Novel recombinant DNA vaccine candidates for human respiratory syncytial virus: Preclinical evaluation of immunogenicity and protection efficiency

• Published in: Human vaccines & immunotherapeutics Vol. 13; no. 7; pp. 1586 - 1597
• Main Authors: Farrag, Mohamed A., Amer, Haitham M., Öhlschläger, Peter, Hamad, Maaweya E., Almajhdi, Fahad N.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 03-07-2017; Taylor & Francis Group
• Subjects: Animals; Antibodies, Neutralizing - blood; Antibodies, Viral - blood; Antigens, Viral - genetics; Antigens, Viral - immunology; CD8-Positive T-Lymphocytes - immunology; disease enhancement; Disease Models, Animal; DNA vaccine; Drug Evaluation, Preclinical; Female; fusion protein; human respiratory syncytial virus; Mice, Inbred BALB C; Potexvirus; pPOE vector; Research Papers; Respiratory Syncytial Virus Infections - prevention & control; Respiratory Syncytial Virus Vaccines - administration & dosage; Respiratory Syncytial Virus Vaccines - genetics; Respiratory Syncytial Virus Vaccines - immunology; Respiratory Syncytial Virus Vaccines - isolation & purification; Respiratory Syncytial Virus, Human - immunology; truncated form; Vaccines, DNA - administration & dosage; Vaccines, DNA - genetics; Vaccines, DNA - immunology; Vaccines, DNA - isolation & purification; Viral Fusion Proteins - genetics; Viral Fusion Proteins - immunology; DNA vaccine; truncated form; fusion protein; disease enhancement; human respiratory syncytial virus; pPOE vector
• ISSN: 2164-5515; 2164-554X
• DOI: 10.1080/21645515.2017.1295190

The development of safe and potent vaccines for human respiratory syncytial virus (HRSV) is still a challenge for researchers worldwide. DNA-based immunization is currently a promising approach that has been used to generate human vaccines for different age groups. In this study, novel HRSV DNA vaccine candidates were generated and preclinically tested in BALB/c mice. Three different versions of the codon-optimized HRSV fusion (F) gene were individually cloned into the pPOE vector. The new recombinant vectors either express full-length (pPOE-F), secretory (pPOE-TF), or M2
82-90
linked (pPOE-FM2) forms of the F protein. Distinctive expression of the F protein was identified in HEp-2 cells transfected with the different recombinant vectors using ELISA and immunofluorescence. Mice immunization verified the potential for recombinant vectors to elicit significant levels of neutralizing antibodies and CD8
+
T-cell lymphocytes. pPOE-TF showed higher levels of gene expression in cell culture and better induction of the humoral and cellular immune responses. Following virus challenge, mice that had been immunized with the recombinant vectors were able to control virus replication and displayed lower inflammation compared with mice immunized with empty pPOE vector or formalin-inactivated HRSV vaccine. Moreover, pulmonary cytokine profiles of mice immunized with the 3 recombinant vectors were similar to those of the mock infected group. In conclusion, recombinant pPOE vectors are promising HRSV vaccine candidates in terms of their safety, immunogenicity and protective efficiency. These data encourage further evaluation in phase I clinical trials.