Viruses growing

Albumin. Albumin is available in highly pure and uniform form, and exhibits low toxicity and good biological stability. It has been used as a carrier for methotrexate and a variety of antiviral drugs [amantadine, fioxuridine (5-fluorodeoxyuridine), and cytar-abine (cytosine arabinoside)] to treat macrophage tumors and infections caused by DNA viruses growing in macrophages. Heavily modified albumins are known... 

What to do Control the pest spreading the virus. Grow resistant cultivars. Plant certified virus-free planting material. 

When mosaic-diseased Turkish tobacco plants were fed a nutrient solution containing radioactive phosphorus in the form of disodium phosphate over a period of several weeks, about 30% of the phosphorus taken up by the plants was isolated (by Stanley) in the form of purified tobacco mo,saic virus. The tobacco mosaic virus growing, in contrast to the plant, at a rapid rate is bound to take up a large percentage of the labeled phosphate which reaches the plant. While an organ or a substance grown in a labeled... 

There are two convenient forms of genetic material, that can be used as vehicles for introducing the new gene into the bacterium a small circular DNA piece, called a plasmid, or a virus that grows in bacteria. The techniques described below apply to both plasmids and viruses. 

The first equation states that cytotoxic cells grow only if helper cells, macrophages and the virus are all present. The second equation implies that, when the virus is not present, helper cells grow if macrophages and/or helper cells are present. The third equation implies that macrophages grow both when the virus is present and there is already a concentration of macrophages. The last equation describes the... 

Both viruses and protozoa are difficult to grow in culture. Viruses need living cells to grow in and their small size makes them difficult to deal with. Protozoa need complex diets of organic materials. Bacteria, fungi and algae are relatively easy to grow in culture. 

Increased amounts of faecal-oral water-borne pathogens (virus, bacteria and protozoa) and microbial indicators (bacterial and viral) have been reported in groundwater bodies [18], karst springs [19, 20], surface freshwater [21-26], marine waters used for bathing [27-29] and shellfish growing [30] as well as tap water [31]. 

In a normally growing culture of lysogenic bacteria, the majority of bacteria manage to keep their prophages in a dormant state. In a very small minority of cells, however, the prophage genes express themselves. This results in the multiplieation of the virus, lysis of the cells and liberation of infectious particles into the medium. 

There are now available a number of lines of cells, mainly originating from malignant tissue, which can be serially subcultured apparently indefinitely. These established cell lines are particularly convenient as they eliminate the requirement for fresh animal tissue for such sets or series of cultures. An example of these continuous cell lines are the famous HeLa cells, which were originally isolated from a cervical carcinoma of a woman called Henrietta Lacks, long since dead but whose cells have been used in laboratories all over the world to grow viruses. 

Fertile chicken eggs, 10-12 days old, have been used as a convenient cell system in which to grow a number of human pathogenic viruses. Figure 3.7 shows that viruses generally have preferences for particular tissues within the embryo. Influenza viruses. 

The virucidal activity of chemicals is difficult to determine in the laboratory. Tissue culture techniques are the most common methods for growing and estimating viruses however, antimicrobial agents may also adversely affect the tissue culture see also Chapter 11. 

The testing of disinfectants for virucidal activity is not an easy matter. As pointed out earlier (Chapter 3), viruses are unable to grow in artificial culture media and thus some other system, usually employing living cells, must be considered. One such example is tissue culture, but not all virus types can propagate under such circumstances and so an alternative approach has to be adopted in specific instances. The principles of such methods are given below. 

The hepatitis B virus (HB V) does not grow in tissue culture and an acceptable animal model has been found to be the chimpanzee. This is observed for clinical infection after inoculation with treated and untreated virus, care being taken in the test series that residual disinfectant is removed by adequate means before inoculation into the animal. 

The human immunodeficiency virus (HIV lymphadenopathy-associated virus, LAV human T-cell lymphotrophic virus type 3, HTLV III) is responsible for acquired immune deficiency syndrome (AIDS see Chapter 3). Because of the hazard and difficulties of growing the virus outside humans, a different approach has to be examined for determining viral sensitivity to disinfectants. 

Sputum cultures The process of growing living material obtained from sputum (as bacteria or viruses) in prepared nutrient media. 

Quaternary-based materials have been used as alternatives to aldehydes and although they provide acceptable kill rates and odour control, the subsequent disposal of effluent presents heightened challenges. The growing concern over virus survival in toilet tanks has also caused some rethinking of the technology and alternative active materials and their combinations are constantly being researched. 

Some cell cultures prepared in this way will grow indefinitely, and can be established as permanent cell lines. Such cell cultures are most convenient for virus research because continuously available cell material can be available for research purposes. In other cases,... 

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