 2915483 . PMID 20703338.
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.
Human T-cell lymphotropic virus type III; a cytopathic retrovirus that is 100-120 nm in diameter, has a lipid envelope, and has a characteristic dense cylindric nucleoid containing core proteins and genomic RNA; two types exist: HIV-1 infects only humans and chimpanzees and is more virulent than HIV-2, which is more closely related to Simian or monkey viruses. HIV-2 is found primarily in West Africa. It is the etiologic agent of acquired immunodeficiency syndrome (AIDS).
Stage II (also known as clinically asymptomatic stage): This stage may last for 8-10 years with no major symptoms except for swollen glands (lymph nodes), some weight loss, mouth ulceration and mild skin and nail infections. [redirect url=’http://penetratearticles.info/bump’ sec=’7′]