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Saturday, January 31, 2009
10:27 AM
Hierarchical classification of virus
This classification of virus was created by Lwoff, R. W. Horne, and P. Tournier in 1962.
It consists of phylum - class - order - family - subfamily - genus - species - strain/type, based on the shared properties of virus
4 main properties are used:
1. Nature of the nucleic acid: RNA or DNA
2. Symmetry of the capsid
3. Presence or absence of an envelope
4. Dimensions of the virion and capsid
Virus families are ordered with genomics, the explanation of relationships through evolution by researching on nucleic acid and protein sequence. All families have suffix -viridae e.g. Caliciviridae, Picornaviridae, Reoviridae, while genera have suffix –virus e.g. in Picornaviridae family there are 5 genera: enterovirus, cardiovirus, rhinovirus, apthovirus and hepatovirus.
Acknowledgement:
http://www.nlv.ch/Virologytutorials/Classification.htmWilson reported
The Mehs virus is spreading...
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9:04 AM
Human Immune-deficiency Virus (HIV)
HIV is a retrovirus is any of a group of viruses that contain two single-strand linear RNA molecules per virion, which means it carries its genetic blueprint in the form of ribonucleic acid (RNA) instead of deoxyribonucleic acid (DNA). Additionally, the enzyme reverse transcriptase is employed to copy its genome into the DNA of the host cell's chromosomes. Usually the cellular process involves transcription of DNA into RNA. Reverse transcriptase makes it possible for genetic material to become permanently incorporated into the DNA genome of an infected cell.
HIV infection mostly occurs through sexual contact.It can also be transmitted via blood such as sharing of needles or blood transfusionStudies have shown that HIV is not transmitted through contact such as touching or sharing towels, bedding, utensils.
It is important to acknowledge that it is not sex that transmits HIV, but certain bodily fluids: blood, semen, vaginal secretions and breast milk.High-risk behaviors that can result in HIV transmission are sharing needles for drugs, tattoos, body piercing, with an HIV-infected person and/or engaging in unprotected anal, vaginal or oral sex with a person who is HIV infected. The virus also can be transmitted from an HIV-infected mother to her child through pregnancy, birth or breastfeeding.
People contracted with other sex diseases are more prone to be affected during sex with an infected partner because mucous membranes are porous and viruses and other pathogens are able to pass through, these areas are rich in immune cells. When a person already has a sexually transmitted disease, sex organs may be flooded with
CD4+T cells, making it much easier for HIVto infect.
Also it is not unusual for HIV-infected persons to experience symptoms years after the initial infection; some may be symptom free for over 10 years. However, during the asymptomatic period, the virus is actively multiplying and destroying cells in the immune system, weakening the body's ability to fight infection. The effect is most keenly observed in the decline of the immune system's key infection fighters in the blood, the CD4+T cells.
Yao Xing reported
The Mehs virus is spreading...
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8:40 AM
Virus
A virus is a sub cellular organism with a parasitic intracellular life cycle. It contains either RNA or DNA but not both. A virus is a non-living thing since it does not meet the requirements of a living thing. But once it has a host, it starts to infect the host. A virus is made up of a virion which contains nucleic acid genome surrounded by protein. The basic objective of a virion is to transfer the viral genome to a cell where it starts to replicate. This requires 2 things which are structures to contain and protect nucleic acid genome and specific receptors on the virion surface which allows virus to enter the target cell.
Classification of virus
Virus Structure - Capsid
The capsid is the protein structure surrounding the viral genome which is assembled around the nucleic acid. The whole part is called nucleocapsid. The use of small protein subunits reduces amount of genetic code capacity that has to be dedicated to produce capsid proteins which are crucial as big viral genomes are very small by cellular standards. Protein components naturally align in the energetically favourable state thus certain structure is preferred. These structures have mostly icosahedral or helical symmetry.
Icosahedral Helical
Viral Genome Size
A large viral genome is still small by cellular standards means that virus can produce many proteins allowing a complex structure whereas viruses with small genome are restricted. Therefore bigger viral genome means that the complexity of the structure is more than those with small viral genome.
Viral genome types
• Double stranded(ds) DNA – These are often among largest of viral genomes
• Single stranded (ss) DNA – These are usually small genomes
• Ds RNA- Compared to all RNA genomes these are smaller than most DNA genome
• Ss RNA - Can be subdivided into (+) & (-) sense. Positive sense can function as mRNA and those that are complementary to mRNA are negative sense.
Viruses with RNA genomes use DNA intermediate stage to produce the RNA genome.
Viruses with DNA genomes use RNA intermediate stage to produce DNA genome
Virus cycle
Attachment
Entry
Uncoating
replication and expression
Assembly
Exit
Replication of Virus
A virion must protect the viral genetic material and it has to be capable of delivering it into host cell. The surface of any virus must have receptor/effectors to bind to the host cell. Binding is mediated on one side by specific viral proteins and the other side by cellular structures. The progeny virus genomes assemble into new viruses and are used to make more viruses.
Mohaan reported
The Mehs virus is spreading...
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Thursday, January 29, 2009
9:08 AM
Acquired Immuno-deficiency Sydrome (AIDS)
I have notice a rising number of people getting HIV Or Aids. This troubles me a lot... is it because we as human are indecent? Or is it we have no sense of having safe Sex Or is it people are jus pure unlucky..Anything can happen to any of us reading this webpage here .Who knows what will happen the moment after u leave your home.... maybe u were run over by a lorry , sent to a nearby hospital for treatment but very unlucky, one of the blood packet contain HIV genome and tada.... you're infected !.. so i personally felt that people should start to notice the importance of preventing getting the virus or seek treatment.
Actually MANY people does not know that actually u does not get aids immediately you have to get the HIV first before your immune system is down and other diseases infect you.
