There are no viruses to infect MP3 audio files. There is one widespread fake warning on such virus in circulation. MP3 are not self executable files nor, they can they contain any scripting. Such files like .mp3 .dat .txt cannot contain virus. Or even if it has the virus signature, the code cannot be activated. People who say that mp3 can contain virus or infect your system are just ignorant, who prefer to give advice without knowing about it. People who get infected by virus (who claim that they got infected by mp3, are usually victims of exploits). There are no worms or virus till date which can use mp3 files as host to infect systems.