Why dilute viral suspension when testing for viral plaque?

Diluting viral suspension when testing for viral plaques is essential to achieve an appropriate concentration of viral particles. This ensures that the plaques formed are countable and distinct, allowing for accurate quantification of viral titer. If the suspension is too concentrated, it may lead to overlapping plaques, making it difficult to assess the viral load accurately. Additionally, dilution helps to prevent saturation of the cell monolayer, which can impede the interpretation of results.