Viruses: noncellular biological entity that can reproduce only within a “host” cell. Viruses consist of “nucleic acid” covered by “protein,” some animal viruses are also surrounded by membrane. (HGPIA)

Viruses have only  a handful of “genes” and some of them overlap. Unable to reproduce on their own, viruses need to ‘hitch a ride’ on a (host cell). (Batista, 65-66) Nonliving “infectious” particles that consist of “DNA” or “RNA” encased in a protein coat. They infect all types of organisms. (Lewis, 327) An infectious agent that occupies a place near the boundary between the living and the nonliving. It is a particle much smaller than a bacterial cell, consisting of a small “genome” of either DNA or RNA surrounded by a protein coat. Viruses enter host cells and hijack the “enzymes” and materials of the host cells to make more copies of themselves. (NHGRI) Because viruses can multiply only inside infected cells, they are not considered to be alive. (NCI1) The “genetic codes” of members of nearly every virus family have been reported. (Venter, 67) Adjective - ‘viral.’

Bacteriophage: viruses whose hosts are bacterial cells. (MeSH) A particular type of virus which infects bacteria and fungi. The ‘T2 bacteriophage’ which attacks bacteria, has been studied in detail and has contributed much to our present knowledge of the life cycle of viruses. Bacteriophages are important in “genetic engineering.” (Indge, 204) A simple virus that causes disintegration of cells in bacteria. (Oxford) Also referred to as  ‘phage.’

phi X 174: this phage was the first DNA virus to be sequenced and the first to have its genome artificially copied and activated. Discovered in the sewers of Paris, phi X 174 targets the human intestine bacterium E. coli. Consists of a circular DNA chromosome - only eleven genes in all - wrapped in a 'coat' of proteins, including a dozen 'spikes.' Injects its DNA through its spikes into a bacterial cell, where it hijacks the cell's biochemical machinery to create many new viruses. Immediately after it has infected its host, enzymes present in the bacterium convert the circle of DNA to the familiar linear double helix. (Venter, 63)

Ebola Virus: a virus (that) causes outbreaks of the contagious ‘ebola fever’ in humans, usually with high mortality. (MeSH) Scientists have identified five types of Ebola virus. Four have been reported to cause disease in humans. The disease can be passed to humans from infected animals and animal materials. Ebola can also be spread between humans by close contact with infected body fluids or through infected needles in the hospital. There is no known cure. Existing medicines that fight viruses (‘antivirals’) do not work well against Ebola virus. (PubMedHealth2) (Consists of) a single strand of “RNA” and seven “proteins.” Its proteins can assemble into a structure capable of reducing a human body to little more than a bag of blood and decomposed tissue. (Lewis, 327)

Ebola Fever: a highly fatal, acute "hemorrhagic" fever caused by the ebola virus, first occurring in the Sudan and adjacent northwestern (what was then) Zaire. (MeSH) Also referred to as ‘ebola hemorrhagic fever.’

Epstein-Barr Virus: a common virus that remains dormant in most people. It causes infectious “mononucleosis” and has been associated with certain “cancers,” including ‘Burkitt lymphoma,’  ‘immunoblastic lymphoma,’ and ‘nasopharyngeal carcinoma.’ (NCI1) Also referred to as ‘EBV.’

Mononucleosis: a viral infection causing fever, sore throat, and swollen lymph glands, especially in the neck. Often spread by saliva and close contact. It occurs most often in those age 15 to 17. However, the infection may develop at any age. Usually linked to the Epstein-Barr virus, but can also be caused by other organisms. (PubMedHealth2) Also referred to as ‘mono’ and ‘the kissing disease.’