Aids is Acquired Immunodeficiency Syndrome (AIDS) is the final stage of HIV infection.
[An infection takes the "opportunity" provided by the weakened immune system to cause an illness that is usually controlled by a healthy immune system These infections are sometimes life-threatening and require medical intervention to prevent or treat serious illnesses. Persons living with advanced HIV infection suffer opportunistic infections of the lungs, brain, eyes and other organs. The 26 CDC-defined AIDS indicator illnesses are opportunistic infection.](http://www.hiv.com/)
To stop aids u have to start from HIV and to stop HIV! U have to….
Practicing safe sex and avoiding high-risk behaviors using a latex condom
Symptoms of HIV
According to the Centres for Disease Control and Prevention, the following are symptoms that may be warning signs of HIV infections:
• Rapid weight loss
• Dry cough
• Recurring fever or profuse night sweats
• Profound and unexplained fatigue
• Swollen lymph glands in the armpits, groin or neck
• Diarrhoea that lasts for more than a week
• White spots or unusual blemishes on the tongue, in the mouth or in the throat
• Pneumonia
• Red, brown, pink or purplish blotches on or under the skin or inside the mouth, nose or eyelids
• Memory loss, depression and other neurological disorders
Yao Xing reported
The Mehs virus is spreading...
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Wednesday, January 21, 2009
9:18 AM
Australian researchers claim breakthrough on dengue fever - SYDNEY : Australian researchers funded by US billionaire Bill Gates Friday claimed a breakthrough which could help in the fight against dengue fever by stopping the often deadly disease in its tracks. University of Queensland researchers said they have successfully infected the mosquito which spreads the tropical disease with a bacterium which halves its 30-day lifespan, thereby reducing its ability to transmit dengue to humans. Scientists hope their work will help halt the spread of the painful and debilitating disease which affects millions of people each year. "The key is that really only very old mosquitos are the only ones that are able to transmit the disease," said researcher Professor Scott O'Neill. "What we've done is put this naturally occurring bacteria into the mosquitos that actually halves their adult lifespan so they don't live long enough to be able to transmit the virus." The research published Friday in the journal Science is the result of injecting 10,000 mosquito embryos with a bacterium that occurs naturally in fruit flies but has never been detected in dengue-carrying mosquitoes. O'Neill said the test was designed to see whether the bacterium reduced the lifespan of the insects without killing them or preventing them from breeding and was able to be passed on to offspring. He said while the laboratory tests, which involved researchers allowing the bacteria-infected mosquitoes to bite their arms because the species needs human blood to breed, had been successful, it would be several years before the technique would be tested in the wild. "It's really a preventative strategy for preventing dengue fever outbreaks and what we've done is show that it's possible to be done in a laboratory," he told AFP. "The next stage is now to move it into a more realistic field setting." There is no known cure or vaccine for dengue fever, which is transmitted by mosquitos and kills more than 20,000 people each year. Also known as "breakbone fever," symptoms include high temperatures and muscle aches. The Bill and Melinda Gates Foundation donated 10 million dollars to an international research team led by the University of Queensland into a means of defeating dengue fever in 2005.
Source: http://www.channelnewsasia.com/stories/afp_asiapacific/view/399799/1/.html
With a New Year new hope and new cure in the future more life can be saved.
Amas reported
The Mehs virus is spreading...
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Tuesday, January 20, 2009
9:40 PM
Do you think that this deer mouse is cute? Do not let it’s cute look mislead you…
Hantavirus pulmonary syndrome (HPS) is a deadly disease from rodents. Humans can contract the disease when they come into contact with infected rodents or their urine and droppings. HPS was first recognized in 1993 and has since been identified throughout the United States. Although rare, HPS is potentially deadly. Rodent control in and around the home remains the primary strategy for preventing Hantavirus infection. These incidents are used to remember that these re-merging viruses could appear once again…
The deadliest United States outbreak was on May 14, 1993 in the Four Corners area. Incubation is similar to Yellow Fever. Symptoms include mild onset with flu-like symptoms that rapidly progresses into kidney failure with intestinal bleeding (which is the hallmark of the disease). The most common symptom in the United States is hypertension with chronic kidney failure. In the Four Corners outbreak, the disease had a very mild onset with flu-like symptoms, developing into lung hemorrhaging causing the infected person to suffocate in his or her own blood. The mortality rate varies with the strain; the most deadly strain had a 62.5% mortality rate.
Transmission is from animal to human. Over 63 bird and rodent vectors have been identified for the 70 known strains of the virus. Scientists have concluded that the outbreak in the Four Corners area was due to a ten-fold increase in the population of the deer mouse and not to a virus mutation.
Amas reported
The Mehs virus is spreading...
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Monday, January 19, 2009
5:30 PM
Pictures of T4 Bacteriophage
Looks like an alien landing pod.
Bacteriophage attaches to surface of bacteria Escherichia coli (E. coli).
Once attached, it injects DNA into bacterium, which uses bacterium to generate more DNA to produce more of such bacteriophage. After cycle is complete, bacterium bursts and dies, releasing newly produced bacteriophages to continue infecting other bacteria.
Bacteriophages have been used as an antibiotic in the former Soviet Union and Eastern Europe. They are seen as a possible therapy against multi drug resistant strains of many bacteria.
T4 bacteriophage undergoes a lytic lifecycle. It takes about 30 minutes (at 37 °C) and consists of:
Adsorption and penetration (immediate)
Arrest of host gene expression (immediate)
Enzyme synthesis (starts after 5 mins)
DNA replication (starts after 10 mins)
Formation of new virus particles (starts after 12 mins)
Courtesy of:
http://www.cellsalive.com/phage.htm,
http://en.wikipedia.org/wiki/T4_phageWilson reported
The Mehs virus is spreading...
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