Immunogenic evaluation of the Giardia-vax vaccine´s activity using an experimental model of giardiasis in gerbils (Meriones unguiculatus)

Abstract

EVALUATION OF THE PROPHYLACTIC ACTIVITY OF A VACCINE GIARDIA-VAX AGAINST EXPERIMENTAL INFECTION ON MERIONES UNGUICULATUS (GERBILS) CHALLENGES WITH GIARDIA INTESTINALIS TROPHOZOITES, WAS TESTED. FORTY FIVE ANIMALS WITH A BODY WEIGHT OF 16.0 ± 0.5 G WERE USED AND DIVIDED IN THREE GROUPS: A) THE CONTROL, WITHOUT INOCULATION; B) THE POSITIVE CONTROL, INFECTED VIA GASTRIC WITH 1 × 107 TROPHOZOITES FROM PORTLAND-I TYPE GIARDIA INTESTINALIS; AND C) THE VACCINATED GROUP, WHICH RECEIVED TWO DOSES OF 1ML OF GIARDIA VACCINE WITH AN INTERVAL OF A WEEK BETWEEN BOTH DOSES. THEREAFTER, ANIMALS WERE INFECTED WITH 1× 107 GIARDIA TROPHOZOITES. A COPROPARASITOSCOPIC (CPS) ANALYSIS WAS CARRIED OUT EVERY THIRD DAY FOR 15 DAYS AFTER THE INFECTION. A SERUM ANTIBODY TEST (ELISA) AGAINST GIARDIA WAS PERFORMED BEFORE- AND AFTER THE VACCINATION OR THE  NFECTION. GROUP A) DID NOT ELIMINATE GIARDIA WHEN CPS ANALYSIS WAS PERFORMED; GROUP B) SHOWED ELIMINATION OF GIARDIA ALL THE TIME; AND IN GROUP C), 5/15 ANIMALS HAD NEGATIVE CPS FROM THE THIRD DAY ON AFTER THE INFECTION UNTIL THE END OF THE STUDY, AND THE OTHER 10/15 ANIMALS SHOWED POSITIVE CPS UNTIL THE SEVENTH DAY; AND AFTER THIS, ALL CPS WERE NEGATIVE. GROUPS B) AND C) HAD SERUM ANTIBODIES THAT STATISTICALLY HAD A P < 0.05 BEFORE- AND AFTER INFECTION. LEVELS OF ANTIBODIES WERE HIGHER IN GROUP C) AND IN FIVE OF THEM. NO COLONIZATION WAS OBSERVED TO TROPHOZOITES. THESE RESULTS SUGGEST THAT THE VACCINE WAS ABLE TO STIMULATE ANTIBODIES TO GIARDIA PROTECTING ANIMALS AGAINST FUTURE INFECTIONS.