Let me educate you. A virus bomb breaks down any organic life at a cellular level into a goo until there is no organic life left in which case the virus burns itself out. But geuss what there's more. The reaction of the virus and the now liquified organic life, gives of a VERY and I mean VERY volatile gas mixture capable of consuming the entire planets atmosphere in the ignition and immediate planet wide fire storm. The planet then remains baren until it is reseeded.