Viruses Microbes

Infection Stage

2010-02-10T08:28:00.000-08:00

Infection stage on human that will cause diseases are through several. All infection diseases depend on essentially the same mechanism: invasion by foreign orgainsm and the reaction of the invaded body to them. Therefore, infectious diseases have a common pattern, marked by the five phases summarized here.

Incubation period: the organism invade and multiply in the host. Length of the phase is varies with the kind of disease and with the individual immune system.
Prodrome Period: brief interval characterized by general symptoms such as headache, fever, runny nose, irritability, and general discomfort. Disease is highly communicable now.
Clinical disease: illness is at its height characteristic symptoms appear, so specitic diagnose is possible now.
Decline Stage: Symptoms subside. Patient may feel well enough to become active before recovery, which increases the danger of relapse.
Convalescence: The recovery period. Disease may still be communicable. Patient who recovers but still gives off disease causing organisms becomes a carrier of that disease.

Animals Viruses

2010-01-19T00:10:00.000-08:00

The most organism structure and function are thoroughly intertwined. At one time or certain time we all likely been infected by a virus. For instance, colds or influenza and chicken pox are two common ailments are the diseases that caused by viruses.

Animals viruses are intracellular obligate parasites that reproduce only after invading the host animal cell. Then the virus will introduce and develop their live in their host, like computer viruses that should find a host to make them can breeding them selves.

The type of viruses that infect animals body are similar with the virus that can infect to human, but virus also have habit, they are usually infect animals. But on certain condition they will improve their life and able to infect human, this called as virus mutation.

There are several types of animals viruses:

Double Stranded DNA
Single Stranded DNA
Double Stranded RNA
Single Stranded RNA

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Treatment Guidance on Getting Bird Flu

2009-11-22T23:23:00.000-08:00

What should to do if getting of new srain flu virus H1N1 (strain Mexico)

The Government will make an announcement in the event of outbreaks.
Following government instructions via radio, television and other media.
Use a mask or other masks.
Practice patterns and use a clean life cover mouth and nose when sneezing and coughing.
Avoid public places.

The Step Prevention from New Flu:

Wash hands with clean water as often as possible when the hand touched a runny nose or other filth before and after meals. Take care of personal hygiene and the environment around you.
When clean and cough, cover it with a tissue and dispose in the garbage the tissue. Keep at least 1 m distance with others, especially if having flu. Do not through away waste in everywhere.

Coughs, Colds and Flu Fever is not necessarily normal

Times have changed, everything changed, as well as the disease is changing. Now comes of new flu strains (Mexico strains), this type of flu hit the U.S., Europe and parts of Asia.

The Symptoms of Flu

Fever with body temperature above 38^oC
Cough, runny nose
Sore throat
Tired, sluggish
May be accompanied by nausea, vomiting and diarrhea
If more severe symptoms, it will be accompanied by shortness of breath or heavy breathing.

Yellow Fever

2009-11-15T23:03:00.000-08:00

Some result of experiment says that their findings bear directly on ideas which are developed in this communication. Thus in their now classic studies with human volunteers, which proved the correctness of the theory that yellow fever was transmitted by the bite of an Aedes mosquito, they made the following observations. Mosquitos become infective when they had the disease. Mosquitos did not become infective when they bit early in the incubation period or late in the disease. Mosquitos were not infective soon after they had bitten and become so only after a period of 12 days of more. They then remained infective for life. These findings, so puzzling at the time, are now fully understood. Each can be explained on the basis of modern knowledge of virus reproduction and the result thereof.

Yellow fever is still one of the most classic of the virus diseases of man, and it may be rewarding to review its pathogenesis briefly. When an infected mosquito bites, a very small amount of yellow fever virus is introduced into the blood. This small amount of virus then promptly dissapears. The virus does not reappear in the peripheral blood until just before the disease develops. Therefore, normal mosquitos biting during the four-day incubation period do not take in virus. However, during the incubation period, the virus is undergoing reproduction in cells, of the liver and other organs. When the number of cells damaged by the reproductive process becomes large enough, symptoms and signs of yellow fever rapidly appear. At about this time large numbers of newly formed virus particles are released from the infected tissues into the blood. Now, if a mosquito bites, it will take in virus.

