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Thursday, November 15, 2012
Virions, Prions, and Viruses
Prions are a type of protein, not an organism, that cause disorders in mammals including humans. They cause progressive neurodegenerative disorders which damage the brain and the rest of the nervous system. The proteins cause proteins in neural tissue to misfold which leads to brain damage. Two common disorders found in humans are Creutzfeld-Jakob Disease (CJD) and Variant Creutzfeldt-Jakob Disease (vCJD). Other mammals are known to contract Bovine Spongiform Encephalopathy (BSE, mad cow) and Chronic Wasting Disease (CWD), which is common among deer. Both types of prions cause brain damage with long incubation periods which can span many years. In 1996 a link between BSE in cattle and vCJD in humans was found. Enough scientific evidence was presented to show that the two disorders could be caused by the same agent. People contract these diseases by eating infected food which contain the proteins, hereditary transmission, or spontaneously where the prion changes. Right now there is no treatment for any of the diseases. There are drugs available which help make the infected more comfortable before they die. The Centers for Disease Control (CDC) has stated that the risk of getting the human prion diseases is rather low within the United States but it can happen. BSE, more commonly known as mad-cow disease, can and has infected humans before. Meat that contains nervous tissue can increase the risk of contracting the disease. Even though prions are not living, they can still be destroyed. The methods to get rid of these hardy proteins are quite extreme. Incineration of infected meat at 1000 degrees Celsius (1832 F), steam heating at 134 degrees C for longer than 15 minutes, boiling in lye for longer than 15 minutes and being submerged in concentrated bleach for an hour. The best way to prevent prion diseases is to test meat regularly and ensure the meat doesn't come in contact with nervous tissue. I would propose completely eliminating foods that contain spinal cords, bone marrow or brain. This may seem drastic but it is a safe way to ensure that prions do not spread. Incidents of prions infecting cattle and humans should be handled correctly. Cattle infected should be incinerated at the appropriate temperature. Luckily, cannibalism is frowned upon in our society, meaning prions will not spread from human to human easily. The people should still be dealt with properly and it should be made sure they are comfortable leading up to their death
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. https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwKC2lHj3dN4PETjHylVWS10PLlNBXQZBDnC5gOE5azyIGHAYKqIesKtRDes3xyhgtqZhmRqniqbENkA-VX8CDIoZTXtZNNZNV5eW0rwd1bNSMDs4558nsQdBBR68xynsVFbFpln-4Pec/s1600/prion1.jpg
Monday, November 12, 2012
Prevention and Treatment Strategies
Viruses Prevention and Treatment
The virus that has killed more people in history than other any other disease is small pox. Recently there has been concern as to whether or not a government or terrorist organization could use smallpox as a biological attack. Small pox was completely eradicated from the world in late 1979. There are some samples that were kept in case there was another outbreak.
The first smallpox vaccine was created in 1796 by the English physician Edward Jenner. He studied how milkmaids that were infected with smallpox did not die when they were infected with the virus, they only got sick. Eventually, Jenner infected an eight year old boy with cowpox and then later with smallpox and the boy was immune.
The immune system is responsible for fighting to get rid of the pathogen, but this takes time. A pathogen can multiply more rapidly than the immune system is able to fight it off. Vaccines expose the immune system to a weakened version of the virus, this which allows it to recognize it more easily.
http://scm-l3.technorati.com/12/06/26/69259/Vaccine.jpg?t=20120626042335
Types of Vaccines
The first step to creating a vaccine is to use a sterile petri dish in order to collect the virus. You may collect bodily fluids which contain the virus depending on the type. If you already have the virus use a tissue culture to grow brand new viruses.
There are 6 types of vaccines.
The first type is called a similar pathogen vaccine. This type of vaccine is used to help prevent smallpox. Usually vaccines use an altered version of the same virus, this is not the case with similar pathogen vaccines. As the name suggests, they use a similar pathogen to original one. For example, smallpox vaccines are created using cowpox, a similar pathogen.
