• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Antigen-Antibody Interactions: an analysis

Extracts from this document...

Introduction

Antigen-Antibody Interactions: an analysis Introduction Common to all antibodies is the specificity they exhibit in binding to epitopes present on the surface of antigen in which ultimately a lattice formation results due to cross-linking. The present experiment exploits this interaction and is physically observed as agglutination (when antigen is present on a cell) or precipitation (antigen free-floating in solution) (Elek et al., 1964). Presently, the experiment uses both qualitative and quantitative analyses in order to ascertain the levels of antibodies in sera; such information, for example, is useful in assessing the presence of a current infection in a patient. More specifically, during Part A, presence of agglutination, due to the interaction between Salmonella H (flagellar) and O (somatic) antigens and the appropriate antibodies, was used as a qualitative measure in order to assess whether the patient is currently infected with Salmonella typhi or paratyphi A strains, a process known as the Widal test (Parry et al., 1999). Part B employed a quantitative analysis to determine the level of precipitation upon interaction between bovine serum albumin (BSA) antigen and antiBSA to allow the determination of the concentration of antibody in an original antiserum sample. Materials and Method As per BIOL3141 Infection and Immunity Laboratory Manual 2011 pg 19 -26. ...read more.

Middle

Bearing this in mind, an analysis of the observed results ensues. S. typhi (group D serotype) expresses O antigen 9 and 12; conversely, S. paratyphi A (group A) possesses O antigen 12 (Carlsson et al., 1972). As both organisms contain O antigen 12 the possibility of cross reactions arises; O antibody of group D serotype can bind to O antigens present on group A and D organisms. Olopoenia et al., 1999 reports that cross-reactions may occur frequently, lessening considerably the diagnostic specificity of the Widal test. The effect here is not clear as only a single test was performed. However, this may explain the observed no increase in titre (yet presence of agglutination) in tubes subject to S. paratyphi A. Another explanation concerning the agglutination in these tubes: small amount of S. paratyphi A antibodies maybe present in sera as a result of immunisation or previous infection. Antigen/antibody interactions of BSA There are three distinct elements in Graph 1. The first, excess antiBSA, resulting in complexes that are small, with limited bridging. The second region, equivalence, represents an optimum ratio of antiBSA to BSA antigen, resulting in a lattice formation and consequently precipitation. In the third region, excess BSA antigen, there is a reduced supply of bridging antibody molecules in relation to BSA antigen (Janeway et al., 2007). ...read more.

Conclusion

1 2 3 4 5 6 7 8 9 10 Precipitation 4 3 2 0 0 0 0 0 0 0 Dilution 1/10 1/20 1/40 1/80 1/160 1/320 1/640 1/1280 1/2560 - Titre 10 20 40 80 160 320 640 1280 2560 - Serum B Tube No. 1 2 3 4 5 6 7 8 9 10 Precipitation 4 4 3 3 3 2 0 0 0 0 Dilution 1/10 1/20 1/40 1/80 1/160 1/320 1/640 1/1280 1/2560 - Titre 10 20 40 80 160 320 640 1280 2560 - Graph and Calculations Amount of antigen at equivalence point: 103 �g (in 1 mL of NaOH). 1 mg/mL solution of the BSA antigen has an OD280 of 0.660. Thus the absorbance due to antigen is 0.103 mg/mL * 0.660 = 0.068. The absorbance due to antibody is then the total absorbance minus the optical density due to the antigen added at equivalence. That is total absorbance at equivalence is 0.68; the absorbance due to antibody is this total absorbance minus the absorbance due to antigen. Therefore 0.68 - 0.068 = 0.612 The mass of antibody is then calculated using the knowledge that 1 mg/mL solution of antibody equates to an absorbance of 1.4. Thus an absorbance of 0.612 gives the concentration of antibody at equivalence point to be 0.44 mg/mL. Considering the original antibody was present in 0.5 mL and was diluted 1 in 2, the antibody present in the original antiserum sample was: 0.88 mg/mL. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Microbiology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Microbiology essays

  1. Making and investigating buffer solutions

    For each dilute buffer, to one beaker I shall add HCl, to the other NaOH from two separate burettes. Initially, I shall add one drop, then 1cm3 and then 5cm3 measuring the pH after each step and recording it in a table.

  2. Investigation into the effect of Temperature on the action of the Enzyme Lipase.

    These scattered results show that there are slight anomalies within the readings for each temperature. These results are only every 10?C so they are not extremely accurate, the anomalies within the temperature repeats also show that there are inaccuracies within the results.

  1. Introduction to Spectrophotometric Analysis - By using spectrophotometric analysis or spectrophotometry, one can determine ...

    Absorbance, A660 0.0 0.00 2.5 0.12 5.0 0.23 7.5 0.35 10.0 0.48 A (undiluted) 0.27 A (diluted 1/10) 0.03 B (undiluted) 1.15 B (diluted 1/10) 0.17 Figure 6: A standard graph of absorbance, A540 against protein concentration (mg/mL). From the graph above, the equation of the straight line is y

  2. COSHH Risk Assessment for a Laboratory

    This requires setting up warning and communication system's to advise employees of emergencies and incidents that have occurred. As well as having preparations in place it is essential that drills and practices should be honored regularly to ensure that in the event such incidents should happen, necessary steps are followed to minimize harm.

  1. The aim of this investigation is to make a series of dilutions using the ...

    dilution for 100�l, all the four values will have need to be added together. So from looking at appendix B, the values are 2.755, 2.723, 2.743 and 2.698.

  2. Compare & Contrast the recognition of Antigens by B & T Lymphocytes

    On the other hand T cell receptors, work in a slightly different way, as the B cell lymphocyte uses surface receptors to detect and recognize antigens, T cell lymphocytes, recognize antigens by T cell receptors.

  1. Free essay

    How had research over the past 25 years led us to think that microbes ...

    Origins of Life and Evolution of the Biosphere 25, 235-249. Irgens, R.L., Gosink, J.J. & Staley, J.T. (1996) Polaromonas vacuolata gen. nov., sp. nov., a Psychrophilic, Marine, Gas Vacuolate Bacterium from Antarctica. International Journal of Systematic Bacteriology, 46, 822-826. Kargel, J.S., Kaye, J.Z., Head, J.W., Marion, G.M., Sassen, R., Crowley, J.K., Ballesteros, O.P., Grant, S.A.

  2. A review of positive and negative impacts of microbes on the environment

    A disadvantage of antibiotics is that they also kill the beneficial gut flora such as L. acidophilus mentioned earlier. 'Disruption of the normal microbiota can increase the host's susceptibility to invasions by opportunistic pathogens', (Atlas and Bartha, 1998: 630). Another way microbes are beneficial to the medical industry is in the production of vaccinations.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work