Zaire ebolavirus
General Viral Replication:
The Lytic Cycle
In the lytic cycle ( the main cycle in viral replication) once the viral DNA enters the cell it transcribes itself into the host cell's messenger RNAs and uses them to direct the ribosomes.The host cell's DNA is destroyed and the virus takes over the cell's metabolism.The virus begins using the cell energy for its own use by creating copies of itself. As the cell starts getting overcrowded of viruses, the original virus releases enzymes to break the cell wall. makes the cell wall burst (lysing) and the new viruses are released. Ebola and Marburg only use the lytic cycle for its replication. Filoviruses target and destroy epithelial cells with the lytic cycle which causes the violent and destructiveness of the disease.
The Lysogenic Cycle
In the lysogenic cycle, the viral DNA or RNA enters the cell and incorporates itself into the host DNA as a new set of genes called prophage (the viral DNA becomes part of the cell's genetic material). Each time the host cell DNA chromosome replicates during cell division, the passive and non-virulent virus genetics replicates too. This may alter the cell's characteristics, but it does not destroy it. There are no viral symptoms in the lysogenic cycle; it occurs after the viral infection is over. But the viral DNA or RNA remains in the cell and it may remain there permanently. However, if the prophage undergoes any stress or mutation or is exposed to UV radiation, the viral lysogenic cycle can change into the viral lytic cycle. In which case, there will be symptoms of a new viral infection. Some viruses first replicate by the lysogenic cycle and then switch to the lytic cycle.
General Virus Classification:
Icosahedral Viruses:
Most animal viruses are icosahedral; a regular icosahedron is the optimum way of forming a closed shell from identical subunits. The minimum number of identical capsomers required is twelve, each composed of five identical subunits. The same protein may act as the subunit of both the pentamers and hexamers or they may be composed of different proteins.
Icosahedral Viruses:
Most animal viruses are icosahedral; a regular icosahedron is the optimum way of forming a closed shell from identical subunits. The minimum number of identical capsomers required is twelve, each composed of five identical subunits. The same protein may act as the subunit of both the pentamers and hexamers or they may be composed of different proteins.
Enveloped Viruses:
Some species of virus envelop themselves in a modified form of one of the cell membranes, either the outer membrane surrounding an infected host cell or internal membranes such as nuclear membrane or endoplasmic reticulum, thus gaining an outer lipid bilayer known as a viral envelope. This membrane is studded with proteins coded for by the viral genome and host genome; the lipid membrane itself and any carbohydrates present originate entirely from the host. The Human Immunodeficiency Virus (HIV) is a famous enveloped virus; its complicated shell makes it very difficult to kill.
Complex Viruses:
Complex viruses have a capsid that is neither icosahedral nor helical. They can come in many shapes and sizes; some complex viruses have tails and other have complex outer wall layers. The tail structure acts like a molecular syringe, attaching to the bacterial host and then injecting the viral genome into the cell. The outer wall serves to protect the virus. The family Poxviridae contains many complex viruses such as smallpox (variola) and cowpox.
Complex viruses have a capsid that is neither icosahedral nor helical. They can come in many shapes and sizes; some complex viruses have tails and other have complex outer wall layers. The tail structure acts like a molecular syringe, attaching to the bacterial host and then injecting the viral genome into the cell. The outer wall serves to protect the virus. The family Poxviridae contains many complex viruses such as smallpox (variola) and cowpox.
Helical Viruses:
These viruses are composed of a single type of capsomer stacked around a central axis to form a helical structure, which may have a central cavity, or tube. This arrangement results in rod-shaped or filamentous virions: These can be short and highly rigid, or long and very flexible. The most common form of genetic material for this viruses is RNA. The length of the virus is the similar length to the nucleic acid within it while width is dependent on the size and arrangement of the capsomers. Tobacco mosaic virus infects many plants including tobacco and cause a mosaic like molting and discoloration.
These viruses are composed of a single type of capsomer stacked around a central axis to form a helical structure, which may have a central cavity, or tube. This arrangement results in rod-shaped or filamentous virions: These can be short and highly rigid, or long and very flexible. The most common form of genetic material for this viruses is RNA. The length of the virus is the similar length to the nucleic acid within it while width is dependent on the size and arrangement of the capsomers. Tobacco mosaic virus infects many plants including tobacco and cause a mosaic like molting and discoloration.
Bacteriophages:
They are very complex viruses that infect bacteria cells that are much larger than itself. They use their six legs to attach to a cell and then they inject their own DNA or RNA into the cell. Bacteriophages can be harmful to bacteria and can kill the cell, and they can also inject some useful DNA. Bacteriophages are becoming more important in genetic modification because they can be used to change the genetic code of bacteria.
They are very complex viruses that infect bacteria cells that are much larger than itself. They use their six legs to attach to a cell and then they inject their own DNA or RNA into the cell. Bacteriophages can be harmful to bacteria and can kill the cell, and they can also inject some useful DNA. Bacteriophages are becoming more important in genetic modification because they can be used to change the genetic code of bacteria.
Filoviruses:
These lot are the nastiest scumbags of the microorganism society. Filoviruses are worm-shaped RNA viruses; because they contain RNA instead of DNA, they can replicate faster as they don't need to transcribe from DNA to RNA first. Filo viruses were first discovered in 1967 as the main cause for several diseases that are known to cause hemorrhagic fever; or massive loss of blood internally and externally. All filoviruses are spread through body fluid and intimate contact. It is believed that the 6 different filoviruses may have originated from one cave, Kitum Cave, in the Congo, but they may be some of the most ancient viruses in the world.
