A Comprehensive in Silico Analysis for Identification of Immunotherapeutic Epitopes of HPV-18

Human papillomavirus (HPV) remains the major cause of cervical cancer, globally. High risk HPV (Hr-HPV) 16 and 18 together account for more than 70% of cervical cancer cases, whereas the hr-HPV-18 is the second most prevalent hr-HPV type, causing about 5.2% of all cancers worldwide. Considering the high prevalence and mortality rate, cervical cancer remains a noteworthy health problem among women. As of now, no registered immunotherapies are available after the HPV infection. Thus, developing an immunotherapeutic candidate against hr-HPV would be of major clinical benefit. Nowadays, the T-and B-cell peptide based targeted vaccines have been considered as the best candidate for vaccine development against viral infections. In this study, both prophylactic and therapeutic vaccine candidates against hr-HPV-18 were predicted. To achieve this, the prediction of T-and B-cell epitopes of major histocompatibility complex (MHC) were accomplished, that can be used for HPV immunotherapy. For MHC-I, a maximum number (20) of potent peptides were found, against HLA-B*51:01 (L1 = 9, L2 = 6, E2 = 4, and E4 = 1) having percentile value < 1 and, immunogenicity scores higher than 0.5, followed by HLA-A*11:01 (L1 = 8, E2 = 7 L2 = 2, and E6 = 1, E7 = 1); 19 epitopes. For MHC-II, the highest number of peptides found, against the HLA-DRB1*04:01 (L2 = 10, E5 = 7, and E4 = 4), HLA-DRB1*04:05 (E5 = 7, E2 = 5, E4 = 5, and L1 = 4) HLA-DPA1*01:03/DPB1*04:01 (E7 = 7, E6 = 5, L2 = 5, and E2 = 2), HLA-DRB5*01:01(E6 = 6, L1 = 6, and L2 = 6); peptides 21, 21, 19 and 18 respectively. For B-cell, total 94, 16 amino acid long B-cell epitopes were predicted. In conclusion, these predicted epitopes can be valuable candidates for in vitro or in vivo therapeutic vaccine studies against hr-HPV-18 associated cancer.

Changes in global gene expression profiles induced by HPV 16 E6 oncoprotein variants in cervical carcinoma C33-A cells

We analyzed the effects of the expression of HPV 16 E6 oncoprotein variants (AA-a, AA-c, E-A176/G350, E-C188/G350, E-G350), and the E-Prototype in global gene expression profiles in an in vitro model. E6 gene was cloned into an expression vector fused to GFP and was transfected in C33-A cells. Affymetrix GeneChip Human Transcriptome Array 2.0 platform was used to analyze the expression of over 245,000 coding transcripts. We found that HPV16 E6 variants altered the expression of 387 different genes in comparison with E-Prototype. The altered genes are involved in cellular processes related to the development of cervical carcinoma, such as adhesion, angiogenesis, apoptosis, differentiation, cell cycle, proliferation, transcription and protein translation. Our results show that polymorphic changes in HPV16 E6 natural variants are sufficient to alter the overall gene expression profile in C33-A cells, explaining in part the observed differences in oncogenic potential of HPV16 variants.