Massive peptide sharing between viral and human proteomes

Abstract

Thirty viral proteomes were examined for amino acid sequence similarity to the human proteome, and, in parallel, a control of 30 sets of human proteins was analyzed for internal human overlapping. We find that all of the analyzed 30 viral proteomes, independently of their structural or pathogenic characteristics, present a high number of pentapeptide overlaps to the human proteome. Among the examined viruses, human T-lymphotropic virus 1, Rubella virus, and hepatitis C virus present the highest number of viral overlaps to the human proteome. The widespread and ample distribution of viral amino acid sequences through the human proteome indicates that viral and human proteins are formed of common peptide backbone units and suggests a fluid compositional chimerism in phylogenetic entities canonically classified distantly as viruses and Homo sapiens. Importantly, the massive viral to human peptide overlapping calls into question the possibility of a direct causal association between virus-host sharing of amino acid sequences and incitement to autoimmune reactions through molecular recognition of common motifs.

Fig. 1

Viral 5-mer occurrences in the human proteome as a function of viral proteome length (see data under Table 4, columns 1 and 4). The symbols refer to: (*), HTLV-1; (■), Rubella virus; (□), HCV; (+), other viral data point. The regression line (—) has an equation of y = 12.636x − 269.01, with a Pearson correlation coefficient (r value) of 0.97452. Both x- and y-axis are log scale.

Fig. 2

Viral versus human pentapeptide overlapping: similarity profile of low-, medium- and high-molecular weight viral proteomes to the human proteome. (A) Human parvovirus B19 (total aa: 2006); (B) SARS coronavirus BJ202 (total aa: 14,209); (C) Variola virus (total aa: 54,289).

Fig. 3

Human versus human pentapeptide overlapping: similarity profile of low-, medium- and large-sized artificial human sub-proteomes to the human proteome. Human sub-proteome set (see also Table 2): (A) 4 (total aa: 2142); (B) 26 (total aa: 14,203); (C) 29 (total aa: 54,263).