Filovirus Strains:
Marburg
Ebola:
Reston ebolavirus
Tai Forest ebolavirus
Bundibugyo ebolavirus
Sudan ebolavirus
Zaire ebolavirus
Marburg Virus Disease (MVD)
These lot are the nastiest scumbags of the microorganism society. Filoviruses are worm-shaped RNA viruses; because they contain RNA instead of DNA, they can replicate faster as they don't need to transcribe from DNA to RNA first. Filo viruses were first discovered in 1967 as the main cause for several diseases that are known to cause hemorrhagic fever; or massive loss of blood internally and externally. All filoviruses are spread through body fluid and intimate contact. It is believed that the 6 different filoviruses may have originated from one cave, Kitum Cave, in the Congo, but they may be some of the most ancient viruses in the world.
Filovirus Strains:
Marburg
Ebola:
Reston ebolavirus
Tai Forest ebolavirus
Bundibugyo ebolavirus
Sudan ebolavirus
Zaire ebolavirus
Marburg Virus Disease (MVD)
- Marburg Marburgvirus
- Zoonotic (Animal borne) RNA virus
- Incubation Period: 5-10 days
- Case Fatality Rate: 23-90%
- Symptoms: Back pain, nausea, vomiting, chest pain, a sore throat, abdominal pain, and diarrhea first appear. Symptoms become increasingly severe and can include jaundice, inflammation of the pancreas, severe weight loss, delirium, shock, liver failure, massive hemorrhaging, and multi-organ dysfunction.
- Transmitted through person to person contact and body fluids. Not known how it jumped to humans.
- Treatment: Supportive Care
- Prevention: No vaccine, avoid contact with infected people and body fluids.
Ebola Viruses:
The sister virus genus to Marburg, the five strains of ebola are very similar. Like Marburg, they cause hemorrhagic fever and are spread through contact with infected fluids. Believed to have originated from reservoirs of the virus from the same Kitum Cave and also believed to have spread from bats to humans. These viruses can infect humans, monkeys, and other mammals. The ebola viruses tend to be even more violent and fatal than Marburg, and they are more common.
Zaire Ebolavirus (ZEBOV)
The sister virus genus to Marburg, the five strains of ebola are very similar. Like Marburg, they cause hemorrhagic fever and are spread through contact with infected fluids. Believed to have originated from reservoirs of the virus from the same Kitum Cave and also believed to have spread from bats to humans. These viruses can infect humans, monkeys, and other mammals. The ebola viruses tend to be even more violent and fatal than Marburg, and they are more common.
Zaire Ebolavirus (ZEBOV)
- Zoonotic (Animal borne) RNA virus
- Incubation Period: 11-21 days
- Case Fatality Rate: 50-90%
- Symptoms: Back pain, nausea, and fatigue are the first signs. As disease develops patients suffer from massive internal and external hemorrhaging, connective tissue failure, shock, behavioral breakdowns, vomiting, organ failure, and connective tissue dissociation which leads to liquification of all tissues in the body.
- Transmitted through person to person contact and body fluids. Not known how it jumped to humans.
- Treatment: Supportive Care
- Prevention: No vaccine, avoid contact with infected people and body fluids
Sudan Ebolavirus (SUDV)
- Zoonotic RNA virus
- Case Fatality: 25-90%
- Incubation Period: 2 to 21 days
- Very similar symptoms to Z. ebolavirus
- First Recognized in an outbreak in Sudan in November of 1976.
- Transmitted through person to person contact.
- Treatment: Supportive Care
- Prevention: None
Reston ebolavirus (RESTV)
- Only known to occur in monkeys
- Causes fever, fatigue, and spleen failure in monkeys.
- Famous for the 1990 outbreak when dozens of monkeys died in a monkey facility in Reston, Virginia.
- No case fatality rate, cannot infect humans
- It is now known to be transmittable to pigs
Tai Forest ebolavirus (CIEBOV/TAFV)
- Two dead monkeys were found in the Tai Forest in 1994
- Found blood inside of heart was brown, lungs filled with blood.
- Research showed the virus was very similar to Zaire and Sudan
- Scientists performing research was infected and had symptoms similar to dengue fever, but she was treatment and recovered.
Bundibugyo ebolavirus (BEBOV)
- Only reported in Bundibugyo region Uganda in 2007.
- 56 reported cases, 43 confirmed in lab tests
- 17 deaths
- Case Fatality Rate: 40%
- Signs and symptoms included headache, vomiting, diarrhea, abdominal pain, conjunctivitis, skin rash, muscle pain, fatigue, difficulty swallowing, difficulty breathing, hiccups, bleeding, unexplained death
Transmission of Ebola:
Ebola is transmitted by direct contact with the blood, secretions, or organs of an infected person. Also, spread of the disease can occur from the reuse of needles or syringes that are contaminated. The 1976 epidemic in Zaire involved transmission of Ebola through contaminated needles and syringes. Because there is a possibility of infection after the recovery(for a short period of time), Ebola may also be transferred through sexual activity.
Prevention:
In order to prevent the spread of Ebola, we must take many cautionary steps. Here are some of the things a person can do to prevent the transmission of Ebola:
-Practice very careful hygiene and avoid blood or secretion from an infected person.
-Avoid funerals or burials of those who were infected with Ebola.
-Do not visit facilities where Ebola patients are being treated.
-Do not handle any objects that may have come in contact with an infected person's
bodily fluids.