A non-pathogenic Leishmania tarentolae vector based- HCV polytope DNA vaccine elicits potent and long lasting Th1 and CTL responses in BALB/c mice model.
Ansari, Nastaran a; Rafati, Sima b; Taheri, Tahereh b; Roohvand, Farzin c; Farahmand, Mohammad a; Hajikhezri, Zamaneh a; Keshavarz, Abolfazl a; Samimi-Rad, Katayoun a,*
[Article] Molecular Immunology. 111:152-161, July 2019.

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HIGHLIGHTS:

* L. tarentolaeis an efficient live delivery system for HCV gene based vaccines.

* Live (L. tarentolae PT-NT(gp96))/live vaccine with CpG induced high level of IFN-[gamma].

* Live/live CpG vaccine induced the highest cytotoxic activity and IgG2a/IgG1 ratio.

* DNA(pCDNA-PT-NT-(gp96))/live vaccine elicited the highest level of IFN-[gamma] and IL-17.

* Live/live CpG vaccine induced potent long term Th1 and CTL responses.

Despite successful anti-viral (DAAs) treatment of Hepatitis C virus (HCV) infection, recent data indicated the need for an effective vaccine. Preexisting anti-vector immunity is an obstacle for application of live vectors for antigen delivery and development of effective T-cell based HCV vaccines. Herein, we report construction of recombinant Leishmania tarentolae, a lizard (non-human) parasite, expressing an HCV polytope DNA, PT-NT(gp96), encoding for several immunogenic HCV epitopes and evaluation of its immunogenicity in three different prime/boost immunization groups (G) of BALB/c mice. Homologous prime/boost immunization by L.tarentolae-PT-NT(gp96) either with or without CpG (G1 and G2 respectively) and heterologous immunization with a PT-NT(gp96) encoding-pCDNA plasmid followed by L.tarentolae-PT-NT (G3) was undertaken. Immune responses were measured three and nine weeks (W) post immunization. Splenocytes (cultured with antigen-stimulant) of mice in G1 showed the highest percentage of specific CTL-cytolytic activity compared to G2 and G3 at both short (W3:70.98% versus 41.29% and 13.12%) and long (W9: 50% versus 24.5% and 20%) term periods, accompanied with high levels of secreted IFN-[gamma]. Comparison of IFN-[gamma], IL-4, IL-17 and TNF-[alpha] cytokines levels obtained from the supernatant of antigen-stimulated splenocytes as well as antibodies level (as IgG1/IgG2a ratio; obtained from sera of immunized mice) indicated higher Th1 oriented responses for G1, G2 groups and balanced Th1-Th17 for G3. Results indicated the potential of L.tarentolae ( CpG), as a non-pathogenic live vaccine vector, for delivery and enhancement of immune responses against HCV-polytope antigens.

(C) 2019Elsevier, Inc.