As the disease progresses, still higher concentrations of virus develop in the liver, lyph nodes, and kidneys. This is the result of continued virus reproduction. In parallel, the concentration of virus in the blood increases rapidly and may reach a level of 10 particles per ml. If a mosquito bites at this time. It will take in considerable amount of virus. After about fourth day of disease, neutralizing antibodies begin to appear, and as they increase in concentration, the number of infective virus particles in the body rapidly decrease, and the disease a biting mosquito fails to take in any infective virus and so cannot transmit to agent.

Hepatitis C Become A Serious Threatened

2009-09-30T01:22:00.000-07:00

Hepatitis C is a serious threaten to public health. This disease easily transmitted. Moreover with drugs that use with needles.

"This disease affects the public health so that important to know its magnitude," said Director General of Disease Control and Environmental Health, Ministry of Health, Tjandra Yoga Aditama, Tuesday (29/9).

The government worked with the drug company record in 21 provinces in the period of October 1, 2009. Along August 2007, the government has not had a comprehensive national data of this disease. Data on hepatitis have not classified into the type and partial. Results and data collection program was submitted to the Ministry of Health.

Based on initial data collection, people with Hepatitis C about 15,736 peoples with the highest risk factor is by injecting drug for about 28 percent and 16 percent from dialysis.

Hepatitis C is one type of viral infection to the liver that cause inflammation, damage, hardening of the liver, causes cancer to liver failure. Transmission system of this viruses among others through transfusion, the use of needles and medical devices, and sexual relations.

The disease has become a global health problem. Based on data from the World Health Organization (WHO) there are approximately 170 million people infected with HVC, or about 3 percent of the population.

Diseases Caused by Viruses

2009-09-10T19:26:00.000-07:00

Diseases that causes by virus are in a lot number. The virus size of about 25-300 micron or 25/million – 300/million meters.

This size of viruses called micro size. Therefore, the virus can not be seen with the eyes or ordinary microscope, but must use electron microscope.

Virus diseases can be classified into two parts:
1. Virus that spread throughout the body through the blood, for example:

a. Smallpox

The symptoms of the affected body will got a fever virus, bubbles arising on the skin, hands, feet, and a whole of the body.

b. Measles

Body symptoms infect by this virus will be fever, red spots appear on the skin after suffering from fever, cough, and runny nose.

c. Dengue fever

The virus causing of dengue fever disease, which is one of four different serotypes of viruses belonging to the antigen group and Flavi virus stereotype is a DEN-1, DEN-2, DEN-3, DEN-4.

The symptoms infected by this virus, the body is experiencing a fever of sudden headache accompanied by a great, feel pain on the joint and muscle, pain behind the eyes, vomiting, weak pulse.

2. Viruses spreading is restricted to certain organs, such as:

a. Influenza (respiratory)

Body symptoms of influenza virus disease characterized by fever, chills, headache, and nausea.

b. Hepatitis (liver)

Body symptoms of hepatitis virus infection, the body easily tired, no appetite, nausea, vomiting, weakness, decreased of stamina, and often sleepy. Meanwhile, for patients with acute hepatitis characterized by heartburn, fever.

Not only that, these symptoms can be seen physically, ie dark urine, white feces, nails, skin and the whites of the eyes are yellow, upper abdomen enlarged, and losses of body weight.

The types of viral hepatitis include:

Viral hepatitis A or VHA,
Hepatitis B virus or HBV,
Hepatitis C virus or VHC,
Hepatitis D virus or VHD,
Hepatitis E virus or VHE,
Hepatitis F virus or VHF,
Hepatitis G virus or VHG.

c. Conjunctivas (inflammation of the eye)

The symptoms of the virus infected eye is feeling itchy, swollen eyelids felt, often eye discharge/secret, eyes red and watery.

d. Polio (nerve)

Polio virus consists of three strains, namely strains 1 (brunhilde), strain 2 (lanzig), and strain 3 (leon).

Body symptoms of mild polio virus high body temperature (but not too high temperature), the whole body feels pain, vomiting, headache, sore throat, and eyes hot.

Body symptoms of acute polio virus, the body temperature is very high, very heavy headache, stiff shoulders, great muscle aches, and skin sensitivity decreases.

e. Mumps

Mumps virus causes mumps disease. The virus is transmitted through the air. Body symptoms of mumps virus infected will get a fever, swallowing, drooling, or open sore mouth, ears buzzing, swelling in the cheek, not feeling well, and headaches.

