Viruses may be classified into several different morphological types on the basis of their capsid architecture.
对称性: 衣壳粒排列的方式不同，使病毒粒子表现出不同的结构类型和对称性。螺旋体对称的病毒形态类似棒状，病毒的核酸位于中空、柱状螺旋形的衣壳内。引起狂犬病、埃博拉出血热等病的病毒具有螺旋对称的结构。
Helical viruses resemble long rods that may be rigid or flexible. The viral nucleic acid is found within hollow, cylindrical capsid that has a helical structure. The viruses that cause rabies and Ebola Hemorrhagic Fever are helical viruses.
烟草花叶病毒
许多动物病毒，植物病毒是多面体结构，或者多面体结构的。这些病毒多数为廿面体的，即20面体的---20个规则的三角形的面和12个角。例如乳腺腺病毒（adenovirus）。
Many animal, plant bacterial viruses are
polyhedral, or many-sided viruses. The capsid of most polyhedral viruses
is in the shape of an icosahedron, a regular polyhedron with 20 triangular
faces and 12 corners.
乳腺腺病毒
有些病毒，例如特别是细菌病毒（噬菌体 bacteriophage），
具有复杂的结构，即多面体头部和螺旋对称的尾部等，称为复合对称形病毒。
Some viruses, particularly bacterial viruses,
have complicated structures and are called complex viruses.
噬菌体 bacteriophage
有部分病毒属于复杂型的，见下图。
弹状病毒
示意图
痘病毒(poxvirus) 200 000X
示意图
４．被膜病毒 Enveloped
Viruses
有些病毒的衣壳包裹在被膜内。这些病毒的形态近球形。流感病毒
The capsid of some viruses is covered by
an envelope. Enveloped viruses are roughly spherical. Influenzavirus
is an enveloped helical virus.
