transfection or infection - difference? (Mar/13/2011 )

I am reading articles and websites on gene knockdown and sometimes they state transfection efficiency or infection efficiency. for example, one website is trying to sell plasmid constructs containing a gene to be expressed in the cell and they talk of both transfection and infection efficiency of the construct being expressed in a cell line. What is the difference between transfecting cells and infecting cells? When should either be used in what situations?

Its hard to tell...

The problem is that those words are used in so many different cases.

Transfection comes originaly from tranfection + infection (using a virus or bacteriophage)

Now transfection is used for the introduction of DNA or RNA in cells by artificial methods eg chemical (so not a viral method).

Infection just means that a parasite (ex virus of bacterium) infects a host...

I think in the papers you read they write infection if they use a virus to infect the bacterium (altough they should use transduction then) and that they write transfection if its not with a virus.