So the donated tissue or organ may contain dangerous pathogens such as HIV, hepatitis B or hepatitis C, rabies, syphilis and many other different types of diseases and pathogens. So basically, if we're transplanting an organ that contains HIV into an individual that does not contain HIV that individual will obtain that HIV and will then be HIV positive. Now, this was a problem in the beginning but nowadays we have different types of ways of testing for these different types of viruses and pathogenic agents. And so before the donation or transplantation actually takes place we know what types of pathogenic agents are found in that donated tissue or donated organ. Now the next question is how exactly do we solve these different complications? What exactly do we do?