How viruses enter the human body?

Disease virus can enter the human body in various ways, including through:

Food
Air
Clothes
Beverages
Blood Transfusion
Water
Contact hands
Mouth
Throat
Milk
Saliva

Viruses, Worms, and Trojan Horses

2009-07-27T00:33:00.000-07:00

Beside human and animals viruses, computer, email and phone cell also have a viruses that attack them and make a damage and even removing the software of those application or make stop work or just make can’t work properly.

The name of the viruses also similar with the animals and other egregious or flagitious animals or creature like Trojan horses, worm and others.

Worm viruses work to copy itself for example from hard disk drive C then copy to another, using email to transport to other PC like winds. Worm viruses can make damage of computer security; sometime this viruses come together with joke or software program that can download freely.

Even though software and viruses are in similar base language but viruses work infect another program, boot sector, partition sector or document that support macros, by attaching itself or inserting itself to the part of application program.

Trojan horse viruses causes damage or compromises the security of computer. The typical work of this virus is transported by individual emails. This viruses also come from joke program software.

Virology

2009-07-05T21:04:00.000-07:00

Virology is a knowledge that study of viruses and virus-like agent or viruses history. This material include of viruses structure, viruses classification and evolution, the way of viruses to infect other creature and then exploit host cell that use for virus reproduction. Virology also study of the diseases that causes, the technique to isolate and culture them, and their use in research and therapy.

Because of the large discussion of viruses, this material often discuses on other subject and often become a parts of microbiology and pathology. The structure of viruses can be changed depend to the host of cell they infect, like animal viruses, plant viruses, fungal viruses and bacteriophages (viruses infecting bacteria, which include the most complex viruses).

If bacteria size still using of micron, viruses have size in smaller range about 30 nm to about 450 nm, this is a very very small size range. Micro size is one per million meter, and nano meter is one per thousand million meters. So a creature with thousandth time of bacteria can infect them. If infect human then this will very very small compare to human cells.

If viruses infect to human cell then virus will become of part of cells, some time unite with human DNA, this is a part of human cell. DNA can change the base structure of human DNA and a bad effect of this DNA character can derivate to the next human.

Because of nano size the technology to kill this viruses should use nano technology, many expert have use other viruses to kill viruses, of build body immune to kill this viruses. Virology that using of nano technology always develop and may on the next generation will available of nano medication to kill this infected viruses.

West Nile Virus

2009-06-08T08:45:00.000-07:00

West Nile disease have frightenen many people in America because this diseases history that ever happened last time. West nile virus merge again since last month in America, and the people and health of department involvel on preventing this diseases become spread over the US country.

The following year, the state's first human cases and deaths from West Nile disease were recorded and all but two of the state's 102 counties eventually reported a positive human, bird, mosquito or horse. By the end of 2002, Illinois had counted more human cases (884) and deaths (67) than any other state in the United States. In 2003, the epicenter of West Nile disease moved westward. Colorado reported the highest number of cases (2,947), easily surpassing the caseload record for the mosquito-borne disease set the previous year by Illinois. The number of West Nile human cases in Illinois fell dramatically with just 54 reported and only one death. Illinois' caseload in 2004 was slightly higher than the previous year with 60 reported cases and four deaths. In 2005, Illinois recorded 252 cases and 12 deaths, both totals the second highest in the nation to California’s 880 cases and 19 deaths, and in 2006, there were 215 cases and 10 deaths reported, the sixth highest number of cases in the U.S.

West Nile virus first found in Africa about in West Nile River. Even though it was discovered all the way back in 1937 in Africa, the West Nile virus probably didn't make its way to the United States until 1999.

According to the U.S. Centers for Disease Control and Prevention (CDC), over 15,000 people in the U.S. have tested positive for WNV infection since 1999, including over 500 deaths. Many more people have likely been infected with WNV, but have experienced mild or no symptoms.

Symptoms of West Nile virus really depend on the person who becomes infected. Kids with normal immune systems, the system of the body that fights off disease and infection, usually get just a mild "flu-like" illness and may not feel bad at all with the infection.
The West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 and has since rapidly spread across the North American continent into all 48 continental states, seven Canadian provinces, and throughout Mexico. In addition, WNV activity has been detected in Puerto Rico, the Dominican Republic, Jamaica, Guadeloupe and El Salvador.

