This document summarizes research on SARS-CoV-2 (COVID-19) infections in humans. It discusses the life cycle and genetics of coronaviruses, including their structure, genome, replication process, and advances in understanding SARS-CoV-2 specifically. It describes coronaviruses' ability to adapt between species and cause illness in humans. The document also reviews reverse genetics applications that have increased knowledge of viral replication, transmission between species, and disease pathogenesis for coronaviruses like SARS-CoV-2.