A more recent discovery that viruses contain substantial amounts of only one type of nucleic acid, DNA or RNA, whereas all organisms contain and need much of both. Viruses can now be defined as infectious "agents" consisting of one or several molecules of RNA or DNA, usually covered by a coat made of protein. These agents are able to transmit their nucleic acid from one host cell to another. They are then able to use the host's cell enzymatic apparatus to achieve their intracellular replication by superimposing their genetic information on that of the host cell. 7.
West Nile Virus lends itself to the classification as a positive-strand RNA virus. The ultimate size of single stranded RNA genomes is limited by the fragility of RNA and the tendency of long strands to break. For this reason West Nile Virus is limited to 10,000 to 11,000 bases in length. Along this strand, West Nile Virus has a 5" methylated cap but is not lacks a 3" terminal poly tail. This is all usually found with a virion composed of a glycoprotein of about 55 K that contains glucosamine and mannose, and an unusually small nucleocapsid protein.
Most recently a research team at Purdue University has made a step forward in providing man with a detailed picture of this specific enemy. Utilizing advance imaging techniques and cryoelectron microscopy, the team has identified and mapped out the location of the surface proteins in the West Nile Virus particle. Since these proteins are the vehicle by which the virus first interacts with the cell, their identification and structure are fundamentally important in the understanding of how West Nile Virus works. The teams" findings show the West Nile Virus contains an icosahedral symmetry. The virus has no "visible" surface projections or spikes that are normally prominent on other envelope-containing viruses like influenza, HIV and measles.5.
A more in-depth view of the virus structure offered a cross sectional map.