In this video lecture, I discuss the different types of RNA viruses that cause infections in humans. I take some time to discuss influenza, measles, mumps and rubella. I also spend sometime discussing Corona viruses and the new vaccines developed to combat against the pandemic. I then turn my attention to HIV and discuss the viral mechanism and treatments that are now available for this infection. Finally I spend sometime discussing about Prion disease, how its spread and the devastating disease it causes to the nervous system.