The FRNT involves the following steps: 1. Preparation of Virus and Cells: A known quantity of the virus is mixed with serial dilutions of the serum sample. 2. Inoculation: The virus-serum mixture is added to a monolayer of susceptible cells cultured in a plate. 3. Incubation: The plate is incubated to allow the virus to infect the cells and form foci (localized areas of infected cells). 4. Staining: The cells are fixed and stained to visualize the foci. 5. Counting: The number of foci is counted, and the reduction in the number of foci compared to a control sample without serum indicates the presence and potency of neutralizing antibodies.
