No, as a matter of fact, I have worked with DNA immunization for some time and have not had that problem. There are several factors that probably need to be considered before someone can address what may be going on- including the nature of the protein the gene encodes for (intracellular, secreted, GPCR, etc), the type of vector being used and delivery method, etc. In my experience,  matching the sequence in the correct orientation/reading frame with an appropriate vector that can present the protein to the immune system is the area where most in-house DNA vaccine trials encounter obstacles.

Dear Jennifer;

Thanks for your kind response. I have checked any factor regarding vector design and protein characteristics and I'm sure of them. I have reached to this conclusion that maybe something like tolerance has occurred!

Dear Raheleh,

It depends on what do you expect as "immunization effect". If you work for Western blot or ELISA detection of antibodies response, this result can be obtained. In majority of cases in vivo delivery falure (low or absence of transfection-infection percentage) is the reason. Sometimes it is low/blockage of expression, but this is not so often if you use commercial vector, and cloning was made properly.

However up to now I do not know DNA vaccines that passed all phases for being recommended as preventive for development of infectious diseases or moreover for therapy of these diseases, neither in medicine, nor in veterinary medicine. Natural pathogen's proteins or recombinant proteins are being used. 

Regards

Dear Raheleh, 

The concentration of purified DNA and route of inoculation also can also affect the outcome. I have worked with DNA vaccine 100ug of DNA I/M or S/C route. S/C route shows better response. Sometimes animals age and maintenance conditions also play important role. 

So far four licenced DNA vaccine available in market for veterinary use out of this two against infectious viral diseases ( West nile virus, Infectious Hematopoietic necrosis virus).