This 3rd edition of Fundamentals of Molecular Virology includes detailed information on the recent COVID-19 pandemic and mRNA vaccine technology, additional sections on pathogenic herpesviruses, and updates on recent outbreaks of Zika virus, Ebola virus and mpox diseases. New chapters describe hepatitis C virus, rhabdoviruses, viruses of invertebrates, oncolytic viruses, and virus-mediated gene therapy. All chapters, including those on innate and adaptive immune responses to virus infections, virus vaccines, and antiviral agents, were revised and updated.