Identification of an immunodominant peptide in the parvovirus B19 VP1 unique region able to elicit a long-lasting immune response in humans.

The immune response against parvovirus B19 is mainly directed against the two structural proteins, VP1 and VP2. The amino terminal half of the VP1 unique region has been shown to elicit a dominant immune response in humans, more effective than other linear epitopes and also it has been seen to contain significant neutralizing linear epitopes. Three overlapping recombinant peptides corresponding to amino acids 2-40 (VP1-A), amino acids 32-71 (VP1-B), and amino acids 60-100 (VP1-C) of the VP1 unique region were produced by a procaryotic expression system. These peptides were used as antigens in a Western blot assay to detect specific immunoglobulin G (IgG) in serum samples from blood donors of different age groups with documented signs of a past B19 infection. Fragment VP1-C appeared significantly immunodominant over the other peptides, reacting with specific IgG in 86% of serum samples. The fragment VP1-C corresponds to a sequence with a known neutralizing activity and seems able to elicit a long-lasting immune response because specific IgG were present in blood donors of all age groups. VP1-C would therefore appear to be an attractive candidate as a component of a subunit vaccine.