Inoculation of plasmid
DNA, encoding an immunogenic
protein gene of an infectious agent, stands out as a novel approach for developing new generation
vaccines for prevention of
infectious diseases of animals. The potential of
DNA vaccines to act in presence of maternal
antibodies, its stability and cost effectiveness and the non-requirement of cold chain have heightened the prospects. Even though great strides have been made in
nucleic acid vaccination, still there are many areas that need further research for its wholesome practical implementation. Major areas of concern are
vaccine delivery, designing of suitable vectors and cytotoxic T cell responses. Also, the induction of immune responses by
DNA vaccines is inconclusive due to the lack of knowledge regarding the concentration of the
protein expressed in vivo. Alternative delivery systems having higher transfection efficiency and the use of
cytokines, as
immunomodulators, needs to be further explored. Recently, efforts are being made to modulate and prolong the active life of dendritic cells, in order to make antigen presentation a more efficacious one. For combating diseases like
acquired immunodeficiency syndrome (
AIDS),
influenza,
malaria and
tuberculosis in humans; and
foot and mouth disease, Aujesky's
disease, swine fever,
rabies,
canine distemper and
brucellosis in animals,
DNA vaccine clinical trials are underway. This review highlights the salient features of
DNA vaccines, and measures to enhance their efficacy so as to devise an effective and novel vaccination strategy against
animal diseases.