West Nile virus is caused by a bite from an infected mosquito that's already carrying the virus, but it's important to remember that not all mosquitoes are infected. In many parts of the United States, the risk of being bitten by an infected mosquito is greatest from July to early September. But in some parts of the country, mosquito bites can be a risk all year long. Not everyone who gets bitten by an infected mosquito will get the virus. And although kids can get West Nile virus, it's rare for them to become very sick from it.

Statistically, a person's risk of contracting West Nile is low, and less than 1% of those infected develop serious illness from the virus. Those at highest risk for serious illness are the elderly and those with lowered immune systems. However, people of all ages can develop serious illness, so it is important for everyone to protect themselves from mosquito bites to minimize the risk of infection.

Good Prevention Action:

Eliminate sources of standing water in your yard where mosquitoes may lay eggs. Fill, cover or remove any items that can trap water. Common mosquito breeding containers include:

Change the water at least once or twice a week, cleaning the bath on a regular basis
Ponds - consider purchasing mosquito-eating fish if the pond is serving as a mosquito breeding site and cannot be drained.
Buried every unused goods not use that can keep water inside.

Those effort is try to cut the mosquito live cycle. The live cycle of mosquito can see here Mosquito Life Cycle

Varicella Zoster Virus

2009-05-16T17:00:00.001-07:00

Even this virus is dangerous for human being but the vaccine have founded for this kind of virus so we can prevent from this virus attack.

Varicella zoster virus (VZV) is one of eight herpes viruses known to infect humans (and other vertebrates). It commonly causes chicken-pox in children and both shingles and postherpetic neuralgia in adults.

Varicella zoster virus is known by many names, including: chickenpox virus, varicella virus, zoster virus, and human herpes virus type 3 (HHV-3).

Primary VZV infection results in chickenpox (varicella), which may rarely result in complications including encephalitis or pneumonia. Even when clinical symptoms of chickenpox have resolved, VZV remains dormant in the nervous system of the infected person (virus latency), in the trigeminal and dorsal root ganglia. In about 10-20% of cases, VZV reactivates later in life producing a disease known as herpes zoster or shingles. Serious complications of shingles include postherpetic neuralgia, zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.

Primary VZV infection results in chickenpox (varicella), which may rarely result in complications including encephalitis or pneumonia. Even when clinical symptoms of chickenpox have resolved, VZV remains dormant in the nervous system of the infected person (virus latency), in the trigeminal and dorsal root ganglia. In about 10-20% of cases, VZV reactivates later in life producing a disease known as herpes zoster or shingles. Serious complications of shingles include postherpetic neuralgia, zoster multiplex, myelitis, herpes ophthalmicus, or zoster sine herpete.

The virus is very susceptible to disinfectants, notably sodium hypochlorite. Within the human body it can be treated by a number of drugs and therapeutic agents including aciclovir, zoster-immune globulin (ZIG), and vidarabine.

Rubella Virus

2009-05-13T18:31:00.000-07:00

Like influenza that have transform into other kind of influenza, have many types of influenze currently, swize flu, bird flu, singpore flu and many others. Rubella also caused by the kind of measles viruses that have transformation into other kind of virus. Rubella virus is not just attact our external body, this virus also can attack out brain network for long effect.

Rubella virus also known as "German Measles" (due to early citation in German medical literature), infection during pregnancy can cause congenital rubella syndrome (CRS) with serious malformations of the developing fetus. The type and degree of abnormality relates to the time of maternal infection.

Rubella peaked in 1964 and 1965, when 12.5 million cases were reported (USA). As a result, 20,000 babies were born with birth defects, 6,200 babies were stillborn, and an estimated 5,000 births were aborted, both naturally and assisted. At that time no treatment by vaccination existed and this only became available in 1969. The disease was dangerous because in children it was almost unnoticable and pregnant women often did not know that they had been exposed.
Children infected with rubella before birth (a condition known as congenital rubella) are at risk for the following: growth retardation; malformations of the heart, eyes, or brain; deafness; and liver, spleen, and bone marrow problems.

