The high statistical significance of these trends is consistent with a possibility that the short viral proteins have resulted from the acquisition of fragments from the host protein. Alternatively, it can be the result of a refinement of the acquired sequences during viral evolution. We separated each protein into three segments: (i) The Pfam domain(s); (ii) The tail linker (TAIL) that combines the amino acid extension towards the N-and the C-termini of the protein, beyond the boundary of the domain(s); (iii) The internal domain linker (IDOL) that comprises the sum of the amino acid spacers between domains. Clearly a single domain protein lacks IDOL.