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90 Cards in this Set
- Front
- Back
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Who was Dmitry Ivanovsky?
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He also worked on tobacco mosaic viruses at St. Petersburg. He called the disease it called wildfire. He noticed that the causative agent passed through filters that trapped bacteria.
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Who was Martinus Beijerinck?
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A microbiology teacher at the ag school in Wageningen. He saw that the virus escaped through bacteria trapping filters. He did notice that the agent grew in dividing cells.
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Are viruses cells?
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They are considered particles, not cells.
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Most viruses are too small to be seen under a light microscope. True/False
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True.They are app. 100-500 times smaller than bacteria, and they vary in size from 20-300nm in diameter.
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What is a mimivirus?
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It is a recently discovered giant of a virus. It is short for microbe mimicking virus. It has a diameter of around 700nm, which is larger than some bacteria.
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How many genes do viruses generally have?
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Between 2 and 200 genes. The mimivirus may have between 600 and 1,000 genes.
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What type of cell does the mimivirus usually infect?
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The amoeba. It has to borrow the amoebas organelles to manufacture its proteins.
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How do plant viruses enter cells?
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Through a break in the cell wall or are injected by a sap suckling vector like an aphid.
They then spread efficiently from cell to cell via plasmadesmata, the pores that transport molecules between cells. |
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Regarding the HIV virus, it carries the entrance key for the CD4 lock, so only cells with CD4 molecules on their surface can be infected. True/False
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True.
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Once inside a cell, DNA viruses masquerade simply as what?
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As pieces of cellular DNA, and their genes are transcribed and translated using as much of the cells machinary as possible.
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RNA viruses are usually considered one step ahead of DNA viruses. What is meant by this statement?
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They already have their genetic code as RNA. As they carry enzymes that enable their RNA to be copied and translated into proteins.
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What is the function of reverse transcriptase?
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Once inside a cell, it converts their RNA to DNA. This viral DNA can then join, or integrate into the cells DNA employing another enzyme carried by the virus, called integrase.
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Why do RNA genomes have a high mutation rate?
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There is no proof reading system for RNA. The rate of mutation(rom) is app. one in every thousand base pairs per generation.
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Are viruses generally considered living?
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No.They are inert, they cannot generate energy or manufacture proteins independently.
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What is LUCA?
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It stands for "Last Universal Cellular Ancestor). This theory suggests that viruses evolved before Archaea, Bacteria(prokarya) and eukarya.
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What is the virusphere?
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Viruses form a hugh biomass of enormous variety and complexity in the environment. This represents the virusphere.
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Globally there are about 5X10(30) bacteria, and viruses are at least 10 times more common. True/False
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True. Viruses are also quite diverse, with an estimated 100 million different types.
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There are up to 10 billion viruses per/liter of sea water. True/False
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True.
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What is the "White Spot Syndrome Virus?
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This virus has devastated shrimp farms around the world.
The Turtle Papillomavirus is threatening endangered wild turtle populations. The flu virus can infect seals and sea birds as well as humans. |
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What is Emiliana huxleyi?
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It is a rather beautiful phytoplankton that regularly undergoes blooms that turn the ocean surface an opaque blue. These blooms can be seen from space. They can disappear as fast as they appear.
These boom and bust cycles are due to viruses. |
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The majority of marine viruses are phage viruses. True/False
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True.
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Ten percent of the worlds photosynthesis is carried out by genes that come from cyanophages. True/False
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True.
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How many different viral species are there in a Kg of marine sediment?
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!0(6) different species. Marine viruses kill an estimated 20-40% of marine bacteria everyday, and they profoundly affecy the carbon cycle by the viral shunt.
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What is panspermia?
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This states that life on earth began with bacteria and viruses seeded from outer space via comets. This was put forth by Sir Fred Hoyle, famous astronomer and sci fi writer.
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Viruses cannot infect the outer layer of our skin or penetrate through the multiple layers of intact skin. True/False
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True. Yet, a microscopic abrasion is enough to allow entry of wart(papilloma and cold sores(herpes) viruses to infect the host.
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What is the causative agent of syphilis?
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Treponema pallidum.
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Regarding host protective mechanisms, what is gene silencing or RNA interference?
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Interfering RNAs are short RNA molecules that are found inside cells of most species, including humans, where they regulate the manufacture of proteins by binding to RNA messages and preventing their translation into proteins.
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How do RNAis respond to viruses?
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When a virus infects a cell and commandeers its protein manufacturing processes, RNAi molecules also bind to viral RNA messages and inhibit their translation into proteins, so aborting the infection before new viruses can be assembled.
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What is the CCR5 gene?
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It has been noted that some people are resistant to the HIV virus. This turned out to be related to an immune response called CCR5 that codes for a protein that is essential for HIV infection.
About 10% of the caucasian population has a deletion in this gene that cinfers resistance to HIV infection. |
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App. how many B and T lymphocytes do our bodies contain?
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App. 2X10(12).
