Virus consists of strand of nuclear material and protein coat. Im not clear with that if virus is hollow or not?
Caitin: note that nothing will be 'hollow' in the sense I believe you mean it--in most cases in biology, any 'space' is occupied by water. In a virus head, the DNA will be packed as tightly as possible. Here are some pages/images that might help you get a sense of things:
One of my favorite images is on the following page; it show the bacterial virus 'T4' and all the DNA that spews out when you crack open the 'head'