Hepatitis A Virus (HVA): causes ‘Hepatitis A’ which is an inflammation of the liver. About 3,600 cases of hepatitis A are reported each year. Because not everyone has symptoms with hepatitis A infection, many more people are infected than are diagnosed or reported. Risk factors include international travel, especially to Asia or South or Central America, IV drug use, and working in a health care, food, or sewage industry. (PubMedHealth2)

Hepatitis B Virus (HVB): a virus that causes ‘hepatitis B.’ It is carried and passed to others through blood or sexual contact. Also, infants born to infected mothers may become infected with the virus. The HBV genome is a partially double stranded circular DNA. (NCIt) Hepatitis B infection is caused by the hepatitis B virus.You can catch hepatitis B through contact with the blood or body fluids of a person who has the virus. Symptoms of hepatitis B may not appear for up to 6 months after the time of infection. Early symptoms include appetite loss, fatigue, and low fever (PubMedHealth2)

Herpes Family Virus: a heterogeneous family of “morphologically” similar viruses, all of which contain double-stranded "DNA" and which infect man and a wide variety of other vertebrates. (NCIt) Any of the small group of viruses causes herpes. (Oxford) Also referred to as ‘herpesviridae.’

Chickenpox: a viral infection in which a person develops extremely itchy blisters all over the body. It used to be one of the classic childhood diseases. However, it has become much less common since the introduction of the chickenpox “vaccine.” Chickenpox is caused by the ‘varicella-zoster virus,’ a member of the herpes virus family. The same virus also causes “shingles” in adults. Chickenpox can be spread very easily to others. You may get chickenpox from touching the fluids from a chickenpox blister, or if someone with the disease coughs or sneezes near you. Even those with mild illness may be contagious. (PubMedHealth2) Also referred to as ‘varicella.’

Shingles: a common dermal and neurologic disorder caused by reactivation of the varicella-zoster virus that has remained dormant within “dorsal root ganglia,” often for decades, after the patient's initial exposure to the virus in the form of chickenpox. It is characterized by severe neuralgic pain along the distribution of the affected nerve. (NCIt) A painful, blistering skin rash. It is caused by the varicella-zoster virus. This is the virus that also causes chickenpox. After you get chickenpox, the virus remains inactive in certain nerves in the body. Shingles occurs after the virus becomes active again in these nerves after many years. The reason the virus suddenly becomes active again is not clear. Often only one attack occurs. Shingles can develop in any age group. You are more likely to develop the condition if one is older than 60, one had chickenpox before age 1, and/or if the immune system is weakened by medications or disease. A health care provider may prescribe a medicine that fights the virus, called an ‘antiviral drug.’ This drug helps reduce pain, prevent complications, and shorten the course of the disease. (PubMedHealth2) Also referred to as ‘herpes zoster.’

Herpes Simplex Virus: delivers the gene encoding ‘enkephalin,’ a pain relieving peptide, to nerve endings in the skin. (Lewis, 397)

Genital Herpes: herpes simplex infection on the genitals, most commonly caused by the herpes simplex-1 virus. (NCIt) A sexually transmitted infection caused by the herpes simplex virus. Affects the skin or mucous membranes of the genitals. Genital herpes cannot be cured. However, antiviral medication can relieve pain and discomfort during an outbreak by healing the sores more quickly. (PubMedHealth2)

Oral Herpes: an infection of the lips, mouth, or gums due to the herpes simplex virus. It causes small, painful blisters commonly called ‘cold sores’ or ‘fever blisters.’ Most people in the United States are infected with this virus by age 20. After the first infection, the virus goes to sleep in the nerve tissues in the face. Sometimes, the virus later ‘wakes reactivates, causing cold sores. (PubMedHealth2) Also referred to as ‘herpes labialis.’

Human Immunodeficiency Virus (HIV): the virus isolated and recognized as the (cause) of AIDS. HIV-1 is classified as a ‘lentivirus,’ a subtype of “retroviruses.” (NCIt) An infectious virus that enters the body with direct contact of bodily fluids. Replicates quickly, changes quickly and can hide. Gradually shuts down the “immune system.” (Lewis, 334-335) The virus is spread person-to-person, through sexual contact, via blood transfusions (now extremely rare in the U.S.), by needle sharing, and from mother to child -- a pregnant woman can spread the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby through her breast milk. The virus is not spread by casual contact such as hugging, mosquitoes, participating in sports, or touching items that were touched by a person infected with the virus. (NHGRI)

