KUNITZ-TYPE MOLECULE IN A LIQUID CRYSTAL NANOSTRUCTURE AS VACCINE PLATFORM AGAINST FASCIOLA HEPATICA INFECTION IN SHEEP

MARÍA DEL ROSARIO AHUMADA; CONSTANZA MARIN; CRISTIAN MENA; LORENA GUASCONI; LAURA SILVINA CHIAPELLO; BELKYS MALETTO; SANTIAGO PALMA; FERNANDO BETTOLLI; RODRIGO SANABRIA; CESAR PRUZZO; DANIEL ALBERTO ALLEMANDI; LEONARDO SILVANE; LAURA CERVI

Congreso; LXIX REUNIÓN SAI; 2021

Fasciolosis is a parasitic disease that affects livestock causing huge economic losses. It is also considered by the WHO as an emerging disease. Triclabendazole is the antiparasitic of choice, however the resistance to this drug has been reported. The development of vaccines against F. hepatica is an alternative of choice for the control of this disease. In this context, our laboratory has developed a vaccine based on F. hepatica Kunitz-type molecule (FhKTM) as an antigen formulated with a nanostructure formed by self-assembly of 6-O-ascorbyl palmitate ester (Coa-ASC16) and oligodeoxynucleotide containing unmethylated cytosine-guanine motifs (CpG-ODN) which induces protection against F. hepatica challenge in mice. Based on these results we immunized lambs, one of the natural host of this disease, and test the ability of the vaccine to induce protection and humoral response. Two immunizations were performed with an interval of 21 days with FhKTM/CpG-ODN/Coa-ASC16 in six-month old Creole biotype lambs. A control group was immunized with CpG-ODN/Coa-ASC16. Thirty days later, the experimental infection was performed with 100 metacercariae per animal in all groups (vaccinated, infected and control). After eight weeks egg count, number of adults in the liver, total eggs/adult and IgG antibody titers were evaluated. The data were statistically analyzed using the T test for difference of means and ANOVA for evaluation of variances. The results show statistically significant differences (p≤0,0001) between total eggs count values between groups. The egg count test in the feces showed an 87.9% reduction in vaccinated vs infected group and a 83% reduction in fertility determined as the ratio between eggs/worms in the vaccinated vs infected group. The reduction in the eggs number correlated with higher titles of IgG antibodies in plasma of vaccinated vs infected lambs showing the ability of the vaccine to reduce the transmission of infection by this parasite.