Enzyme Linked Immuno Sorbant Assay Biology Essay

Recombinant protein appraisal is by and large done by any one of the protein quantification methods such as Lowry ‘s or Bradford ‘s or BCA method or even by UV spectrometry. These quantification methods are instead non-specific, non accurate and arduous. Hence sensing and quantification can be done by the method of ELISA, where the consequences are specific to the mark protein. Rather, more figure of samples ( atleast 96 ) can easy be processed in a individual manus. Our proposed merger protein consists of a SUMO protein and a 6xHis ticket. The presence of these mergers can be exploited for sensing and quantification of the mark protein as given in figure 1. During or after agitation procedure, the civilization medium is harvested and centrifuged to obtain supernatant. This supernatant can straight be used for the sensing and protein quantification by the ELISA method.

Coevals of antibodies

Monoclonal and polyclonal antibodies are of great value in biological research and medical specialty, where they serve as indispensable constituents in a assortment of diagnostic systems used for the qualitative and quantitative finding of a broad scope of substances.

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Antibodies soon available for research, diagnostic and therapies are largely mammalian monoclonal or polyclonal antibodies. Antibody production usually requires the usage of research lab animate beings ( largely rabbits, mice, rats and guinea hogs ) or larger mammals, such as Equus caballuss, sheep and caprine animals. The process involves two stairss, each of which causes hurt to the animate beings involved: a ) The immunisation and B ) hemorrhage, which is a fringe benefit for antibody readying ( Schande et al. , 1996 ) .

The major job of monoclonal antibody production is that some antigens are weakly or non at all immunogenic for mice. In polyclonal antibody production, purification of antibodies from mammalian blood has been found low giving up and arduous in many instances. Both engineerings besides involve some stairss, each of which causes hurt to the animate beings involved ( Narat, 2003 ) .

Figure 1: ELISA method for sensing and quantification of recombinant protein produced in E.coli

Chicken Antibodies – an alternate beginning

Chickens, as a beginning of coveted antibodies, represent an surrogate animate being system that offers some advantages with regard to animal attention, high productiveness and particular suitableness of antibodies for certain applications. Chickens are known to bring forth higher degrees of antibodies than mammals, therefore minimising the figure of animate being needed.

Further the yolk of the egg having the same antibodies from the maternal poulet serum can be a suited alternate beginning ; it can avoid hemorrhage of the animate being. Further the egg provides a uninterrupted day-to-day beginning of glandular fever specific polyclonal antibody and can be stored at 4 & A ; deg ; C up to 1 twelvemonth. Despite being an first-class opposite number to mammalian IgG, poulet IgY antibodies still represent an underused resource.

Egg yolk – the IgY reservoir

The yolks of eggs laid by immunised poulets have been recognized as an first-class beginning of polyclonal antibodies for over a decennary ( Jensenics et al. , 1981 ) . The serum IgG antibodies of immunised poulet were expeditiously transported and accumulated in the egg yolk ( Patterson et al. , 1962 ; Rose et al. , 1974 ; Larsson et al. , 1993 ) . The chief type of Ig isolated from egg yolk is by and large referred to as IgY. Other Ig categories are present, but merely in negligible sum. The term IgY is originally coined to mention to the larger molecular weight IgY found in egg yolk, but it is now accepted that IgY is the major antibody in both the blood and yolk in concentration of around 10-20 mg/ml.

The surveies carried out by Leslie and Clem ( 1972 ) has shown that poulet, like coneies, can bring forth high degrees of precipitating antibodies to a streptococcic saccharide. Immunization of poulets for polyclonal antibody production is comparable to that of coneies with regard to the path of injection, the sum of antigen used and the dynamicss of specific antibody coevals ( Song et al. , 1985 ) . Specific antibodies produced in poulets offer several of import advantages over antibodies produced in mammals, because a individual egg contains every bit much antibody as an mean bleed from a coney, this simple, noninvasive attack presents an appealing option to conventional polyclonal antibody production methods.

Purification of poulet egg yolk Ig Y ( IgY ) does non necessitate carnal hemorrhage. In add-on, the eggs from immunized poulets provide a uninterrupted, day-to-day beginning of polyclonal antibody and this convenient attack offers greater compatibility with carnal protection ordinances ( Gottstein and Hemmeler, 1985 ) . High degrees of antibody activity in egg yolk were maintained for several months by periodic immunisation ( Polson et al. , 1980 ) . Furthermore, inoculation of little animate beings such as poulets can be performed easy.

