Viruses (biological)

Viruses lack any form of energy and are not alive according to this definition. Computer viruses make slight changes in their code (mutate) but they are not alive. Computer viruses can mutate to overcome antiviral software but they are not considered to be alive anymore than what we call viruses that infect microorganisms or host cells.

Plasmodium is a genus of parasitic protozoa. Infection with these parasites is known as malaria. The genus Plasmodium was created in 1885 by Marchiafava and Celli. Currently over 200 species in this genus are recognized and new species continue to be described.[1] [2] Of the 200+ known species of Plasmodium, at least 10 species infect humans. Other species infect animals, including birds, reptiles and rodents. The parasite always has two hosts in its life cycle: a mosquito vector and a vertebrate host. The genus is currently (2006) in need of reorganization as it has been shown that parasites belonging to the genera Haemocystis and Hepatocystis appear to be closely related to Plasmodium. It is likely that other species such as Haemoproteus meleagridis will be included in this genus once it is revised. Life Cycle Mosquitoes of the genera Culex, Anopheles, Culiceta, Mansonia and Aedes may act as vectors. The currently known vectors for human malaria (> 100 species) all belong to the genus Anopheles. Bird malaria is commonly carried by species belonging to the genus Culex. Only female mosquitoes bite. Aside from blood both sexes live on nectar, but one or more blood meals are needed by the female for egg laying as the protein content of nectar is very low. The life cycle of Plasmodium was discovered by Ross who worked with species from the genus Culex. The life cycle of Plasmodium is complex. Sporozoites from the saliva of a biting female mosquito are transmitted to either the blood or the lymphatic system [3] of the recipient. The sporozoites then migrate to the liver and invade hepatocytes. This latent or dormant stage of the Plasmodium sporozoite in the liver is called the hypnozoite. The development from the hepatic stages to the erythrocytic stages has until very recently been obscure. In 2006[4] it was shown that the parasite buds off the hepatocytes in merosomes containing hundreds or thousands of merozoites. These merosomes have been subsequently shown[5] to lodge in the pulmonary capilaries and to slowly disintegrate there over 48-72 hours releasing merozoites. Erythrocyte invasion is enhanced when blood flow is slow and the cells are tightly packed: both of these conditions are found in the alveolar capilaries. Within the erythrocytes the merozoite grow first to a ring-shaped form and then to a larger trophozoite form. In the schizont stage, the parasite divides several times to produce new merozoites, which leave the red blood cells and travel within the bloodstream to invade new red blood cells. The parasite feeds by ingesting haemoglobin and other materials from red blood cells and serum. The feeding process damages the erythrocytes. Details of this process have not been studied in species other than Plasmodium falciparum so generalisations may be premature at this time. At the molecular level a set of enzymes known as plasmepsins which are aspartic acid proteases are used to degrade hemoglobin. The parasite digests 70-80% of the erythrocyte's haemoglobin [6] but utilises only ~15% in de novo protein synthesis [7] The excess amino acids are exported from the infected erythorocyte by new transport pathways created by the parasite. [8] The reason proposed for this apparently excessive digestion of haemoglobin is the colloid-osmotic hypothesis [9] which suggests that the digestion of haemoglobin increases the osmotic pressure within the infected erythrocyte leading to its premature rupture and subsequent death of the parasite. To avoid this fate much of the haemoglobin is digested and exported from the erythrocyte. This hypothesis has been experimentally confirmed. [10] Most merozoites continue this replicative cycle, but some merozoites differentiate into male or female sexual forms (gametocytes) (also in the blood), which are taken up by the female mosquito. In the mosquito's midgut, the gametocytes develop into gametes and fertilize each other, forming motile zygotes called ookinetes. The ookinetes penetrate and escape the midgut, then embed themselves onto the exterior of the gut membrane. Here they divide many times to produce large numbers of tiny elongated sporozoites. These sporozoites migrate to the salivary glands of the mosquito where they are injected into the blood and subcutaneous tissue of the next host the mosquito bites. The majority appear to be injected into the subcutaneous tissue from which they migrate into the capillaries. A proportion are ingested by macrophages and still others are taken up by the lymphatic system where they are presumably destroyed. The sporozoites which successfully enter the blood stream move to the liver where they begin the cycle again. The pattern of alternation of sexual and asexual reproduction which may seem confusing at first is a very common pattern in parasitic species. The evolutionary advantages of this type of life cycle were recognised by Mendel. Under favourable conditions asexual reproduction is superior to sexual as the parent is well adapted to its environment and its descendents share these genes. Transferring to a new host or in times of stress, sexual reproduction is generally superior as this produces a shuffling of genes which on average at a population level will produce individuals better adapted to the new environment. Reactivation of the hypnozoites has been reported for up to 30 years after the initial infection in humans. The factors precipating this reactivation are not known. In the species Plasmodium malariae, Plasmodium ovale and Plasmodium vivax hypnozoites have been shown to occur. Reactivation was not thought to occur in infections with Plasmodium falciparum but there are been two reports to date suggesting that this may occur (see below) . It is not known if hypnozoite reactivaction may occur with any of the remaining species that infect humans but this is presumed to be the case. A report of recurrence of P. falciparum in a patient with sickle cell anaemia has been published [11] but this needs confirmation as hypnozoites are not known to occur in P. falciparum infections. A second report of P. falciparum malaria eight years after leaving an endemic area has also been published.[12] While this is consistent with the existence of a hypnozoite stage additional confirmation seems desirable.

