Within viruses, methyltransferases are used to form the 5′cap-0 structure for optimal evasion of the host innate immune system. By studying the N7 methyltransferase of the West Nile Virus, more information can be found on the single stranded virus. Mutations were performed on the WNV wildtype and complemented within yeast to determine if their methyltransferases could recover function. The results demonstrated that the mutations I147A and truncation 268 were able to recover function within yeast.