The complete genomic sequence (Dominguez etal., 1990) of Rubella is now known. Rubella is a 9755 bp single stranded RNA positive-strand virus with no DNA stage (Togaviridae; Rubivirus) encoding nonstructural protein, capsid protein, glycoproteins E1 and E2. (More?

Swine Flu Found as New Strain

2009-04-29T23:30:00.000-07:00

On Friday, NPR reported: “The deadly swine flu combines genetic material from pigs, birds and humans flu in a way researchers have not seen before, thus leading us to suspect it was cooked up in a lab.”

Swine flu panic is spreading in Mexico and soldiers are patrolling the streets after it was confirmed that human to human transmission is occurring and that the virus is a brand new strain which is seemingly affecting young, healthy people the worst. Questions about the source of the outbreak are also being asked after a public health official said that the virus was cultured in a laboratory.

This strain of swine influenza that’s been cultured in a laboratory is something that’s not been seen anywhere actually in the United States and the world, so this is actually a new strain of influenza that’s been identified, said Dr. John Carlo, Dallas Co. Medical Director

Many people react with incredulity when the assertion is made that the so-called swine flu outbreak in Mexico may be manufactured crisis. And yet history is replete with examples of government using biological and chemical agents for political purpose.

Influenza

2009-04-22T19:42:00.001-07:00

Influenza, or “flu”, is not usually a serious disease unless it is complicated by secondary viral infection. When bacteria become involved, or when the flu virus spreads to the lungs, the condition may be lethal, particularly for the very young, the elderly, and those with heart or respiratory disease. The flu has killed more than a million Americans in the last twenty years?

According to recent research, the flu virus is “packaged” in a distinct way. In other viruses the strands of nucleic acid are strong together in one line, but in flu virus the strands are in eight separate pieces, which makes it easier for a strand to become detached and change places with a strand from another virus. Thus, the genetic information in the virus can change rapidly. Not surprisingly, there are not only three major varieties of flu virus. A (the most virulent), B, and C, but numerous changing strain do not necessary have immunity against any other.

There is a fascinating possibility that flu viruses may actually “go south for the summer”! Sometime at the end of one winter epidemic, there is a cluster of flu cases caused not by the viral strain in that epidemic, but by another strain, this second strain often turns out to be the one that will cause the epidemic of the next winter. What happens to this new strain of viruses over the summer? One researcher believes they may actually migrate to another geographic location (possibly in the Southern Hemisphere), and return later.

How to prevent from flu?

There are vaccines against specific strains of flu virus, but they are not effective against other strains. Nevertheless, people over sixty-five, pregnant women, and people with chronic cardiovascular disease and certain other disease should be vaccinated periodically, so individuals must be revaccinated each year.
Beyond that, at this point, you can only take the precautions you would take against colds. Stay away from people with the disease, and they try to keep your resistance up.
Eventually, scientists may be able to offer more in the way of concrete help. Experiments are currently under way with two new drug, amantadine and rimantadine, that may have some effectiveness. A vaccine that will give a longer period of immunity is also being worked on.

My Experience:

When I am going for pilgrimage, I have vaccinated for flu, this because of certain flu in Arab can’t be cured and every people should have this vaccinated. This vaccine is not preventing from other kind of flu or ordinary flu. Our pilgrimage groups become have flu there as averages. But after I am home Alhamdullilah never get heavy cough and flu for about 2 years, the last flu I got just for 1 day. Is this because of vaccinated of certain kind of flu? I don’t know yet.

VIRUSES

2009-02-18T07:28:00.000-08:00

VIRUSES

When student took college biology twenty-five years ago, they were taught that one celled animals and plants were the simplest living things that existed . But more recently , scientists realized that there is an even simpler form of life –viruses. Viruses causes mumps, measles, rubella (German measles), smallpox, and number of other disease

Viruses have a mysterious ability to exist and proliferate without carrying out the life functions of respiration and metabolism as we usually think of these functions. Viruses are parasites of cell and live within the cell themselves. Some scientist doubt that they should even be considered totally living things.

What viruses do is reproduce. A single virus is nothing more than a bit of nucleic acid within a protein coat. Nucleic acid is the biochemical substance that caries genetic information –the information an organism needs in order to produce more organisms just like itself. There are two kinds of nucleic acid, RNA and DNA; a virus contains one of these, but never both.)

