Viral assay means determination of number of viral particles per unit volume of a sample. Through this slide the role of redioactivity in viral assay is described.

1. Role of Radioactivity in Viral Assay
SEMINAR REPORT
M.Sc MICROBIOLOGY (SEM.3rd)
SUBMITTED TO :- SUBMITTED BY:-
DR. ABHISHEK ROY Mr. VISHNU KUMAR SHARMA

2. Viral Assay
• Viral assay means determination of number of
viral particles per unit volume of a sample.
• Or It is measurement of amount of
biomolecules (virus) by different methods.

3. Methods of Viral Assay
• Plaque assay.
• Endpoint dilution assay.
• Protein assay.
• Transmission electron microscopy (TEM)
• Tunable resistive pulse sensing (TRPS)
• Flow cytometry.
• Quantitative polymerase chain reaction (qPCR)
• Enzyme-linked immunosorbent assay (ELISA)

4. Role of Radioactivity in Viral Assay
• Radioactive Tracer:-A ”radioactive tracer, or radioactive label”, is
a chemical compound in which one or more atoms have been replaced by
a radionuclide so by virtue of its radioactive decay, it can be used to
explore the mechanism of chemical reactions by tracing the path that the
radioisotope follows from reactants to products. Radiolabelling is thus, the
radioactive form of isotopic labeling.
• Radioisotopes of hydrogen, carbon, phosphorus, sulfur, and iodine have
been used extensively to trace the path of biochemical reactions.

5. Hershey–Chase experiment

6. Radioimmunoassay
• Is used to determine concentration of antigen
present in the sample.
• This antigen can be hormone, serum protein,
drug, or vitamin.
• The technique was developed by “Berson and
Yalow” in 1960.
• This technique is so sensitive that it can detect
0.001 g/ml.

7. Procedure

8. In First step, Microtiter plate is taken and than
it is coated with Anti A Antibody (Ab)
Radiolabelled Antigen(Ag) is added in excess
quantity , so all the Ag binding sites of Ab is
saturated by the Ag
Unbounded Ag is removed by the help of
washing

9. So, now radioactivity is assumed 100%
Known amount of non labelled Ag is added to the well
This addition will create competition b/w labelled and
unlabelled Ag for binding with Ab
Few labelled Ag is replaced by unlabelled Ag

10. Washing to remove unbounded Ag
Now no. of radiolabelled Ag bounded with Ab is decreased due to binding of unlabelled
Ag. Hence, the radioactivity will not remain 100%
So, now a standard graph is plotted b/w radioactivity and amount of unlabelled Ag
unlabelled Ag (ng) Radioactivity %
0 100
1 90
2 80
3 70
4 60
5 50

11. Now all the steps are repeated with serum sample and graph is plotted and this
graph is compared with standard graph to determine the quantity of A antigen.

12. Research Paper
Radioactive Labelling of Viruses: an Iodination Technique Preserving
Biological Properties
An iodination procedure suitable for the radioactive labelling of viruses
to be used in biological experiments is described. It is characterized
by the addition of carrier protein to small amounts of virus before
iodination with chloramine T, the use of low concentrations of
chemicals, and a rapid purification of the labelled virus to minimize
radiation inactivation. Using this procedure, polyoma virus was
labelled to a specific activity ioo times greater than that which can
be obtained with tritiated amino acids, while its sedimentation
coefficient, buoyant density, decapsidation and haemagglutinating
activity remained unaffected. Reduction in infectivity, possibly due
to radiation inactivation, was slight. Similar results were obtained
with adenovirus.

13. Refrences
• http://www.biologydiscussion.com/viruses/isolation-assay-
and-cultivation-of-viruses/50075
• https://en.wikipedia.org/wiki/Radioactive_tracer
• https://msu.edu/course/lbs/333/fall/hersheychaseexpt.html
• Study.com
• https://www.youtube.com/watch?v=hJ8AYS5rpyu
• Virology/Dr. A. Maharajan/ 2011
• Rao Chervu, L., & Murty, D. R. K. (1975). Radiolabeling of
antigens: Procedures andassessment of properties. Seminars
in Nuclear Medicine, 5(2), 157–172. doi:10.1016/s0001-
2998(75)80030-4

14. • From the Department of Radiology. Albert Einstein College of
Medicine, Bronx. N.Y., and the Squibb Institute for Medical
Research, New Brunswick, N.J. L. Rao Chervu, Albert Einstein
College of Medicine, Bronx, N.Y. D.R.K. Murty, In Vitro
Diagnostics R&D. Squibb Institute for Medical Research. New
Brunswick. N.J. © 1975 by Grune & Stratton, Inc.