The spring semester has begun at Columbia University, which means that it is time to teach my virology course. The fourth annual installment of my virology course, Biology W3310, has begun. This course, which I taught for the first time in 2009, is intended for advanced undergraduates and convenes at the Morningside Campus. Readers of virology blog can watch every lecture in the course. You will find a videocast of each lecture at the course website, at my YouTube channel, and at iTunes University. The complete 2012 version of this course is available online, at iTunes University, and YouTube.