New adenoviral vaccine candidate against T. cruzi infection.

TRINITARIO SEBASTIAN N; DELFINO MARÍA ALICIA; DZVONYK POLINA; RUSSO MELISSA; CARDOSO ALEJANDRO; CERNY NATACHA; BIVONA AUGUSTO; MALCHIODI EMILIO L; SÁNCHEZ ALBERTI ANDRÉS

Simposio; XX Simposio Internacional sobre Enfermedades Desatendidas; 2021

Mundo Sano

INTRODUCTIONChagas disease is a neglected andtropical disease caused by the infection of the parasite Trypanosoma cruzi affecting around 6-7 millionpeople worldwide. Benznidazole, the first line antiparasitic drug is effectiveduring the acute phase of the infection, but its use in chronic phase, wheremost cases are diagnosed, is still controversial. The current 60-days treatmentpresents many side effects and can lead to treatment abandonment, therefore weconsider developing prophylactic and/or therapeutic vaccines might contributeto public health reducing the treatment length and improving adherence.Here we present the design and development of a low-seroprevalence recombinantadenoviral vector (adenovirus 48) carrying Traspain gene alone or tag by afluorescent protein (mScarlet), its preliminary performance as immunogenicantigen and the cross reactivity with the most prevalent serotype (adenovirus 5).METHODSTraspain gene was fused to mouse immunoglobulin Kappa light chain signal peptide DNA sequence (SPTrasp) tofacilitate extracellular antigen export upon vaccination. Monomeric redfluorescent protein mScarlet was fused to SPTrasp. Adenovirus 48 carrying bothgene contructions were generated using traditional cloning and homologousrecombination in HEK293 cells. Antigen expression was assessed in-vitro by RT-PCR and Western blot.Exploratory immunization experiments were carried out in C57/BL6 mice,administering two subcutaneous doses of Ad48-SPTrasp every 15 days.RESULTSWe were able to rescue both replication deficient viruses and detect Traspainand Traspain-mScarlet expression upon 48 hours of in-vitro infection. Animals vaccinated with Ad48-SPTrasp developedanti-Traspain antibodies (immunized vs control animals ELISA titers: 1782 and235 respectively) and isotype determination indicated an IgG1/IgG2a ratio of3.4. Robust antigen-specific CTL response was detected using tetramer staining(CD8+ VNHRLTVL+ cells, immunized: 3.5 % vs control: 0.6 %, p<0.01).Ad48-SPTrasp was not recognized by Ad5 immunized mice serum in Western blot.CONCLUSIONSConsidering these results and the recently updated global vaccine portfolio,Ad48-SPTrasp appears as a high potential approach for improving the currentstrategies of vaccine-mediated control of T.cruzi.