Chicken antibodies recognize more antigenic determinants on a mammalian protein than the corresponding coney antibody does, doing it advantageous to utilize IgY in immunological checks of mammalian proteins. This is particularly true when he antigen is a extremely conserver protein, such as a hormore ( Gassmann et al. , 1986 and Gourele et al. , 1990 ) . Another advantage of poulet IgY over mammalian antibodies is that it does non trip the complement system ; the latter has been shown to cut down antigen binding and cause false negative consequences ( Koch and Jongenelen, 1988 ) . Chicken IgY does non respond with anti-mammalian antibodies in human serum, such as arthritic factors and human anti-mammalina anti-IgG. In immunological checks, the intervention caused by these antibodies can be debatable, peculiarly as the sensitiveness of the check additions.

Table 1 – Comparison of the features of mammalian IgG and avian IgY ( Schade et al. , 1991 )


Mammalian IgG

Avian IgY

Antibody trying



Antibody sum

200mg IgG per shed blooding

( 40 mL blood )

50-100mg IgY per egg

( 5-7 eggs per hebdomad )

Sum of antibody per month



Sum of Specific antibody

5 %

2-10 %

Protein-A/G binding



Intervention with mammalian IgG



Activation of mammalian complement



Therefore, if chicken IgY is used, intervention by anti-mammalian IgG antibodies is eliminated ( Lindmark et al. , 1983 ) . Due to the phyletic distance between birds and mammals when utilizing poulets there is a greater potency of bring forthing a higher per centum of specific antibody against mammalian antigens, ( Akita and Nakai, 1992 ) . Highly conserved mammalian proteins sometimes fail to arouse a humoral immune response in animate beings such as coneies that are traditionally used for bring forthing polyclonal antibodies. Since Chicken IgY does non cross-react with mammalian IgG and does non adhere bacterial or mammalian Fc receptors, non-specific binding is reduced, and the demand for cross-species immunoabsorptions is besides limited. Polson et Al. ( 1980 ) besides corroborated the production of poulet antibodies at lower cost and convenience.


Experience with egg yolk antibodies is that, they are stable over clip, which contradicts some rumours that poulet antibodies are labile. Egg yolk antibodies are stable and can be stored for over 10 old ages at 4 & A ; deg ; C without any important loss in antibody activity. Chicken antibodies have besides retained their activity after 6 months, at room temperature or 1 month at 37 & A ; deg ; C. Chicken antibodies are besides utile in immunoprecipitation checks in agar. Chicken antibodies offer many advantages over mammalian antibodies, and a alteration from mammalian to chicken antibodies improves an immunological check.

Isolation and purification methods

Several methods can be used for the extraction of IgY from egg yolk, and commercial extraction kits are available ( Van regnmortel, 1993 ) . The most often used processs involve protein precipitation with ammonium sulfate, dextran sulfate or polythene ethanediol ( PEG ) and separation by ion exchange chromatography. Harmonizing to Chang et al. , ( 1996 ) isolation of Ig from egg yolk by anionic polyoses was followed for the best recovery of IgG. In pattern, the pick of a specific extraction process is normally influenced by the intended application of the antibody, every bit good as the experience of the research lab concerned ( Lvsch et al. , 1986 ) .

A practically efficient method consists of two consecutive precipitations in PEG, utilizing 3.5 % PEG to take fatty substances, and so 12 % PEG to precipitate the IgY. An betterment of this method incorporates an emulsification measure, adding one volume of trichloromethane instead than utilizing 3.5 % PEG ( Polson et al. , 1980 and Polson, 1990 ) . Harmonizing to Schwarzkopf and Thiele ( 1996 ) , the ammonium sulphate precipitation proved to be the most environmentally compatible and economical one. The advantage of this method becomes peculiarly obvious when the method is followed by affinity chromatography.

Applications of poulet antibodies

Chicken antibodies can be used in both diagnostic and curative intents. The yolk antibodies besides used in a dual antibody sandwich ELISA for observing African Equus caballus illness virus ( Du Plessis et al. , 1999 ) . Chicken antibodies used in the development of serpent antivenom antibodies ( Almeida et al. , 1998 ) .


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