Heterogeneous progeny viruses are produced by a budding enveloped phage.

Infection of Acholeplasma laidlawii cells by the temperate enveloped mycoplasma virus L2 results in production of three morphological forms of progeny L2 virus: L2-I, L2-II, and L2-III. These morphological forms can be separated by velocity sedimentation and agarose gel electrophoresis. The latter technique was used to size the quasi-spherical particles: L2-I is 74 nm, L2-II is 88 nm, and L2-III is 132 nm in diameter. The protein composition of the three L2 forms is the same, although there are differences in protein stoichiometric ratios. L2-I, L2-II, and L2-III have the same 11.8 kilobase pair superhelical DNA genome. However, UV inactivation studies and restriction frequency measurements indicate that L2-I and L2-III each contain 1 genome copy, while L2-II contains 2-3 genome copies.