الفهرس 
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Abstract
Measles is a ubiquitous, highly infectious disease affecting nearly every person in a given population by adolescence in the absence of immunization programmes. The availability of safe and effective measles vaccines since 1963, has enabled prevention of much of this disease burden. However, problems remain and unnecessary disease, disability, and death are still occurring. Most of the serious complications of measles are due to secondary bacterial and viral infections causing pneumonia and diarrhea, or due to autoimmune disease leading to encephalomyelitis. Both types of complications are thought to be related to the immunologic abnormalities that accompany acute measles. A global consultation on measles concluded that measles could eventually be eradicated with the proper application of a measles elimination strategy. One of the major elements of measles elimination, eradication strategy is achieving and sustaining high levels of immunization coverage. Thus, it will become increasingly important to evaluate the efficacy of measles vaccines currently in use. Also, one of the most important elements of this strategy is strengthening measles surveillance and laboratory confirmation of cases. The aim of this study was to diagnose measles cases using ELISA and HI techniques, to determine the level of circulating soluble IL-2R in measles cases as a marker of cell-mediated immune-activation and its relation to the outcome of the disease, and to evaluate the levels of specific IgG antibodies following measles vaccination among different age groups. Five hundred and thirty four subjects were enrolled in this study, their ages ranged from 10 months to twenty five years. They were divided into three groups: • Four hundred apparently healthy children who had received measles vaccine one months to fifteen years previously, and did not report past history of measles, were tested by ELISA technique for the determination of measles IgG antibodies. • Ninety two cases of clinically diagnosed measles attending Alexandria Fever Hospital and El-Shatby Pediatric Hospital, were tested by ELISA technique for detection of measles IgM antibodies, and by chemiluminescence technique for determination of sIL-2R level. Out of these 92 measles cases, 40 were chosen and were tested by HI technique for detection of measles IgM antibodies. • The third group, included forty two apparently healthy subjects as a control group, tested by chemiluminescene technique for determination of sIL-2R level. Detection of serum IgG and IgM antibodies against measles virus by ELISA technique IgG or IgM antibodies present in serum samples reacted with measles antigens coated on the microtiter plates. Unbound reactants were then washed out. Subsequently, peroxidase conjugated antibodies to human IgG or IgM were added, following incubation and washing, substrate was added and the peroxidase conjugate bound to IgM or IgG antibodies reacted with the substrate producing a colour. The enzymatic reaction was stopped by the addition of sulphuric acid, and the resulting colours was measured. Detection of measles IgM antibodies by HI technique The serum was allowed to react with suspension of measles antigen. If corresponding antibodies were present, they would coat the hemagglutinins on measles particles and prevent hemagglutination when erythrocytes were added. For determination of the IgM antibody, two titrations were done. The first was carried out by using serum that has been extracted with Staph. aureus protein A to bind IgG, and the second was conducted on sera that have been further treated with 2-mercaptoethanol. The IgM level is the difference between the arithmetic titers of the two tests. Determination of sIL-2R levels in serum samples by chemiluminescence technique The Immulite Automated Analyzer was used. The solid phase is coated with anti-ligand. While, the patient serum sample, alkaline phosphatase conjugated monoclonal antibody, and ligand labelled antibody were incubated in the test unit. The IL-2R in the sample formed sandwich complex with the two antibodies. The sandwich was bound to the solid phase by the ligand-anti-ligand bridge. Unbound conjugate was then removed by centrifugal wash, and the substrate was added which undergoes hydrolysis in the presence of alkaline phosphatase to yield an unstable intermediate. The continuous production of this intermediate results in the sustained emission of light which was measured by the luminometer, and was proportional to the concentration of sIL-2R in the sample. From the results of this study, it was found that protective serum IgG antibodies against measles virus were present in 358 (89.5) out of 400 tested subjects. The IgG antibodies were higher following vaccination, then decreased slightly by increasing age. However, there was relative increase in measles IgG antibodies in the higher age groups which may be attributed to the continuous exposure to circulating wild measles virus.