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Where was SARS first seen?
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SARS is a coronavirus, and it first emerged in November of 2002 in Foshan, Guangdong Province, China, where it caused an outbreak of atypical pneumonia.
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How does SARS spread?
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It spreads through the air and causes disease in almost everyone it infects. Its incubation is app. 2-14 days.
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Can HIV infect mouse CD4 cells?
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No. The molecular structure of the mouse CD4 molecule differs from the human equivalent in ways that make it unrecognizable to the virus.
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What if mouse T cells are transplanted with the human HIV receptor molecules(CD4 and CCR5) in the laboratory?
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The infection is still abortive because mouse T cells lack the essentail proteins that the virus requires for its replication.
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SARS coronavirus and H5N1 (bird flu) have both managed to infect humans but differ in their success rate. Why?
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SARS coronavirus can spread between humans, H5N1 flu, which first jumped from birds to humans in 1997 is unable to do so. This flu virus strain is still poorly adapted to its new human host and we will be in danger of an H5N1 flu pandemic only once it evolves an efficient method of spreading between us.
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What are the three different flu starins?
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A,B, and C. Flu A is zoonotic. With the help of wild birds, this virus can also go recombination, or antigenic shift, producing an entirely new strain of flu in one go by exchanging fragments of its genome with other strains.
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Who are the natural hosts of Flu A viruses?
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Acquatic birds, particularly ducts, but the viruses also infect a variety of other animals, including poultry, pigs, horses, cats and seals. It replicates in bird guts and is excreted in their feces.
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Flu viruses have 8 genes and are segmented. True/False
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True. Segmented means that instead of its genome being continuous strand of RNA, each gene forms a separate strand.
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Which genes are responsible for stimulating protective host immunity?
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The H(hemagglutinin) and N(neuraminidase) genes.
There are 16 different H and 9 different N genes all of which can be found in all combinations in bird flu viruses. |
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Can these genes get mixed up in recombination mechanisms?
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Yes. Because these genes are separate RNA strands in the virus, on occasion they become mixed up, or recombined. So, if two flu A viruses with different H and or N genes infect a single cell, the offspring will carry varying combinations of genes from the 2 parent viruses.
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What is the NS1 gene?
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A mutation in a gene called NS1 prevents virus infected cells from producing interferon. the key cytokine for preventing virus spread and triggering the whole immune cascade. The virus gets a head start, and in some cases the body responds with an uncontrolled outpouring of cytokines, referred to as a cytokine storm.
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Bats have been known to spread the Ebola virus/ True/False
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True.
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What is a Nipah virus?
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A novel paramyxovirus was isolated from a victims brain and named Nipah virus after the village in which he lived. The virus was traced to fruit bats, and its trail to humans, probably began when a colony of bats was left homeless by deforestation.. The bats relocated to trees near the pig farms and the virus spread to the pigs via bat droppings, and then from thepigs to the farmers and abbattoir workers.
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What is the Bluetongue virus?
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It is an insect borne microbethat infects domestic animals, mainly sheep and is spread between them by midges. Sheep develop a blue tongue(cyanosis) due to low O2 levels.
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Which virus is still considered the worlds worst killer virus historically?
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Smallpox. It infected humans at least 5,000 years ago and killed around 300 million in the 20th century alone.
The Antonine plague, which began in AD 166 is though to represent the first ever smallpox pandemic. The plague hit the Roman empire during the reign of Marcus Aurelius Antoninus. |
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Why is Rubella commonly called the German Measles?
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It was first described by Frederich Hoffman, (1660-1742).
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Is Rinderpest virus closely related to measles virus?
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Yes.The diseases are different. Rinderpest infects cloven hoofed animals, oxen, buffalo, yak, sheep, goats, pigs, camels, hippopotamus, giraffe and warthog.
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Rinderpest(cattleplague) is described as the three Ds disease. True/False
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True. Three Ds, Discharge, Diarrhea and Death.
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What are the three Herpes virus subfamilies?
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Alpha, Beta and Gamma.
So far , 8 human herpesvirus have been discovered, HHV 1 to 8 in order of discovery. |
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HSV-1 and 2 are alpha viruses. True/False
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True.
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Which nerve ganglia is HSV-1 found in?
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Trigeminal ganglia. HSV-2 is found in the sacral ganglia. As nerve cells do not really divide, they are an ideal environment for a virus.
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Of the three human beta herpesviruses, CMV is the only one that causes significant health problems. True/False
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True. CMV establishes latency in the bone marrow stem cells that develop into blood monocytes and tissue macrophages. These cells transport the latent virus to the tissues.
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What are the two human gamma herpesviruses?
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EBV and KSHS(Kaposi's).
EBV establishes latency in blood B cells and perhaps because these cells are themselves part of the immune system, the infection engenders an exaggerated T cell response. |
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Human HIVs include not only HIV-1, group M, the pandemic strain of HIV, but also HIV strains, N, O and P, and HIV-2. True/False
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True.