The second type of vaccine is called an attenuated vaccine. In this kind of vaccine the virus is altered slighlty. It must be similar enough that it still stimulates an imunne response, but different enough that it doesn't cause the disease that is trying to be prevented. An example of virus that is used in this way is the measles virus.
A killed vaccine is a vaccine where a virus has lost its ability to reproduce but hold all other characteristics, especially the ones that allow it to stimulate the immune system. Polio vaccines are made in this way.
Toxoid vaccines condition the immune system to resist a toxin produced by invading organisms. A tetanus shot helps the target and remove toxins that are produced by the Clostridium tetani bacteria.
Subunit vaccines use a small part of the original virus that can still stimulate a response from the immune system. Some vaccines only use a protein coat from a virus. These vaccines are used to protect against Hepatitis B.
The last type of vaccine is the naked-DNA vaccine. These are being made to aid in fighting AIDS. Only a gene is used in this type of vaccine in order to trigger an immune response. Small loops of the disease's DNA enters a cell and becomes part of the cell's DNA. Now the cell can produce proteins according to the gene.
http://dermatology.cdlib.org/DOJvol6num1/transactions/melanoma/fig012.gif
Vectors of Rabies
Over 55,000 people die from rabies every year, that is one person every 10 minutes. Rabies is caused by a virus that damages the brain. The virus is carried by almost any mammal and is found everywhere except Antarctica. In North America, rabies is carried by raccoons, skunks, foxes, wolves, and bats. Rabies spreads from organism to organism through saliva by biting. The disease affects the nervous system by spreading to the brain and then the rest of the system.
A human infected with rabies will exhibit flu-like symptoms and later fall into a coma. Rabies can be prevented by staying away from wild animals, stray animals, and sick looking animals. Bats are a major carrier for rabies and should never be handled. If bitten, a person needs to wash the wound and see a doctor. Rabies shots are no longer given in the stomach and are no different than a regular shot. They use to be given in the stomach which made them painful but now are given in the arm.
http://www.diagnosisaday.com/wp-content/uploads/2010/11/Rabies.jpg
(Click the link to view a map showing rabies trends worldwide.)
All animals are at risk of being rabid if they have not been vaccinated. Dogs, foxes, raccoons, skunks and bats are known to be the biggest carriers of rabies.
The symptoms of rabies starts out with a fever, aches and pains, and other flu-like symptoms. After a few days hallucinations, tingling around wound, insomnia and salivation can occur. Respiratory problems and heart deterioration follow, ending in coma and eventually death.
Drug Therapy
Source:
http://www.medsafe.govt.nz/profs/datasheet/g/Globalaciclovirtab.htm
The drug acyclovir is an antiviral agent that is used to treat different types of the herpes viruses like chickenpox, shingles, genital herpes and oral herpes. Acyclovir isn't a cure, there are no cures for any of the herpes viruses, but it is used to treat outbreaks and symptoms that are associated with the viruses. The drug can also reduce the severity of future outbreaks. Acyclovir has not shown any carcinogenic side effects but acts as a chromosome mutagen and should not be administered to pregnant women, even thought it frequently is.
The virus that has killed more people in history than other any other disease is small pox. Recently there has been concern as to whether or not a government or terrorist organization could use smallpox as a biological attack. Small pox was completely eradicated from the world in late 1979. There are some samples that were kept in case there was another outbreak.
The first smallpox vaccine was created in 1796 by the English physician Edward Jenner. He studied how milkmaids that were infected with smallpox did not die when they were infected with the virus, they only got sick. Eventually, Jenner infected an eight year old boy with cowpox and then later with smallpox and the boy was immune.
The immune system is responsible for fighting to get rid of the pathogen, but this takes time. A pathogen can multiply more rapidly than the immune system is able to fight it off. Vaccines expose the immune system to a weakened version of the virus, this which allows it to recognize it more easily.
http://scm-l3.technorati.com/12/06/26/69259/Vaccine.jpg?t=20120626042335
Types of Vaccines
The first step to creating a vaccine is to use a sterile petri dish in order to collect the virus. You may collect bodily fluids which contain the virus depending on the type. If you already have the virus use a tissue culture to grow brand new viruses.
