Third-Generation Vaccines: Features of Nucleic Acid Vaccines and Strategies to Improve Their Efficiency.

Gene immunization comprises mRNA and DNA vaccines, which stand out due to their simple design, maintenance, and high efficacy. Several studies indicate promising results in preclinical and clinical trials regarding immunization against ebola, human immunodeficiency virus (HIV), influenza, and human papillomavirus (HPV). The efficiency of nucleic acid vaccines has been highlighted in the fight against COVID-19 with unprecedented approval of their use in humans. However, their low intrinsic immunogenicity points to the need to use strategies capable of overcoming this characteristic and increasing the efficiency of vaccine campaigns. These strategies include the improvement of the epitopes' presentation to the system via MHC, the evaluation of immunodominant epitopes with high coverage against emerging viral subtypes, the use of adjuvants that enhance immunogenicity, and the increase in the efficiency of vaccine transfection. In this review, we provide updates regarding some characteristics, construction, and improvement of such vaccines, especially about the production of synthetic multi-epitope genes, widely employed in the current gene-based vaccines.

Current research into novel therapeutic vaccines against cervical cancer.

INTRODUCTION: Cervical cancer and cervical intraepithelial neoplasia (CIN) are well-known outcomes of a human papillomavirus (HPV) infection. Viral oncogenes expressions like E6, E7, and, recently recognized E5, lead to HPV-related malignant progression. Although HPV prevention by powerful vaccines against most frequent and oncogenic genotypes is feasible, current treatment against cervical neoplasia is distant from an ideal one. In addition, late diagnosis is commonly associated with a poor prognosis. On top of that, radiotherapy, chemotherapy, or surgery are less effective in high-grade lesions. Areas covered: Due to their peculiarities, HPV oncogenes represent an excellent target for cancer immunotherapy. Safety, efficacy, and potential immunogenicity are features achieved by DNA vaccines targeting HPV. The literature search has indicated that genetic immunotherapy is becoming a pharmacological tool and therapeutic option against cervical disease, as more and more DNA vaccines are reaching clinical trial phases. Expert commentary: Among some of the promising results, a phase II randomized trial showed a clinical activity of a nucleic acid-based vaccine in HPV16 or HPV18 positive CIN patients. The concept of a synergic combination of anti-HPV DNA vaccines with radiotherapy, chemotherapy, sophisticated delivery methods, immunomodulators or immune adjuvants opens a new and interesting perspective in cervical malignancy treatment.

Global and gene-specific DNA methylation and hydroxymethylation in human skin exposed and not exposed to sun radiation

Abstract: Background: epigenomes can be influenced by environmental factors leading to the development of diseases. Objective: To investigate the influence of sun exposure on global DNA methylation and hydroxymethylation status and at specific sites of the miR-9-1, miR-9-3 and MTHFR genes in skin samples of subjects with no history of skin diseases. Methods: Skin samples were obtained by punch on sun-exposed and sun-protected arm areas from 24 corpses of 16-89 years of age. Genomic DNA was extracted from skin samples that were ranked according to Fitzpatrick's criteria as light, moderate, and dark brown. Global DNA methylation and hydroxymethylation and DNA methylation analyses at specific sites were performed using ELISA and MSP, respectively. Results: No significant differences in global DNA methylation and hydroxymethylation levels were found among the skin areas, skin types, or age. However, gender-related differences were detected, where women showed higher methylation levels. Global DNA methylation levels were higher than hydroxymethylation levels, and the levels of these DNA modifications correlated in skin tissue. For specific sites, no differences among the areas were detected. Additional analyses showed no differences in the methylation status when age, gender, and skin type were considered; however, the methylation status of the miR-9-1 gene seems to be gender related. Study limitations: there was no separation of dermis and epidermis and low sample size. Conclusion: sun exposure does not induce changes in the DNA methylation and hydroxymethylation status or in miR-9-1, miR-9-3 and MTHFR genes for the studied skin types.

Global and gene-specific DNA methylation and hydroxymethylation in human skin exposed and not exposed to sun radiation.

BACKGROUND: epigenomes can be influenced by environmental factors leading to the development of diseases. OBJECTIVE: To investigate the influence of sun exposure on global DNA methylation and hydroxymethylation status and at specific sites of the miR-9-1, miR-9-3 and MTHFR genes in skin samples of subjects with no history of skin diseases. METHODS: Skin samples were obtained by punch on sun-exposed and sun-protected arm areas from 24 corpses of 16-89 years of age. Genomic DNA was extracted from skin samples that were ranked according to Fitzpatrick's criteria as light, moderate, and dark brown. Global DNA methylation and hydroxymethylation and DNA methylation analyses at specific sites were performed using ELISA and MSP, respectively. RESULTS: No significant differences in global DNA methylation and hydroxymethylation levels were found among the skin areas, skin types, or age. However, gender-related differences were detected, where women showed higher methylation levels. Global DNA methylation levels were higher than hydroxymethylation levels, and the levels of these DNA modifications correlated in skin tissue. For specific sites, no differences among the areas were detected. Additional analyses showed no differences in the methylation status when age, gender, and skin type were considered; however, the methylation status of the miR-9-1 gene seems to be gender related. STUDY LIMITATIONS: there was no separation of dermis and epidermis and low sample size. CONCLUSION: sun exposure does not induce changes in the DNA methylation and hydroxymethylation status or in miR-9-1, miR-9-3 and MTHFR genes for the studied skin types.