Dogs vaccinated with gentamicin‐attenuated L eishmania infantum or infected with wild‐type parasite can be distinguished by Western blotting

Summary An attenuated line of L eishmania infantum (the H‐line), developed through exposure to gentamicin, has been shown to protect dogs against canine visceral leishmaniasis. A specific diagnostic test to differentiate dogs vaccinated with the attenuated line from dogs infected with L . infantum wild‐type ( L . infantum WT ) could be a valuable tool in evaluating the effectiveness of canine vaccination. In this study, 28 healthy dogs were allocated into four groups. In Group I and Group II (eight dogs per group), dogs were immunized subcutaneously (s.c.) with L . infantum H‐line, and the dogs of Group II challenged s.c. with L . infantum WT , at 2 months post‐immunization. In Group III, eight animals were challenged s.c. with L . infantum WT , and four dogs of Group IV were injected s.c. with PBS . We found that sera from vaccinated dogs recognize a 21 kDa antigen of promastigotes of L . infantum H‐line but not of L . infantum WT , whereas sera from unvaccinated dogs challenged with L . infantum WT , recognized a 21 kDa antigen of promastigotes of L . infantum WT but not of L . infantum H‐line. Sera from dogs challenged with L . infantum WT with prior vaccination with L . infantum H‐line, recognized a 21 kDa antigen of both L . infantum WT and L . infantum H‐line. These results suggest that the Western blot analysis of antibodies against 21 kDa antigens of L . infantum H‐line and WT may be a useful technique for distinguishing between dogs vaccinated with L . infantum H‐line and dogs naturally infected with L . infantum WT .