Identification of immunodominant T-cell epitopes present in glycoprotein 5 of the North American genotype of porcine reproductive and respiratory syndrome virus

Ninty-six pentadecapeptides spanning glycoprotein 5 (GP5) of porcine reproductive and respiratory virus (PRRSV) were screened for their ability to elicit a recall interferon-γ response from peripheral blood mononuclear cells isolated from 22 pigs infected with up to two genetically divergent PRRSV strains. Two distinct regions (amino acid residues 117–131, LAALICFVIRLAKNC, and 149–163, KGRLYRWRSPVII/VEK) appeared to contain immunodominant T-cell epitopes based on their ability to stimulate above average numbers of interferon-γ secreting cells as compared to other GP5 peptides. A survey of PRRSV isolates indicated that these two sites are relatively conserved with at most a two amino acid variation and thus should be considered for incorporation into a multi-valent vaccine against PRRS.