A molluscum contagiosum (MC), sometimes called a water wart, is a viral infection of the skin that can be spread by contact, to other areas or to other people. The virus does not have a dormant stage.

There is a specific difference between the 2 cycles. In the Lytic cycle, the virus DNA/RNA remains separate from the Host's DNA. In the Lysogenic cycle, the virus DNA/RNA is incorporated (combined) into the host's DNA.

Any virus injects its DNA into a host's cell. No matter what, in both cycles, the host cell ends up bursting and releasing the viruses.

The Marburg virus incubates (grows) inside a host's cell, usually from 5-7 days, but can range from 3-10 days overall. It also produces new viruses which release into the organism (in this case, the human or primate). The Marburg Virus goes through both lytic and lysogenic cycles.

No, there are other methods. One sometimes called the "shotgun" method takes microscopic tungsten pellets, coats them with the genetic material to be inserted, places them in a microscopic "gun", places the gun aimed at the organ to be treated and fires it with a pulse of air or water. A tiny fraction of the tungsten pellets enter cells, a fraction of those enter the nucleus, and in a fraction of those nuclei the material incorporates somewhere randomly into one or more chromosomes.

Viruses are composed of two main parts an outer protein covering called a capsid and an inside core of either DNA or RNA. Not both DNA and RNA. Some of these have an envelope over the capsid. The ones that do not are said to be naked. The proteins in the capsid allow the virus to attach to the "docking stations" proteins of the host cell. The naked viruses are more resistant to changes in the environment.

Viruses are considered to be non-living and because they are not alive, they can not reproduce. A better term is to replicate or make a copy of themselves. It is like using a copy machine.
Another interesting thing is that you can't kill a virus since it isn't alive. You can remove it physically by washing a counter top or your hands.
Or you can use an antiviral drug which actually causes an inactivation of the virus particles outside the cell, prevent viral attachment and/or entry, prevent replication of the viral genes, prevent synthesis of viral proteins and prevent assembly or release of new infectious virions. They totally interfere with the viral cycle.

It is thought that the common cold virus has no seasonal preference, and that the only reason more people get it in winter is because they spend more time indoors with other people, making it easier to pass from person to person.I don't think a winter cold is any longer lasting than a summer cold.

The common cold is an upper respiratory tract infection of viral origin, usually caused by a rhinovirus (up to 40% of colds), or by Coronaviruses (about 20%). These are the more common viruses, but there are more than 200 different viruses (some say as many as 700) that can cause the common cold. There are a huge number of different viruses from a number of different viral 'families' that cause cold symptoms.

This is the main reason there is no vaccine for the common cold - there are simply too many different viruses to develop vaccines specific to each virus, and before a vaccine can be developed for a new viral mutation, it can mutate again.

The Norwalk virus (Norovirus) does not have a lyosgenic cycle. It does not remain dormant as lysogenic viruses can.

envelope

It is in the "reproduction" process when in the lytic cycle, so the effect will be that the virus will force the organism to replicate more and more "baby" viruses. The host cells will eventually die or be killed when it splits open (or buds) to release the new virus particles. The new particles will infect more and more cells of the host, killing the host's cells each time they split, making the host feel sicker and sicker until their defense systems figure out how to kill the viruses.
The Norwalk virus (Norovirus) does not have a lyosgenic cycle. It does not remain dormant as lysogenic viruses can. It is lytic and is considered virulent.

Tea tree oil is an anti-bacterial, among many other properties. When used to clean and prevent the spread of germs it is effective in the prevention of the flu. Tea tree in combination with eucalyptus oil is used in an aromatherapy steam as well as When diluted in a carrier oil as a massage oil in the treatment of the flu.

Filth!

Retroviruses like HIV use RNA as their genetic material. When they infect a host cell, they convert their RNA into DNA using an enzyme called reverse transcriptase. This DNA is then integrated into the host cell's genome, allowing the virus to hijack the cell's machinery to replicate itself.

Relenza is touted to be a super drug for the flu. Other than it, Tamaflu is well known for treating the flu as well. Which drug is used is up to the doctor prescribing it and he has to take into account many factors before deciding which drug will work best.

It is due to viral infection specifically the paramyxovirus group.

2 cases. One from a 67 year old. And the other from a doctor.

yes

No, it is a filovirus

yes

Someone sneezing on you would allow their cold viruses to contact you directly, since they are contained in the respiratory droplets that result from coughs and sneezes and are expelled into the air in an approximate 6 foot diameter until they fall to the surfaces. Once on the surfaces you could still be contaminated by their viruses through indirect exposure.

Cold temperatures and rain do not cause infectious diseases like the cold or the flu, that is what was once believed before we knew what viruses were and that they are what caused the flu. It was the cyclic trend of the flu season that made it seem related to the fall and winter weather back then. It is disproved and debunked many times over.

There is not evidence of a direct link between types of foods eaten and directly catching colds.

Unlike enveloped viruses that have glycoproteins on their envelopes, glycoproteins project out from the capsid of a naked virus. Most diagrams will show them on the end of spider looking legs projecting from the bottom of the capsid.

capsid wall