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| Infectious Diseases |
Available kits: HBsAg, HBsAb, HBeAg, HBeAb, HBcAb, HAV, Anti-HCV, HIV 1+2, Anti-TB IgG, Syphilis, HDV, HEV, HGV-Ab
Introduction
Almost one in every ten adults, who have been infected by hepatitis B Virus (HBV), develops some form of chronic liver disease and becomes a long-term carrier of HBV. Hepatitis B has become a significant problem for public health management. Screening for hepatitis B is therefore urgently needed.The components of the virus (antigens), the host responses (antibodies) and the so-called immunologic markers have often been used as diagnostic tools. There are six immunologic markers of HBV: HBsAg, HBcAg, HBeAg and their respective antibodies. The HBsAg however is the first marker appearing in serum. The presence of HBsAg indicates recent infection and if it persists for more than 6 months the patient may become a chronic carrier.
HbsAb ELISA
Anti-HBs titer can be determined to monitor the prognosis of patients recovering from the hepatitis B viral infection. It also can be used as an indicator of prior exposure to Hepatitis B viruses. The anti-HBs ELISA is a solid-phase simultaneous immunoassay to detect antibodies against HBsAg. Microwells are coated with hepatitis B surface antigen (HBsAg). A serum specimen is added to the microwells together with horseradish peroxidase (HRP) Labeled HBsAg. After incubation, the complex of antigen-antibody-antigen (HRP-conjugated HBsAg, anti-HBs antibody and HBsAg on the wells) will be formed. Thus, the amount of HRP-HBsAg conjugate bound to the well is proportional to the concentration of anti-HBs in the specimen. The unbound enzyme conjugates will be washed away and then the chromogen and substrate solutions containing hydrogen peroxide is added to the wells. A blue color is developed in proportion to the amount of anti-HBs antibodies the specimens. The enzyme-substrate reaction is terminated with the addition of acid. The absorbance of controls and specimens is read in a microplate reader at the wavelength of 450 nm and 620nm.
HbeAg ELISA
Hepatitis B has become a significant problem for public health management. Almost one in every ten adults, who have been infected by Hepatitis B Virus (HBV), develops some form of chronic liver disease and becomes a long-term carrier of HBV. Screening for Hepatitis B is therefore urgently needed.Hepatitis B is an immune disease. Invasion of the human body by HBV induces auto-immune reactions which damage the liver. The components of the virus (antigens) and the host responses (antibodies), the so called immunologic markers have often been used as diagnostic tools.
There are six immunologic markers of HBV: HBeAg, HBcAg, HBsAg and their respective antibodies. HBeAg however is detected only in HBsAg positive sera. Its presence coincides with the rapid propagation of HBV and high infectivity. It is also a marker of questionable prognosis including the development of chronic Hepatitis. On the contrary, anti-HBe represents minimum viral replication and greatly reduced infectivity. When a patient changes from HBeAg to its antibody, he or she is likely to enter convalescent stage. But it is also possible that patients with anti-HBe are long-term carriers of HBV. Nevertheless, patients with anti-HBe generally have optimistic prognosis.
HbeAb ELISA
The presence of antibody against hepatitis B viral e antigen is used as an indicator for early HBs antigenemia before the peak of viral replication and early convalescence when HBeAg has declined below detectable levels. It is also useful to confirm a seroconversion. The seroconversion from HBeAg positivity to anti-HBe positivity indicates a reduced level of infectious virus because virus replication has decreased
HbcAb ELISA
The determination of anti-HBc levels can be sued to examine the progress of hepatitis B virus (HBV) infection. In acute case of hepatitis B infection, anti-HBc is detectable in the blood shortly after the apperance of HBsAg. HBsAg levels often decline before the appearance of anti-HBs. During this interval between the decline of HBsAg and the rise in anti-HBs, total anti-HBc may be the only reliable marker of HBV infection. In chronic HBV infections, HBsAg rises during the incubation phase and may persist for years. Anti-HBc also apperars during this early phase and reaches high titers which may persist for years. In asymptomatic HBV infections, HBsAg and HBeAg are present only briefly and are quickly followed by the apperance of anti-HBs and anti-HBc. Therefore in such patients, sometimes the only evidence of an infection may be the detection of anti-HBs and anti-HBc.
