Virus and heat inactivation

 While viruses are not considered living organisms they depend upon living cells to replicate. The structure of the virus includes an envelope constituted by proteins and genetic material of DNA or RNA. All of these components are thermo-sensible. The genetic material and the proteins have complex structures regulating their function, and change in this structure may result in a loss of function known as denaturizing. There are two basic means by which denaturing occurs: a change in PH or temperature.

Some examples: viruses and heat inactivation

  Numerous studies have focused on virus inactivation through heat application. For example, HIV virus in the blood will die when exposedto 77 degrees C1 for as little as  0.006 seconds1. In another study, parvovirus and phage phiX174 were completely inactivated when exposed to 103 degrees C for 90 seconds2. In the case of the Herpes virus, high temperatures inhibit the release of proteins necessary for the success of the infection3.
            Airborne viruses are no different. One study of respiratory sincytyal virus (the major cause of wheezing in children less than 2 years old) showed that when the virus is exposed to 65 degrees C for 45 minutes, the infection capacity  is diminished and conformational proteins are transformed, resulting in a reduction of  of substances responsible for the inflammation, hyper-responsiveness and damage to airpassages4. The SARS virus (causative agent of severe acute respiratory syndrome) has thermo-sensible proteins in its envelope, which can be totally denaturized at 55 degrees C, the same temperature at  which SARS virus was also reported to be inactivated5. The influenza virus (the following information is redundant I believe)contains proteins essential for  infectious transmission that are sensible to variations of pH and temperature between 55-70 degrees C 6.

The avian flu

The virus, responsible for the bird flu, can be spread from the poultry to humans and until now, about 20 millions of chickens have been slaughtered in order to control the spread of the virus10. Since 1997, it has been reported more than 100 cases of the disease in humans, resulting in more than 50 deaths8. Experts are very concerned about the rising of a pandemic new strain of the virus because of the mixing between avian and human viruses. It’s suspected that the virus could infect someone who is already infected with a human flu virus like A, resulting in genetic rearrangement and a novel pathogen that could be highly virulent 11 and easily transmitted human-to-human13.

Transmission and symptoms.

All birds are susceptible to the avian virus and some types of wild birds are natural reservoir of influenza type A virus. They have a large amount of avian virus in their secretion, saliva and feces that can contaminate domestic poultry when in contact. Furthermore, their dropping or saliva may contaminate water, rivers, feed and even human shoes8. Infected droplets may settle on conjunctival, nasopharyngeal or other respiratory mucosal epithelium in humans12 leading to symptons ranged from typical influenza-like symptoms (e.g., fever, cough, sore throat, and muscle aches) to eye infections (conjunctivitis), pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications13.

Avian Flu characteristics and your heat instability.

The avian virus, H5N1, is a negative-sense, single-stranded RNA virus12, which has two types of proteins in its surface: hemagglutinin (HA) and neuraminidase (NA)13. It is known from the literature that the virus can be inactivated by 56ºC in 3 hours and 60ºC in 30 minutes8. Thus, only four degrees of temperature elevation reduced the time of inactivation exposure about 85%.

Airfree and its HETD Ceramic Core internal temperature.

Here, we have listed only few examples of viruses’ inactivation by heating and in all those cases, the temperatures were below the Airfree’s HETD ceramic core internal temperature of 200 degrees Celsius. Since 1977, studies have showed that the higher the temperature, the faster the proteins get denatured7. Therefore, we may infer that the Airfree purifier may be efficient in the inactivation of the virus proteins in most cases, resulting in the lost of the infection ability.

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