An isolated sequence or peptide isolated from an E2, E4, E6, E7 early or late coding region of human papillomavirus (HPV) that is soluble in aqueous medium, and characterized by a linkage to another protein sequence or peptide isolated from the E2, E4, E6, E7 early or late coding region of HPV by a spacer sequence, wherein the isolated protein sequence or peptide consists of more than 50% hydrophilic amino acids, and is recognized by a specific antibody of HPV. Also disclosed are isolated protein sequences or peptides from Harvey Ras (H-Ras), Kirsten Ras (K-Ras), and phosphatase and tensin homologue (PTEN) tumor suppressor proteins and Chlamydia trachomatis heat shock protein 60 (CHSP60 groEL1) and methods for detecting or diagnosing cancer or cellular abnormalities.