Pasteurization has been used to sterilize and inactivate viruses for a long time. The Bangkok Biomaterial Center under the leadership of Prof. Yongyudh Vajaradul, at the IAEA workshop meeting on radiation sterilization of human tissue allografts at South Korea in 1992 proposed pasteurization of bone allografts at 570C to inactivate HIV and HBV, C viruses. In order to keep up with the quality assurance program and sterility guarantee of its products, the Center maintains a routine validation check for the processes involved in all stages of production. In the interest of readers as stated in the begining of this chapter, we bring forward and describe a validation check study conducted during 01 - 20.04.1999 at the Center to determine the inactivation of HIV in bone allografts after Pasteurization.
The first steps towards tissue recovery is to follow a strict regime of donor selection criteria. This helps in eliminating to a good extent the potential risk of HIV and other lethal viruses and VDRL diseases transmission from donors to recipients. Due to high incidence of HIV virus infection globally, it has become additionally important for tissue banks to be extra careful in sterility assurance of their allografts. At the Bangkok Biomaterial Center each and every piece of tissue allograft is subjected to pass through four stages of a sterility assurance program:
1. Strict donor selection criteria following WHO and Red Cross Standards.
2. Microbiology tests for sterility control.
3. Pasteurization at 570 C for 4 hours
4. Irradiation dose of 25 kGy from Gamma Ray Cobalt60 source.
Although donor selection criteria, microbiology test and irradiation eliminates the possibility of virus transmission, but the Center in addition to the above three steps, also incorporates Pasteurization for additional safety of its grafts. It is because of these extra care that till date there has been not a single case of virus transmission in over 2200 recipients.
1. To assess the incidence of HIV infection in bone and tissue of donors
2. To prevent HIV transmission from donor to recipients
3. To improve the level of processing technique
4. To help in research and development of techniques related to detection of HIV.
5. To compare incidence of HIV infection among various bones and tissues of donors
Tested virus (57OC)
Control virus (Room Temperature)
|Dilution of virus Concentration||1||2||3||4||1||2||3||4|
|TCID50 / ml||< 10-1||3.2 x 10-5|
Table 2 represents the intramedullary temperature in the bone with Virus in glass tube
|Time||The Intramedullary Temperature ( OC )|
|Intramedullary Hole made in the specimen bone for the Hiv study||
|Hiv Specimen along with digital thermometer inserted inside the intramedullary hole||Specimen of Bone Allograft kept in the incubator|
Temperature inside the incubator under recording Number of Well Hiv-IFA positive M-10 cells of Virus
It was found after this study that Pasteurization at 56O C for 30 minutes inactivates HIV virus in bones and tissue allograft. Although it is a single case study but we can use the result for routine processing of bones and tissues at tissue banks. This process has also been recommended by World Health Organization.
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