1.   And pigs have receptors in their snouts not just for their own swine virus but for bird and human viruses as well.

2.   Another study in Nature showed that mice receiving pig tissue transplants did become infected with a swine virus.

3.   As science moves closer to using pig organs for human transplants, some experts caution that the technique could transfer deadly swine viruses.

4.   Others agree that swine viruses are a serious, complex problem with no clear solution presently, but they believe science will find a way.

5.   Some researchers are concerned that using pig organs for transplantation could cause humans to contract some unusual swine viruses.