RT Book, Section A1 Ryan, Kenneth J. SR Print(0) ID 1148672791 T1 Retroviruses: Human T-Lymphotropic Virus, Human Immunodeficiency Virus, and Acquired Immunodeficiency Syndrome T2 Sherris Medical Microbiology, 7e YR 2017 FD 2017 PB McGraw-Hill Education PP New York, NY SN 9781259859809 LK accessmedicine.mhmedical.com/content.aspx?aid=1148672791 RD 2024/03/29 AB Retroviruses are enveloped, single-stranded, positive-sense RNA viruses. These viruses are known as retroviruses because they encode an enzyme called reverse transcriptase, which converts the RNA genome into a double-stranded DNA copy that subsequently becomes integrated into the host chromosome. The discovery of reverse transcriptase in 1970 by two American virologists, David Baltimore and Howard Temin, earned them a Nobel Prize in Medicine. There are two major groups of retroviruses that infect humans: the oncoretroviruses (onco-, “related to a tumor”) and the lentiviruses (lenti-, “slow”). There are several other groups of retroviruses that infect animals. Endogenous retrovirus sequences are found throughout the human genome. Like most enveloped viruses, all retroviruses are highly susceptible to factors that affect surface tension and are thus not transmissible through air, dust, or fomites under normal conditions, but instead require intimate contact with the infecting sources, such as bodily fluids, blood, and blood-derived products.