There are 6 types of vaccines.
The first type is called a similar pathogen vaccine. This type of vaccine is used to help prevent smallpox. Usually vaccines use an altered version of the same virus, this is not the case with similar pathogen vaccines. As the name suggests, they use a similar pathogen to original one. For example, smallpox vaccines are created using cowpox, a similar pathogen.
The second type of vaccine is called an attenuated vaccine. In this kind of vaccine the virus is altered slighlty. It must be similar enough that it still stimulates an imunne response, but different enough that it doesn't cause the disease that is trying to be prevented. An example of virus that is used in this way is the measles virus.
A killed vaccine is a vaccine where a virus has lost its ability to reproduce but hold all other characteristics, especially the ones that allow it to stimulate the immune system. Polio vaccines are made in this way.
Toxoid vaccines condition the immune system to resist a toxin produced by invading organisms. A tetanus shot helps the target and remove toxins that are produced by the Clostridium tetani bacteria.
Subunit vaccines use a small part of the original virus that can still stimulate a response from the immune system. Some vaccines only use a protein coat from a virus. These vaccines are used to protect against Hepatitis B.
The last type of vaccine is the naked-DNA vaccine. These are being made to aid in fighting AIDS. Only a gene is used in this type of vaccine in order to trigger an immune response. Small loops of the disease's DNA enters a cell and becomes part of the cell's DNA. Now the cell can produce proteins according to the gene.
http://dermatology.cdlib.org/DOJvol6num1/transactions/melanoma/fig012.gif
Vectors of Rabies
Over 55,000 people die from rabies every year, that is one person every 10 minutes. Rabies is caused by a virus that damages the brain. The virus is carried by almost any mammal and is found everywhere except Antarctica. In North America, rabies is carried by raccoons, skunks, foxes, wolves, and bats. Rabies spreads from organism to organism through saliva by biting. The disease affects the nervous system by spreading to the brain and then the rest of the system.
A human infected with rabies will exhibit flu-like symptoms and later fall into a coma. Rabies can be prevented by staying away from wild animals, stray animals, and sick looking animals. Bats are a major carrier for rabies and should never be handled. If bitten, a person needs to wash the wound and see a doctor. Rabies shots are no longer given in the stomach and are no different than a regular shot. They use to be given in the stomach which made them painful but now are given in the arm.
http://www.diagnosisaday.com/wp-content/uploads/2010/11/Rabies.jpg
(Click the link to view a map showing rabies trends worldwide.)
All animals are at risk of being rabid if they have not been vaccinated. Dogs, foxes, raccoons, skunks and bats are known to be the biggest carriers of rabies.
The symptoms of rabies starts out with a fever, aches and pains, and other flu-like symptoms. After a few days hallucinations, tingling around wound, insomnia and salivation can occur. Respiratory problems and heart deterioration follow, ending in coma and eventually death.
Drug Therapy
Source:
http://www.medsafe.govt.nz/profs/datasheet/g/Globalaciclovirtab.htm
The drug acyclovir is an antiviral agent that is used to treat different types of the herpes viruses like chickenpox, shingles, genital herpes and oral herpes. Acyclovir isn't a cure, there are no cures for any of the herpes viruses, but it is used to treat outbreaks and symptoms that are associated with the viruses. The drug can also reduce the severity of future outbreaks. Acyclovir has not shown any carcinogenic side effects but acts as a chromosome mutagen and should not be administered to pregnant women, even thought it frequently is.
Tuesday, November 6, 2012
Viral Infection and Replication
Lytic Stage
There are two cycles of viral reproduction. The first cycle is called the lytic cycle. First, a virus must attach to a host, in this case a bacteria. Once connected, the virus injects its DNA into the host which proceeds to take over the cell. The virus then uses the cell's own organelles to copy itself over and over. The host cell is then destroyed and the copied viruses are released into the surrounding environment to find a host to infect.