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HCV has many ways of dodging the body's immunity. How is this possible?
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As an RNA virus, HCV, like HIV mutates rapidly and this combined with its extremely high replication rate, generates a whole array of minor genetic variants called quasispecies in a single individual.
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Can HCV also block production of interferon?
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Yes. It also can induce regulatory T cells that paradoxically damp down anti HCV immunity. Those with a high level of Reg T cells have a higher viral load and are more likely to develop a persistent infection than those with a lower level of the same cells.
There is no vaccine for HCV. |
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Most healthy adults will clear primary HBV within 6 months. True/False
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True. Just 1-5% of adult cases lead to lifelong persistence.
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HTLV-1 was first isolated by whom?
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Robert Gallo in 1980 during an intensive hunt for human tumor retroviruses. They employed the recently identified T cell growth factor called interleukin 2 to grow leukemic T cells for the first time in culture.
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What is HTLV-1 tax gene?
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It is the major transforming gene. It codes for the tax protein that has a multitude of functions including driving cell proliferation, decreasing cell death and increasing virus replication.
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Who discovered EBV?
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In 1964, the London based virologist, Anthony Epstein spent 2 years searching for a virus in biopsy material from Burkitt lymphoma.
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EBV is also found in app. 50% of Hodgkin's lymphoma. True/False
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True.
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What type of cells are found in Kaposi's sarcoma?
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KS lesions are composed of KSHV infected endothelial cells known as spindle cells. The virus produces factors that stimulate excessive new blood vessel formation, giving the tumor its characteristic reddish blotchy appearance.
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HBV is a small DNA hepadnavirus and HCV is a flavivirus with an RNA genome. True/False
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True.
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Who was Richard Shope?
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He worked along side Payton Rous at the Rockefeller institute in NY. Shope took wart lesion material from rabbits with Shope tumors and painted them onto the skin of healthy rabbits. These healthy rabbits also developed these invasive tumors.
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HPV targets what type of cell?
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Squamous epithelial cells.
The basal layer of the epithelium that contains self renewing stem cells capable of lifetime cell division. |
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The link between HPV and cervical cancer was suggested by whom?
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Harald zur Hausen
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What is HAART therapy?
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It is used for HIV infection. (Highly Active Anti-Retroviral Therapy)
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What is Oseltamivir?
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It is a neuroaminadas inhibitor of the flu virus. It is generically known as Tamiflu.
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What is the incubation period for smallpox?
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12-24 days.
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What is antigenic drift?
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The slow accumulation of mutations in the genome of a virus such as flu virus that eventually allows it to overcome the immune response generated against its parent virus.
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What is antigenic shift?
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A major genetic change in a viral genome, such as a flu virus resulting from gene re assortment and possibly generating a pandemic strain.
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The Bluetongue virus is of what viral genus?
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Orbivirus.
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What is Bocavirus?
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It is a parvovirus. Bo-Ca comes from bovine and canine.
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What is CD4?
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It is a molecule on the surface of T cells, denoting their helper function.
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What is c-myc?
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It is an oncogene, implicated in several forms of cancer, including Burkitt's lymphoma.
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What is cyanophage?
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A virus infecting cyanobacteria.
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What is Dengue fever virus?
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A flavivirus that causes dengue fever, often referred to as breakbone fever.
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What is the echovirus?
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EntericCytopathicHumanOrphan virus. It is a picornavirus(pico-small and rna. Causes conjunctivitis and flu like febrile illness.
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What is a Hendra virus?
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A paramyxovirus originally called equine morbillivirus. Named after Hendra, Australia where it caused a fatal respiratory outbreak in horses and humans.
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What is Herpaton?
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It means reptile. Refers to the creeping nature of Shingles.
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What is integrase?
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The enzyme that facilitates integration of the retroviral provirus into host DNA.
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What is Marek's disease?
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A herpesvirus that causes tumors in chickens.
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What is Norovirus?
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It is a calicivirus that causes outbreaks of acute gastroenteritis. Previously referred to as the Norwalk agent.
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What is a nucleoside?
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A base, for example cytosine bound to a sugar molecule. Nucleosides may be phosphorylated in a cell to form nucleotides, the building blocks of DNA and RNA.
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What is a recombinant vaccine?
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A synthetic vaccine, made from a subunit of a virus. May be a genome or protein sequence.
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Rinderpest is a morbillivirus. True/False
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True.
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What is thymidine kinase?
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An enzyme found in most mammalian cells that phosphorylates deoxythymidine, an essential process for building DNA.
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What is a TT vrus?
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A recently described ubiquitous anellovirus. Named after the initials of the person from whom it was first isolated, it appears to be non-pathogenic.
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What is Yellow Fever?
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A mosquito transmitted flavivirus, that causes yellow fever, characterized by fever and jaundice.
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What is Yellow Fever?
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A mosquito transmitted flavivirus, that causes yellow fever, characterized by fever and jaundice.
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