A retrovirus is a type of RNA virus that inserts a copy of its genome into the DNA of a host cell that it invades, thus changing the genome of that cell.
An RNA virus is a virus that has RNA as its genetic material. This nucleic acid is usually single-stranded RNA (ssRNA) but may be double-stranded RNA (dsRNA). Notable human diseases caused by RNA viruses include Ebola virus disease, SARS, COVID-19, rabies, common cold, influenza, hepatitis C, hepatitis E, West Nile fever, polio and measles.
A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by retroviruses to replicate their genomes, by retrotransposon mobile genetic elements to proliferate within the host genome, by eukaryotic cells to extend the telomeres at the ends of their linear chromosomes, and by some non-retroviruses such as the hepatitis B virus, a member of the Hepadnaviridae, which are dsDNA-RT viruses.
Virology is the study of viral – submicroscopic, parasitic particles of genetic material contained in a protein coat – and virus-like agents. It focuses on the following aspects of viruses: their structure, classification and evolution, their ways to infect and exploit host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy. Virology is considered to be a subfield of microbiology or of medicine.
Virus classification is the process of naming viruses and placing them into a taxonomic system. Similar to the classification systems used for cellular organisms, virus classification is the subject of ongoing debate and proposals. This is mainly due to the pseudo-living nature of viruses, which is to say they are non-living particles with some chemical characteristics similar to those of life, or non-cellular life. As such, they do not fit neatly into the established biological classification system in place for cellular organisms.
David Baltimore is an American biologist, university administrator, and 1975 Nobel laureate in Physiology or Medicine, he is a Professor of Biology at the California Institute of Technology, where he served as president from 1997 to 2006. He also serves as the director of the Joint Center for Translational Medicine, which joins Caltech and UCLA in a program to translate basic science discoveries into clinical realities. He served as president of the California Institute of Technology (Caltech) from 1997 to 2006, and is currently the President Emeritus and Robert Andrews Millikan Professor of Biology at Caltech. He also served as president of Rockefeller University from 1990 to 1991, and was president of the American Association for the Advancement of Science in 2007. Baltimore has profoundly influenced international science, including key contributions to immunology, virology, cancer research, biotechnology, and recombinant DNA research, through his accomplishments as a researcher, administrator, educator, and public advocate for science and engineering. He has trained many doctoral students and postdoctoral fellows, several of whom have gone on to notable and distinguished research careers. In addition to the Nobel Prize, he has received a number of awards, including the U.S. National Medal of Science in 1999. Baltimore currently sits on the Board of Sponsors for the Bulletin of the Atomic Scientists and is a consultant to the Science Philanthropy Alliance.
Zidovudine (ZDV), also known as azidothymidine (AZT), is an antiretroviral medication used to prevent and treat HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used to prevent mother-to-child spread during birth or after a needlestick injury or other potential exposure. It is sold both by itself and together as lamivudine/zidovudine and abacavir/lamivudine/zidovudine. It can be used by mouth or by slow injection into a vein.
Renato Dulbecco was an Italian–American virologist who won the 1975 Nobel Prize in Physiology or Medicine for his work on oncoviruses, which are viruses that can cause cancer when they infect animal cells. He studied at the University of Turin under Giuseppe Levi, along with fellow students Salvador Luria and Rita Levi-Montalcini, who also moved to the U.S. with him and won Nobel prizes. He was drafted into the Italian army in World War II, but later joined the resistance.
Howard Martin Temin was a US geneticist and virologist. He discovered reverse transcriptase in the 1970s at the University of Wisconsin–Madison, for which he shared the 1975 Nobel Prize in Physiology or Medicine with Renato Dulbecco and David Baltimore.
Caulimoviridae is a family of viruses infecting plants. There are currently 68 species in this family, divided among 8 genera. Viruses belonging to the family Caulimoviridae are termed double-stranded DNA (dsDNA) reverse-transcribing viruses i.e. viruses that contain a reverse transcription stage in their replication cycle. This family contains all plant viruses with a dsDNA genome that have a reverse transcribing phase in its lifecycle.
Viral replication is the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its genome and packaging these copies, the virus continues infecting new hosts. Replication between viruses is greatly varied and depends on the type of genes involved in them. Most DNA viruses assemble in the nucleus while most RNA viruses develop solely in cytoplasm.
Molecular virology is the study of viruses on a molecular level. Viruses are submicroscopic parasites that replicate inside host cells. They are able to successfully infect and parasitize all kinds of life forms- from microorganisms to plants and animals- and as a result viruses have more biological diversity than the rest of the bacterial, plant, and animal kingdoms combined. Studying this diversity is the key to a better understanding of how viruses interact with their hosts, replicate inside them, and cause diseases.
The Caudovirales are an order of viruses also known as the tailed bacteriophages. Under the Baltimore classification scheme, the Caudovirales are group I viruses as they have double stranded DNA (dsDNA) genomes, which can be anywhere from 18,000 base pairs to 500,000 base pairs in length. The virus particles have a distinct shape; each virion has an icosahedral head that contains the viral genome, and is attached to a flexible tail by a connector protein. The order encompasses a wide range of viruses, many containing genes of similar nucleotide sequence and function. However, some tailed bacteriophage genomes can vary quite significantly in nucleotide sequence, even among the same genus. Due to their characteristic structure and possession of potentially homologous genes, it is believed these bacteriophages possess a common origin.
The Baltimore classification, developed by David Baltimore, is a virus classification system that groups viruses into families, depending on their type of genome and their method of replication.
Reverse-transcribing virus is a generic term, which may refer to any member of the families:
Avian sarcoma leukosis virus (ASLV) is an endogenous retrovirus that infects and can lead to cancer in chickens; experimentally it can infect other species of birds and mammals. ASLV replicates in chicken embryo fibroblasts, the cells that contribute to the formation of connective tissues. Different forms of the disease exist, including lymphoblastic, erythroblastic, and osteopetrotic.
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants, and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, about 5,000 virus species have been described in detail, of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology.
Alice S. Huang (simplified Chinese: 黄诗厚; traditional Chinese: 黃詩厚; pinyin: Huáng Shīhòu; Wade–Giles: Huang Shih-hou; is an American biologist specialized in microbiology and virology. She is Senior Faculty Associate in Biology at the California Institute of Technology, and served as President of AAAS during the 2010-2011 term.
Paleovirology is the study of viruses that existed in the past but are now extinct. In general, viruses cannot leave behind physical fossils, therefore indirect evidence is used to reconstruct the past. For example, viruses can cause evolution of their hosts, and the signatures of that evolution can be found and interpreted in the present day. Also, some viral genetic fragments which were integrated into germline cells of an ancient organism have been passed down to our time as viral fossils, or endogenous viral elements (EVEs). EVEs that originate from the integration of retroviruses are known as endogenous retroviruses, or ERVs, and most viral fossils are ERVs. They may preserve genetic code from millions of years go, hence the "fossil" terminology, although no one has detected a virus in mineral fossils. The most surprising viral fossils originate from non-retroviral DNA and RNA viruses.
This glossary of virology is a list of definitions of terms and concepts used in the study of virology, particularly in the description of viruses and their actions. Related fields include microbiology, molecular biology, and genetics.