Thus a Virus is really just a machine designed to duplicate itself . In fact, a virus is best defined as a microorganism that can reproduce only in living cells of a person or animal.

Once inside a cell, a virus takes over the cell’s machinery and directs it to produce many hundreds of new viruses. The cells, thus engorged with new viruses, break a part and spews its contents in all directions. Each new virus can enter another cell, capture its machinery, and start the cycle again.

Viruses don’t’ seem to be affected by antibiotics: once an individual has contracted a viral infection, drugs will not help fight the infection, nor will they cure it. But there is a brighter side to the picture: When exposed to some viruses , the body produces its own protective substance to help ward the Virus off. The substance is called interferon.

Viral Infections: The Common Cold

2008-12-10T05:34:00.000-08:00

The common cold is practically a universal nuisance; it contributes heavily to the amount of time lost from school and work each year. One theory suggests that healthy people carry cold viruses in their noses and throats all the time, but they exhibit cold symptoms only when something the fatigue or lowered resistance produces favorable circumstances for the viruses to proliferate. Be this as it may, colds are “catching.” Cold viruses seem to survive in the air, beginning their journey to another person either in the spray of droplets from a sneeze or in the air exhaled when a cold victim talks or breathes. They are also transmitted by skin contact, as when an infected person shakes another person’s hand. The period of time between first exposure to the virus and the appearance of symptoms, the incubation period, is short, usually eighteen to forty eight hours.

Scientists know frustratingly little about cold viruses. They do know that a large number for different viruses can cause colds, and more may still be discovered. Also, cold viruses seem to differ from other viruses in that they do not cause the body to produce interferon on any other substance that could give long lasting immunity. It may be that cold viruses mutate (change their genetic information) rapidly. If so, each successive cold could be caused by a different virus, resulting in an endless series of apparently similar diseases.

What you can do to help prevent colds?
There is little you can do beyond avoiding people with “new colds” (cold are most communicable during the first twenty four hours) or staying away from others when you yourself have a new cold. It is probably useful to keep your resistance up through adequate nutrition, rest, control of stress, and exercise.

Viroid

2008-11-15T04:46:00.001-08:00

On the last article about viruses always says about viroids that is resulted from viruses. After the viruses contaminated the plant and other hospes, viruses that create a viroid that causes the hospes will suffer from viruses.

Viroids are extremely small infections particles that are thus far known to cause diseases only in higher plants, including the potato, tomato, and chrysanthemum. They consist solely of RNA and are about 1/₁₀₀₀ the size of the smallest known virus. Viroids can cause stunting of overall plant growth, distortions of leaf shape, discoloration of leaves, or even death of the entire plant.

Viroids can be transmitted between plant generations through both pollen and ovules. They can also be transmitted from an infected to a noninfected plant by farm implements. Their mode of reproduction in host cells, however, has not yet been determined, nor has any protein been found in host cells that could be associated with a particular viroid. It is thought that viroids represent segment of normal cellular RNA that somehow have become transmissible, disrupting the host’s metabolism.

Herpes Simplex

2008-11-09T22:42:00.001-08:00

There are two kind and different strains of herpes simplex viruses, herpes simplex virus type 1 (HSV-1) and herpes simplex virus 2 (HSV-2), the description of those virus simplex as follows:

Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus and is usually acquired in childhood. HSV-1 often causes lesions inside the mouth such as cold sores (fever blisters) and is transmitted by contact with infected saliva. By adulthood, up to 90% of individuals will have antibodies to HSV-1.

Herpes simplex virus 2 (HSV-2) is sexually transmitted. Symptoms include genital ulcers or sores. In addition to oral and genital lesions, the virus can also lead to complications such as meningoencephalitis (infection of the lining of the brain and the brain itself) or cause infection of the eye -- in particular the conjunctiva, and cornea. However, some people have HSV-2but do not display symptoms. Up to 30% of U.S. adults have antibodies against HSV-2. Cross-infection of type 1 and 2 viruses may occur from oral-genital contact.

A finger infection, called herpetic whit low, is another form of herpes infection. It usually affects health care providers who are exposures to oral secretions during procedures. Sometimes, young children contract the disease.

A herpes virus can infect the fetus and cause congenital abnormalities. It may also be transmitted to a newborn during vaginal delivery in mothers infected with herpes viruses, particularly if the mother has active infection at the time. However, the virus may be transmitted even in the absence of symptoms or visible lesions.

