RT Book, Section A1 Ryan, Kenneth J. SR Print(0) ID 1185630652 T1 Human Retroviruses: HTLV, HIV, and AIDS T2 Sherris & Ryan's Medical Microbiology, 8th Edition YR 2022 FD 2022 PB McGraw-Hill Education PP New York, NY SN 9781260464283 LK accessmedicine.mhmedical.com/content.aspx?aid=1185630652 RD 2024/03/28 AB Retroviruses are enveloped, icosahedral, single-stranded, positive-sense RNA viruses. These viruses are known as retroviruses because they encode an enzyme called reverse transcriptase (RT), which converts the RNA genome into a double-stranded DNA copy that subsequently becomes integrated into the host chromosome. The discovery of RT 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.