Virus mediated gene transfer is the technology in which virus is used as a vector. We use in transferring our desired gene or targeted gene of interest to host cell by viral vector, such as bacteriophage. It attacks the bacterial cell and by degrading bacterial genome it release the desired gene of interest in bacterial cell and by using bacterial replisome it replicates in more number. By this process it also uses some sequence of bacterial genome too and create a recombinant genome and multiplies in a large number inside the host. This special phase of gene transfer or lysogenic gene transfer. After the process viral cell get degraded and comes out of the host cell.