Virus Transduction and Integration

2008-10-31T17:05:00.000-07:00

Some viruses produce a small proportion of viruses that contain host DNA in addition to or instead of viral DNA. These virions are able to transfer host genes from one cell to another. In bacteriophages, during the process called transduction, these genes can be incorporated into the recipient cell’s chromosome, thus effecting genetic recombination.

Integration

Many viruses also interact with the host cell in such a way that the viral DNA, instead of replicating independently within the host cell, is integrated into the host cell DNA. It is then replicated and passed on to daughter cells, as are the host cell’s genes. Single or multiple copies of part or all of the viral DNA infecting animals may be incorporated into the host cell DNA. When the viral DNA is integrated, virions are not produced and the host cell is not killed. When a complete copy of viral DNA is present, the cell may return at some time to a lytic mode of virus replication with subsequent production of new virions.

RNA as Genetic Material

The RNA containing viruses are unique living system because they use RNA as their primary genetic material. Some RNA containing viruses produce enzymes that are capable of making new copies of RNA directly from the original molecule, thus circumventing DNA entirely. Retroviruses produce the enzyme called RNA-directed DNA polymerase, or reverse transcriptase, which can make a DNA molecule from the RNA molecule. This DNA formed from RNA then serves as the principal genetic molecule within the infected cell.

Slow Virus Infection

2008-10-23T01:33:00.001-07:00

Slow viruses are disease agents not yet identified but assumed to exist, because the disease resembles viral diseases in their epidemiology. Slow virus diseases are degenerative nerve disorders that take years to develop. They include the human diseases called kuru and Creutzfelt-Jakob disease, a fatal sheep and goat disease called scrapie, and possibly a recently identified cattle disease called bovine spongiform enchepalophaty, among others.

Theories on the nature of slow viruses include the prion theory that they are nothing but infectious proteins; this idea is not generally accepted. The virino theory proposed that the agent do have nucleic acids, as do known viruses, but lack proteins. A third theory suggests that the agents are viruses that simply are very adept at hiding in body systems. Several known viruses can also act slowly such as the AIDS virus and hepatitis viruses.

Slow viruses diseases sometimes difficult to cure, even some of the diseases still don’t any medicine yet. Slow viruses diseases will attack slow to our body organ, but if don’t cure for long time the disease will very acute and have a damage effect to body organ. Slow virus diseases also will very slowly to cure, for certain diseases need to be cured for a year minimum such as hepatitis. This condition make many people are not patient for waiting and not continue for medication, the effect, the diseases will recurrence again and more difficult to be cured.

Virus Reproduction

2008-10-14T08:05:00.000-07:00

Viruses reproduction begins when the virion comes into contact with a suitable host cell. The DNA or RNA enters the host cell and begins to function as genetic information by directing the synthesis of specific types of proteins that have enzymatic and structural roles. The infectious cycle usually consists of two different stages. In the first, the proteins are produced that are required for the reproduction of the viral DNA or RNA in conjunction with components of the host cell. In the second stage, proteins that make up the virion are produced; these combine with the DNA or RNA to form mature virions, which are the released from the cell. In some cases this release involves the complete disruption and death of the cell, a process known as lysis. In other cases individual virions are released through the cell membrane without killing the cell.

A virus contains the information needed to reproduce itself coded in its nucleic acid. Because it lacks its own protein producing machinery, however, the virus must use the machinery of the host cell in order to multiply. A bacteriophage virion attaches to a bacterial cell and injects its DNA into the bacterium. Using bacterial ribosomes enzyme the viral DNA direct the synthesis of messenger RNA (mRNA), enzymes that break up bacterial DNA, and enzymes that allow replication of viral DNA. Protein synthesized, using mRNA, from the DNA code, these proteins from heads, tails, and tail fibers, and the virus parts assemble into complete virions. An enzymes break up the bacterial cell and liberates the new virions, which can infect other bacterial cells. The information that bring by DNA will procude a virus with the same virus characteristic.