Lysogenic Stage
A virus found in the lysogenic stage can switch to the lytic stage if needed. Viruses found in the lysogenic stage exist in harsh conditions. The begining of the lysogenic stage is much like the lytic stage. First the virus connects to a host and injects DNA into it. This is the point where the two stages diverge. In the lysogenic stage the DNA becomes part of the cell's chromosome. When the cell's chromosome is replicated the viral DNA is also replicated.
Source:
http://biology.kenyon.edu/HHMI/Biol113/2virus.htm
There are two cycles of viral reproduction. The first cycle is called the lytic cycle. First, a virus must attach to a host, in this case a bacteria. Once connected, the virus injects its DNA into the host which proceeds to take over the cell. The virus then uses the cell's own organelles to copy itself over and over. The host cell is then destroyed and the copied viruses are released into the surrounding environment to find a host to infect.
Lysogenic Stage
A virus found in the lysogenic stage can switch to the lytic stage if needed. Viruses found in the lysogenic stage exist in harsh conditions. The begining of the lysogenic stage is much like the lytic stage. First the virus connects to a host and injects DNA into it. This is the point where the two stages diverge. In the lysogenic stage the DNA becomes part of the cell's chromosome. When the cell's chromosome is replicated the viral DNA is also replicated.
Source:
http://biology.kenyon.edu/HHMI/Biol113/2virus.htm
Monday, November 5, 2012
The Structure and Function of a Virus
The first person to observer viruses in a lab setting was a physician by the name of Robert Buist. He conducted an experiment where he viewed cells taken from skin eruptions of small pox patients. He noticed there were particles that were not part of the original cell, they were completely independent. He dubbed these particles "inclusion bodies." The inclusion bodies will later become known as viruses.
Scientists are unsure whether or not viruses are living organisms or simply assemblies of molecules. They seem to straddle the definition of life with some functions that can be attributed to an organism and others not. One person described a virus being as alive as a rock. They are composed only as genetic material. Some scientists say they are alive while others say they aren't.
Viruses cannot be seen with the naked eye because they are smaller than the wave length of light. They can't be seen with a normal microscope, an electron microscope is needed. Electron microscopes direct a beam of electrons at an object rather than a beam of light. The beam of electrons is small enough that it can magnify the virus enough times for the human eye.
Viruses assume a variety of shapes. There are helical viruses, which obviously have a helical structure, polyhedral viruses, many sided, enveloped viruses, surrounded by an envelope, and binal viruses that are irregularly shaped with complex structures.
A virus have to infect a host in order to reproduce. Some viruses release material into a host cell while others simply trick the cell. In order to trick a cell, the virus will attach itself to surface molecules and are carried into the cell. Both types of invasion involve penetrating the cell's membrane. A virus is rogue DNA, this means that once it is inside of the cell it is able to take over the host cell and use its own machinery to replicate itself.
Scientists are unsure whether or not viruses are living organisms or simply assemblies of molecules. They seem to straddle the definition of life with some functions that can be attributed to an organism and others not. One person described a virus being as alive as a rock. They are composed only as genetic material. Some scientists say they are alive while others say they aren't.
Viruses cannot be seen with the naked eye because they are smaller than the wave length of light. They can't be seen with a normal microscope, an electron microscope is needed. Electron microscopes direct a beam of electrons at an object rather than a beam of light. The beam of electrons is small enough that it can magnify the virus enough times for the human eye.
Viruses assume a variety of shapes. There are helical viruses, which obviously have a helical structure, polyhedral viruses, many sided, enveloped viruses, surrounded by an envelope, and binal viruses that are irregularly shaped with complex structures.
A virus have to infect a host in order to reproduce. Some viruses release material into a host cell while others simply trick the cell. In order to trick a cell, the virus will attach itself to surface molecules and are carried into the cell. Both types of invasion involve penetrating the cell's membrane. A virus is rogue DNA, this means that once it is inside of the cell it is able to take over the host cell and use its own machinery to replicate itself.
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