Anti-HCV ELISA Hepatitis C virus (HCV), which was formerly described as the parenterally transmitted form of non-A, non-B hepatitis (NANBH), becomes a chronic disease in 50% of the cases.HCV can also be transmitted through intravenous drug abuse, sexual, and household contact.
Hepatitis C virus is a single stranded RNA virus with some structural relations to the flavivirus family. Nucleic acid sequences of HCV cDNA clones provided the basis for the construction of recombinant peptides representing putative hepatitis C virus proteins. Anti-hepatitis C virus antibody screening of blood using synthetic or recombinant proteins helped to identify apparently healthy blood donors with anti-HCV antibodies who otherwise might have transmitted the virus. This is an enzyme linked immunosorbent assay using recombinant proteins derived from core regions of HCV virus to detect the presence of HCV antibodies in human sera.
HIV 1+2 ELISA
HIV-1 is one of the causes of AIDS (Acquired Immunodeficiency Syndrome). AIDS is the end stage of a drawn out process in which the immune system of an infected person and its ability to control infections or malignant proliferative disorders are progressively destroyed[1]. HIV is mainly transmitted through unprotected sexual intercourse or from mother to child. Most frequently, HIV infection is diagnosed by tests that assess whether an individual’s immune system has produced an HIV-specific immune response (antibodies to HIV).In the USA the standard laboratory test algorithm (set of different tests) may take 48 hours to one week before results may be made available. This algorithm consists of screening with an enzyme immunoassay (EIA) followed by confirmation by Western Blot (WB) or immuno-fluorescent (IFA) methods.
During the last 20 years, HIV infection and severe HIV-related diseases (e.g., AIDS) have become a leading cause of illness and death in the United States. Approximately 800,000-900,000 persons in the United States are infected with HIV and approximately 275,000 of these persons might not know they are infected. Approximately 25 million persons each year in the United States are tested for HIV. Publicly funded counseling and testing programs conduct approximately 2.5 million of these tests each year. In 1995, 25% of these individuals tested HIV positive and 33% of persons tested HIV negative at publicly funded clinics did not return for their test results. Rapid tests to detect HIV antibody can be performed within 20 minutes, enabling healthcare providers to supply definitive negative and preliminary positive results to patients at the time of testing, potentially increasing the overall effectiveness of counseling and testing programs. In comparison, results from enzyme immunoassays (EIAs) currently used for HIV screening often are not available until after 1-2 weeks. Using rapid tests, during 1995, a total of 697,495 more persons would have learned their HIV status[3]. Many advances have been made in HIV/AIDS prevention and treatment, including the development of effective antiretroviral therapies that have reduced HIV-related illness and death. Early knowledge of HIV infection is now recognized as a critical component in controlling the spread of HIV infection[2]. Rapid HIV testing allows clients to receive results the same day in a single visit, which is useful in urgent medical circumstances and settings where clients tend not to return for HIV test results (e.g., some STD clinics). Advances in these areas have resulted in revised recommendations for HIV screening of pregnant women treating opportunistic infections and other sexually transmitted and blood-borne diseases and managing occupational and non-occupational exposures and prophylaxis.
Anti-TB IgG ELISA
Mycobacterium tuberculosis (MTB) is a pathogenic bacterial species in the genus Mycobacterium and the pathogen of most cases of tuberculosis(TB). Globally, the TB disease is an enormous problem. TB is the world’s most significant infectious disease from a single infection agent.Hence, the early screening and detection of MTB infection is of great benefit to the control of this disease. |
