Overlapping genes in viruses: seeking a unified theory

Despite a large diversity in shape, size and modes of replication, most viruses (75%) contain overlapping genes (OG). Most theories claim that OG serve for compression purposes. Other theories suggest a role for OG in gene regulation or protein novelty. We seek a unified theory that may explain the extent and patterns of OG throughout the viral world. An unbiased analysis was performed on ~100 families from ViralZone that account for all known viruses.
The genome length and OG rate are in a strong negative correlation. Remarkably, we found that this is mostly a side effect of an overlooked phenomenon – the amount of overlapping is tightly bounded (from 0 to 1500 nt) throughout the entire viral world, regardless to genome length.