Vaccine compositions useful in inducing immune protection in a host against arthritogenic peptides involved in the pathogenesis of rheumatoid arthritis are disclosed. Each vaccine composition provides antigenic dnaJp1 peptide (by including the peptide or a polynucleotide which encodes the peptide) and, optionally, other peptide fragments of the microbial dnaJ protein and/or human homologs thereof. Methods for identifying persons who are predisposed to develop rheumatoid arthritis and methods for use of the inventive vaccines are also disclosed.