Viruses Characteristics

2008-10-05T07:04:00.000-07:00

Certain type of virus exists in several forms of stages. The free virus particle, or virion, consists of a molecule of nucleic acid, either DNA or RNA, depending on the specific virus, surrounded by protein and in some viruses, also lipid and carbohydrate. The virion is inert, because its lacks many of the components that are necessary for independent life and reproduction; it does, however, provide for the transfer of the nucleic acid from host cell to host cell. Replication can occur only when the nucleic acid enters a host cell. Within the cell, the nucleic acid functions as genetic material and directs the synthesis of proteins. This results in the production of new virions, which then are released from the cell and can initiate new cycles of infection.

The virions of different viruses vary greatly in size, shape, and complexity, but those of any virus are uniform. The simplest types are rods and regular 20 sided polygons (icosahedrons); the tobacco mosaic virus, for example, consists of a single molecule of a single molecule of RNA surrounded by about 2,200 molecule of a single type of protein arranged in helical fashion to produce a rod 3,000 angstroms (1/100,000 in) long.

Many virions having a simple rod or polygonal shape are composed of several types of proteins, and some of these virions are surrounded by a less regularly shaped envelope, which often includes components of the host-cell membrane. At the other extreme of complexity, bacteriophage T4 has a virion composed of at least 25 different types of protein that make up a hollow head in which a DNA molecule is enclosed, and a tubular tail by which the virion attaches to its host cell and injects its DNA into it.

Virus History

2008-09-26T06:01:00.000-07:00

Viruses were discovered at the end of the 19^th century. In 1892, Dimitri Ivanovsky, a Rusian botanist, discovered that the sap from tobacco plants affected by mosaic diseases could be passed through filters so fine as to exclude all known bacteria and still retain the ability to produce the diseases in new plants. In 1898, Frederich Loeffler and Paul Frosch reported similar results for the infectious agent of foot-and-mouth diseases of cattle. They also showed that an animal inoculated with a tiny amount of filtered material could itself subsequently give rise to a very potent inoculums. This indicated that the infectious agent was able to reproduce itself within the infected animal. During the next three decades many viruses were discovered. Unlike other microorganisms, none of the viruses could be propagated in the absence of host cells, which led researchers to conclude that viruses are intracellular parasites.

Beginning in the 1930s, a number of new techniques were developed for virology, or the study of viruses. The discovery that many animal viruses can be grown in mice and in chicken embryos allowed the course of viral infection to be studied under controlled laboratory conditions. Very high-speed centrifuges were developed that made possible the preparation highly purified virions. Chemical analysis showed that viruses consist primarily of nucleic acid and protein, and the development of the electron microscope during the 1940s permitted scientists to study the size and shape of these virions in great detail.

Because of the ease with which bacteria can be grown and manipulated in the laboratory, many of the features of intracellular viral development were first discovered by studying bacteriophage, which are viruses that grow in bacteria. During the late 1950s techniques for growing animal cells in tissue culture were developed, making possible the detailed study of the intracellular growth of animal viruses.

Viruses

2008-09-19T03:40:00.000-07:00

Viruses is a creature that can't be seen but can make our body destroy in short time. Their growing is like the Einstein equation about energy. Very vast, their cell is just to slice and grown.

Science branch that study about this knowledge called as Virology. This subject is learn by many knowledge discipline background. Virus is not only live in human, but they are life in every creature in the world, human, animals and plant. From a big creature until a micro creature size. The creature which is viruses live called as host.

Viruses are extremely small parasites, that are able to reproduce only within the cells of their hosts, upon which they depend for many of their fundamental life processes. They are the causal agents of many Infection Diseases. Many hundreds of different types of viruses exist, each of which normally grows in a restricted range of hosts; different viruses, however, have a very wide variety of hosts, including bacteria, plants, and animals. Recently scientist have found that viruses are more than 1,000 times more plentiful in water than originally suspected, possibly making them the most numerous life-forms on Earth.

Any given type of viruses exists in several forms or stages. The free virus particle, or virion, consist of a molecule of nucleic acid-either DNA or RNA, depending on the specific virus-surrounded by protein and, in some viruses, also lipid and carbohydrate. The virion is inert, because it lacks many of the components that are necessary for independent life and reproduction; it does, however, provide for the transfer of the nucleic acid from host cell to host cell. Replication can occur only when the nucleic acid enters a host cell. Within the cell, the nucleic acid functions as genetic material and directs the synthetics of proteins. This production of new virions, which then are released from the cell and can initiate new cycles of infections.