serology

Serology


What is serology?
Serology is the scientific study of blood serum and immune responses. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection against a given microorganism or against other foreign proteins (Eg. to a mismatched blood transfusion), or to one's own proteins (Eg. autoimmune disease).There are several serology techniques that can be used depending on the antibodies being studied. These include ELISA, agglutination, precipitation, complement-fixation and fluorescent antibodies.


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What is the purpose of Serological testing?


Serological tests may be performed for diagnostic purposes such as detecting serum antibodies or antibody-like substances that appear specifically in association with certain diseases. Serology blood tests help to diagnose patients with certain immune deficiencies associated with the lack of antibodies, such as X-linked agammaglobulinemia. The various types of serological tests include:

(1) Flocculation tests The most common test is the complement-fixation tests. They are based on the precipitation, or flocculation, that takes place when antibody and specially prepared antigens are mixed together.



(2) Neutralization testsThis test depends on the capacity of antibody to neutralize the infectious properties of the infectious organisms.


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(3) Hemagglutinin-inhibition testsThis test make use of the finding that certain viruses will cause the red blood cells of certain animal species to agglutinate (congeal, or clump together) and that this agglutination will be prevented by antibody.What are the benefits of serological testing?Serological testing is particularly helpful in the diagnosis of rickettsial and viral diseases such as Rocky Mountain spotted fever, influenza, measles, poliomyelitis, and yellow fever, as well as of infectious mononucleosis and rheumatoid arthritis. As a practical mass-screening diagnostic tool, it has proved valuable in the detection of such conditions as syphilis.



DNA fingerprinting

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Some true facts on DNA fingerprinting!



The chemical structure of everyone's DNA is the same. The only difference between people (or any animal) is the order of the base pairs. There are so many millions of base pairs in each person's DNA that every person has a different sequence. Using these sequences, every person could be identified solely by the sequence of their base pairs. However, because there are so many millions of base pairs, the task wouldtake up a lot of time. Instead, scientists are able to use a shorter method, due to the repeating patterns in DNA. These patterns do not, however, give an individual "fingerprint," but they are able to determine whether two DNA samples are from the same person, related people, or non-related people. Scientists use a small number of sequences of DNA that are known to vary among individuals a great deal, and analyze those to get a certain probability of a match.



The ribosomal RNA (rRNA) gene region of the microsporidium,Nosema apis,has been examined. A new method for extracting microsporidian genomic DNA from infected host tissue is described. Complete DNA sequence data are presented for the small subunit gene (1242 bp), the internal transcribed spacer (33 bp), and the large subunit gene (2481 bp to a putative termination point). This is the first time that the complete large subunit rRNA gene has been published for any microsporidian species.



The relation between different organism can be seen by comparing the genes that code the important function of the organisms. Some regions of this 16S rRNA are highly conserved in all organisms, but other regions maybe more variable.





DNA sequencing of ribosomal RNA gene


DNA sequence is also presented for the regions flanking the 5′ end of the small subunit gene and the 3′ end of the large subunit gene. The intergenic spacer is shown to be heterogeneous, showing variation in sequence and restriction sites rather than length and containing sequence repeats, which are a characteristic feature of intergenic spacers. The rRNA gene region ofN. apisis shown to occur in a head-to-tail, tandemly repeated manner, as in other eukaryotes. The complete DNA sequence of the nuclear ribosomal RNA gene complex of Verticillium dahliae: Intraspecific heterogeneity within the intergenic spacer region. Fungal Genetics and Biology 29, 19–27.

The complete sequence of the nuclear ribosomal DNA gene complex of the phytopathogenic fungus Verticillium dahliae has been determined. The tandemly repeated unit was 7216 bp long and appears to be the shortest rDNA cluster described so far among filamentous fungi. Primer pairs were designed for amplification of the region spanning half of the 28S subunit, the intergenic spacer (IGS), and the 5 end of 18S subunit of a number of Verticillium strains, isolated from various hosts and geographic origins.