Acquired Immune Deficiency Syndrome (AIDS): a disease caused by the human immunodeficiency virus. People with AIDS are at an increased risk for developing certain cancers and for infections that usually occur only in individuals with a weak immune system. (NCI1) A collection of symptoms caused by infection with HIV, which leads to loss of immune cells and leaves individuals susceptible to other infections. There is no cure for AIDS, though drugs can slow down and stabilize the disease's progress. (NHGRI) One percent of Caucasians do not have the “receptor” that recognizes the AIDS virus and allows it to enter “T cells.” (They) are therefore immune to the HIV virus that causes AIDS. (Batiza, 6) "Reverse transcriptase" is an enzyme that copies the AIDS virus “genome” so it can live inside our cells. (Batiza, 64) The HIV virus attacks the immune system. Once a person has the virus, it stays inside the body for life. HIV infection is a condition that can gradually destroy the immune system, which makes it harder for the body to fight infections. When this happens, the person has AIDS. (PubMedHealth2) Not inherited, but acquired by infection with HIV. (Lewis, 334)

Influenza Virus Type A:  one of three types of virus that cause the illness called influenza (flu). Influenza type A viruses can infect people, birds, pigs, horses, and other animals, but wild birds are the natural hosts for these viruses. It is the main cause of most influenza epidemics. ‘Influenza B’ viruses are usually found only in humans. Unlike influenza A viruses, these viruses are not classified according to subtype. Influenza C virus can cause a rare form of influenza. (NCIt)

Avian Flu Virus (H5N1): (caused by) a subtype of type A influenza virus found chiefly in birds, but infections with these viruses can occur in humans. (NCIt) A flu infection in birds. The first avian influenza in humans was reported in Hong Kong in 1997. The outbreak was linked to chickens. Since then there have been human cases of H5N1 in Asia, Africa, Europe, Indonesia, Vietnam, the Pacific, and the near East. Hundreds of people have become sick with this virus. Up to half of the people who get this virus die from the illness. The chance of a worldwide outbreak in humans goes up the more the avian flu virus spreads. Your risk of getting the bird flu virus is higher if you work with poultry (such as farmers), you travel to countries where the virus is present, or you touch an infected bird. (PubMedHealth2) Researchers rapidly developed vaccines against H5N1 in 2005 using ‘reverse vaccinology.’ (Lewis, 344) Also referred to as ‘bird flu virus.’

Influenza: an acute viral infection in humans involving the “respiratory” tract. It is marked by inflammation of the ‘nasal mucosa,’ the “pharynx,” and the thin membrane that covers the inner surface of the eyelid and the white part of the eyeball. (MeSH) An infection of the nose, throat, and lungs. It spreads easily. Caused by an influenza virus. Most people get the flu when they breathe in tiny droplets from coughs or sneezes of someone who has the flu. Can also catch the flu if you touch something with the virus on it, and then touch your mouth, nose, or eyes. Sometimes people confuse ‘colds’ and flu. They are different. But, you might have some of the same symptoms. Most people get a cold several times each year. Usually, a person gets the flu once every few years. (PubMedHealth2) Also referred to as ‘flu.

Swine Flu Virus (H1N1): a new flu virus strain that caused a worldwide pandemic in humans from June 2009 to August 2010. Earlier forms of the H1N1 virus were found in pigs. Over time, the virus mutated and infected humans. It spread quickly around the world. (PubMedHealth2) Researchers rapidly developed vaccines against H1N1 in 2009 using ‘reverse vaccinology.’ (Lewis, 344)

Retrovirus: a type of “RNA" virus. Retroviral sequences in chromosomes are carried from “generation” to generation of the host, rather than acquired as an infection. (Lewis, 207) An RNA containing virus that can convert its “genetic material” into DNA by means which enable it to become integrated into the DNA of the host’s cells. (OxfordMed) A family of RNA viruses that infects birds and mammals and encodes the enzyme “reverse transcriptase.” A key feature of retrovirus biology is the synthesis of a DNA copy of the “genome” which is integrated into cellular DNA. After integration it is sometimes not expressed but maintained in a latent state. (MeSH) Adjective - ‘retroviral.’

