Specificity of the coxsackievirus B4 VP4 capsid protein investigated in silico.

The Enterovirus genus encompasses several species and various serotypes, like coxsackievirus-B1 (CV-B1) to CV-B6, and many variants. The role of these viruses, especially CV-B4, in the pathogenesis of type 1 diabetes is strongly suspected. It has been reported that antibodies directed towards the region of amino acids 11-30 of the VP4 capsid protein enhance the infection of human peripheral blood mononuclear cells with CV-B4. In order to predict the inter- and intra-serotype specificity of the region 11-30 of CV-B4 VP4, 362 available protein sequences of CV-B1 to -B6, CV-A9, and swine vesicular disease virus (SVDV) have been aligned and levels of homology have been calculated. Serine residue substitutions in this region of VP4 were observed without predictable subsequent modification of conformation or charge. The amino acids 16-24 region was the most variable. The sequence of amino acids 16-24 of the CV-B4E2 VP4 protein was highly homologous to those of other CV-B4 (64.4%) whereas there was no homology with CV-B3 and B5 and very low levels of homology with CV-B1 and B2 (3.3% and 9.9%, respectively). In conclusion, the bioinformatic analysis suggests that the region 16-24 of the VP4 capsid protein is the feature of the specificity of the target of infection-enhancing antibodies directed towards CV-B.