Sanjay Kumar Yadav*1, Anjana Yadav1, Shahana Majumder2
*1Dept of Pharmaceutical Chemistry, B.B.S. Institute of Pharmaceutical & Allied Sciences, Greater Noida, (U.P.), India
1Dept of Biotechnology, Chhatrapati Sahu Ji Maharaj University, Kanpur, (U.P.), India
2Dept of Biotechnology, Sharda University, School of Engineering and Technology,
Greater Noida, (U.P.), India
Viruses are pathogens with an extremely narrow host range. Their phylogenetic origin is vague, tough it has always been considered that viruses are genes that became vagrant after having excluded themselves of the host’s or a related species’ genome (Anderson et.al., 2004). Viruses are usually units consisting of nucleic acids and coat proteins called capsids. Viroids consist only of RNA, i.e. they contain no protein at all. Except for a few cases, Viruses have no energy metabolism of their own. Consequently, they cannot perform syntheses and are thus unable to replicate themselves. Depending on their host species, it is distinguished between plant viruses multiplying almost exclusively within plant cells, bacterial viruses (bacteriophages) that depend on living bacteria, and animal viruses. The genetic information of viruses is either encoded by single-stranded RNA (Most plant viruses), double-stranded RNA (Wound tumor viruses), single-stranded DNA (Gemini viruses) or double stranded DNA (Cauliflower mosaic virus). Based on the shape of the viruses particle, it is distinguished between rod shaped and icosahedral viruses with a capsid that seem almost spherical. Viruses’ cause many disease in humans of international importance for example smallpox polio, hepatitis etc. viruses cause also many important plant disease and are responsible for huge loss in crop production and quality in all part of the world. Around 25 years ago, when genomic properties of geminiviruses were studied, many scientists regarded them as ‘friends of humans’, because of their potential as gene transfer vectors in plant genetic engineering and non-harmful effects on host plants. But far from being friends, these viruses have now emerged as foes and are a serious threat to world agriculture now. Increase in international commodity trade, intercontinental transportation networks and a changing global climate have contribute to the spread of this virus and its whitefly vector (Moffat et.al.,1999).