Human Endogenous Retrovirus (HERV): a retrovirus whose genetic material is in our chromosomes. Researchers traced HERVs to a virus that infected our ancestors' genomes about 5 million years ago. Since then, HERV sequences have exchanged parts and mutated to the extent that they no longer make us sick. Harmless HERVs silently pass from human generation to generation as parts of chromosomes. (Lewis, 207) Have lost infectious capability but retained the capability to transpose. (MeSH) Also referred to as ‘endogenous retrovirus.’

Rubella Virus: an enveloped, single-stranded RNA virus that is the causative agent of Rubella. (NCIt)

Rubella: an infection in which there is a (“skin rash”). Children generally have few symptoms. Adults may experience a fever, headache, general discomfort, and a runny nose before the rash appears. Caused by a virus that is spread through the air or by close contact. Because the ‘measles-mumps-rubella vaccine’ is given to most children, rubella is much less common now. Almost everyone who receives the vaccine (is immune) to rubella. Children and adults who were never vaccinated against rubella may still get this infection. (PubMedHealth2) Also referred to as ‘german measles’ and ‘three day measles.’

SARS Corona Virus: a virus that was first identified in 2003. Causes “severe acute respiratory syndrome.” (PubMedHealth2)

Severe Acute Respiratory Syndrome (SARS): a viral respiratory infection caused by the SARS coronavirus. It is transmitted through close person-to-person contact. It is manifested with high fever, headache, dry cough and “myalgias.” (NCIt) It may progress to “pneumonia” and cause death. A serious form of pneumonia. Infection with the SARS virus causes severe breathing difficulty and sometimes death. Quickly it infected thousands of people around the world, including people in Asia, Australia, Europe, Africa, and North and South America. Schools closed throughout Hong Kong and Singapore. National economies were affected. The World Health Organization identified SARS as a global health threat, and issued a travel advisory. WHO updates closely tracked the spread of SARS. The 2003 outbreak had an estimated 8,000 cases and 750 deaths. The fast global public health response helped to stem the spread of the virus. SARS is a dramatic example of how quickly world travel can spread a disease. It is also an example of how quickly a connected health system can respond to a new health threat. (PubMedHealth2) Researchers rapidly developed vaccines against SARS in 2003 using ‘reverse vaccinology.’ (Lewis, 344)

Smallpox Virus: an (enveloped, double-stranded DNA virus) that is the causative agent of “smallpox.” (NCIt) Has more than 100 different types of proteins. A massive program by the World Health Organization wiped out all known smallpox viruses from the world in the 1970s, except for a few samples saved for government research. Researchers continue to debate whether or not to kill the last remaining samples of the virus, or to preserve it in case there may be some future reason to study it. (PubMedHealth2) Also referred to as ‘variola virus.’

Smallpox: a serious and contagious disease due to a virus. Was once found throughout the world, causing illness and death wherever it occurred. It mainly affected children and young adults. Family members often infected each other. Smallpox spreads easily from one person to another from saliva droplets. It may also be spread from bed sheets and clothing. (PubMedHealth2) (Research into smallpox) led to the development of the first “vaccine.” The disease was eradicated in 1977. (Lewis, 340)

Viral DNA: may take over directly, inserting into a chromosome or remaining outside the nucleus. DNA sequences that represent viruses. (Lewis, 207) Deoxyribonucleic acid that makes up the genetic material of viruses. (MeSH) Also referred to as “DNA virus.”

Viral RNA: virus that must first copy its RNA into DNA before it can insert into (the host’s DNA). (Lewis, 207) Ribonucleic acid that makes up the genetic material of viruses. (MeSH) Virus that first uses (the) enzyme reverse transcriptase to copy its genetic material into DNA, which then inserts into a host chromosome. (Lewis, 207) Also referred to as “RNA virus.”