Accuracy of virus counting methods - (May/12/2009 )

A question from a non-virologist...

Just how accurate are methods for enumerating viruses or getting estimates of viral titre?

For instance, just how accurate are plaque assays or TCID50 methods?

I've heard they are frequently no better than estimating to within a log !!!

Can this be true!!!!

the most accurate method is plaque assay I guess. because it will give you the number of active virus particles.

I also think methods can vary depending on the virus type. for example HA assay only applies to certain viruses like Influenza and NDV.

I think it's probably pretty true with plaque assay counts - but I also think it's true for bacteria with spread/spot plating. However, the more plates (replicates) you do, the more accuracy you get. It also depends on how well you dilute your cultures.