The influence of elevated temperature on the viruses in most cases negative, and sensitivity of the

. All the basic tests in virology always begin by examining the sensitivity of the virus to physical and chemical factors and comparing viral families according to these criteria. The practical application of this knowledge is used for canning and preserving virus, treatment of viral suspension, disinfection when working with viral material, as well as for the use of viral antigens and vaccines. Viruses inhabit the aquatic environment (sea, oceans, rivers, lakes), land, air, tissues, plants, animals, people; So viruses are present everywhere and therefore must know the physical and chemical factors that assist us in preventing, and treating viral infections.
Effect of temperature All viruses can survive only in a certain temperature range, monte brasil for some viruses, these intervals may be very narrow, while for some other viruses they can be broad few tenths C. Heating of virus suspension monte brasil (inoculum) at different temperatures in a given period (usually 10 min.) Is determined by the temperature value at which the virus loses its infectivity. This value is referred to as thermal inactivation point. It, therefore, represents the lowest temperature at which the infectious ability of viruses stops. For example for plant viruses thermal monte brasil inactivation point ranges usually between 45oC (tomato spotted wilt virus) and 90oC and 95oC and even (tobacco mosaic virus strains), but most are located between 55o and 70oC. The thermal monte brasil inactivation point may vary and in some strains of the same virus types. So for strain B tobacco monte brasil necrosis virus it is between 85 C-80, with strain monte brasil A 85-90oC, and in strains C and D range lies between 90 and 95oC.
The influence of elevated temperature on the viruses in most cases negative, and sensitivity of the virus to high temperatures depends monte brasil on: the sensitivity of the protein level of sensitivity of nucleic acid temperature duration high temperature composition is a suspension in which the virus (the presence of water, pH, proteins, lipids, salts, MgCl2 , Na2SO4 ...)
Thermal denaturation and inactivation of viral proteins occurs at lower temperatures increase, monte brasil but denaturation of nucleic acids. Gradual heating of viruses first lose the power of reproduction, then the infectious power, antigenicity and immunogenicity, which has been used in making the vaccine. Temperature monte brasil of 60 C for 30 minutes, the capacity for reproduction, monte brasil infectivity and antigenicity of most viruses. Exceptions are, for example, hepatitis A and B, for which the effect of inactivation required temperature of 60 C for ten hours, and at 100 C for 10 minutes and still retains the antigenic properties. monte brasil
The sensitivity of the virus to elevated temperatures can be reduced by the addition of bivalent cations MgCl, Na2SO4 or MgSO4. This feature bivalent cations used for the preparation and storage of the vaccine used in the tropics.
Lowering the temperature does not reflect the harmful viruses. Low temperatures have "the conservative" effect on viruses. For example, the patient's material, in which it is expected that a virus is transported to the virology laboratory at a temperature of 0 C (ice on the fractures), because the temperature stabilizes their activity. Lowering the temperature for every 10 C contributes to biochemical reactions take place twice a slower, roughly double the prolonged survival of the virus. Freezing the virus at a temperature of less than -70 C is used for the storage of the virus of viral materijala.Većina thus be held over. However, viruses containing lipoprotein envelope, lose virulence after prolonged storage, even at this low temperature, because they are stabilized by the addition of 5% dimethyl sulfoxide. Viruses with a lipoprotein envelope are particularly sensitive to alternating freezing and thawing. Repeated freezing and thawing in a short period of time affects more or less harmful to the biological activity of most viruses, although monte brasil there are some viruses that are resistant to such actions. A significant influence on the sensitivity of the virus has the speed of freezing and thawing, the frequency of these procedures, as well as the composition of the environment in which viruses are suspended.
The effect of drying monte brasil temperatures above 0 C, at normal or elevated pressure, many viruses are sensitive to dry-dehydration (poliovirus, Coxsackie virus), while some viruses monte brasil (virus variolae virus vacciniae) months may keep its biological function is completely dry. For the preservation of virus used and lyophilization, monte brasil drying at low temperature (freezing and evaporation of ice) under vacuum. Thus prepared viral material may years to retain its biological activity, monte brasil if the optimal pH, dovolnja amount of water (depending on the virus) and if they are material to add ingredients that protect viruses (some colloids, serum, plasma ...)
Influence jonizujećeg radiation Ionizing radiation inactivates viruses, but does not destroy their antigenicity, and this procedure monte brasil is applied in the production of viral vaccines. Ionizing radiation is used for sterilization of food