Tyagi & Rai (2016) Biotechnology International 9(3): 60-68 60 ©Biotechnology Society www.bti.org.in ISSN 0974-1453 Review Article r-DNA VACCINES AND DRUGS FOR HUMAN AND ANIMALS Manjusha Tyagi 1 and Anant Rai* 1 Department of Microbiology, Sri Guru Ram Rai (PG) College, Dehradun, Uttarakhand. *Institute of Biotechnology & IT, Mudiya Ahmadnagar, Bareilly-243122, UP. Corresponding author: raia48@gmail.com ABSTRACT Recombinant DNA (r-DNA) vaccines based on replicase gene plasmid vectors are best suited for large scale production of human and animal vaccines because they mount a high level of immune response and a very small amount of DNA is required for immunization. The r-DNA drugs need to be based on conventional plasmid DNA vectors because here we do not want to induce immune response but want to deliver proteins for therapeutic use. Keywords: r-DNA vaccine, r-DNA drugs, replicase gene, pAlpha vector. INTRODUCTION The vaccines currently used are either live attenuated or inactivated vaccines. The live-attenuated vaccines induce humoral as well as cell mediated immune responses but their immunogenicity is somewhat lowered in the process of attenuation. The inactivated vaccines although are capable of inducing humoral as well as cell mediated immune responses, these are not long lasting (Ferraro et al., 2011). DNA based vaccines DNA vaccines got the attention with the findings that when plasmid DNA was delivered into skin or muscle, they induced antibody responses to viral and non-viral antigens (Tang et al., 1992; Fynan et al., 1993; Ulmer et al., 1993). DNA vaccines could induce broad immune responses similar to live attenuated viruses without the need for a replicating pathogen. Wang et al., (1998) reported that DNA vaccines could activate CD 8+ cytotoxic T cells (CTL) in larger animal models. In construction of DNA vaccine, the immunogenic component/gene is cloned in a mammalian expression vector in right orientation. The amount of DNA required to produce immune response is 50-100µg in an animal model. However these immune responses were not as effective as desired and hence different strategies were employed to enhance their immunogenicity including use of immuno-stimulatory (CpG) sequences, dendritic cells (DC), co-stimulatory molecules and cytokine-adjuvants (Leitner et al., 2000). One promising approach is making them ‘self- replicating). This can be accomplished by using a gene encoding RNA replicase, a polyprotein derived from positive-strand RNA alphaviruses, such as Sindbis virus (Herweijer et al., 1995; Hariharan et al., 1998; Ahi et al., 2008; Miller et al. , 2008; Saxena et al., 2008;